Merge pull request #1010 from kak-tus/pipe_timeouts

Add comments about pipeline technique.

pipeline.go

@@ -8,6 +8,19 @@ import (
 
 type pipelineExecer func([]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
 	Do(args ...interface{}) *Cmd