package redis import ( "context" ) type pipelineExecer func(context.Context, []Cmder) error // Pipeliner is an mechanism to realise Redis Pipeline technique. // // Pipelining is a technique to extremely speed up processing by packing // operations to batches, send them at once to Redis and read a replies in a // singe step. // See https://redis.io/topics/pipelining // // Pay attention, that Pipeline is not a transaction, so you can get unexpected // results in case of big pipelines and small read/write timeouts. // Redis client has retransmission logic in case of timeouts, pipeline // can be retransmitted and commands can be executed more then once. // To avoid this: it is good idea to use reasonable bigger read/write timeouts // depends of your batch size and/or use TxPipeline. type Pipeliner interface { StatefulCmdable Len() int Do(ctx context.Context, args ...interface{}) *Cmd Process(ctx context.Context, cmd Cmder) error Discard() Exec(ctx context.Context) ([]Cmder, error) } var _ Pipeliner = (*Pipeline)(nil) // Pipeline implements pipelining as described in // http://redis.io/topics/pipelining. // Please note: it is not safe for concurrent use by multiple goroutines. type Pipeline struct { cmdable statefulCmdable exec pipelineExecer cmds []Cmder } func (c *Pipeline) init() { c.cmdable = c.Process c.statefulCmdable = c.Process } // Len returns the number of queued commands. func (c *Pipeline) Len() int { return len(c.cmds) } // Do queues the custom command for later execution. func (c *Pipeline) Do(ctx context.Context, args ...interface{}) *Cmd { cmd := NewCmd(ctx, args...) _ = c.Process(ctx, cmd) return cmd } // Process queues the cmd for later execution. func (c *Pipeline) Process(ctx context.Context, cmd Cmder) error { c.cmds = append(c.cmds, cmd) return nil } // Discard resets the pipeline and discards queued commands. func (c *Pipeline) Discard() { c.cmds = c.cmds[:0] } // Exec executes all previously queued commands using one // client-server roundtrip. // // Exec always returns list of commands and error of the first failed // command if any. func (c *Pipeline) Exec(ctx context.Context) ([]Cmder, error) { if len(c.cmds) == 0 { return nil, nil } cmds := c.cmds c.cmds = nil return cmds, c.exec(ctx, cmds) } func (c *Pipeline) Pipelined(ctx context.Context, fn func(Pipeliner) error) ([]Cmder, error) { if err := fn(c); err != nil { return nil, err } return c.Exec(ctx) } func (c *Pipeline) Pipeline() Pipeliner { return c } func (c *Pipeline) TxPipelined(ctx context.Context, fn func(Pipeliner) error) ([]Cmder, error) { return c.Pipelined(ctx, fn) } func (c *Pipeline) TxPipeline() Pipeliner { return c }