command.go

// Copyright 2014-2022 Aerospike, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package aerospike

import (
	"bytes"
	"compress/zlib"
	"encoding/binary"
	"errors"
	"fmt"
	"time"

	"github.com/aerospike/aerospike-client-go/v7/logger"
	"github.com/aerospike/aerospike-client-go/v7/types"
	"github.com/aerospike/aerospike-client-go/v7/types/pool"

	ParticleType "github.com/aerospike/aerospike-client-go/v7/types/particle_type"
	Buffer "github.com/aerospike/aerospike-client-go/v7/utils/buffer"
)

const (
	// Flags commented out are not supported by cmd client.
	// Contains a read operation.
	_INFO1_READ int = (1 << 0)
	// Get all bins.
	_INFO1_GET_ALL int = (1 << 1)
	// Short query
	_INFO1_SHORT_QUERY int = (1 << 2)
	// Batch read or exists.
	_INFO1_BATCH int = (1 << 3)

	// Do not read the bins
	_INFO1_NOBINDATA int = (1 << 5)

	// Involve all replicas in read operation.
	_INFO1_READ_MODE_AP_ALL = (1 << 6)

	// Tell server to compress its response.
	_INFO1_COMPRESS_RESPONSE = (1 << 7)

	// Create or update record
	_INFO2_WRITE int = (1 << 0)
	// Fling a record into the belly of Moloch.
	_INFO2_DELETE int = (1 << 1)
	// Update if expected generation == old.
	_INFO2_GENERATION int = (1 << 2)
	// Update if new generation >= old, good for restore.
	_INFO2_GENERATION_GT int = (1 << 3)
	// Transaction resulting in record deletion leaves tombstone (Enterprise only).
	_INFO2_DURABLE_DELETE int = (1 << 4)
	// Create only. Fail if record already exists.
	_INFO2_CREATE_ONLY int = (1 << 5)
	// Treat as long query, but relax read consistency.
	_INFO2_RELAX_AP_LONG_QUERY = (1 << 6)
	// Return a result for every operation.
	_INFO2_RESPOND_ALL_OPS int = (1 << 7)

	// This is the last of a multi-part message.
	_INFO3_LAST int = (1 << 0)
	// Commit to master only before declaring success.
	_INFO3_COMMIT_MASTER int = (1 << 1)
	// On send: Do not return partition done in scan/query.
	// On receive: Specified partition is done in scan/query.
	_INFO3_PARTITION_DONE int = (1 << 2)
	// Update only. Merge bins.
	_INFO3_UPDATE_ONLY int = (1 << 3)

	// Create or completely replace record.
	_INFO3_CREATE_OR_REPLACE int = (1 << 4)
	// Completely replace existing record only.
	_INFO3_REPLACE_ONLY int = (1 << 5)
	// See Below
	_INFO3_SC_READ_TYPE int = (1 << 6)
	// See Below
	_INFO3_SC_READ_RELAX int = (1 << 7)

	// Interpret SC_READ bits in info3.
	//
	// RELAX   TYPE
	//	                strict
	//	                ------
	//   0      0     sequential (default)
	//   0      1     linearize
	//
	//	                relaxed
	//	                -------
	//   1      0     allow replica
	//   1      1     allow unavailable

	_STATE_READ_AUTH_HEADER uint8 = 1
	_STATE_READ_HEADER      uint8 = 2
	_STATE_READ_DETAIL      uint8 = 3
	_STATE_COMPLETE         uint8 = 4

	_BATCH_MSG_READ   uint8 = 0x0
	_BATCH_MSG_REPEAT uint8 = 0x1
	_BATCH_MSG_INFO   uint8 = 0x2
	_BATCH_MSG_GEN    uint8 = 0x4
	_BATCH_MSG_TTL    uint8 = 0x8

	_MSG_TOTAL_HEADER_SIZE     uint8 = 30
	_FIELD_HEADER_SIZE         uint8 = 5
	_OPERATION_HEADER_SIZE     uint8 = 8
	_MSG_REMAINING_HEADER_SIZE uint8 = 22
	_DIGEST_SIZE               uint8 = 20
	_COMPRESS_THRESHOLD        int   = 128
	_CL_MSG_VERSION            int64 = 2
	_AS_MSG_TYPE               int64 = 3
	_AS_MSG_TYPE_COMPRESSED    int64 = 4
)

type transactionType int

const (
	ttNone transactionType = iota
	ttGet
	ttGetHeader
	ttExists
	ttPut
	ttDelete
	ttOperate
	ttQuery
	ttScan
	ttUDF
	ttBatchRead
	ttBatchWrite
)

var (
	buffPool = pool.NewTieredBufferPool(MinBufferSize, PoolCutOffBufferSize)
)

// command interface describes all commands available
type command interface {
	getPolicy(ifc command) Policy

	writeBuffer(ifc command) Error
	getNode(ifc command) (*Node, Error)
	getConnection(policy Policy) (*Connection, Error)
	putConnection(conn *Connection)
	parseResult(ifc command, conn *Connection) Error
	parseRecordResults(ifc command, receiveSize int) (bool, Error)
	prepareRetry(ifc command, isTimeout bool) bool

	transactionType() transactionType

	isRead() bool

	execute(ifc command) Error
	executeAt(ifc command, policy *BasePolicy, deadline time.Time, iterations int) Error

	canPutConnBack() bool

	// Executes the command
	Execute() Error
}

// Holds data buffer for the command
type baseCommand struct {
	bufferEx

	node *Node
	conn *Connection

	// dataBufferCompress is not a second buffer; it is just a pointer to
	// the beginning of the dataBuffer.
	// To avoid allocating multiple buffers before compression, the dataBuffer
	// will be referencing to a padded buffer. After the command is written to
	// the buffer, this padding will be used to compress the command in-place,
	// and then the compressed proto header will be written.
	dataBufferCompress []byte
	// oneShot determines if streaming commands like query, scan or queryAggregate
	// are not retried if they error out mid-parsing
	oneShot bool

	// will determine if the buffer will be compressed
	// before being sent to the server
	compressed bool

	commandSentCounter int
	commandWasSent     bool
}

// Writes the command for write operations
func (cmd *baseCommand) setWrite(policy *WritePolicy, operation OperationType, key *Key, bins []*Bin, binMap BinMap) Error {
	cmd.begin()
	fieldCount, err := cmd.estimateKeySize(key, policy.SendKey)
	if err != nil {
		return err
	}

	predSize := 0
	if policy.FilterExpression != nil {
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}

	if binMap == nil {
		for i := range bins {
			if err := cmd.estimateOperationSizeForBin(bins[i]); err != nil {
				return err
			}
		}
	} else {
		for name, value := range binMap {
			if err := cmd.estimateOperationSizeForBinNameAndValue(name, value); err != nil {
				return err
			}
		}
	}

	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return err
	}

	if binMap == nil {
		cmd.writeHeaderWrite(policy, _INFO2_WRITE, fieldCount, len(bins))
	} else {
		cmd.writeHeaderWrite(policy, _INFO2_WRITE, fieldCount, len(binMap))
	}

	if err := cmd.writeKey(key, policy.SendKey); err != nil {
		return err
	}

	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}

	if binMap == nil {
		for i := range bins {
			if err := cmd.writeOperationForBin(bins[i], operation); err != nil {
				return err
			}
		}
	} else {
		for name, value := range binMap {
			if err := cmd.writeOperationForBinNameAndValue(name, value, operation); err != nil {
				return err
			}
		}
	}

	cmd.end()
	cmd.markCompressed(policy)

	return nil
}

// Writes the command for delete operations
func (cmd *baseCommand) setDelete(policy *WritePolicy, key *Key) Error {
	cmd.begin()
	fieldCount, err := cmd.estimateKeySize(key, false)
	if err != nil {
		return err
	}

	predSize := 0
	if policy.FilterExpression != nil {
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}

	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return err
	}
	cmd.writeHeaderWrite(policy, _INFO2_WRITE|_INFO2_DELETE, fieldCount, 0)
	if err := cmd.writeKey(key, false); err != nil {
		return err
	}
	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}
	cmd.end()
	cmd.markCompressed(policy)

	return nil

}

// Writes the command for touch operations
func (cmd *baseCommand) setTouch(policy *WritePolicy, key *Key) Error {
	cmd.begin()
	fieldCount, err := cmd.estimateKeySize(key, policy.SendKey)
	if err != nil {
		return err
	}

	predSize := 0
	if policy.FilterExpression != nil {
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}

	cmd.estimateOperationSize()
	if err := cmd.sizeBuffer(false); err != nil {
		return err
	}
	cmd.writeHeaderWrite(policy, _INFO2_WRITE, fieldCount, 1)
	if err := cmd.writeKey(key, policy.SendKey); err != nil {
		return err
	}
	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}
	cmd.writeOperationForOperationType(_TOUCH)
	cmd.end()
	return nil

}

// Writes the command for exist operations
func (cmd *baseCommand) setExists(policy *BasePolicy, key *Key) Error {
	cmd.begin()
	fieldCount, err := cmd.estimateKeySize(key, false)
	if err != nil {
		return err
	}

	predSize := 0
	if policy.FilterExpression != nil {
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}

	if err := cmd.sizeBuffer(false); err != nil {
		return err
	}
	cmd.writeHeaderReadHeader(policy, _INFO1_READ|_INFO1_NOBINDATA, fieldCount, 0)
	if err := cmd.writeKey(key, false); err != nil {
		return err
	}
	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}
	cmd.end()
	return nil

}

// Writes the command for get operations (all bins)
func (cmd *baseCommand) setReadForKeyOnly(policy *BasePolicy, key *Key) Error {
	cmd.begin()
	fieldCount, err := cmd.estimateKeySize(key, false)
	if err != nil {
		return err
	}
	predSize := 0
	if policy.FilterExpression != nil {
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}
	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return err
	}

	cmd.writeHeaderRead(policy, _INFO1_READ|_INFO1_GET_ALL, 0, 0, fieldCount, 0)
	if err := cmd.writeKey(key, false); err != nil {
		return err
	}
	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}
	cmd.end()
	cmd.markCompressed(policy)

	return nil

}

// Writes the command for get operations (specified bins)
func (cmd *baseCommand) setRead(policy *BasePolicy, key *Key, binNames []string) Error {
	if len(binNames) > 0 {
		cmd.begin()
		fieldCount, err := cmd.estimateKeySize(key, false)
		if err != nil {
			return err
		}

		predSize := 0
		if policy.FilterExpression != nil {
			predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
			if err != nil {
				return err
			}
			if predSize > 0 {
				fieldCount++
			}
		}

		for i := range binNames {
			cmd.estimateOperationSizeForBinName(binNames[i])
		}
		if err := cmd.sizeBuffer(policy.compress()); err != nil {
			return err
		}

		attr := _INFO1_READ
		if len(binNames) == 0 {
			attr |= _INFO1_GET_ALL
		}
		cmd.writeHeaderRead(policy, attr, 0, 0, fieldCount, len(binNames))

		if err := cmd.writeKey(key, false); err != nil {
			return err
		}

		if policy.FilterExpression != nil {
			if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
				return err
			}
		}

		for i := range binNames {
			cmd.writeOperationForBinName(binNames[i], _READ)
		}
		cmd.end()
		cmd.markCompressed(policy)
		return nil
	}
	return cmd.setReadForKeyOnly(policy, key)
}

// Writes the command for getting metadata operations
func (cmd *baseCommand) setReadHeader(policy *BasePolicy, key *Key) Error {
	cmd.begin()
	fieldCount, err := cmd.estimateKeySize(key, false)
	if err != nil {
		return err
	}

	predSize := 0
	if policy.FilterExpression != nil {
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}

	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return err
	}

	cmd.writeHeaderReadHeader(policy, _INFO1_READ|_INFO1_NOBINDATA, fieldCount, 0)
	if err := cmd.writeKey(key, false); err != nil {
		return err
	}
	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}
	cmd.end()
	cmd.markCompressed(policy)

	return nil

}

// Implements different command operations
func (cmd *baseCommand) setOperate(policy *WritePolicy, key *Key, args *operateArgs) Error {
	if len(args.operations) == 0 {
		return newError(types.PARAMETER_ERROR, "No operations were passed.")
	}

	cmd.begin()
	fieldCount := 0

	for i := range args.operations {
		if err := cmd.estimateOperationSizeForOperation(args.operations[i], false); err != nil {
			return err
		}
	}

	ksz, err := cmd.estimateKeySize(key, policy.SendKey && args.hasWrite)
	if err != nil {
		return err
	}
	fieldCount += ksz

	predSize := 0
	if policy.FilterExpression != nil {
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}

	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return err
	}

	cmd.writeHeaderReadWrite(policy, args, fieldCount)

	if err := cmd.writeKey(key, policy.SendKey && args.hasWrite); err != nil {
		return err
	}

	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}

	for _, operation := range args.operations {
		if err := cmd.writeOperationForOperation(operation); err != nil {
			return err
		}
	}

	cmd.end()
	cmd.markCompressed(policy)

	return nil
}

func (cmd *baseCommand) setUdf(policy *WritePolicy, key *Key, packageName string, functionName string, args *ValueArray) Error {
	cmd.begin()
	fieldCount, err := cmd.estimateKeySize(key, policy.SendKey)
	if err != nil {
		return err
	}

	predSize := 0
	if policy.FilterExpression != nil {
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}

	fc, err := cmd.estimateUdfSize(packageName, functionName, args)
	if err != nil {
		return err
	}
	fieldCount += fc

	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return err
	}

	cmd.writeHeaderWrite(policy, _INFO2_WRITE, fieldCount, 0)
	if err := cmd.writeKey(key, policy.SendKey); err != nil {
		return err
	}
	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}
	cmd.writeFieldString(packageName, UDF_PACKAGE_NAME)
	cmd.writeFieldString(functionName, UDF_FUNCTION)
	if err := cmd.writeUdfArgs(args); err != nil {
		return err
	}
	cmd.end()
	cmd.markCompressed(policy)

	return nil
}

func (cmd *baseCommand) setBatchOperateIfc(client ClientIfc, policy *BatchPolicy, records []BatchRecordIfc, batch *batchNode) (*batchAttr, Error) {
	offsets := batch.offsets
	max := len(batch.offsets)

	// Estimate buffer size
	cmd.begin()
	fieldCount := 1
	predSize := 0
	if policy.FilterExpression != nil {
		var err Error
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return nil, err
		}
		if predSize > 0 {
			fieldCount++
		}
	}
	cmd.dataOffset += predSize

	cmd.dataOffset += int(_FIELD_HEADER_SIZE) + 5

	var prev BatchRecordIfc
	for i := 0; i < max; i++ {
		record := records[offsets[i]]
		key := record.key()
		cmd.dataOffset += len(key.digest) + 4

		// Try reference equality in hope that namespace/set for all keys is set from fixed variables.
		if !policy.SendKey && prev != nil && prev.key().namespace == key.namespace && (prev.key().setName == key.setName) && record.equals(prev) {
			// Can set repeat previous namespace/bin names to save space.
			cmd.dataOffset++
		} else {
			// Must write full header and namespace/set/bin names.
			cmd.dataOffset += 12 // header(4) + ttl(4) + fielCount(2) + opCount(2) = 12
			cmd.dataOffset += len(key.namespace) + int(_FIELD_HEADER_SIZE)
			cmd.dataOffset += len(key.setName) + int(_FIELD_HEADER_SIZE)

			if sz, err := record.size(&policy.BasePolicy); err != nil {
				return nil, err
			} else {
				cmd.dataOffset += sz
			}

			prev = record
		}

	}

	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return nil, err
	}

	cmd.writeBatchHeader(policy, fieldCount)

	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return nil, err
		}
	}

	// Write real field size.
	fieldSizeOffset := cmd.dataOffset
	cmd.writeFieldHeader(0, BATCH_INDEX)

	cmd.WriteUint32(uint32(max))

	cmd.WriteByte(cmd.getBatchFlags(policy))

	attr := &batchAttr{}
	prev = nil
	for i := 0; i < max; i++ {
		index := offsets[i]
		cmd.WriteUint32(uint32(index))

		record := records[index]
		key := record.key()
		if _, err := cmd.Write(key.digest[:]); err != nil {
			return nil, newCommonError(err)
		}

		// Try reference equality in hope that namespace/set for all keys is set from fixed variables.
		if !policy.SendKey && prev != nil && prev.key().namespace == key.namespace && prev.key().setName == key.setName && record.equals(prev) {
			// Can set repeat previous namespace/bin names to save space.
			cmd.WriteByte(_BATCH_MSG_REPEAT) // repeat
		} else {
			// Write full message.
			switch record.getType() {
			case _BRT_BATCH_READ:
				br := record.(*BatchRead)

				attr.setBatchRead(client.getUsableBatchReadPolicy(br.Policy))
				if len(br.BinNames) > 0 {
					cmd.writeBatchBinNames(key, br.BinNames, attr, attr.filterExp)
				} else if br.Ops != nil {
					attr.adjustRead(br.Ops)
					cmd.writeBatchOperations(key, br.Ops, attr, attr.filterExp)
				} else {
					attr.adjustReadForAllBins(br.ReadAllBins)
					cmd.writeBatchRead(key, attr, attr.filterExp, 0)
				}

			case _BRT_BATCH_WRITE:
				bw := record.(*BatchWrite)

				attr.setBatchWrite(client.getUsableBatchWritePolicy(bw.Policy))
				attr.adjustWrite(bw.Ops)
				cmd.writeBatchOperations(key, bw.Ops, attr, attr.filterExp)

			case _BRT_BATCH_UDF:
				bu := record.(*BatchUDF)

				attr.setBatchUDF(client.getUsableBatchUDFPolicy(bu.Policy))
				cmd.writeBatchWrite(key, attr, attr.filterExp, 3, 0)
				cmd.writeFieldString(bu.PackageName, UDF_PACKAGE_NAME)
				cmd.writeFieldString(bu.FunctionName, UDF_FUNCTION)
				cmd.writeFieldBytes(bu.argBytes, UDF_ARGLIST)

			case _BRT_BATCH_DELETE:
				bd := record.(*BatchDelete)

				attr.setBatchDelete(client.getUsableBatchDeletePolicy(bd.Policy))
				cmd.writeBatchWrite(key, attr, attr.filterExp, 0, 0)
			}
			prev = record
		}
	}

	cmd.WriteUint32At(uint32(cmd.dataOffset)-uint32(_MSG_TOTAL_HEADER_SIZE)-4, fieldSizeOffset)
	cmd.end()
	cmd.markCompressed(policy)

	return attr, nil

}

func (cmd *baseCommand) setBatchOperate(policy *BatchPolicy, keys []*Key, batch *batchNode, binNames []string, ops []*Operation, attr *batchAttr) Error {
	offsets := batch.offsets
	max := len(batch.offsets)
	// Estimate buffer size
	cmd.begin()
	fieldCount := 1
	predSize := 0

	exp := policy.FilterExpression
	if attr.filterExp != nil {
		exp = attr.filterExp
	}

	if exp != nil {
		var err Error
		predSize, err = cmd.estimateExpressionSize(exp)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}
	cmd.dataOffset += predSize

	cmd.dataOffset += int(_FIELD_HEADER_SIZE) + 5

	var prev *Key
	for i := 0; i < max; i++ {
		key := keys[offsets[i]]
		cmd.dataOffset += len(key.digest) + 4

		// Try reference equality in hope that namespace/set for all keys is set from fixed variables.
		if !attr.sendKey && prev != nil && prev.namespace == key.namespace && (prev.setName == key.setName) {
			// Can set repeat previous namespace/bin names to save space.
			cmd.dataOffset++
		} else {
			// Must write full header and namespace/set/bin names.
			cmd.dataOffset += 12 // header(4) + ttl(4) + fielCount(2) + opCount(2) = 12
			cmd.dataOffset += len(key.namespace) + int(_FIELD_HEADER_SIZE)
			cmd.dataOffset += len(key.setName) + int(_FIELD_HEADER_SIZE)

			if attr.sendKey {
				if sz, err := key.userKey.EstimateSize(); err != nil {
					return err
				} else {
					cmd.dataOffset += sz + int(_FIELD_HEADER_SIZE) + 1
				}
			}

			if len(binNames) > 0 {
				for _, binName := range binNames {
					cmd.estimateOperationSizeForBinName(binName)
				}
			} else if len(ops) > 0 {
				for _, op := range ops {
					if op.opType.isWrite {
						if !attr.hasWrite {
							return newError(types.PARAMETER_ERROR, "batch operation is write but isWrite flag not set in attrs")
						}
						cmd.dataOffset += 2 // Extra write specific fields.
					}

					if err := cmd.estimateOperationSizeForOperation(op, true); err != nil {
						return err
					}
				}
			} else if (attr.writeAttr & _INFO2_DELETE) != 0 {
				cmd.dataOffset += 2 // Extra write specific fields.
			}

			prev = key
		}
	}

	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return err
	}

	cmd.writeBatchHeader(policy, fieldCount)

	if exp != nil {
		if err := cmd.writeFilterExpression(exp, predSize); err != nil {
			return err
		}
	}

	// Write real field size.
	fieldSizeOffset := cmd.dataOffset
	cmd.writeFieldHeader(0, BATCH_INDEX)

	cmd.WriteUint32(uint32(max))

	cmd.WriteByte(cmd.getBatchFlags(policy))

	prev = nil
	for i := 0; i < max; i++ {
		index := offsets[i]
		cmd.WriteUint32(uint32(index))

		key := keys[index]
		if _, err := cmd.Write(key.digest[:]); err != nil {
			return newCommonError(err)
		}

		// Try reference equality in hope that namespace/set for all keys is set from fixed variables.
		if !attr.sendKey && prev != nil && prev.namespace == key.namespace && prev.setName == key.setName {
			// Can set repeat previous namespace/bin names to save space.
			cmd.WriteByte(_BATCH_MSG_REPEAT) // repeat
		} else {
			// Write full header, namespace and bin names.
			if len(binNames) > 0 {
				cmd.writeBatchBinNames(key, binNames, attr, nil)
			} else if len(ops) > 0 {
				cmd.writeBatchOperations(key, ops, attr, nil)
			} else if (attr.writeAttr & _INFO2_DELETE) != 0 {
				cmd.writeBatchWrite(key, attr, nil, 0, 0)
			} else {
				cmd.writeBatchRead(key, attr, nil, 0)
			}

			prev = key
		}
	}

	cmd.WriteUint32At(uint32(cmd.dataOffset)-uint32(_MSG_TOTAL_HEADER_SIZE)-4, fieldSizeOffset)
	cmd.end()
	cmd.markCompressed(policy)

	return nil
}

func (cmd *baseCommand) setBatchUDF(policy *BatchPolicy, keys []*Key, batch *batchNode, packageName, functionName string, args ValueArray, attr *batchAttr) Error {
	offsets := batch.offsets
	max := len(batch.offsets)

	// Estimate buffer size
	cmd.begin()
	fieldCount := 1
	predSize := 0
	if policy.FilterExpression != nil {
		var err Error
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}
	cmd.dataOffset += predSize

	cmd.dataOffset += int(_FIELD_HEADER_SIZE) + 5

	var prev *Key
	for i := 0; i < max; i++ {
		key := keys[offsets[i]]
		cmd.dataOffset += len(key.digest) + 4

		// Try reference equality in hope that namespace/set for all keys is set from fixed variables.
		if !attr.sendKey && prev != nil && prev.namespace == key.namespace && (prev.setName == key.setName) {
			// Can set repeat previous namespace/bin names to save space.
			cmd.dataOffset++
		} else {
			// Must write full header and namespace/set/bin names.
			cmd.dataOffset += 12 // header(4) + ttl(4) + fieldCount(2) + opCount(2) = 12
			cmd.dataOffset += len(key.namespace) + int(_FIELD_HEADER_SIZE)
			cmd.dataOffset += len(key.setName) + int(_FIELD_HEADER_SIZE)

			if attr.sendKey {
				if sz, err := key.userKey.EstimateSize(); err != nil {
					return err
				} else {
					cmd.dataOffset += sz + int(_FIELD_HEADER_SIZE) + 1
				}
			}

			cmd.dataOffset += 2 // gen(2) = 2
			if sz, err := cmd.estimateUdfSize(packageName, functionName, &args); err != nil {
				return err
			} else {
				cmd.dataOffset += sz
			}

			prev = key
		}
	}

	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return err
	}

	cmd.writeBatchHeader(policy, fieldCount)

	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}

	// Write real field size.
	fieldSizeOffset := cmd.dataOffset
	cmd.writeFieldHeader(0, BATCH_INDEX)

	cmd.WriteUint32(uint32(max))

	cmd.WriteByte(cmd.getBatchFlags(policy))

	prev = nil
	for i := 0; i < max; i++ {
		index := offsets[i]
		cmd.WriteUint32(uint32(index))

		key := keys[index]
		if _, err := cmd.Write(key.digest[:]); err != nil {
			return newCommonError(err)
		}

		// Try reference equality in hope that namespace/set for all keys is set from fixed variables.
		if !attr.sendKey && prev != nil && prev.namespace == key.namespace && prev.setName == key.setName {
			// Can set repeat previous namespace/bin names to save space.
			cmd.WriteByte(_BATCH_MSG_REPEAT) // repeat
		} else {
			cmd.writeBatchWrite(key, attr, nil, 3, 0)
			cmd.writeFieldString(packageName, UDF_PACKAGE_NAME)
			cmd.writeFieldString(functionName, UDF_FUNCTION)
			if err := cmd.writeUdfArgs(&args); err != nil {
				return err
			}
			prev = key
		}
	}

	cmd.WriteUint32At(uint32(cmd.dataOffset)-uint32(_MSG_TOTAL_HEADER_SIZE)-4, fieldSizeOffset)
	cmd.end()
	cmd.markCompressed(policy)

	// fmt.Printf("len: %d\n", len(cmd.dataBuffer[:cmd.dataOffset]))
	// fmt.Printf("%s\n", hex.Dump(cmd.dataBuffer[:cmd.dataOffset]))

	return nil
}

func (cmd *baseCommand) writeBatchHeader(policy *BatchPolicy, fieldCount int) {
	readAttr := _INFO1_BATCH

	if policy.UseCompression {
		readAttr |= _INFO1_COMPRESS_RESPONSE
	}

	cmd.dataOffset = 8

	// Write all header data except total size which must be written last.
	cmd.WriteByte(_MSG_REMAINING_HEADER_SIZE) // Message header length.
	cmd.WriteByte(byte(readAttr))
	cmd.WriteByte(0)
	cmd.WriteByte(0)
	for i := 12; i < 22; i++ {
		cmd.WriteByte(0)
	}
	cmd.WriteUint32(0) // timeout will be rewritten later
	cmd.WriteUint16(uint16(fieldCount))
	cmd.WriteUint16(0)
	// cmd.dataOffset = int(_MSG_TOTAL_HEADER_SIZE)
}

func (cmd *baseCommand) writeBatchBinNames(key *Key, binNames []string, attr *batchAttr, filter *Expression) {
	cmd.writeBatchRead(key, attr, filter, len(binNames))

	for i := range binNames {
		cmd.writeOperationForBinName(binNames[i], _READ)
	}
}

func (cmd *baseCommand) writeBatchOperations(key *Key, ops []*Operation, attr *batchAttr, filter *Expression) {
	if attr.hasWrite {
		cmd.writeBatchWrite(key, attr, filter, 0, len(ops))
	} else {
		cmd.writeBatchRead(key, attr, filter, len(ops))
	}

	for i := range ops {
		cmd.writeOperationForOperation(ops[i])
	}
}

func (cmd *baseCommand) writeBatchRead(key *Key, attr *batchAttr, filter *Expression, opCount int) {
	cmd.WriteByte(_BATCH_MSG_INFO | _BATCH_MSG_TTL)
	cmd.WriteByte(byte(attr.readAttr))
	cmd.WriteByte(byte(attr.writeAttr))
	cmd.WriteByte(byte(attr.infoAttr))
	cmd.WriteUint32(attr.expiration)
	cmd.writeBatchFieldsWithFilter(key, filter, 0, opCount)
}

func (cmd *baseCommand) writeBatchWrite(key *Key, attr *batchAttr, filter *Expression, fieldCount, opCount int) {
	cmd.WriteByte(_BATCH_MSG_INFO | _BATCH_MSG_GEN | _BATCH_MSG_TTL)
	cmd.WriteByte(byte(attr.readAttr))
	cmd.WriteByte(byte(attr.writeAttr))
	cmd.WriteByte(byte(attr.infoAttr))
	cmd.WriteUint16(uint16(attr.generation))
	cmd.WriteUint32(attr.expiration)

	if attr.sendKey {
		fieldCount++
		cmd.writeBatchFieldsWithFilter(key, filter, fieldCount, opCount)
		cmd.writeFieldValue(key.userKey, KEY)
	} else {
		cmd.writeBatchFieldsWithFilter(key, filter, fieldCount, opCount)
	}
}

func (cmd *baseCommand) getBatchFlags(policy *BatchPolicy) byte {
	flags := byte(0)
	if policy.AllowInline {
		flags = 1
	}

	if policy.AllowInlineSSD {
		flags |= 0x2
	}

	if policy.RespondAllKeys {
		flags |= 0x4
	}
	return flags
}

func (cmd *baseCommand) setBatchRead(policy *BatchPolicy, keys []*Key, batch *batchNode, binNames []string, ops []*Operation, readAttr int) Error {
	offsets := batch.offsets
	max := len(batch.offsets)

	// Estimate buffer size
	cmd.begin()
	fieldCount := 1
	predSize := 0
	if policy.FilterExpression != nil {
		var err Error
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}
	cmd.dataOffset += predSize

	cmd.dataOffset += int(_FIELD_HEADER_SIZE) + 5

	var prev *Key
	for i := 0; i < max; i++ {
		key := keys[offsets[i]]
		cmd.dataOffset += len(key.digest) + 4

		// Try reference equality in hope that namespace/set for all keys is set from fixed variables.
		if prev != nil && prev.namespace == key.namespace &&
			(prev.setName == key.setName) {
			// Can set repeat previous namespace/bin names to save space.
			cmd.dataOffset++
		} else {
			// Must write full header and namespace/set/bin names.
			cmd.dataOffset += len(key.namespace) + int(_FIELD_HEADER_SIZE) + 6
			cmd.dataOffset += len(key.setName) + int(_FIELD_HEADER_SIZE)

			if len(binNames) > 0 {
				for _, binName := range binNames {
					cmd.estimateOperationSizeForBinName(binName)
				}
			} else if len(ops) > 0 {
				for _, op := range ops {
					if err := cmd.estimateOperationSizeForOperation(op, true); err != nil {
						return err
					}
				}
			}

			prev = key
		}
	}

	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return err
	}

	if policy.ReadModeAP == ReadModeAPAll {
		readAttr |= _INFO1_READ_MODE_AP_ALL
	}

	cmd.writeHeaderRead(&policy.BasePolicy, readAttr|_INFO1_BATCH, 0, 0, fieldCount, 0)

	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}

	// Write real field size.
	fieldSizeOffset := cmd.dataOffset
	cmd.writeFieldHeader(0, BATCH_INDEX_WITH_SET)

	cmd.WriteUint32(uint32(max))

	if policy.AllowInline {
		cmd.WriteByte(1)
	} else {
		cmd.WriteByte(0)
	}

	prev = nil
	for i := 0; i < max; i++ {
		index := offsets[i]
		cmd.WriteUint32(uint32(index))

		key := keys[index]
		if _, err := cmd.Write(key.digest[:]); err != nil {
			return newCommonError(err)
		}
		// Try reference equality in hope that namespace/set for all keys is set from fixed variables.
		if prev != nil && prev.namespace == key.namespace &&
			(prev.setName == key.setName) {
			// Can set repeat previous namespace/bin names to save space.
			cmd.WriteByte(1) // repeat
		} else {
			// Write full header, namespace and bin names.
			cmd.WriteByte(0) // do not repeat
			if len(binNames) > 0 {
				cmd.WriteByte(byte(readAttr))
				cmd.writeBatchFields(key, 0, len(binNames))
				for _, binName := range binNames {
					cmd.writeOperationForBinName(binName, _READ)
				}
			} else if len(ops) > 0 {
				offset := cmd.dataOffset
				cmd.dataOffset++
				cmd.writeBatchFields(key, 0, len(ops))
				cmd.dataBuffer[offset], _ = cmd.writeBatchReadOperations(ops, readAttr)
			} else {
				attr := byte(readAttr)
				if len(binNames) == 0 {
					attr |= byte(_INFO1_GET_ALL)
				} else {
					attr |= byte(_INFO1_NOBINDATA)
				}
				cmd.WriteByte(attr)
				cmd.writeBatchFields(key, 0, 0)
			}

			prev = key
		}
	}

	cmd.WriteUint32At(uint32(cmd.dataOffset)-uint32(_MSG_TOTAL_HEADER_SIZE)-4, fieldSizeOffset)
	cmd.end()
	cmd.markCompressed(policy)

	return nil
}

func (cmd *baseCommand) setBatchIndexRead(policy *BatchPolicy, records []*BatchRead, batch *batchNode) Error {
	offsets := batch.offsets
	max := len(batch.offsets)

	// Estimate buffer size
	cmd.begin()
	fieldCount := 1
	predSize := 0
	if policy.FilterExpression != nil {
		var err Error
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}

	cmd.dataOffset += int(_FIELD_HEADER_SIZE) + 5

	var prev *BatchRead
	for i := 0; i < max; i++ {
		record := records[offsets[i]]
		key := record.Key
		binNames := record.BinNames
		ops := record.Ops

		cmd.dataOffset += len(key.digest) + 4

		// Try reference equality in hope that namespace/set for all keys is set from fixed variables.
		if prev != nil && prev.Key.namespace == key.namespace &&
			(prev.Key.setName == key.setName) &&
			&prev.BinNames == &binNames && prev.ReadAllBins == record.ReadAllBins &&
			&prev.Ops == &ops {
			// Can set repeat previous namespace/bin names to save space.
			cmd.dataOffset++
		} else {
			// Must write full header and namespace/set/bin names.
			cmd.dataOffset += len(key.namespace) + int(_FIELD_HEADER_SIZE) + 6
			cmd.dataOffset += len(key.setName) + int(_FIELD_HEADER_SIZE)

			if len(binNames) != 0 {
				for _, binName := range binNames {
					cmd.estimateOperationSizeForBinName(binName)
				}
			} else if len(ops) != 0 {
				for _, op := range ops {
					cmd.estimateOperationSizeForOperation(op, true)
				}
			}

			prev = record
		}
	}

	if err := cmd.sizeBuffer(policy.compress()); err != nil {
		return err
	}

	readAttr := _INFO1_READ
	if policy.ReadModeAP == ReadModeAPAll {
		readAttr |= _INFO1_READ_MODE_AP_ALL
	}

	cmd.writeHeaderRead(&policy.BasePolicy, readAttr|_INFO1_BATCH, 0, 0, fieldCount, 0)

	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}

	// Write real field size.
	fieldSizeOffset := cmd.dataOffset
	cmd.writeFieldHeader(0, BATCH_INDEX_WITH_SET)

	cmd.WriteUint32(uint32(max))

	if policy.AllowInline {
		cmd.WriteByte(1)
	} else {
		cmd.WriteByte(0)
	}

	prev = nil
	for i := 0; i < max; i++ {
		index := offsets[i]
		cmd.WriteUint32(uint32(index))

		record := records[index]
		key := record.Key
		binNames := record.BinNames
		ops := record.Ops
		if _, err := cmd.Write(key.digest[:]); err != nil {
			return newCommonError(err)
		}

		// Try reference equality in hope that namespace/set for all keys is set from fixed variables.
		if prev != nil && prev.Key.namespace == key.namespace &&
			(prev.Key.setName == key.setName) &&
			&prev.BinNames == &binNames && prev.ReadAllBins == record.ReadAllBins &&
			&prev.Ops == &ops {
			// Can set repeat previous namespace/bin names to save space.
			cmd.WriteByte(1) // repeat
		} else {
			// Write full header, namespace and bin names.
			cmd.WriteByte(0) // do not repeat
			if len(binNames) > 0 {
				cmd.WriteByte(byte(readAttr))
				cmd.writeBatchFields(key, 0, len(binNames))
				for _, binName := range binNames {
					cmd.writeOperationForBinName(binName, _READ)
				}
			} else if len(ops) > 0 {
				offset := cmd.dataOffset
				cmd.dataOffset++
				cmd.writeBatchFields(key, 0, len(ops))
				cmd.dataBuffer[offset], _ = cmd.writeBatchReadOperations(ops, readAttr)
			} else {
				attr := byte(readAttr)
				if record.ReadAllBins {
					attr |= byte(_INFO1_GET_ALL)
				} else {
					attr |= byte(_INFO1_NOBINDATA)
				}
				cmd.WriteByte(attr)
				cmd.writeBatchFields(key, 0, 0)
			}

			prev = record
		}
	}

	cmd.WriteUint32At(uint32(cmd.dataOffset)-uint32(_MSG_TOTAL_HEADER_SIZE)-4, fieldSizeOffset)
	cmd.end()
	cmd.markCompressed(policy)

	return nil
}

func (cmd *baseCommand) writeBatchFieldsWithFilter(key *Key, filter *Expression, fieldCount, opCount int) Error {
	if filter != nil {
		fieldCount++
		cmd.writeBatchFields(key, fieldCount, opCount)
		expSize, err := filter.size()
		if err != nil {
			return err
		}
		if err := cmd.writeFilterExpression(filter, expSize); err != nil {
			return err
		}
	} else {
		cmd.writeBatchFields(key, fieldCount, opCount)
	}
	return nil
}

func (cmd *baseCommand) writeBatchFields(key *Key, fieldCount, opCount int) Error {
	fieldCount += 2
	cmd.WriteUint16(uint16(fieldCount))
	cmd.WriteUint16(uint16(opCount))
	cmd.writeFieldString(key.namespace, NAMESPACE)
	cmd.writeFieldString(key.setName, TABLE)

	return nil
}

func (cmd *baseCommand) setScan(policy *ScanPolicy, namespace *string, setName *string, binNames []string, taskID uint64, nodePartitions *nodePartitions) Error {
	cmd.begin()
	fieldCount := 0

	// for grpc
	partsFullSize := 0
	partsPartialSize := 0
	maxRecords := int64(0)
	if nodePartitions != nil {
		partsFullSize = len(nodePartitions.partsFull) * 2
		partsPartialSize = len(nodePartitions.partsPartial) * 20
		maxRecords = int64(nodePartitions.recordMax)
	}

	predSize := 0
	if policy.FilterExpression != nil {
		var err Error
		predSize, err = cmd.estimateExpressionSize(policy.FilterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}

	if namespace != nil {
		cmd.dataOffset += len(*namespace) + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	if setName != nil {
		cmd.dataOffset += len(*setName) + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	if partsFullSize > 0 {
		cmd.dataOffset += partsFullSize + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	if partsPartialSize > 0 {
		cmd.dataOffset += partsPartialSize + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	if maxRecords > 0 {
		cmd.dataOffset += 8 + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	if policy.RecordsPerSecond > 0 {
		cmd.dataOffset += 4 + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	// Estimate scan timeout size.
	cmd.dataOffset += 4 + int(_FIELD_HEADER_SIZE)
	fieldCount++

	// Allocate space for TaskId field.
	cmd.dataOffset += 8 + int(_FIELD_HEADER_SIZE)
	fieldCount++

	for i := range binNames {
		cmd.estimateOperationSizeForBinName(binNames[i])
	}

	if err := cmd.sizeBuffer(false); err != nil {
		return err
	}
	readAttr := _INFO1_READ

	if !policy.IncludeBinData {
		readAttr |= _INFO1_NOBINDATA
	}

	infoAttr := 0
	if cmd.node == nil || cmd.node.cluster.supportsPartitionQuery.Get() {
		infoAttr = _INFO3_PARTITION_DONE
	}

	operationCount := 0
	if len(binNames) > 0 {
		operationCount = len(binNames)
	}
	cmd.writeHeaderRead(&policy.BasePolicy, readAttr, 0, infoAttr, fieldCount, operationCount)

	if namespace != nil {
		cmd.writeFieldString(*namespace, NAMESPACE)
	}

	if setName != nil {
		cmd.writeFieldString(*setName, TABLE)
	}

	if partsFullSize > 0 {
		cmd.writeFieldHeader(partsFullSize, PID_ARRAY)

		for _, part := range nodePartitions.partsFull {
			cmd.WriteInt16LittleEndian(uint16(part.Id))
		}
	}

	if partsPartialSize > 0 {
		cmd.writeFieldHeader(partsPartialSize, DIGEST_ARRAY)

		for _, part := range nodePartitions.partsPartial {
			if _, err := cmd.Write(part.Digest[:]); err != nil {
				return newCommonError(err)
			}
		}
	}

	if policy.FilterExpression != nil {
		if err := cmd.writeFilterExpression(policy.FilterExpression, predSize); err != nil {
			return err
		}
	}

	if maxRecords > 0 {
		cmd.writeFieldInt64(maxRecords, MAX_RECORDS)
	}

	if policy.RecordsPerSecond > 0 {
		cmd.writeFieldInt32(int32(policy.RecordsPerSecond), RECORDS_PER_SECOND)
	}

	// Write scan timeout
	cmd.writeFieldHeader(4, SOCKET_TIMEOUT)
	cmd.WriteInt32(int32(policy.SocketTimeout / time.Millisecond)) // in milliseconds

	cmd.writeFieldHeader(8, TRAN_ID)
	cmd.WriteUint64(taskID)

	for i := range binNames {
		cmd.writeOperationForBinName(binNames[i], _READ)
	}

	cmd.end()

	return nil
}

func (cmd *baseCommand) setQuery(policy *QueryPolicy, wpolicy *WritePolicy, statement *Statement, taskID uint64, operations []*Operation, background bool, nodePartitions *nodePartitions) Error {
	fieldCount := 0
	filterSize := 0
	binNameSize := 0
	predSize := 0
	var ctxSize int

	filterExpression := policy.FilterExpression
	if filterExpression == nil && wpolicy != nil {
		filterExpression = wpolicy.FilterExpression
	}

	isNew := false
	if cmd.node != nil {
		isNew = cmd.node.cluster.supportsPartitionQuery.Get()
	}

	cmd.begin()

	if statement.Namespace != "" {
		cmd.dataOffset += len(statement.Namespace) + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	// if statement.IndexName != "" {
	// 	cmd.dataOffset += len(statement.IndexName) + int(_FIELD_HEADER_SIZE)
	// 	fieldCount++
	// }

	if statement.SetName != "" {
		cmd.dataOffset += len(statement.SetName) + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	// Estimate recordsPerSecond field size. This field is used in new servers and not used
	// (but harmless to add) in old servers.
	if policy.RecordsPerSecond > 0 {
		cmd.dataOffset += 4 + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	// Estimate socket timeout field size. This field is used in new servers and not used
	// (but harmless to add) in old servers.
	cmd.dataOffset += 4 + int(_FIELD_HEADER_SIZE)
	fieldCount++

	// Allocate space for TaskId field.
	cmd.dataOffset += 8 + int(_FIELD_HEADER_SIZE)
	fieldCount++

	if statement.Filter != nil {
		idxType := statement.Filter.IndexCollectionType()

		// Estimate INDEX_TYPE field.
		if idxType != ICT_DEFAULT {
			cmd.dataOffset += int(_FIELD_HEADER_SIZE) + 1
			fieldCount++
		}

		// Estimate INDEX_RANGE field.
		cmd.dataOffset += int(_FIELD_HEADER_SIZE)
		filterSize++ // num filters

		sz, err := statement.Filter.EstimateSize()
		if err != nil {
			return err
		}
		filterSize += sz

		cmd.dataOffset += filterSize
		fieldCount++

		// Query bin names are specified as a field (Scan bin names are specified later as operations)
		// in old servers. Estimate size for selected bin names.
		if !isNew {
			if len(statement.BinNames) > 0 {
				cmd.dataOffset += int(_FIELD_HEADER_SIZE)
				binNameSize++ // num bin names

				for _, binName := range statement.BinNames {
					binNameSize += len(binName) + 1
				}
				cmd.dataOffset += binNameSize
				fieldCount++
			}
		}

		if statement.Filter.ctx != nil {
			ctxSize, err = statement.Filter.estimatePackedCtxSize()
			if err != nil {
				return newCommonError(err)
			}
			if ctxSize > 0 {
				cmd.dataOffset += int(_FIELD_HEADER_SIZE) + ctxSize
				fieldCount++
			}
		}
	}

	partsFullSize := 0
	partsPartialSize := 0
	maxRecords := int64(0)
	partsPartialBValSize := 0

	// Calling query with no filters is more efficiently handled by a primary index scan.
	// Estimate scan options size.
	if nodePartitions != nil {
		partsFullSize = len(nodePartitions.partsFull) * 2
		partsPartialSize = len(nodePartitions.partsPartial) * 20
		if statement.Filter != nil {
			partsPartialBValSize = len(nodePartitions.partsPartial) * 8
		}
		maxRecords = nodePartitions.recordMax
	}

	if partsFullSize > 0 {
		cmd.dataOffset += partsFullSize + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	if partsPartialSize > 0 {
		cmd.dataOffset += partsPartialSize + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	if partsPartialBValSize > 0 {
		cmd.dataOffset += partsPartialBValSize + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	// Estimate max records size;
	if maxRecords > 0 {
		cmd.dataOffset += 8 + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	if filterExpression != nil {
		var err Error
		predSize, err = cmd.estimateExpressionSize(filterExpression)
		if err != nil {
			return err
		}
		if predSize > 0 {
			fieldCount++
		}
	}

	var functionArgs *ValueArray
	if statement.functionName != "" {
		cmd.dataOffset += int(_FIELD_HEADER_SIZE) + 1 // udf type
		cmd.dataOffset += len(statement.packageName) + int(_FIELD_HEADER_SIZE)
		cmd.dataOffset += len(statement.functionName) + int(_FIELD_HEADER_SIZE)

		// function args
		cmd.dataOffset += int(_FIELD_HEADER_SIZE)
		if len(statement.functionArgs) > 0 {
			functionArgs = NewValueArray(statement.functionArgs)
			fasz, err := functionArgs.EstimateSize()
			if err != nil {
				return err
			}

			cmd.dataOffset += fasz
		}

		fieldCount += 4
	}

	operationCount := 0

	// Operations (used in query execute) and bin names (used in scan/query) are mutually exclusive.
	if len(operations) > 0 {
		if !background {
			return newError(types.PARAMETER_ERROR, "Operations not allowed in foreground query")
		}

		for _, op := range operations {
			if !op.opType.isWrite {
				return newError(types.PARAMETER_ERROR, "Read operations not allowed in background query")
			}
			if err := cmd.estimateOperationSizeForOperation(op, false); err != nil {
				return err
			}
		}
		operationCount = len(operations)
	} else if len(statement.BinNames) > 0 && (isNew || statement.Filter == nil) {
		for _, binName := range statement.BinNames {
			cmd.estimateOperationSizeForBinName(binName)
		}
		operationCount = len(statement.BinNames)
	}

	//////////////////////////////////////////////////////////////////////////

	if err := cmd.sizeBuffer(false); err != nil {
		return err
	}

	if background {
		cmd.writeHeaderWrite(wpolicy, _INFO2_WRITE, fieldCount, operationCount)
	} else {
		readAttr := _INFO1_READ | _INFO1_NOBINDATA
		writeAttr := 0

		if policy.IncludeBinData {
			readAttr = _INFO1_READ
		}
		if policy.ShortQuery || policy.ExpectedDuration == SHORT {
			readAttr |= _INFO1_SHORT_QUERY
		} else if policy.ExpectedDuration == LONG_RELAX_AP {
			writeAttr |= _INFO2_RELAX_AP_LONG_QUERY
		}
		infoAttr := 0
		if isNew {
			infoAttr = _INFO3_PARTITION_DONE
		}
		cmd.writeHeaderRead(&policy.BasePolicy, readAttr, writeAttr, infoAttr, fieldCount, operationCount)
	}

	if statement.Namespace != "" {
		cmd.writeFieldString(statement.Namespace, NAMESPACE)
	}

	if statement.IndexName != "" {
		cmd.writeFieldString(statement.IndexName, INDEX_NAME)
	}

	if statement.SetName != "" {
		cmd.writeFieldString(statement.SetName, TABLE)
	}

	cmd.writeFieldHeader(8, TRAN_ID)
	cmd.WriteUint64(taskID)

	if statement.Filter != nil {
		idxType := statement.Filter.IndexCollectionType()

		if idxType != ICT_DEFAULT {
			cmd.writeFieldHeader(1, INDEX_TYPE)
			cmd.WriteByte(byte(idxType))
		}

		cmd.writeFieldHeader(filterSize, INDEX_RANGE)
		cmd.WriteByte(byte(1)) // number of filters

		_, err := statement.Filter.write(cmd)
		if err != nil {
			return err
		}

		if !isNew {
			// Query bin names are specified as a field (Scan bin names are specified later as operations)
			// in old servers.
			if len(statement.BinNames) > 0 {
				cmd.writeFieldHeader(binNameSize, QUERY_BINLIST)
				cmd.WriteByte(byte(len(statement.BinNames)))

				for _, binName := range statement.BinNames {
					len := copy(cmd.dataBuffer[cmd.dataOffset+1:], binName)
					cmd.dataBuffer[cmd.dataOffset] = byte(len)
					cmd.dataOffset += len + 1
				}
			}
		}

		if ctxSize > 0 {
			cmd.writeFieldHeader(ctxSize, INDEX_CONTEXT)
			if _, err = statement.Filter.packCtx(cmd); err != nil {
				return newCommonError(err)
			}
		}
	}

	// Calling query with no filters is more efficiently handled by a primary index scan.
	if partsFullSize > 0 {
		cmd.writeFieldHeader(partsFullSize, PID_ARRAY)

		for _, part := range nodePartitions.partsFull {
			cmd.WriteInt16LittleEndian(uint16(part.Id))
		}
	}

	if partsPartialSize > 0 {
		cmd.writeFieldHeader(partsPartialSize, DIGEST_ARRAY)

		for _, part := range nodePartitions.partsPartial {
			if _, err := cmd.Write(part.Digest[:]); err != nil {
				return newCommonError(err)
			}
		}
	}

	if partsPartialBValSize > 0 {
		cmd.writeFieldHeader(partsPartialBValSize, BVAL_ARRAY)

		for _, part := range nodePartitions.partsPartial {
			cmd.WriteInt64LittleEndian(uint64(part.BVal))
		}
	}

	if maxRecords > 0 {
		cmd.writeFieldInt64(maxRecords, MAX_RECORDS)
	}

	// Write scan timeout
	cmd.writeFieldHeader(4, SOCKET_TIMEOUT)
	cmd.WriteInt32(int32(policy.SocketTimeout / time.Millisecond)) // in milliseconds

	// Write records per second.
	if policy.RecordsPerSecond > 0 {
		cmd.writeFieldInt32(int32(policy.RecordsPerSecond), RECORDS_PER_SECOND)
	}

	if filterExpression != nil {
		if err := cmd.writeFilterExpression(filterExpression, predSize); err != nil {
			return err
		}
	}

	if statement.functionName != "" {
		cmd.writeFieldHeader(1, UDF_OP)
		if statement.ReturnData {
			cmd.dataBuffer[cmd.dataOffset] = byte(1)
		} else {
			cmd.dataBuffer[cmd.dataOffset] = byte(2)
		}
		cmd.dataOffset++

		cmd.writeFieldString(statement.packageName, UDF_PACKAGE_NAME)
		cmd.writeFieldString(statement.functionName, UDF_FUNCTION)
		if err := cmd.writeUdfArgs(functionArgs); err != nil {
			return err
		}
	}

	if len(operations) > 0 {
		for _, op := range operations {
			if err := cmd.writeOperationForOperation(op); err != nil {
				return err
			}
		}
	} else if len(statement.BinNames) > 0 && (isNew || statement.Filter == nil) {
		// scan binNames come last
		for _, binName := range statement.BinNames {
			cmd.writeOperationForBinName(binName, _READ)
		}
	}

	cmd.end()

	return nil
}

func (cmd *baseCommand) estimateKeySize(key *Key, sendKey bool) (int, Error) {
	fieldCount := 0

	if key.namespace != "" {
		cmd.dataOffset += len(key.namespace) + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	if key.setName != "" {
		cmd.dataOffset += len(key.setName) + int(_FIELD_HEADER_SIZE)
		fieldCount++
	}

	cmd.dataOffset += int(_DIGEST_SIZE + _FIELD_HEADER_SIZE)
	fieldCount++

	if sendKey {
		// field header size + key size
		sz, err := key.userKey.EstimateSize()
		if err != nil {
			return sz, err
		}
		cmd.dataOffset += sz + int(_FIELD_HEADER_SIZE) + 1
		fieldCount++
	}

	return fieldCount, nil
}

func (cmd *baseCommand) estimateUdfSize(packageName string, functionName string, args *ValueArray) (int, Error) {
	cmd.dataOffset += len(packageName) + int(_FIELD_HEADER_SIZE)
	cmd.dataOffset += len(functionName) + int(_FIELD_HEADER_SIZE)

	sz, err := args.EstimateSize()
	if err != nil {
		return 0, err
	}

	// fmt.Println(args, sz)

	cmd.dataOffset += sz + int(_FIELD_HEADER_SIZE)
	return 3, nil
}

func (cmd *baseCommand) estimateOperationSizeForBin(bin *Bin) Error {
	cmd.dataOffset += len(bin.Name) + int(_OPERATION_HEADER_SIZE)
	sz, err := bin.Value.EstimateSize()
	if err != nil {
		return err
	}
	cmd.dataOffset += sz
	return nil
}

func (cmd *baseCommand) estimateOperationSizeForBinNameAndValue(name string, value interface{}) Error {
	cmd.dataOffset += len(name) + int(_OPERATION_HEADER_SIZE)
	sz, err := NewValue(value).EstimateSize()
	if err != nil {
		return err
	}
	cmd.dataOffset += sz
	return nil
}

func (cmd *baseCommand) estimateOperationSizeForOperation(operation *Operation, isBatch bool) Error {
	if isBatch && operation.opType.isWrite {
		return newError(types.PARAMETER_ERROR, "Write operations not allowed in batch read")
	}

	size, err := operation.size()
	if err != nil {
		return err
	}

	cmd.dataOffset += size
	return nil
}

func (cmd *baseCommand) estimateOperationSizeForBinName(binName string) {
	cmd.dataOffset += len(binName) + int(_OPERATION_HEADER_SIZE)
}

func (cmd *baseCommand) estimateOperationSize() {
	cmd.dataOffset += int(_OPERATION_HEADER_SIZE)
}

func (cmd *baseCommand) estimateExpressionSize(exp *Expression) (int, Error) {
	size, err := exp.size()
	if err != nil {
		return size, err
	}

	cmd.dataOffset += size + int(_FIELD_HEADER_SIZE)
	return size, nil
}

// Header write for write commands.
func (cmd *baseCommand) writeHeaderWrite(policy *WritePolicy, writeAttr, fieldCount, operationCount int) {
	// Set flags.
	generation := uint32(0)
	readAttr := 0
	infoAttr := 0

	switch policy.RecordExistsAction {
	case UPDATE:
	case UPDATE_ONLY:
		infoAttr |= _INFO3_UPDATE_ONLY
	case REPLACE:
		infoAttr |= _INFO3_CREATE_OR_REPLACE
	case REPLACE_ONLY:
		infoAttr |= _INFO3_REPLACE_ONLY
	case CREATE_ONLY:
		writeAttr |= _INFO2_CREATE_ONLY
	}

	switch policy.GenerationPolicy {
	case NONE:
	case EXPECT_GEN_EQUAL:
		generation = policy.Generation
		writeAttr |= _INFO2_GENERATION
	case EXPECT_GEN_GT:
		generation = policy.Generation
		writeAttr |= _INFO2_GENERATION_GT
	}

	if policy.CommitLevel == COMMIT_MASTER {
		infoAttr |= _INFO3_COMMIT_MASTER
	}

	if policy.DurableDelete {
		writeAttr |= _INFO2_DURABLE_DELETE
	}

	// if (policy.Xdr) {
	// 	readAttr |= _INFO1_XDR;
	// }

	// Write all header data except total size which must be written last.
	cmd.dataBuffer[8] = _MSG_REMAINING_HEADER_SIZE // Message header length.
	cmd.dataBuffer[9] = byte(readAttr)
	cmd.dataBuffer[10] = byte(writeAttr)
	cmd.dataBuffer[11] = byte(infoAttr)
	cmd.dataBuffer[12] = 0 // unused
	cmd.dataBuffer[13] = 0 // clear the result code
	cmd.dataOffset = 14
	cmd.WriteUint32(generation)
	cmd.WriteUint32(policy.Expiration)
	cmd.WriteInt32(0) // TODO: server timeout
	cmd.WriteInt16(int16(fieldCount))
	cmd.WriteInt16(int16(operationCount))
	cmd.dataOffset = int(_MSG_TOTAL_HEADER_SIZE)
}

// Header write for operate command.
func (cmd *baseCommand) writeHeaderReadWrite(policy *WritePolicy, args *operateArgs, fieldCount int) {
	// Set flags.
	generation := uint32(0)
	ttl := int64(policy.ReadTouchTTLPercent)
	if args.hasWrite {
		ttl = int64(policy.Expiration)
	}
	readAttr := args.readAttr
	writeAttr := args.writeAttr
	infoAttr := 0
	operationCount := len(args.operations)

	switch policy.RecordExistsAction {
	case UPDATE:
	case UPDATE_ONLY:
		infoAttr |= _INFO3_UPDATE_ONLY
	case REPLACE:
		infoAttr |= _INFO3_CREATE_OR_REPLACE
	case REPLACE_ONLY:
		infoAttr |= _INFO3_REPLACE_ONLY
	case CREATE_ONLY:
		writeAttr |= _INFO2_CREATE_ONLY
	}

	switch policy.GenerationPolicy {
	case NONE:
	case EXPECT_GEN_EQUAL:
		generation = policy.Generation
		writeAttr |= _INFO2_GENERATION
	case EXPECT_GEN_GT:
		generation = policy.Generation
		writeAttr |= _INFO2_GENERATION_GT
	}

	if policy.CommitLevel == COMMIT_MASTER {
		infoAttr |= _INFO3_COMMIT_MASTER
	}

	if policy.DurableDelete {
		writeAttr |= _INFO2_DURABLE_DELETE
	}

	// if (policy.xdr) {
	// 	readAttr |= _INFO1_XDR;
	// }

	switch policy.ReadModeSC {
	case ReadModeSCSession:
	case ReadModeSCLinearize:
		infoAttr |= _INFO3_SC_READ_TYPE
	case ReadModeSCAllowReplica:
		infoAttr |= _INFO3_SC_READ_RELAX
	case ReadModeSCAllowUnavailable:
		infoAttr |= _INFO3_SC_READ_TYPE | _INFO3_SC_READ_RELAX
	}

	if policy.ReadModeAP == ReadModeAPAll {
		readAttr |= _INFO1_READ_MODE_AP_ALL
	}

	if policy.UseCompression {
		readAttr |= _INFO1_COMPRESS_RESPONSE
	}

	// Write all header data except total size which must be written last.
	cmd.dataBuffer[8] = _MSG_REMAINING_HEADER_SIZE // Message header length.
	cmd.dataBuffer[9] = byte(readAttr)
	cmd.dataBuffer[10] = byte(writeAttr)
	cmd.dataBuffer[11] = byte(infoAttr)
	cmd.dataBuffer[12] = 0 // unused
	cmd.dataBuffer[13] = 0 // clear the result code
	cmd.dataOffset = 14
	cmd.WriteUint32(generation)
	cmd.WriteInt32(int32(ttl))
	cmd.WriteInt32(0) // timeout
	cmd.WriteInt16(int16(fieldCount))
	cmd.WriteInt16(int16(operationCount))
	cmd.dataOffset = int(_MSG_TOTAL_HEADER_SIZE)
}

// Header write for read commands.
func (cmd *baseCommand) writeHeaderRead(policy *BasePolicy, readAttr, writeAttr, infoAttr, fieldCount, operationCount int) {
	switch policy.ReadModeSC {
	case ReadModeSCSession:
	case ReadModeSCLinearize:
		infoAttr |= _INFO3_SC_READ_TYPE
	case ReadModeSCAllowReplica:
		infoAttr |= _INFO3_SC_READ_RELAX
	case ReadModeSCAllowUnavailable:
		infoAttr |= _INFO3_SC_READ_TYPE | _INFO3_SC_READ_RELAX
	}

	if policy.ReadModeAP == ReadModeAPAll {
		readAttr |= _INFO1_READ_MODE_AP_ALL
	}

	if policy.UseCompression {
		readAttr |= _INFO1_COMPRESS_RESPONSE
	}

	// Write all header data except total size which must be written last.
	cmd.dataBuffer[8] = _MSG_REMAINING_HEADER_SIZE // Message header length.
	cmd.dataBuffer[9] = byte(readAttr)
	cmd.dataBuffer[10] = byte(writeAttr)
	cmd.dataBuffer[11] = byte(infoAttr)

	for i := 12; i < 18; i++ {
		cmd.dataBuffer[i] = 0
	}
	cmd.dataOffset = 18
	cmd.WriteInt32(policy.ReadTouchTTLPercent)
	cmd.WriteInt32(0) // timeout
	cmd.WriteInt16(int16(fieldCount))
	cmd.WriteInt16(int16(operationCount))
	cmd.dataOffset = int(_MSG_TOTAL_HEADER_SIZE)
}

// Header write for read header commands.
func (cmd *baseCommand) writeHeaderReadHeader(policy *BasePolicy, readAttr, fieldCount, operationCount int) {
	infoAttr := 0

	switch policy.ReadModeSC {
	case ReadModeSCSession:
	case ReadModeSCLinearize:
		infoAttr |= _INFO3_SC_READ_TYPE
	case ReadModeSCAllowReplica:
		infoAttr |= _INFO3_SC_READ_RELAX
	case ReadModeSCAllowUnavailable:
		infoAttr |= _INFO3_SC_READ_TYPE | _INFO3_SC_READ_RELAX
	}

	if policy.ReadModeAP == ReadModeAPAll {
		readAttr |= _INFO1_READ_MODE_AP_ALL
	}

	// Write all header data except total size which must be written last.
	cmd.dataBuffer[8] = _MSG_REMAINING_HEADER_SIZE // Message header length.
	cmd.dataBuffer[9] = byte(readAttr)
	cmd.dataBuffer[10] = byte(0)
	cmd.dataBuffer[11] = byte(infoAttr)

	for i := 12; i < 18; i++ {
		cmd.dataBuffer[i] = 0
	}

	cmd.dataOffset = 18
	cmd.WriteInt32(policy.ReadTouchTTLPercent)
	// cmd.WriteInt32(serverTimeout) // TODO: handle argument
	cmd.WriteInt32(0)
	cmd.WriteInt16(int16(fieldCount))
	cmd.WriteInt16(int16(operationCount))
	cmd.dataOffset = int(_MSG_TOTAL_HEADER_SIZE)
}

func (cmd *baseCommand) writeKey(key *Key, sendKey bool) Error {
	// Write key into buffer.
	if key.namespace != "" {
		cmd.writeFieldString(key.namespace, NAMESPACE)
	}

	if key.setName != "" {
		cmd.writeFieldString(key.setName, TABLE)
	}

	cmd.writeFieldBytes(key.digest[:], DIGEST_RIPE)

	if sendKey {
		if err := cmd.writeFieldValue(key.userKey, KEY); err != nil {
			return err
		}
	}

	return nil
}

func (cmd *baseCommand) writeOperationForBin(bin *Bin, operation OperationType) Error {
	nameLength := copy(cmd.dataBuffer[(cmd.dataOffset+int(_OPERATION_HEADER_SIZE)):], bin.Name)

	valueLength, err := bin.Value.EstimateSize()
	if err != nil {
		return err
	}

	cmd.WriteInt32(int32(nameLength + valueLength + 4))
	cmd.WriteByte((operation.op))
	cmd.WriteByte((byte(bin.Value.GetType())))
	cmd.WriteByte((byte(0)))
	cmd.WriteByte((byte(nameLength)))
	cmd.dataOffset += nameLength
	_, err = bin.Value.write(cmd)
	return err
}

func (cmd *baseCommand) writeOperationForBinNameAndValue(name string, val interface{}, operation OperationType) Error {
	nameLength := copy(cmd.dataBuffer[(cmd.dataOffset+int(_OPERATION_HEADER_SIZE)):], name)

	v := NewValue(val)

	valueLength, err := v.EstimateSize()
	if err != nil {
		return err
	}

	cmd.WriteInt32(int32(nameLength + valueLength + 4))
	cmd.WriteByte((operation.op))
	cmd.WriteByte((byte(v.GetType())))
	cmd.WriteByte((byte(0)))
	cmd.WriteByte((byte(nameLength)))
	cmd.dataOffset += nameLength
	_, err = v.write(cmd)
	return err
}

func (cmd *baseCommand) writeBatchReadOperations(ops []*Operation, readAttr int) (byte, Error) {
	for _, op := range ops {
		switch op.opType {
		case _READ_HEADER:
			readAttr |= _INFO1_NOBINDATA
		case _READ:
			// Read all bins if no bin is specified.
			if len(op.binName) == 0 {
				readAttr |= _INFO1_GET_ALL
			}
		default:
		}
		if err := cmd.writeOperationForOperation(op); err != nil {
			return byte(readAttr), err
		}
	}

	return byte(readAttr), nil
}

func (cmd *baseCommand) writeOperationForOperation(operation *Operation) Error {
	nameLength := copy(cmd.dataBuffer[(cmd.dataOffset+int(_OPERATION_HEADER_SIZE)):], operation.binName)

	if operation.encoder == nil {
		valueLength, err := operation.binValue.EstimateSize()
		if err != nil {
			return err
		}

		cmd.WriteInt32(int32(nameLength + valueLength + 4))
		cmd.WriteByte((operation.opType.op))
		cmd.WriteByte((byte(operation.binValue.GetType())))
		cmd.WriteByte((byte(0)))
		cmd.WriteByte((byte(nameLength)))
		cmd.dataOffset += nameLength
		_, err = operation.binValue.write(cmd)
		return err
	}

	valueLength, err := operation.encoder(operation, nil)
	if err != nil {
		return err
	}

	cmd.WriteInt32(int32(nameLength + valueLength + 4))
	cmd.WriteByte((operation.opType.op))
	cmd.WriteByte((byte(ParticleType.BLOB)))
	cmd.WriteByte((byte(0)))
	cmd.WriteByte((byte(nameLength)))
	cmd.dataOffset += nameLength
	_, err = operation.encoder(operation, cmd)
	return err
}

func (cmd *baseCommand) writeOperationForBinName(name string, operation OperationType) {
	nameLength := copy(cmd.dataBuffer[(cmd.dataOffset+int(_OPERATION_HEADER_SIZE)):], name)
	cmd.WriteInt32(int32(nameLength + 4))
	cmd.WriteByte((operation.op))
	cmd.WriteByte(byte(0))
	cmd.WriteByte(byte(0))
	cmd.WriteByte(byte(nameLength))
	cmd.dataOffset += nameLength
}

func (cmd *baseCommand) writeOperationForOperationType(operation OperationType) {
	cmd.WriteInt32(int32(4))
	cmd.WriteByte(operation.op)
	cmd.WriteByte(0)
	cmd.WriteByte(0)
	cmd.WriteByte(0)
}

func (cmd *baseCommand) writeFilterExpression(exp *Expression, expSize int) Error {
	cmd.writeFieldHeader(expSize, FILTER_EXP)
	if _, err := exp.pack(cmd); err != nil {
		return err
	}
	return nil
}

func (cmd *baseCommand) writeFieldValue(value Value, ftype FieldType) Error {
	vlen, err := value.EstimateSize()
	if err != nil {
		return err
	}
	cmd.writeFieldHeader(vlen+1, ftype)
	cmd.WriteByte(byte(value.GetType()))

	_, err = value.write(cmd)
	return err
}

func (cmd *baseCommand) writeUdfArgs(value *ValueArray) Error {
	if value != nil {
		vlen, err := value.EstimateSize()
		if err != nil {
			return err
		}
		cmd.writeFieldHeader(vlen, UDF_ARGLIST)
		_, err = value.pack(cmd)
		return err
	}

	cmd.writeFieldHeader(0, UDF_ARGLIST)
	return nil
}

func (cmd *baseCommand) writeFieldInt32(val int32, ftype FieldType) {
	cmd.writeFieldHeader(4, ftype)
	cmd.WriteInt32(val)
}

func (cmd *baseCommand) writeFieldInt64(val int64, ftype FieldType) {
	cmd.writeFieldHeader(8, ftype)
	cmd.WriteInt64(val)
}

func (cmd *baseCommand) writeFieldString(str string, ftype FieldType) {
	flen := copy(cmd.dataBuffer[(cmd.dataOffset+int(_FIELD_HEADER_SIZE)):], str)
	cmd.writeFieldHeader(flen, ftype)
	cmd.dataOffset += flen
}

func (cmd *baseCommand) writeFieldBytes(bytes []byte, ftype FieldType) {
	copy(cmd.dataBuffer[cmd.dataOffset+int(_FIELD_HEADER_SIZE):], bytes)

	cmd.writeFieldHeader(len(bytes), ftype)
	cmd.dataOffset += len(bytes)
}

func (cmd *baseCommand) writeFieldHeader(size int, ftype FieldType) {
	cmd.WriteInt32(int32(size + 1))
	cmd.WriteByte((byte(ftype)))
}

func (cmd *baseCommand) begin() {
	cmd.dataOffset = int(_MSG_TOTAL_HEADER_SIZE)
}

func (cmd *baseCommand) sizeBuffer(compress bool) Error {
	return cmd.sizeBufferSz(cmd.dataOffset, compress)
}

func (cmd *baseCommand) validateHeader(header int64) Error {
	msgVersion := (uint64(header) & 0xFF00000000000000) >> 56
	if msgVersion != 2 {
		return newCustomNodeError(cmd.node, types.PARSE_ERROR, fmt.Sprintf("Invalid Message Header: Expected version to be 2, but got %v", msgVersion))
	}

	msgType := (uint64(header) & 0x00FF000000000000) >> 49
	if !(msgType == 1 || msgType == 3 || msgType == 4) {
		return newCustomNodeError(cmd.node, types.PARSE_ERROR, fmt.Sprintf("Invalid Message Header: Expected type to be 1, 3 or 4, but got %v", msgType))
	}

	msgSize := header & 0x0000FFFFFFFFFFFF
	if msgSize > int64(MaxBufferSize) {
		return newCustomNodeError(cmd.node, types.PARSE_ERROR, fmt.Sprintf("Invalid Message Header: Expected size to be under 10MiB, but got %v", msgSize))
	}

	return nil
}

const (
	msgHeaderPad  = 16
	zlibHeaderPad = 2
)

func (cmd *baseCommand) sizeBufferSz(size int, willCompress bool) Error {

	if willCompress {
		// adds zlib and proto pads to the size of the buffer
		size += msgHeaderPad + zlibHeaderPad
	}

	// Corrupted data streams can result in a huge length.
	// Do a sanity check here.
	if size > MaxBufferSize || size < 0 {
		return newCustomNodeError(cmd.node, types.PARSE_ERROR, fmt.Sprintf("Invalid size for buffer: %d", size))
	}

	if cmd.conn != nil && cmd.conn.buffHist != nil {
		cmd.conn.buffHist.Add(uint64(size))
	}

	if size <= len(cmd.dataBuffer) {
		// don't touch the buffer
		// this is a noop, here to silence the linters
		cmd.dataBuffer = cmd.dataBuffer
	} else if size <= cap(cmd.dataBuffer) {
		cmd.dataBuffer = cmd.dataBuffer[:size]
	} else {
		// not enough space
		cmd.dataBuffer = buffPool.Get(size)
	}

	// The trick here to keep a ref to the buffer, and set the buffer itself
	// to a padded version of the original:
	// | Proto Header | Original Compressed Size | compressed message |
	// |    8 Bytes   |          8 Bytes         |                    |
	if willCompress {
		cmd.dataBufferCompress = cmd.dataBuffer
		cmd.dataBuffer = cmd.dataBufferCompress[msgHeaderPad+zlibHeaderPad:]
	}

	return nil
}

func (cmd *baseCommand) end() {
	var proto = int64(cmd.dataOffset-8) | (_CL_MSG_VERSION << 56) | (_AS_MSG_TYPE << 48)
	binary.BigEndian.PutUint64(cmd.dataBuffer[0:], uint64(proto))
}

func (cmd *baseCommand) markCompressed(policy Policy) {
	cmd.compressed = policy.compress()
}

func (cmd *baseCommand) compress() Error {
	if cmd.compressed && cmd.dataOffset > _COMPRESS_THRESHOLD {
		b := bytes.NewBuffer(cmd.dataBufferCompress[msgHeaderPad:])
		b.Reset()
		w := zlib.NewWriter(b)

		// There seems to be a bug either in Go's zlib or in zlibc
		// which messes up a single write block of bigger than 64KB to
		// the deflater.
		// Things work in multiple writes of 64KB though, so this is
		// how we're going to do it.
		i := 0
		const step = 64 * 1024
		for i+step < cmd.dataOffset {
			n, err := w.Write(cmd.dataBuffer[i : i+step])
			i += n
			if err != nil {
				return newErrorAndWrap(err, types.SERIALIZE_ERROR)
			}
		}

		if i < cmd.dataOffset {
			if _, err := w.Write(cmd.dataBuffer[i:cmd.dataOffset]); err != nil {
				return newErrorAndWrap(err, types.SERIALIZE_ERROR)
			}
		}

		// flush
		if err := w.Close(); err != nil {
			return newErrorAndWrap(err, types.SERIALIZE_ERROR)
		}

		compressedSz := b.Len()

		// check if compression ended up inflating the data.
		// If so, the internal buffer has grown and reallocated, try to reuse it.
		// If not possible to reuse it, reallocate a buffer.
		if compressedSz+msgHeaderPad > len(cmd.dataBufferCompress) {
			// compression added to the size of the message
			buf := buffPool.Get(compressedSz + msgHeaderPad)
			if n := copy(buf[msgHeaderPad:], b.Bytes()); n < compressedSz {
				return newError(types.SERIALIZE_ERROR)
			}
			cmd.dataBufferCompress = buf
		}

		// Use compressed buffer if compression completed within original buffer size.
		var proto = int64(compressedSz+8) | (_CL_MSG_VERSION << 56) | (_AS_MSG_TYPE_COMPRESSED << 48)
		binary.BigEndian.PutUint64(cmd.dataBufferCompress[0:], uint64(proto))
		binary.BigEndian.PutUint64(cmd.dataBufferCompress[8:], uint64(cmd.dataOffset))

		cmd.dataBuffer = cmd.dataBufferCompress
		cmd.dataOffset = compressedSz + msgHeaderPad
		cmd.dataBufferCompress = nil
	}

	return nil
}

// isCompressed returns the length of the compressed buffer.
// If the buffer is not compressed, the result will be -1
func (cmd *baseCommand) compressedSize() int {
	proto := Buffer.BytesToInt64(cmd.dataBuffer, 0)
	size := proto & 0xFFFFFFFFFFFF

	msgType := (proto >> 48) & 0xff

	if msgType != _AS_MSG_TYPE_COMPRESSED {
		return -1
	}

	return int(size)
}

func (cmd *baseCommand) batchInDoubt(isWrite bool, commandSentCounter int) bool {
	return isWrite && commandSentCounter > 1
}

func (cmd *baseCommand) isRead() bool {
	return true
}

// grpcPutBufferBack puts the assigned buffer back in the pool.
// This function should only be called from grpc commands.
func (cmd *baseCommand) grpcPutBufferBack() {
	// put the data buffer back in the pool in case it gets used again
	buffPool.Put(cmd.dataBuffer)
	cmd.dataBuffer = nil
}

///////////////////////////////////////////////////////////////////////////////
//
//	Execute
//
///////////////////////////////////////////////////////////////////////////////

func (cmd *baseCommand) execute(ifc command) Error {
	policy := ifc.getPolicy(ifc).GetBasePolicy()
	deadline := policy.deadline()

	return cmd.executeAt(ifc, policy, deadline, -1)
}

func (cmd *baseCommand) executeAt(ifc command, policy *BasePolicy, deadline time.Time, iterations int) (errChain Error) {
	// for exponential backoff
	interval := policy.SleepBetweenRetries

	transStart := time.Now()

	notFirstIteration := false
	isClientTimeout := false
	loopCount := 0

	var err Error

	// Execute command until successful, timed out or maximum iterations have been reached.
	for {
		cmd.commandSentCounter++
		loopCount++

		// too many retries
		if (policy.MaxRetries <= 0 && cmd.commandSentCounter > 1) || (policy.MaxRetries > 0 && cmd.commandSentCounter > policy.MaxRetries) {
			if cmd.node != nil && cmd.node.cluster != nil {
				cmd.node.cluster.maxRetriesExceededCount.GetAndIncrement()
			}
			applyTransactionMetrics(cmd.node, ifc.transactionType(), transStart)
			return chainErrors(ErrMaxRetriesExceeded.err(), errChain).iter(cmd.commandSentCounter).setInDoubt(ifc.isRead(), cmd.commandSentCounter).setNode(cmd.node)
		}

		// Sleep before trying again, after the first iteration
		if policy.SleepBetweenRetries > 0 && notFirstIteration {
			// Do not sleep if you know you'll wake up after the deadline
			if policy.TotalTimeout > 0 && time.Now().Add(interval).After(deadline) {
				break
			}

			time.Sleep(interval)
			if policy.SleepMultiplier > 1 {
				interval = time.Duration(float64(interval) * policy.SleepMultiplier)
			}
		}

		if notFirstIteration {
			applyTransactionRetryMetrics(cmd.node)

			if !ifc.prepareRetry(ifc, isClientTimeout || (err != nil && err.Matches(types.SERVER_NOT_AVAILABLE))) {
				if bc, ok := ifc.(batcher); ok {
					// Batch may be retried in separate commands.
					alreadyRetried, err := bc.retryBatch(bc, cmd.node.cluster, deadline, cmd.commandSentCounter)
					if alreadyRetried {
						// Batch was retried in separate subcommands. Complete this command.
						applyTransactionMetrics(cmd.node, ifc.transactionType(), transStart)
						if err != nil {
							return chainErrors(err, errChain).iter(cmd.commandSentCounter).setNode(cmd.node).setInDoubt(ifc.isRead(), cmd.commandSentCounter)
						}
						return nil
					}

					// chain the errors and retry
					if err != nil {
						errChain = chainErrors(err, errChain).iter(cmd.commandSentCounter).setNode(cmd.node).setInDoubt(ifc.isRead(), cmd.commandSentCounter)
						continue
					}
				}
			}
		}

		// NOTE: This is important to be after the prepareRetry block above
		isClientTimeout = false

		notFirstIteration = true

		// check for command timeout
		if policy.TotalTimeout > 0 && time.Now().After(deadline) {
			break
		}

		// set command node, so when you return a record it has the node
		cmd.node, err = ifc.getNode(ifc)
		if cmd.node == nil || !cmd.node.IsActive() || err != nil {
			isClientTimeout = false

			// chain the errors
			if err != nil {
				errChain = chainErrors(err, errChain).iter(cmd.commandSentCounter).setInDoubt(ifc.isRead(), cmd.commandSentCounter)
			}

			// Node is currently inactive. Retry.
			continue
		}

		// check if node has encountered too many errors
		if err = cmd.node.validateErrorCount(); err != nil {
			isClientTimeout = false

			applyTransactionErrorMetrics(cmd.node)

			// chain the errors
			errChain = chainErrors(err, errChain).iter(cmd.commandSentCounter).setNode(cmd.node).setInDoubt(ifc.isRead(), cmd.commandSentCounter)

			// Max error rate achieved, try again per policy
			continue
		}

		cmd.conn, err = ifc.getConnection(policy)
		if err != nil {
			isClientTimeout = false

			// chain the errors
			errChain = chainErrors(err, errChain).iter(cmd.commandSentCounter).setNode(cmd.node).setInDoubt(ifc.isRead(), cmd.commandSentCounter)

			applyTransactionErrorMetrics(cmd.node)

			// exit immediately if connection pool is exhausted and the corresponding policy option is set
			if policy.ExitFastOnExhaustedConnectionPool && errors.Is(err, ErrConnectionPoolExhausted) {
				break
			}

			if errors.Is(err, ErrConnectionPoolEmpty) || errors.Is(err, ErrConnectionPoolExhausted) {
				if errors.Is(err, ErrConnectionPoolExhausted) || (errors.Is(err, ErrConnectionPoolEmpty) && loopCount == 1) {
					isClientTimeout = true
				}
				// if the connection pool is empty, we still haven't tried
				// the transaction to increase the iteration count.
				cmd.commandSentCounter--
			}
			logger.Logger.Debug("Node " + cmd.node.String() + ": " + err.Error())
			continue
		}

		// Assign the connection buffer to the command buffer
		cmd.dataBuffer = cmd.conn.dataBuffer

		// Set command buffer.
		err = ifc.writeBuffer(ifc)
		if err != nil {
			applyTransactionErrorMetrics(cmd.node)

			// chain the errors
			err = chainErrors(err, errChain).iter(cmd.commandSentCounter).setNode(cmd.node).setInDoubt(ifc.isRead(), cmd.commandSentCounter)

			// All runtime exceptions are considered fatal. Do not retry.
			// Close socket to flush out possible garbage. Do not put back in pool.
			cmd.conn.Close()
			cmd.conn = nil
			applyTransactionMetrics(cmd.node, ifc.transactionType(), transStart)
			return err
		}

		// Reset timeout in send buffer (destined for server) and socket.
		binary.BigEndian.PutUint32(cmd.dataBuffer[22:], 0)
		if !deadline.IsZero() {
			serverTimeout := time.Until(deadline)
			if serverTimeout < time.Millisecond {
				serverTimeout = time.Millisecond
			}
			binary.BigEndian.PutUint32(cmd.dataBuffer[22:], uint32(serverTimeout/time.Millisecond))
		}

		// now that the deadline has been set in the buffer, compress the contents
		if err = cmd.compress(); err != nil {
			applyTransactionErrorMetrics(cmd.node)
			return chainErrors(err, errChain).iter(cmd.commandSentCounter).setNode(cmd.node).setInDoubt(ifc.isRead(), cmd.commandSentCounter)
		}

		// now that the deadline has been set in the buffer, compress the contents
		if err = cmd.prepareBuffer(ifc, deadline); err != nil {
			applyTransactionErrorMetrics(cmd.node)
			applyTransactionMetrics(cmd.node, ifc.transactionType(), transStart)
			return chainErrors(err, errChain).iter(cmd.commandSentCounter).setNode(cmd.node)
		}

		// Send command.
		cmd.commandWasSent = true
		_, err = cmd.conn.Write(cmd.dataBuffer[:cmd.dataOffset])
		if err != nil {
			applyTransactionErrorMetrics(cmd.node)

			// chain the errors
			errChain = chainErrors(err, errChain).iter(cmd.commandSentCounter).setNode(cmd.node).setInDoubt(ifc.isRead(), cmd.commandSentCounter)

			isClientTimeout = false
			if deviceOverloadError(err) {
				cmd.node.incrErrorCount()
			}

			// IO errors are considered temporary anomalies. Retry.
			// Close socket to flush out possible garbage. Do not put back in pool.
			cmd.conn.Close()
			cmd.conn = nil

			logger.Logger.Debug("Node " + cmd.node.String() + ": " + err.Error())
			continue
		}

		// Parse results.
		err = ifc.parseResult(ifc, cmd.conn)
		if err != nil {
			applyTransactionErrorMetrics(cmd.node)

			// chain the errors
			errChain = chainErrors(err, errChain).iter(cmd.commandSentCounter).setNode(cmd.node).setInDoubt(ifc.isRead(), cmd.commandSentCounter)

			if networkError(err) {
				isTimeout := errors.Is(err, ErrTimeout)
				isClientTimeout = isTimeout
				if !isTimeout {
					if deviceOverloadError(err) {
						cmd.node.incrErrorCount()
					}
				}

				// IO errors are considered temporary anomalies. Retry.
				// Close socket to flush out possible garbage. Do not put back in pool.
				cmd.conn.Close()

				logger.Logger.Debug("Node " + cmd.node.String() + ": " + err.Error())

				// retry only for non-streaming commands
				if !cmd.oneShot {
					cmd.conn = nil
					continue
				}
			}

			// close the connection
			// cancelling/closing the batch/multi commands will return an error, which will
			// close the connection to throw away its data and signal the server about the
			// situation. We will not put back the connection in the buffer.
			if ifc.canPutConnBack() && cmd.conn.IsConnected() && KeepConnection(err) {
				// Put connection back in pool.
				cmd.node.PutConnection(cmd.conn)
			} else {
				cmd.conn.Close()
				cmd.conn = nil
			}

			applyTransactionMetrics(cmd.node, ifc.transactionType(), transStart)
			return errChain.setInDoubt(ifc.isRead(), cmd.commandSentCounter)
		}

		applyTransactionMetrics(cmd.node, ifc.transactionType(), transStart)

		// in case it has grown and re-allocated, it means
		// it was borrowed from the pool, sp put it back.
		if &cmd.dataBufferCompress != &cmd.conn.origDataBuffer {
			buffPool.Put(cmd.dataBufferCompress)
		} else if &cmd.dataBuffer != &cmd.conn.origDataBuffer {
			buffPool.Put(cmd.dataBuffer)
		}

		cmd.dataBuffer = nil
		cmd.dataBufferCompress = nil
		cmd.conn.dataBuffer = cmd.conn.origDataBuffer

		// Put connection back in pool.
		ifc.putConnection(cmd.conn)

		// command has completed successfully. Exit method.
		return nil

	}

	// execution timeout
	if cmd.node != nil && cmd.node.cluster != nil {
		cmd.node.cluster.totalTimeoutExceededCount.GetAndIncrement()
	}
	errChain = chainErrors(ErrTimeout.err(), errChain).iter(cmd.commandSentCounter).setNode(cmd.node).setInDoubt(ifc.isRead(), cmd.commandSentCounter)
	return errChain
}

func (cmd *baseCommand) prepareBuffer(ifc command, deadline time.Time) Error {
	// Set command buffer.
	if err := ifc.writeBuffer(ifc); err != nil {
		return err
	}

	// Reset timeout in send buffer (destined for server) and socket.
	binary.BigEndian.PutUint32(cmd.dataBuffer[22:], 0)
	if !deadline.IsZero() {
		serverTimeout := time.Until(deadline)
		if serverTimeout < time.Millisecond {
			serverTimeout = time.Millisecond
		}
		binary.BigEndian.PutUint32(cmd.dataBuffer[22:], uint32(serverTimeout/time.Millisecond))
	}

	// now that the deadline has been set in the buffer, compress the contents
	return cmd.compress()
}

func (cmd *baseCommand) canPutConnBack() bool {
	return true
}

func (cmd *baseCommand) parseRecordResults(ifc command, receiveSize int) (bool, Error) {
	panic("Abstract method. Should not end up here")
}

func networkError(err Error) bool {
	return err.Matches(types.NETWORK_ERROR, types.TIMEOUT)
}

func deviceOverloadError(err Error) bool {
	return err.Matches(types.DEVICE_OVERLOAD)
}

func applyTransactionMetrics(node *Node, tt transactionType, tb time.Time) {
	if node != nil && node.cluster.MetricsEnabled() {
		applyMetrics(tt, &node.stats, tb)
	}
}

func applyTransactionErrorMetrics(node *Node) {
	if node != nil {
		node.stats.TransactionErrorCount.GetAndIncrement()
	}
}

func applyTransactionRetryMetrics(node *Node) {
	if node != nil {
		node.stats.TransactionRetryCount.GetAndIncrement()
	}
}

func applyMetrics(tt transactionType, metrics *nodeStats, s time.Time) {
	d := uint64(time.Since(s).Microseconds())
	switch tt {
	case ttGet:
		metrics.GetMetrics.Add(d)
	case ttGetHeader:
		metrics.GetHeaderMetrics.Add(d)
	case ttExists:
		metrics.ExistsMetrics.Add(d)
	case ttPut:
		metrics.PutMetrics.Add(d)
	case ttDelete:
		metrics.DeleteMetrics.Add(d)
	case ttOperate:
		metrics.OperateMetrics.Add(d)
	case ttQuery:
		metrics.QueryMetrics.Add(d)
	case ttScan:
		metrics.ScanMetrics.Add(d)
	case ttUDF:
		metrics.UDFMetrics.Add(d)
	case ttBatchRead:
		metrics.BatchReadMetrics.Add(d)
	case ttBatchWrite:
		metrics.BatchWriteMetrics.Add(d)
	}
}