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package redis
import (
"context"
"github.com/go-redis/redis/v8/internal/pool"
"github.com/go-redis/redis/v8/internal/proto"
)
// TxFailedErr transaction redis failed.
const TxFailedErr = proto.RedisError("redis: transaction failed")
// Tx implements Redis transactions as described in
// http://redis.io/topics/transactions. It's NOT safe for concurrent use
// by multiple goroutines, because Exec resets list of watched keys.
// If you don't need WATCH it is better to use Pipeline.
type Tx struct {
baseClient
cmdable
statefulCmdable
hooks
ctx context.Context
}
func (c *Client) newTx(ctx context.Context) *Tx {
tx := Tx{
baseClient: baseClient{
opt: c.opt,
connPool: pool.NewStickyConnPool(c.connPool),
},
hooks: c.hooks.clone(),
ctx: ctx,
}
tx.init()
return &tx
}
func (c *Tx) init() {
c.cmdable = c.Process
c.statefulCmdable = c.Process
}
func (c *Tx) Context() context.Context {
return c.ctx
}
func (c *Tx) WithContext(ctx context.Context) *Tx {
if ctx == nil {
panic("nil context")
}
clone := *c
clone.init()
clone.hooks.lock()
clone.ctx = ctx
return &clone
}
func (c *Tx) Process(ctx context.Context, cmd Cmder) error {
return c.hooks.process(ctx, cmd, c.baseClient.process)
}
// Watch prepares a transaction and marks the keys to be watched
// for conditional execution if there are any keys.
//
// The transaction is automatically closed when fn exits.
func (c *Client) Watch(ctx context.Context, fn func(*Tx) error, keys ...string) error {
tx := c.newTx(ctx)
defer tx.Close(ctx)
if len(keys) > 0 {
if err := tx.Watch(ctx, keys...).Err(); err != nil {
return err
}
}
return fn(tx)
}
// Close closes the transaction, releasing any open resources.
func (c *Tx) Close(ctx context.Context) error {
_ = c.Unwatch(ctx).Err()
return c.baseClient.Close()
}
// Watch marks the keys to be watched for conditional execution
// of a transaction.
func (c *Tx) Watch(ctx context.Context, keys ...string) *StatusCmd {
args := make([]interface{}, 1+len(keys))
args[0] = "watch"
for i, key := range keys {
args[1+i] = key
}
cmd := NewStatusCmd(ctx, args...)
_ = c.Process(ctx, cmd)
return cmd
}
// Unwatch flushes all the previously watched keys for a transaction.
func (c *Tx) Unwatch(ctx context.Context, keys ...string) *StatusCmd {
args := make([]interface{}, 1+len(keys))
args[0] = "unwatch"
for i, key := range keys {
args[1+i] = key
}
cmd := NewStatusCmd(ctx, args...)
_ = c.Process(ctx, cmd)
return cmd
}
// Pipeline creates a pipeline. Usually it is more convenient to use Pipelined.
func (c *Tx) Pipeline() Pipeliner {
pipe := Pipeline{
ctx: c.ctx,
exec: func(ctx context.Context, cmds []Cmder) error {
return c.hooks.processPipeline(ctx, cmds, c.baseClient.processPipeline)
},
}
pipe.init()
return &pipe
}
// Pipelined executes commands queued in the fn outside of the transaction.
// Use TxPipelined if you need transactional behavior.
func (c *Tx) Pipelined(ctx context.Context, fn func(Pipeliner) error) ([]Cmder, error) {
return c.Pipeline().Pipelined(ctx, fn)
}
// TxPipelined executes commands queued in the fn in the transaction.
//
// When using WATCH, EXEC will execute commands only if the watched keys
// were not modified, allowing for a check-and-set mechanism.
//
// Exec always returns list of commands. If transaction fails
// TxFailedErr is returned. Otherwise Exec returns an error of the first
// failed command or nil.
func (c *Tx) TxPipelined(ctx context.Context, fn func(Pipeliner) error) ([]Cmder, error) {
return c.TxPipeline().Pipelined(ctx, fn)
}
// TxPipeline creates a pipeline. Usually it is more convenient to use TxPipelined.
func (c *Tx) TxPipeline() Pipeliner {
pipe := Pipeline{
ctx: c.ctx,
exec: func(ctx context.Context, cmds []Cmder) error {
return c.hooks.processTxPipeline(ctx, cmds, c.baseClient.processTxPipeline)
},
}
pipe.init()
return &pipe
}