Apache 模块 mod_slotmem_shm

Description:	基于插槽的共享内存提供程序。
Status:	Extension
Module Identifier:	slotmem_shm_module
Source File:	mod_slotmem_shm.c

Summary

mod_slotmem_shm是一种内存提供程序，用于创建和访问共享内存段，在该内存段中，数据集按“插槽”组织。

每次重新启动都会清除并清除所有共享内存，无论是否正常。数据本身存储和恢复到create和attach调用中name参数表示的文件中。如果未指定绝对路径，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)