set sess_binary_protocol off by default with older libmemcached

Author: remicollet

memcached.ini

@@ -64,7 +64,9 @@
 ; Use the memcached binary protocol for memcached sessions (Instead of the text protocol)
 ; libmemcached replicas work only if binary mode is enabled.
 ; However, certain proxies (such as twemproxy) will work only if the binary protocol is disabled.
-; Default is On. In older versions of php-memcached, this setting was Off and was called memcached.sess_binary.
+; In older versions of php-memcached, this setting was Off and was called memcached.sess_binary.
+; Default is On with libmemcached 1.0.18 or newer.
+; Default is Off with older version.
 ;memcached.sess_binary_protocol = On
 
 ; memcached session replica read randomize

php_memcached.c

@@ -332,7 +332,11 @@ PHP_INI_BEGIN()
 	MEMC_SESSION_INI_ENTRY("lock_wait_max",          "2000",       OnUpdateLongGEZero,     lock_wait_max)
 	MEMC_SESSION_INI_ENTRY("lock_retries",           "5",          OnUpdateLong,           lock_retries)
 	MEMC_SESSION_INI_ENTRY("lock_expire",            "0",          OnUpdateLongGEZero,     lock_expiration)
+#if defined(LIBMEMCACHED_VERSION_HEX) && LIBMEMCACHED_VERSION_HEX < 0x01000018
+	MEMC_SESSION_INI_ENTRY("binary_protocol",        "0",          OnUpdateBool,           binary_protocol_enabled)
+#else
 	MEMC_SESSION_INI_ENTRY("binary_protocol",        "1",          OnUpdateBool,           binary_protocol_enabled)
+#endif
 	MEMC_SESSION_INI_ENTRY("consistent_hash",        "1",          OnUpdateBool,           consistent_hash_enabled)
 	MEMC_SESSION_INI_ENTRY("number_of_replicas",     "0",          OnUpdateLongGEZero,     number_of_replicas)
 	MEMC_SESSION_INI_ENTRY("randomize_replica_read", "0",          OnUpdateLongGEZero,     randomize_replica_read_enabled)