niki/vendor/github.com/redis/go-redis/v9/pipeline.go

package redis

import (
	"context"
	"errors"
)

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

// single 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 is to obtain the number of commands in the pipeline that have not yet been executed.

	Len() int

	// Do is an API for executing any command.

	// If a certain Redis command is not yet supported, you can use Do to execute it.

	Do(ctx context.Context, args ...interface{}) *Cmd

	// Process is to put the commands to be executed into the pipeline buffer.

	Process(ctx context.Context, cmd Cmder) error

	// Discard is to discard all commands in the cache that have not yet been executed.

	Discard()

	// Exec is to send all the commands buffered in the pipeline to the redis-server.

	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...)

	if len(args) == 0 {

		cmd.SetErr(errors.New("redis: please enter the command to be executed"))

		return cmd

	}

	_ = 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

}