Add INI setting to choose session consistent hash (ketama or ketama_weighted) (#392)

Provides a new INI option to select the same consistent hash behavior as
older versions of php-memcached, to aid in migration from PHP 5.x to PHP
7.x. When `memcached_sess_consistent_hash_type` is set to `ketama` or
`ketama_weighted`, that sets either MEMCACHED_BEHAVIOR_KETAMA or
MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED, respectively.

Resolves #344

Author: sodabrew

memcached.ini

@@ -43,6 +43,13 @@
 ; default is On
 ;memcached.sess_consistent_hash = On
 
+; memcached session consistent hash type
+; if set to 'ketama', consistent hashing (libketama) is used
+; for session handling (default for php-memcached 3.x)
+; if set to 'ketama_weighted', weighted consistent hashing (libketama) is used
+; for session handling (default for php-memcached 2.x)
+;memcached.sess_consistent_hash_type = "ketama"
+
 ; Allow failed memcached server to automatically be removed.
 ; Default is Off. (In previous versions, this setting was called memcached.sess_remove_failed)
 ;memcached.sess_remove_failed_servers = Off

php_memcached.c

@@ -323,6 +323,22 @@ PHP_INI_MH(OnUpdateSessionPrefixString)
 	return OnUpdateString(entry, new_value, mh_arg1, mh_arg2, mh_arg3, stage);
 }
 
+static
+PHP_INI_MH(OnUpdateConsistentHash)
+{
+	if (!new_value) {
+		MEMC_SESS_INI(consistent_hash_type) = MEMCACHED_BEHAVIOR_KETAMA;
+	} else if (!strcmp(ZSTR_VAL(new_value), "ketama")) {
+		MEMC_SESS_INI(consistent_hash_type) = MEMCACHED_BEHAVIOR_KETAMA;
+	} else if (!strcmp(ZSTR_VAL(new_value), "ketama_weighted")) {
+		MEMC_SESS_INI(consistent_hash_type) = MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED;
+	} else {
+		php_error_docref(NULL, E_WARNING, "memcached.sess_consistent_hash_type must be ketama or ketama_weighted");
+		return FAILURE;
+	}
+	return OnUpdateString(entry, new_value, mh_arg1, mh_arg2, mh_arg3, stage);
+}
+
 #define MEMC_INI_ENTRY(key, default_value, update_fn, gkey) \
 	STD_PHP_INI_ENTRY("memcached."key, default_value, PHP_INI_ALL, update_fn, memc.gkey, zend_php_memcached_globals, php_memcached_globals)
 
@@ -357,6 +373,7 @@ PHP_INI_BEGIN()
 	MEMC_SESSION_INI_BOOL ("binary_protocol",        "1",          OnUpdateBool,           binary_protocol_enabled)
 #endif
 	MEMC_SESSION_INI_BOOL ("consistent_hash",        "1",          OnUpdateBool,           consistent_hash_enabled)
+	MEMC_SESSION_INI_ENTRY("consistent_hash_type",   "ketama",     OnUpdateConsistentHash, consistent_hash_name)
 	MEMC_SESSION_INI_ENTRY("number_of_replicas",     "0",          OnUpdateLongGEZero,     number_of_replicas)
 	MEMC_SESSION_INI_BOOL ("randomize_replica_read", "0",          OnUpdateBool,           randomize_replica_read_enabled)
 	MEMC_SESSION_INI_BOOL ("remove_failed_servers",  "0",          OnUpdateBool,           remove_failed_servers_enabled)
@@ -1254,7 +1271,6 @@ static PHP_METHOD(Memcached, __construct)
 
 	/* Set default behaviors */
 	if (MEMC_G(default_behavior.consistent_hash_enabled)) {
-
 		memcached_return rc = memcached_behavior_set(intern->memc, MEMCACHED_BEHAVIOR_DISTRIBUTION, MEMCACHED_DISTRIBUTION_CONSISTENT);
 		if (rc != MEMCACHED_SUCCESS) {
 			php_error_docref(NULL, E_WARNING, "Failed to turn on consistent hash: %s", memcached_strerror(intern->memc, rc));
@@ -4263,6 +4279,8 @@ PHP_GINIT_FUNCTION(php_memcached)
 	php_memcached_globals->session.lock_expiration = 30;
 	php_memcached_globals->session.binary_protocol_enabled = 1;
 	php_memcached_globals->session.consistent_hash_enabled = 1;
+	php_memcached_globals->session.consistent_hash_type = MEMCACHED_BEHAVIOR_KETAMA;
+	php_memcached_globals->session.consistent_hash_name = NULL;
 	php_memcached_globals->session.number_of_replicas = 0;
 	php_memcached_globals->session.server_failure_limit = 1;
 	php_memcached_globals->session.randomize_replica_read_enabled = 1;

php_memcached.h

@@ -42,14 +42,6 @@ PHP_MEMCACHED_API zend_class_entry *php_memc_get_exception_base(int root);
 extern zend_module_entry memcached_module_entry;
 #define phpext_memcached_ptr &memcached_module_entry
 
-#ifdef ZTS
-#define MEMC_G(v) TSRMG(php_memcached_globals_id, zend_php_memcached_globals *, memc.v)
-#define MEMC_SERVER_G(v) TSRMG(php_memcached_globals_id, zend_php_memcached_globals *, server.v)
-#else
-#define MEMC_G(v) (php_memcached_globals.memc.v)
-#define MEMC_SERVER_G(v) (php_memcached_globals.server.v)
-#endif
-
 #endif /* PHP_MEMCACHED_H */
 
 /*

php_memcached_private.h

@@ -156,6 +156,8 @@ ZEND_BEGIN_MODULE_GLOBALS(php_memcached)
 
 		zend_bool binary_protocol_enabled;
 		zend_bool consistent_hash_enabled;
+		char     *consistent_hash_name;
+		int       consistent_hash_type;
 
 		zend_long server_failure_limit;
 		zend_long number_of_replicas;
@@ -207,6 +209,19 @@ ZEND_BEGIN_MODULE_GLOBALS(php_memcached)
 
 ZEND_END_MODULE_GLOBALS(php_memcached)
 
+/* Globals accessor macros */
+#ifdef ZTS
+#  define MEMC_G(v) TSRMG(php_memcached_globals_id, zend_php_memcached_globals *, memc.v)
+#  define MEMC_SERVER_G(v) TSRMG(php_memcached_globals_id, zend_php_memcached_globals *, server.v)
+#  define MEMC_SESS_INI(v) TSRMG(php_memcached_globals_id, zend_php_memcached_globals *, session.v)
+#else
+#  define MEMC_G(v) (php_memcached_globals.memc.v)
+#  define MEMC_SERVER_G(v) (php_memcached_globals.server.v)
+#  define MEMC_SESS_INI(v) (php_memcached_globals.session.v)
+#endif
+
+#define MEMC_SESS_STR_INI(vv) ((MEMC_SESS_INI(vv) && *MEMC_SESS_INI(vv)) ? MEMC_SESS_INI(vv) : NULL)
+
 PHP_RINIT_FUNCTION(memcached);
 PHP_RSHUTDOWN_FUNCTION(memcached);
 PHP_MINIT_FUNCTION(memcached);

php_memcached_session.c

@@ -43,14 +43,6 @@ typedef struct  {
 # define MAX(a,b) (((a)>(b))?(a):(b))
 #endif
 
-#ifdef ZTS
-#define MEMC_SESS_INI(v) TSRMG(php_memcached_globals_id, zend_php_memcached_globals *, session.v)
-#else
-#define MEMC_SESS_INI(v) (php_memcached_globals.session.v)
-#endif
-
-#define MEMC_SESS_STR_INI(vv) ((MEMC_SESS_INI(vv) && *MEMC_SESS_INI(vv)) ? MEMC_SESS_INI(vv) : NULL)
-
 static
 	int le_memc_sess;
 
@@ -187,9 +179,11 @@ static
 zend_bool s_configure_from_ini_values(memcached_st *memc, zend_bool silent)
 {
 #define check_set_behavior(behavior, value) \
-	if ((value) != memcached_behavior_get(memc, (behavior))) { \
+	int b = (behavior); \
+	uint64_t v = (value); \
+	if (v != memcached_behavior_get(memc, b)) { \
 		memcached_return rc; \
-		if ((rc = memcached_behavior_set(memc, (behavior), (value))) != MEMCACHED_SUCCESS) { \
+		if ((rc = memcached_behavior_set(memc, b, v)) != MEMCACHED_SUCCESS) { \
 			if (!silent) { \
 				php_error_docref(NULL, E_WARNING, "failed to initialise session memcached configuration: %s", memcached_strerror(memc, rc)); \
 			} \
@@ -202,7 +196,7 @@ zend_bool s_configure_from_ini_values(memcached_st *memc, zend_bool silent)
 	}
 
 	if (MEMC_SESS_INI(consistent_hash_enabled)) {
-		check_set_behavior(MEMCACHED_BEHAVIOR_KETAMA, 1);
+		check_set_behavior(MEMC_SESS_INI(consistent_hash_type), 1);
 	}
 
 	if (MEMC_SESS_INI(server_failure_limit)) {