Improved empty string handling. Now ZE uses an interned string instead of allocation new empty string each time. (Some extensions might need to be fixed using str_efree() instead of efree() to support interned strings).

Author: dstogov

Diff for: NEWS

@@ -7,6 +7,8 @@ PHP                                                                        NEWS
 
 - Core:
   . Improved IS_VAR operands fetching. (Laruence, Dmitry)
+  . Improved empty string handling. Now ZE uses an interned string instead of
+    allocation new empty string each time. (Laruence, Dmitry)
   . Implemented internal operator overloading
     (RFC: https://wiki.php.net/rfc/operator_overloading_gmp). (Nikita)
   . Made calls from incompatible context issue an E_DEPRECATED warning instead

Diff for: Zend/zend.h

@@ -680,7 +680,11 @@ END_EXTERN_C()
 #define STR_FREE(ptr) if (ptr) { str_efree(ptr); }
 #define STR_FREE_REL(ptr) if (ptr) { str_efree_rel(ptr); }
 
+#ifndef ZTS
+#define STR_EMPTY_ALLOC() CG(interned_empty_string)? CG(interned_empty_string) : estrndup("", sizeof("")-1)
+#else
 #define STR_EMPTY_ALLOC() estrndup("", sizeof("")-1)
+#endif
 
 #define STR_REALLOC(ptr, size) \
 			ptr = (char *) erealloc(ptr, size);

Diff for: Zend/zend_compile.c

@@ -2461,14 +2461,14 @@ void zend_do_build_full_name(znode *result, znode *prefix, znode *name, int is_c
 
 	if (is_class_member) {
 		length = sizeof("::")-1 + Z_STRLEN(result->u.constant) + Z_STRLEN(name->u.constant);
-		Z_STRVAL(result->u.constant) = erealloc(Z_STRVAL(result->u.constant), length+1);
+		Z_STRVAL(result->u.constant) = str_erealloc(Z_STRVAL(result->u.constant), length+1);
 		memcpy(&Z_STRVAL(result->u.constant)[Z_STRLEN(result->u.constant)], "::", sizeof("::")-1);
 		memcpy(&Z_STRVAL(result->u.constant)[Z_STRLEN(result->u.constant) + sizeof("::")-1], Z_STRVAL(name->u.constant), Z_STRLEN(name->u.constant)+1);
 		str_efree(Z_STRVAL(name->u.constant));
 		Z_STRLEN(result->u.constant) = length;
 	} else {
 		length = sizeof("\\")-1 + Z_STRLEN(result->u.constant) + Z_STRLEN(name->u.constant);
-		Z_STRVAL(result->u.constant) = erealloc(Z_STRVAL(result->u.constant), length+1);
+		Z_STRVAL(result->u.constant) = str_erealloc(Z_STRVAL(result->u.constant), length+1);
 		memcpy(&Z_STRVAL(result->u.constant)[Z_STRLEN(result->u.constant)], "\\", sizeof("\\")-1);
 		memcpy(&Z_STRVAL(result->u.constant)[Z_STRLEN(result->u.constant) + sizeof("\\")-1], Z_STRVAL(name->u.constant), Z_STRLEN(name->u.constant)+1);
 		str_efree(Z_STRVAL(name->u.constant));

Diff for: Zend/zend_extensions.h

@@ -28,7 +28,7 @@
 /* The first number is the engine version and the rest is the date.
  * This way engine 2/3 API no. is always greater than engine 1 API no..
  */
-#define ZEND_EXTENSION_API_NO	220131107
+#define ZEND_EXTENSION_API_NO	220131226
 
 typedef struct _zend_extension_version_info {
 	int zend_extension_api_no;

Diff for: Zend/zend_globals.h

@@ -146,6 +146,9 @@ struct _zend_compiler_globals {
 	char *interned_strings_end;
 	char *interned_strings_top;
 	char *interned_strings_snapshot_top;
+#ifndef ZTS
+	char *interned_empty_string;
+#endif
 
 	HashTable interned_strings;
 

Diff for: Zend/zend_modules.h

@@ -33,7 +33,7 @@
 #define ZEND_MODULE_INFO_FUNC_ARGS zend_module_entry *zend_module TSRMLS_DC
 #define ZEND_MODULE_INFO_FUNC_ARGS_PASSTHRU zend_module TSRMLS_CC
 
-#define ZEND_MODULE_API_NO 20131106
+#define ZEND_MODULE_API_NO 20131226
 #ifdef ZTS
 #define USING_ZTS 1
 #else

Diff for: Zend/zend_string.c

@@ -61,6 +61,8 @@ void zend_interned_strings_init(TSRMLS_D)
 	mprotect(CG(interned_strings_start), CG(interned_strings_end) - CG(interned_strings_start), PROT_READ);
 #endif
 
+    /* interned empty string */
+	CG(interned_empty_string) = zend_new_interned_string_int("", sizeof(""), 0 TSRMLS_CC);
 #endif
 
 	zend_new_interned_string = zend_new_interned_string_int;

Diff for: ext/opcache/ZendAccelerator.c

@@ -387,6 +387,9 @@ static void accel_use_shm_interned_strings(TSRMLS_D)
 {
 	Bucket *p, *q;
 
+	/* empty string */
+	CG(interned_empty_string) = accel_new_interned_string("", sizeof(""), 0 TSRMLS_CC);
+
 	/* function table hash keys */
 	p = CG(function_table)->pListHead;
 	while (p) {

Diff for: ext/session/mod_user_class.c

@@ -86,7 +86,7 @@ PHP_METHOD(SessionHandler, read)
 	}
 
 	RETVAL_STRINGL(val, val_len, 1);
-	efree(val);
+	str_efree(val);
 	return;
 }
 /* }}} */

Diff for: ext/session/session.c

@@ -513,9 +513,9 @@ static void php_session_initialize(TSRMLS_D) /* {{{ */
 		PHP_MD5Final(PS(session_data_hash), &context);
 
 		php_session_decode(val, vallen TSRMLS_CC);
-		efree(val);
+		str_efree(val);
 	} else {
-			memset(PS(session_data_hash),'\0', 16);
+		memset(PS(session_data_hash),'\0', 16);
 	}
 
 	if (!PS(use_cookies) && PS(send_cookie)) {

Diff for: ext/spl/spl_iterators.c

@@ -2059,7 +2059,7 @@ SPL_METHOD(RegexIterator, accept)
 	}
 
 	if (use_copy) {
-		efree(subject);
+		str_efree(subject);
 	}
 } /* }}} */