Merge pull request phpredis#1383 from marcing/develop

Added subsection of PHP Session handler: "Session locking".

Author: yatsukhnenko

README.markdown

@@ -63,6 +63,18 @@ Sessions have a lifetime expressed in seconds and stored in the INI variable "se
 The session handler requires a version of Redis with the `SETEX` command (at least 2.0).
 phpredis can also connect to a unix domain socket: `session.save_path = "unix:///var/run/redis/redis.sock?persistent=1&weight=1&database=0`.
 
+### Session locking
+Following INI variables can be used to configure session locking:
+~~~
+# Should the locking be enabled? Defaults to: 0.
+redis.session.locking_enabled: 1
+# How long should the lock live (in seconds)? Defaults to: value of max_execution_time.
+redis.session.lock_expire: 60
+# How long to wait between attempts to acquire lock, in microseconds (µs)?. Defaults to: 2000
+redis.session.lock_wait_time: 50000
+# Maximum number of times to retry (-1 means infinite). Defaults to: 10
+redis.session.lock_retries: 10
+~~~
 
 ## Distributed Redis Array