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package redis
import (
"context"
"sync"
"github.com/go-redis/redis/v8/internal/pool"
)
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
Close() error
Discard() error
Exec(ctx context.Context) ([]Cmder, error)
}
var _ Pipeliner = (*Pipeline)(nil)
// Pipeline implements pipelining as described in
// http://redis.io/topics/pipelining. It's safe for concurrent use
// by multiple goroutines.
type Pipeline struct {
cmdable
statefulCmdable
ctx context.Context
exec pipelineExecer
mu sync.Mutex
cmds []Cmder
closed bool
}
func (c *Pipeline) init() {
c.cmdable = c.Process
c.statefulCmdable = c.Process
}
// Len returns the number of queued commands.
func (c *Pipeline) Len() int {
c.mu.Lock()
ln := len(c.cmds)
c.mu.Unlock()
return ln
}
// 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.mu.Lock()
c.cmds = append(c.cmds, cmd)
c.mu.Unlock()
return nil
}
// Close closes the pipeline, releasing any open resources.
func (c *Pipeline) Close() error {
c.mu.Lock()
_ = c.discard()
c.closed = true
c.mu.Unlock()
return nil
}
// Discard resets the pipeline and discards queued commands.
func (c *Pipeline) Discard() error {
c.mu.Lock()
err := c.discard()
c.mu.Unlock()
return err
}
func (c *Pipeline) discard() error {
if c.closed {
return pool.ErrClosed
}
c.cmds = c.cmds[:0]
return nil
}
// 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) {
c.mu.Lock()
defer c.mu.Unlock()
if c.closed {
return nil, pool.ErrClosed
}
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
}
cmds, err := c.Exec(ctx)
_ = c.Close()
return cmds, err
}
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
}
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