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Memory optimization for embedded devices #1643

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mdamle opened this issue Feb 19, 2020 · 0 comments
Closed

Memory optimization for embedded devices #1643

mdamle opened this issue Feb 19, 2020 · 0 comments

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@mdamle
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mdamle commented Feb 19, 2020

  1. rapidjson uses MemoryPoolAllocator by default.
  2. GenericValue uses kDefaultObjectCapacity=16 and kDefaultObjectCapacity=16.

For #1:
On embedded platforms with limited memory CrtAllocator can be a good choice. You can use CrtAllocator in a module today by explicitly creating your own typedef:
"
typedef GenericValue<UTF8<>, CrtAllocator> Value
"
This is cumbersome when working on a platform with multiple modules using rapidjson since each module has to have the same definition of rapidjson::Value so as to interoperate.

One solution is to create a pre-processor directive (#define RAPIDJSON_USE_CRTALLOCATOR) such that all modules that want to use CrtAllocator can do so at compile time without having to explicitly typedef them individually.

For #2:
On the same lines as this commit: 6f58746 allow default object and array capacity to be configured using pre-processor directives.
mdamle added a commit to mdamle/rapidjson that referenced this issue Feb 20, 2020
@mdamle
Closes Tencent#1643
ad7f4db 
This change comes up with compile time pre-processor directives to
tune the behavior of rapidjson wrt memory consumption. The idea is to
allow each module using this library to choose the right defaults based
on how it consumes memory and what performance it expects.

1. RAPIDJSON_USE_CRTALLOCATOR: If defined allows you to choose
   	CrtAllocator over MemoryPoolAllocator. If it is not defined,
        chooses MemoryPoolAllocator by default.
    3. RAPIDJSON_VALUE_DEFAULT_OBJECT_CAPACITY and
       RAPIDJSON_VALUE_DEFAULT_ARRAY_CAPACITY: If defined and set to a
       	value, uses that value for default number of objects/array
       	elements to be pre-allocated. If not defined, uses value of 16:
	the current default.

Verified that all tests pass.
mdamle added a commit to mdamle/rapidjson that referenced this issue Feb 20, 2020
@mdamle
Closes Tencent#1643
093c988 
This change comes up with compile time pre-processor directives to
tune the behavior of rapidjson wrt memory consumption. The idea is to
allow each module using this library to choose the right defaults based
on how it consumes memory and what performance it expects.

1. RAPIDJSON_DEFAULT_ALLOCATOR: If defined allows you to choose
	CrtAllocator over MemoryPoolAllocator. If it is not defined, chooses MemoryPoolAllocator by default.
2. RAPIDJSON_VALUE_DEFAULT_OBJECT_CAPACITY and RAPIDJSON_VALUE_DEFAULT_ARRAY_CAPACITY: If defined and set to a
	value, uses that value for default number of objects/array elements to be pre-allocated. If not defined,
	uses value of 16: the current default.

Verified that all tests pass.
mdamle added a commit to mdamle/rapidjson that referenced this issue Feb 21, 2020
@mdamle
Closes Tencent#1643
f44e220 
This change comes up with compile time pre-processor directives to
tune the behavior of rapidjson wrt memory consumption. The idea is to
allow each module using this library to choose the right defaults based
on how it consumes memory and what performance it expects.

1. RAPIDJSON_DEFAULT_ALLOCATOR: If defined allows you to choose
	CrtAllocator over MemoryPoolAllocator. If it is not defined, chooses MemoryPoolAllocator by default.
2. RAPIDJSON_VALUE_DEFAULT_OBJECT_CAPACITY and RAPIDJSON_VALUE_DEFAULT_ARRAY_CAPACITY: If defined and set to a
	value, uses that value for default number of objects/array elements to be pre-allocated. If not defined,
	uses value of 16: the current default.

Verified that all tests pass.
mdamle added a commit to mdamle/rapidjson that referenced this issue Feb 21, 2020
@mdamle
Closes Tencent#1643
c8e89e7 
This change comes up with compile time pre-processor directives to
tune the behavior of rapidjson wrt memory consumption. The idea is to
allow each module using this library to choose the right defaults based
on how it consumes memory and what performance it expects.

1. RAPIDJSON_DEFAULT_ALLOCATOR: If defined allows you to choose
	CrtAllocator over MemoryPoolAllocator. If it is not defined, chooses MemoryPoolAllocator by default.
2. RAPIDJSON_VALUE_DEFAULT_OBJECT_CAPACITY and RAPIDJSON_VALUE_DEFAULT_ARRAY_CAPACITY: If defined and set to a
	value, uses that value for default number of objects/array elements to be pre-allocated. If not defined,
	uses value of 16: the current default.

Verified that all tests pass.
mdamle added a commit to mdamle/rapidjson that referenced this issue Feb 25, 2020
@mdamle
Closes Tencent#1643
faabc25 
This change comes up with compile time pre-processor directives to
tune the behavior of rapidjson wrt memory consumption. The idea is to
allow each module using this library to choose the right defaults based
on how it consumes memory and what performance it expects.

1. RAPIDJSON_DEFAULT_ALLOCATOR: If defined allows you to choose
	CrtAllocator over MemoryPoolAllocator. If it is not defined, chooses MemoryPoolAllocator by default.
2. RAPIDJSON_DEFAULT_STACK_ALLOCATOR: If defined allows you to choose
	MemoryPoolAllocator over CrtAllocator. If it is not defined, chooses CrtAllocator by default.
3. RAPIDJSON_VALUE_DEFAULT_OBJECT_CAPACITY and RAPIDJSON_VALUE_DEFAULT_ARRAY_CAPACITY: If defined and set to a
	value, uses that value for default number of objects/array elements to be pre-allocated. If not defined,
	uses value of 16: the current default.

Verified that all tests pass.
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@mdamle