Improve locale character tables handling and reduce pattern cache size

If a locale other than C is active, character tables are saved into the
compile context. Every compiled pattern will have a pointer to the
character table, that was present in the context at the time of the
pattern compilation. Thus, the cache entries don't need to carry char
tables pointer, which reduces their size to 8 bytes on 64-bit. Instead,
the generated character tables are tracked in a separate HashTable. If a
character table was generated before, it'll be assigned to the compile
context when the locale changes. Otherwise a new char table will be
generated and cached.

Author: weltling

ext/pcre/php_pcre.c

@@ -55,9 +55,6 @@ struct _pcre_cache_entry {
 	uint32_t compile_options;
 	uint32_t extra_compile_options;
 	uint32_t refcount;
-#if HAVE_SETLOCALE
-	const uint8_t *tables;
-#endif
 };
 
 enum {
@@ -100,6 +97,16 @@ static MUTEX_T pcre_mt = NULL;
 #define php_pcre_mutex_unlock()
 #endif
 
+#if HAVE_SETLOCALE
+ZEND_TLS HashTable char_tables;
+
+static void php_pcre_free_char_table(zval *data)
+{/*{{{*/
+	void *ptr = Z_PTR_P(data);
+	pefree(ptr, 1);
+}/*}}}*/
+#endif
+
 static void pcre_handle_exec_error(int pcre_code) /* {{{ */
 {
 	int preg_code = 0;
@@ -141,9 +148,6 @@ static void php_free_pcre_cache(zval *data) /* {{{ */
 	pcre_cache_entry *pce = (pcre_cache_entry *) Z_PTR_P(data);
 	if (!pce) return;
 	pcre2_code_free(pce->re);
-#if HAVE_SETLOCALE
-	if ((void*)pce->tables) pefree((void*)pce->tables, 1);
-#endif
 	pefree(pce, 1);
 }
 /* }}} */
@@ -262,6 +266,9 @@ static PHP_GINIT_FUNCTION(pcre) /* {{{ */
 #endif
 
 	php_pcre_init_pcre2(1);
+#if HAVE_SETLOCALE
+	zend_hash_init(&char_tables, 1, NULL, php_pcre_free_char_table, 1);
+#endif
 }
 /* }}} */
 
@@ -270,6 +277,9 @@ static PHP_GSHUTDOWN_FUNCTION(pcre) /* {{{ */
 	zend_hash_destroy(&pcre_globals->pcre_cache);
 
 	php_pcre_shutdown_pcre2();
+#if HAVE_SETLOCALE
+	zend_hash_destroy(&char_tables);
+#endif
 
 	php_pcre_mutex_free();
 }
@@ -535,6 +545,7 @@ PHPAPI pcre_cache_entry* pcre_get_compiled_regex_cache(zend_string *regex)
 	size_t				 pattern_len;
 	uint32_t			 poptions = 0;
 	const uint8_t       *tables = NULL;
+	uint8_t              save_tables = 0;
 	zval                *zv;
 	pcre_cache_entry	 new_entry;
 	int					 rc;
@@ -705,13 +716,11 @@ PHPAPI pcre_cache_entry* pcre_get_compiled_regex_cache(zend_string *regex)
 
 #if HAVE_SETLOCALE
 	if (key != regex) {
-		/* XXX a better solution here were to create a copy of cctx
-			and to cache it along with the generated tables. Once same locale
-			is encountered, the cached cctx and tables would be fetched.
-			Currently the tables are generated every time a locale based
-			pattern is used, and the tables are overwritten in the global
-			cctx. */
-		tables = pcre2_maketables(gctx);
+		tables = (uint8_t *)zend_hash_find_ptr(&char_tables, BG(locale_string));
+		if (!tables) {
+			save_tables = 1;
+			tables = pcre2_maketables(gctx);
+		}
 		pcre2_set_character_tables(cctx, tables);
 	}
 #endif
@@ -739,7 +748,7 @@ PHPAPI pcre_cache_entry* pcre_get_compiled_regex_cache(zend_string *regex)
 		php_error_docref(NULL,E_WARNING, "Compilation failed: %s at offset %zu", error, erroffset);
 		pcre_handle_exec_error(PCRE2_ERROR_INTERNAL);
 		efree(pattern);
-		if (tables) {
+		if (save_tables) {
 			pefree((void*)tables, 1);
 		}
 		return NULL;
@@ -779,7 +788,9 @@ PHPAPI pcre_cache_entry* pcre_get_compiled_regex_cache(zend_string *regex)
 	new_entry.compile_options = coptions;
 	new_entry.extra_compile_options = extra_coptions;
 #if HAVE_SETLOCALE
-	new_entry.tables = tables;
+	if (save_tables) {
+		zend_hash_add_ptr(&char_tables, BG(locale_string), (void *)tables);
+	}
 #endif
 	new_entry.refcount = 0;