mod_slotmem_shm

摘要

mod_slotmem_shm是一个 memory 提供程序，它提供对共享 memory 段的创建和访问，其中数据集在“槽”中组织。

每次重启都清除并清除所有共享的 memory，无论是否优雅。数据本身在create和attach calls 中name参数标注的文件中存储和恢复。如果未使用绝对路径指定，则将相对于DefaultRuntimeDir指令指定的路径创建文件。

mod_slotmem_shm提供以下 API 函数：

/* call the callback on all worker slots */
apr_status_t doall(ap_slotmem_instance_t *s, ap_slotmem_callback_fn_t *func, void *data, apr_pool_t *pool)

/* create a new slotmem with each item size is item_size. 'name' is used to generate a filename for the persistent
   store of the shared memory if configured. Values are:
      "none"                - Anonymous shared memory and no persistent store
      "file-name"           - [DefaultRuntimeDir]/file-name
      "/absolute-file-name" - Absolute file name */
apr_status_t create(ap_slotmem_instance_t **new, const char *name, apr_size_t item_size, unsigned int item_num, ap_slotmem_type_t type, apr_pool_t *pool)

/* attach to an existing slotmem. See 'create()' for description of 'name' parameter */
apr_status_t attach(ap_slotmem_instance_t **new, const char *name, apr_size_t *item_size, unsigned int *item_num, apr_pool_t *pool)

/* get the direct pointer to the memory associated with this worker slot */
apr_status_t dptr(ap_slotmem_instance_t *s, unsigned int item_id, void **mem)

/* get/read the memory from this slot to dest */
apr_status_t get(ap_slotmem_instance_t *s, unsigned int item_id, unsigned char *dest, apr_size_t dest_len)

/* put/write the data from src to this slot */
apr_status_t put(ap_slotmem_instance_t *slot, unsigned int item_id, unsigned char *src, apr_size_t src_len)

/* return the total number of slots in the segment */
unsigned int num_slots(ap_slotmem_instance_t *s)

/* return the total data size, in bytes, of a slot in the segment */
apr_size_t slot_size(ap_slotmem_instance_t *s)

/* grab or allocate the first free slot and mark as in-use (does not do any data copying) */
apr_status_t grab(ap_slotmem_instance_t *s, unsigned int *item_id)

/* forced grab or allocate the specified slot and mark as in-use (does not do any data copying) */
apr_status_t fgrab(ap_slotmem_instance_t *s, unsigned int item_id)

/* release or free a slot and mark as not in-use (does not do any data copying) */
apr_status_t release(ap_slotmem_instance_t *s, unsigned int item_id)