ngx_palloc.h 和 ngx_palloc.c主要用于nginx管理內存池
#include <ngx_config.h>
#include <ngx_core.h>
/*
* NGX_MAX_ALLOC_FROM_POOL should be (ngx_pagesize - 1), i.e. 4095 on x86.
* On Windows NT it decreases a number of locked pages in a kernel.
*/
#define NGX_MAX_ALLOC_FROM_POOL (ngx_pagesize - 1)
//內存池默認大小
#define NGX_DEFAULT_POOL_SIZE (16 * 1024)
//#define ngx_align(d, a) (((d) + (a - 1)) & ~(a - 1)) 將d向上取a的倍數。
#define NGX_POOL_ALIGNMENT 16
//內存池的最小大小，為16的倍數
#define NGX_MIN_POOL_SIZE \
ngx_align((sizeof(ngx_pool_t) + 2 * sizeof(ngx_pool_large_t)), \
NGX_POOL_ALIGNMENT)
//ngx_pool_cleanup_pt 為函數指針
typedef void (*ngx_pool_cleanup_pt)(void *data);
typedef struct ngx_pool_cleanup_s ngx_pool_cleanup_t;
//這個結構用來表示內存池中的數據的清理handler
//handler表示清理函數，data表示傳遞給清理函數的數據，next表示下一個清理handler,
//也就是說當destroy這個pool的時候會遍歷清理handler鏈表，然后調用handler.
struct ngx_pool_cleanup_s {
ngx_pool_cleanup_pt handler;
void *data;
ngx_pool_cleanup_t *next;
};
typedef struct ngx_pool_large_s ngx_pool_large_t;
//該結構表示大塊內存，這個結構很簡單，就是一個指針指向下一塊large，一個alloc指向數據
struct ngx_pool_large_s {
ngx_pool_large_t *next;
void *alloc;
};
//數據區的指針ngx_pool_data_t。其中last表示當前的數據區的已經使用的數據的結尾。
//end表示當前的內存池的結尾。也就是說end-last就是內存池未使用的大小。
typedef struct {
u_char *last;
u_char *end;
//指向下一塊內存池
ngx_pool_t *next;
//申請該內存池失敗的標記
ngx_uint_t failed;
} ngx_pool_data_t;
struct ngx_pool_s {
ngx_pool_data_t d;
size_t max;
ngx_pool_t *current;
ngx_chain_t *chain;
ngx_pool_large_t *large;
ngx_pool_cleanup_t *cleanup;
ngx_log_t *log;
};
typedef struct {
ngx_fd_t fd;
u_char *name;
ngx_log_t *log;
} ngx_pool_cleanup_file_t;
void *ngx_alloc(size_t size, ngx_log_t *log);
void *ngx_calloc(size_t size, ngx_log_t *log);
ngx_pool_t *ngx_create_pool(size_t size, ngx_log_t *log);
void ngx_destroy_pool(ngx_pool_t *pool);
void ngx_reset_pool(ngx_pool_t *pool);
void *ngx_palloc(ngx_pool_t *pool, size_t size);
void *ngx_pnalloc(ngx_pool_t *pool, size_t size);
void *ngx_pcalloc(ngx_pool_t *pool, size_t size);
void *ngx_pmemalign(ngx_pool_t *pool, size_t size, size_t alignment);
ngx_int_t ngx_pfree(ngx_pool_t *pool, void *p);
ngx_pool_cleanup_t *ngx_pool_cleanup_add(ngx_pool_t *p, size_t size);
void ngx_pool_run_cleanup_file(ngx_pool_t *p, ngx_fd_t fd);
void ngx_pool_cleanup_file(void *data);
void ngx_pool_delete_file(void *data);
#endif /* _NGX_PALLOC_H_INCLUDED_ */