Module: Redis::Commands::Transactions

Included in:
Redis::Commands
Defined in:
lib/redis/commands/transactions.rb

Instance Method Summary collapse

Instance Method Details

#discard ⇒ String

Discard all commands issued after MULTI.

Only call this method when ‘#multi` was called without a block.

Returns:

  • (String) —

    ‘“OK”`

See Also:



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# File 'lib/redis/commands/transactions.rb', line 134

def discard
  send_command([:discard])
end

#exec ⇒ nil, Array<...>

Execute all commands issued after MULTI.

Only call this method when ‘#multi` was called without a block.

Returns:

  • (nil, Array<...>) —

    • when commands were not executed, ‘nil`

    • when commands were executed, an array with their replies

See Also:



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# File 'lib/redis/commands/transactions.rb', line 122

def exec
  send_command([:exec])
end

#multi {|multi| ... } ⇒ String, Array<...>

Mark the start of a transaction block.

Passing a block is optional.

Examples:

With a block

redis.multi do |multi|
  multi.set("key", "value")
  multi.incr("counter")
end # => ["OK", 6]

Without a block

redis.multi
  # => "OK"
redis.set("key", "value")
  # => "QUEUED"
redis.incr("counter")
  # => "QUEUED"
redis.exec
  # => ["OK", 6]

Yields:

  • (multi) —

    the commands that are called inside this block are cached and written to the server upon returning from it

Yield Parameters:

  • multi (Redis) —

    ‘self`

Returns:

  • (String, Array<...>) —

    • when a block is not given, ‘OK`

    • when a block is given, an array with replies

See Also:



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# File 'lib/redis/commands/transactions.rb', line 36

def multi(&block) # :nodoc:
  if block_given?
    if block&.arity == 0
      Pipeline.deprecation_warning("multi", Kernel.caller_locations(1, 5))
    end

    synchronize do |prior_client|
      pipeline = Pipeline::Multi.new(prior_client)
      pipelined_connection = PipelinedConnection.new(pipeline)
      yield pipelined_connection
      prior_client.call_pipeline(pipeline)
    end
  else
    send_command([:multi])
  end
end

#unwatch ⇒ String

Forget about all watched keys.

Returns:

  • (String) —

    ‘OK`

See Also:



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# File 'lib/redis/commands/transactions.rb', line 108

def unwatch
  send_command([:unwatch])
end

#watch(*keys) ⇒ Object, String

Watch the given keys to determine execution of the MULTI/EXEC block.

Using a block is optional, but is necessary for thread-safety.

An ‘#unwatch` is automatically issued if an exception is raised within the block that is a subclass of StandardError and is not a ConnectionError.

Examples:

With a block

redis.watch("key") do
  if redis.get("key") == "some value"
    redis.multi do |multi|
      multi.set("key", "other value")
      multi.incr("counter")
    end
  else
    redis.unwatch
  end
end
  # => ["OK", 6]

Without a block

redis.watch("key")
  # => "OK"

Parameters:

  • keys (String, Array<String>) —

    one or more keys to watch

Returns:

  • (Object) —

    if using a block, returns the return value of the block

  • (String) —

    if not using a block, returns ‘OK`

See Also:



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# File 'lib/redis/commands/transactions.rb', line 83

def watch(*keys)
  synchronize do |client|
    res = client.call([:watch, *keys])

    if block_given?
      begin
        yield(self)
      rescue ConnectionError
        raise
      rescue StandardError
        unwatch
        raise
      end
    else
      res
    end
  end
end