Changed zend_smart_str allocation granularity to do the better job together with Zend MM and avoid useless calls to erealloc().

Author: dstogov

Zend/zend_alloc.c

@@ -287,16 +287,6 @@ struct _zend_mm_bin {
 	char               bytes[ZEND_MM_PAGE_SIZE * 8];
 };
 
-#if ZEND_DEBUG
-typedef struct _zend_mm_debug_info {
-	size_t             size;
-	const char        *filename;
-	const char        *orig_filename;
-	uint               lineno;
-	uint               orig_lineno;
-} zend_mm_debug_info;
-#endif
-
 struct _zend_mm_free_slot {
 	zend_mm_free_slot *next_free_slot;
 };

Zend/zend_alloc.h

@@ -50,6 +50,20 @@ typedef struct _zend_leak_info {
 	uint orig_lineno;
 } zend_leak_info;
 
+#if ZEND_DEBUG
+typedef struct _zend_mm_debug_info {
+	size_t             size;
+	const char        *filename;
+	const char        *orig_filename;
+	uint               lineno;
+	uint               orig_lineno;
+} zend_mm_debug_info;
+
+# define ZEND_MM_OVERHEAD ZEND_MM_ALIGNED_SIZE(sizeof(zend_mm_debug_info))
+#else 
+# define ZEND_MM_OVERHEAD 0
+#endif
+
 BEGIN_EXTERN_C()
 
 ZEND_API char*  ZEND_FASTCALL zend_strndup(const char *s, size_t length) ZEND_ATTRIBUTE_MALLOC;

Zend/zend_smart_str.h

@@ -22,14 +22,19 @@
 #include <zend.h>
 #include "zend_smart_str_public.h"
 
-#ifndef SMART_STR_PREALLOC
-#define SMART_STR_PREALLOC 128
+#define SMART_STR_OVERHEAD (ZEND_MM_OVERHEAD + _STR_HEADER_SIZE)
+
+#ifndef SMART_STR_PAGE
+# define SMART_STR_PAGE 4096
 #endif
 
 #ifndef SMART_STR_START_SIZE
-#define SMART_STR_START_SIZE 78
+# define SMART_STR_START_SIZE (256 - SMART_STR_OVERHEAD - 1)
 #endif
 
+#define SMART_STR_NEW_SIZE(newlen) \
+	(((newlen + SMART_STR_OVERHEAD + SMART_STR_PAGE) & ~(SMART_STR_PAGE - 1)) - SMART_STR_OVERHEAD - 1)
+
 #define smart_str_appends_ex(dest, src, what) \
 	smart_str_appendl_ex((dest), (src), strlen(src), (what))
 #define smart_str_appends(dest, src) \
@@ -55,14 +60,14 @@ static zend_always_inline size_t smart_str_alloc(smart_str *str, size_t len, zen
 		newlen = len;
 		str->a = newlen < SMART_STR_START_SIZE
 				? SMART_STR_START_SIZE
-				: newlen + SMART_STR_PREALLOC;
+				: SMART_STR_NEW_SIZE(newlen);
 		str->s = zend_string_alloc(str->a, persistent);
 		str->s->len = 0;
 	} else {
 		newlen = str->s->len + len;
 		if (newlen >= str->a) {
-			str->a = newlen + SMART_STR_PREALLOC;
-			str->s = (zend_string *) perealloc(str->s, _STR_HEADER_SIZE + str->a + 1, persistent);
+			str->a = SMART_STR_NEW_SIZE(newlen);
+			str->s = (zend_string *) perealloc2(str->s, _STR_HEADER_SIZE + str->a + 1, _STR_HEADER_SIZE + str->s->len + 1, persistent);
 		}
 	}
 	return newlen;