add ZendMM

Author: Leon2012

004.md

@@ -0,0 +1,170 @@
+# ZendMM
+
+1, php内存管理内置函数
+
+    void *emalloc(size_t size)                                       分配 size 字节的内存。
+    void *ecalloc(size_t nmemb, size_t size)                         给 nmemb 元素分配 size 字节的缓冲区并初始化为零。
+    void *erealloc(void *ptr, size_t size)                           修改使用 emalloc 分配的缓冲区 ptr 的大小为 size 字节。 
+    void efree(void *ptr)                                            释放 ptr 指向的缓冲区。缓冲区必须是由 emalloc 分配的。
+    void *safe_emalloc(size_t nmemb, size_t size, size_t offset)     
+    char *estrdup(const char *s)            分配一个可存放 NULL 结尾的字符串 s 的缓冲区，并将 s复制到缓冲区内。                         
+    char *estrndup(const char *s, unsigned int length) 类似于 estrdup，但 NULL 结尾的字符串长度是已知的。
+
+2，由emalloc分配的内存都是在zend_mm_heap上
+
+    //zend_mm_mem_handlers
+    typedef struct _zend_mm_mem_handlers {
+        const char *name;
+        zend_mm_storage* (*init)(void *params);
+        void (*dtor)(zend_mm_storage *storage);
+        void (*compact)(zend_mm_storage *storage);
+        zend_mm_segment* (*_alloc)(zend_mm_storage *storage, size_t size);
+        zend_mm_segment* (*_realloc)(zend_mm_storage *storage, zend_mm_segment *ptr, size_t size);
+        void (*_free)(zend_mm_storage *storage, zend_mm_segment *ptr);
+    } zend_mm_mem_handlers;
+
+    //zend_mm_segment
+    typedef struct _zend_mm_segment {
+        size_t  size;
+        struct _zend_mm_segment *next_segment;
+    } zend_mm_segment;
+    
+    //zend_mm_storage结构
+    struct _zend_mm_storage {
+        const zend_mm_mem_handlers *handlers;//zend_mm_storage方法 (ZEND_MM_MEM_MALLOC_DSC)
+        void *data;
+    };
+    
+    //zend_mm_heap结构
+    struct _zend_mm_heap {
+        int                 use_zend_alloc;
+        void               *(*_malloc)(size_t);
+        void                (*_free)(void*);
+        void               *(*_realloc)(void*, size_t);
+        size_t              free_bitmap;
+        size_t              large_free_bitmap;
+        size_t              block_size;
+        size_t              compact_size;
+        zend_mm_segment    *segments_list;
+        zend_mm_storage    *storage;
+        size_t              real_size;
+        size_t              real_peak;
+        size_t              limit;
+        size_t              size;
+        size_t              peak;
+        size_t              reserve_size;
+        void               *reserve;
+        int                 overflow;
+        int                 internal;
+    #if ZEND_MM_CACHE
+        unsigned int        cached;
+        zend_mm_free_block *cache[ZEND_MM_NUM_BUCKETS];
+    #endif
+        zend_mm_free_block *free_buckets[ZEND_MM_NUM_BUCKETS*2];
+        zend_mm_free_block *large_free_buckets[ZEND_MM_NUM_BUCKETS];
+        zend_mm_free_block *rest_buckets[2];
+        int                 rest_count;
+    #if ZEND_MM_CACHE_STAT
+        struct {
+            int count;
+            int max_count;
+            int hit;
+            int miss;
+        } cache_stat[ZEND_MM_NUM_BUCKETS+1];
+    #endif
+    };
+    
+    //zend_alloc_globals结构
+    typedef struct _zend_alloc_globals {
+        zend_mm_heap *mm_heap;
+    } 
+    
+    //AG宏定义
+    # define AG(v) TSRMG(alloc_globals_id, zend_alloc_globals *, v)
+
+    //emalloc函数原型
+    ZEND_API void *_emalloc(size_t size ZEND_FILE_LINE_DC ZEND_FILE_LINE_ORIG_DC)
+    {
+        TSRMLS_FETCH();
+
+        if (UNEXPECTED(!AG(mm_heap)->use_zend_alloc)) {
+            return AG(mm_heap)->_malloc(size);
+        }
+        return _zend_mm_alloc_int(AG(mm_heap), size ZEND_FILE_LINE_RELAY_CC ZEND_FILE_LINE_ORIG_RELAY_CC);
+    }
+
+3，ZendMM环境变量
+
+USE_ZEND_ALLOC 是否使用 ZendMM 进行内存管理。
+ZEND_MM_MEM_TYPE 指定内存分配的方案，默认 malloc
+ZEND_MM_COMPACT 指定压缩边界值
+
+//默认ZEND_MM_MEM_TYPE初始化
+
+    # define ZEND_MM_MEM_MALLOC_DSC {"malloc", zend_mm_mem_dummy_init, zend_mm_mem_dummy_dtor, zend_mm_mem_dummy_compact, zend_mm_mem_malloc_alloc, zend_mm_mem_malloc_realloc, zend_mm_mem_malloc_free}
+
+    # define ZEND_MM_MEM_WIN32_DSC {"win32", zend_mm_mem_win32_init, zend_mm_mem_win32_dtor, zend_mm_mem_win32_compact, zend_mm_mem_win32_alloc, zend_mm_mem_win32_realloc, zend_mm_mem_win32_free}
+
+    # define ZEND_MM_MEM_MMAP_ZERO_DSC {"mmap_zero", zend_mm_mem_mmap_zero_init, zend_mm_mem_mmap_zero_dtor, zend_mm_mem_dummy_compact, zend_mm_mem_mmap_zero_alloc, zend_mm_mem_mmap_realloc, zend_mm_mem_mmap_free}
+
+    # define ZEND_MM_MEM_MMAP_ANON_DSC {"mmap_anon", zend_mm_mem_dummy_init, zend_mm_mem_dummy_dtor, zend_mm_mem_dummy_compact, zend_mm_mem_mmap_anon_alloc, zend_mm_mem_mmap_realloc, zend_mm_mem_mmap_free}
+
+4，ZendMM 流程
+
+    ->SAPI
+    ->php_module_startup (main.c 2065)
+    ->zend_startup() //zend引擎启动
+    ->start_memory_manager(TSRMLS_C) //开始内存管理 
+    ->ts_allocate_id(&alloc_globals_id, sizeof(zend_alloc_globals), (ts_allocate_ctor) alloc_globals_ctor, (ts_allocate_dtor) alloc_globals_dtor) //初始化AG
+
+    ->alloc_globals_ctor(&alloc_globals) //申请内存
+
+        //分配内存,读取环境变量USE_ZEND_ALLOC，如果USE_ZEND_ALLOC==0 则禁用 ZendMMApi(emalloc/efree/...)
+        //初始化mm_heap的代码(USE_ZEND_ALLOC != 0)
+            alloc_globals->mm_heap = malloc(sizeof(struct _zend_mm_heap));
+            memset(alloc_globals->mm_heap, 0, sizeof(struct _zend_mm_heap));
+            alloc_globals->mm_heap->use_zend_alloc = 0;
+            alloc_globals->mm_heap->_malloc = malloc;
+            alloc_globals->mm_heap->_free = free;
+            alloc_globals->mm_heap->_realloc = realloc;
+
+        //初始化mm_heap的代码(USE_ZEND_ALLOC != 0), 则启用 ZendMMApi(emalloc/efree/...)
+            alloc_globals->mm_heap = zend_mm_startup();
+
+    ->zend_mm_startup()     //读取内存分配方案(默认malloc)
+    ->zend_mm_startup_ex()  //实例化zend_mm_heap分配内存 (heap = malloc(sizeof(struct _zend_mm_heap));)
+
+    ->emalloc()             //申请内存，
+                            //zend_mm_heap->use_zend_alloc==0 调用 mm_heap->_malloc方法初始化分配内存
+                            //zend_mm_heap->use_zend_alloc!=0 调用 _zend_mm_alloc_int
+    ->_zend_mm_alloc_int()
+        ->ZEND_MM_STORAGE_ALLOC(segment_size) // 
+            -> heap->storage->handlers->_alloc
+
+                //ZEND_MM_MEM_WIN32_DSC
+                ->zend_mm_mem_win32_alloc()
+                ->HeapAlloc((HANDLE)storage->data, HEAP_NO_SERIALIZE, size)//最终把内存分配到了heap->storage->data
+
+                //ZEND_MM_MEM_MALLOC_DSC
+                ->zend_mm_mem_malloc_alloc()
+                ->return (zend_mm_segment*)malloc(size) //最终把内存分配到了 heap->segments_list
+
+                //ZEND_MM_MEM_MMAP_ZERO_DSC
+                ->zend_mm_mem_mmap_zero_alloc()
+                ->(zend_mm_segment*)mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, zend_mm_dev_zero_fd, 0) //通过mmap把内存影射到heap->storage
+
+                //ZEND_MM_MEM_MMAP_ANON_DSC
+                ->zend_mm_mem_mmap_anon_alloc
+                ->(zend_mm_segment*)mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0) 
+                //最终把内存分配到了 heap->segments_list
+
+    ->alloc_globals_dtor() //释放内存
+    ->shutdown_memory_manager (main.c 2410) //结束内存管理
+    ->zend_mm_shutdown(AG(mm_heap), full_shutdown, silent TSRMLS_CC) //最终调用释放内存的方法
+
+5，总结
+
+  a) ZEND_MM_MEM_WIN32_DSC|ZEND_MM_MEM_MMAP_ZERO_DSC   内存保存到了 heap->storage
+     ZEND_MM_MEM_MMAP_ANON_DSC|ZEND_MM_MEM_MALLOC_DSC  内存保存到了 heap->segments_list
+
+  b) 

README.md

@@ -36,6 +36,8 @@
 
 [3，zval](./003.md)
 
+[4, ZendMM](./004.md)
+
 ##### 参考
 
 [https://github.com/sgolemon/phptek2013](https://github.com/sgolemon/phptek2013)