[Redis 6.2] Add LMOVE/BLMOVE commands

lib/redis.rb

@@ -1176,6 +1176,59 @@ def llen(key)
     end
   end
 
+  # Remove the first/last element in a list, append/prepend it to another list and return it.
+  #
+  # @param [String] source source key
+  # @param [String] destination destination key
+  # @param [String, Symbol] where_source from where to remove the element from the source list
+  #     e.g. 'LEFT' - from head, 'RIGHT' - from tail
+  # @param [String, Symbol] where_destination where to push the element to the source list
+  #     e.g. 'LEFT' - to head, 'RIGHT' - to tail
+  #
+  # @return [nil, String] the element, or nil when the source key does not exist
+  #
+  # @note This command comes in place of the now deprecated RPOPLPUSH.
+  #     Doing LMOVE RIGHT LEFT is equivalent.
+  def lmove(source, destination, where_source, where_destination)
+    where_source, where_destination = _normalize_move_wheres(where_source, where_destination)
+
+    synchronize do |client|
+      client.call([:lmove, source, destination, where_source, where_destination])
+    end
+  end
+
+  # Remove the first/last element in a list and append/prepend it
+  # to another list and return it, or block until one is available.
+  #
+  # @example With timeout
+  #   element = redis.blmove("foo", "bar", "LEFT", "RIGHT", timeout: 5)
+  #     # => nil on timeout
+  #     # => "element" on success
+  # @example Without timeout
+  #   element = redis.blmove("foo", "bar", "LEFT", "RIGHT")
+  #     # => "element"
+  #
+  # @param [String] source source key
+  # @param [String] destination destination key
+  # @param [String, Symbol] where_source from where to remove the element from the source list
+  #     e.g. 'LEFT' - from head, 'RIGHT' - from tail
+  # @param [String, Symbol] where_destination where to push the element to the source list
+  #     e.g. 'LEFT' - to head, 'RIGHT' - to tail
+  # @param [Hash] options
+  #   - `:timeout => Numeric`: timeout in seconds, defaults to no timeout
+  #
+  # @return [nil, String] the element, or nil when the source key does not exist or the timeout expired
+  #
+  def blmove(source, destination, where_source, where_destination, timeout: 0)
+    where_source, where_destination = _normalize_move_wheres(where_source, where_destination)
+
+    synchronize do |client|
+      command = [:blmove, source, destination, where_source, where_destination, timeout]
+      timeout += client.timeout if timeout > 0
+      client.call_with_timeout(command, timeout)
+    end
+  end
+
   # Prepend one or more values to a list, creating the list if it doesn't exist
   #
   # @param [String] key
@@ -3716,6 +3769,21 @@ def _xread(args, keys, ids, blocking_timeout_msec)
       end
     end
   end
+
+  def _normalize_move_wheres(where_source, where_destination)
+    where_source      = where_source.to_s.upcase
+    where_destination = where_destination.to_s.upcase
+
+    if where_source != "LEFT" && where_source != "RIGHT"
+      raise ArgumentError, "where_source must be 'LEFT' or 'RIGHT'"
+    end
+
+    if where_destination != "LEFT" && where_destination != "RIGHT"
+      raise ArgumentError, "where_destination must be 'LEFT' or 'RIGHT'"
+    end
+
+    [where_source, where_destination]
+  end
 end
 
 require_relative "redis/version"

lib/redis/distributed.rb

@@ -403,6 +403,21 @@ def llen(key)
       node_for(key).llen(key)
     end
 
+    # Remove the first/last element in a list, append/prepend it to another list and return it.
+    def lmove(source, destination, where_source, where_destination)
+      ensure_same_node(:lmove, [source, destination]) do |node|
+        node.lmove(source, destination, where_source, where_destination)
+      end
+    end
+
+    # Remove the first/last element in a list and append/prepend it
+    # to another list and return it, or block until one is available.
+    def blmove(source, destination, where_source, where_destination, timeout: 0)
+      ensure_same_node(:lmove, [source, destination]) do |node|
+        node.blmove(source, destination, where_source, where_destination, timeout: timeout)
+      end
+    end
+
     # Prepend one or more values to a list.
     def lpush(key, value)
       node_for(key).lpush(key, value)

test/blocking_commands_test.rb

@@ -21,6 +21,14 @@ def assert_takes_longer_than_client_timeout
     end
   end
 
+  def test_blmove_disable_client_timeout
+    target_version "6.2" do
+      assert_takes_longer_than_client_timeout do |r|
+        assert_equal '0', r.blmove('foo', 'bar', 'LEFT', 'RIGHT')
+      end
+    end
+  end
+
   def test_blpop_disable_client_timeout
     assert_takes_longer_than_client_timeout do |r|
       assert_equal %w[foo 0], r.blpop('foo')

test/cluster_commands_on_lists_test.rb

@@ -9,6 +9,12 @@ class TestClusterCommandsOnLists < Minitest::Test
   include Helper::Cluster
   include Lint::Lists
 
+  def test_lmove
+    target_version "6.2" do
+      assert_raises(Redis::CommandError) { super }
+    end
+  end
+
   def test_rpoplpush
     assert_raises(Redis::CommandError) { super }
   end

test/distributed_blocking_commands_test.rb

@@ -7,6 +7,14 @@ class TestDistributedBlockingCommands < Minitest::Test
   include Helper::Distributed
   include Lint::BlockingCommands
 
+  def test_blmove_raises
+    target_version "6.2" do
+      assert_raises(Redis::Distributed::CannotDistribute) do
+        r.blmove('foo', 'bar', 'LEFT', 'RIGHT')
+      end
+    end
+  end
+
   def test_blpop_raises
     assert_raises(Redis::Distributed::CannotDistribute) do
       r.blpop(%w[foo bar])

test/distributed_commands_on_lists_test.rb

@@ -7,6 +7,14 @@ class TestDistributedCommandsOnLists < Minitest::Test
   include Helper::Distributed
   include Lint::Lists
 
+  def test_lmove
+    target_version "6.2" do
+      assert_raises Redis::Distributed::CannotDistribute do
+        r.lmove('foo', 'bar', 'LEFT', 'RIGHT')
+      end
+    end
+  end
+
   def test_rpoplpush
     assert_raises Redis::Distributed::CannotDistribute do
       r.rpoplpush('foo', 'bar')

test/distributed_commands_requiring_clustering_test.rb

@@ -23,6 +23,19 @@ def test_renamenx
     assert_equal "s2", r.get("{qux}bar")
   end
 
+  def test_lmove
+    target_version "6.2" do
+      r.rpush("{qux}foo", "s1")
+      r.rpush("{qux}foo", "s2")
+      r.rpush("{qux}bar", "s3")
+      r.rpush("{qux}bar", "s4")
+
+      assert_equal "s1", r.lmove("{qux}foo", "{qux}bar", "LEFT", "RIGHT")
+      assert_equal ["s2"], r.lrange("{qux}foo", 0, -1)
+      assert_equal ["s3", "s4", "s1"], r.lrange("{qux}bar", 0, -1)
+    end
+  end
+
   def test_brpoplpush
     r.rpush "{qux}foo", "s1"
     r.rpush "{qux}foo", "s2"

test/lint/blocking_commands.rb

@@ -32,6 +32,10 @@ def mock(options = {}, &blk)
 
     def build_mock_commands(options = {})
       {
+        blmove: lambda do |*args|
+          sleep options[:delay] if options.key?(:delay)
+          to_protocol(args.last)
+        end,
         blpop: lambda do |*args|
           sleep options[:delay] if options.key?(:delay)
           to_protocol([args.first, args.last])
@@ -55,6 +59,23 @@ def build_mock_commands(options = {})
       }
     end
 
+    def test_blmove
+      target_version "6.2" do
+        assert_equal 's1', r.blmove('{zap}foo', '{zap}bar', 'LEFT', 'RIGHT')
+        assert_equal ['s2'], r.lrange('{zap}foo', 0, -1)
+        assert_equal ['s1', 's2', 's1'], r.lrange('{zap}bar', 0, -1)
+      end
+    end
+
+    def test_blmove_timeout
+      target_version "6.2" do
+        mock do |r|
+          assert_equal '0', r.blmove('{zap}foo', '{zap}bar', 'LEFT', 'RIGHT')
+          assert_equal LOW_TIMEOUT.to_s, r.blmove('{zap}foo', '{zap}bar', 'LEFT', 'RIGHT', timeout: LOW_TIMEOUT)
+        end
+      end
+    end
+
     def test_blpop
       assert_equal ['{zap}foo', 's1'], r.blpop('{zap}foo')
       assert_equal ['{zap}foo', 's2'], r.blpop(['{zap}foo'])
@@ -166,6 +187,16 @@ def test_bzpopmax
     end
 
     driver(:ruby, :hiredis) do
+      def test_blmove_socket_timeout
+        target_version "6.2" do
+          mock(delay: LOW_TIMEOUT * 5) do |r|
+            assert_raises(Redis::TimeoutError) do
+              r.blmove('{zap}foo', '{zap}bar', 'LEFT', 'RIGHT', timeout: LOW_TIMEOUT)
+            end
+          end
+        end
+      end
+
       def test_blpop_socket_timeout
         mock(delay: LOW_TIMEOUT * 5) do |r|
           assert_raises(Redis::TimeoutError) do

test/lint/lists.rb

@@ -2,6 +2,33 @@
 
 module Lint
   module Lists
+    def test_lmove
+      target_version "6.2" do
+        r.lpush("foo", "s1")
+        r.lpush("foo", "s2") # foo = [s2, s1]
+        r.lpush("bar", "s3")
+        r.lpush("bar", "s4") # bar = [s4, s3]
+
+        assert_nil r.lmove("nonexistent", "foo", "LEFT", "LEFT")
+
+        assert_equal "s2", r.lmove("foo", "foo", "LEFT", "RIGHT") # foo = [s1, s2]
+        assert_equal "s1", r.lmove("foo", "foo", "LEFT", "LEFT") # foo = [s1, s2]
+
+        assert_equal "s1", r.lmove("foo", "bar", "LEFT", "RIGHT") # foo = [s2], bar = [s4, s3, s1]
+        assert_equal ["s2"], r.lrange("foo", 0, -1)
+        assert_equal ["s4", "s3", "s1"], r.lrange("bar", 0, -1)
+
+        assert_equal "s2", r.lmove("foo", "bar", "LEFT", "LEFT") # foo = [], bar = [s2, s4, s3, s1]
+        assert_nil r.lmove("foo", "bar", "LEFT", "LEFT") # foo = [], bar = [s2, s4, s3, s1]
+        assert_equal ["s2", "s4", "s3", "s1"], r.lrange("bar", 0, -1)
+
+        error = assert_raises(ArgumentError) do
+          r.lmove("foo", "bar", "LEFT", "MIDDLE")
+        end
+        assert_equal "where_destination must be 'LEFT' or 'RIGHT'", error.message
+      end
+    end
+
     def test_lpush
       r.lpush "foo", "s1"
       r.lpush "foo", "s2"