ngx_palloc.h 和 ngx_palloc.c主要用于nginx管理内存池
#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)
//内存池默认大小
#define NGX_DEFAULT_POOL_SIZE (16 * 1024)
//#define ngx_align(d, a) (((d) + (a - 1)) & ~(a - 1)) 将d向上取a的倍数。
#define NGX_POOL_ALIGNMENT 16
//内存池的最小大小，为16的倍数
#define NGX_MIN_POOL_SIZE \
ngx_align((sizeof(ngx_pool_t) + 2 * sizeof(ngx_pool_large_t)), \
NGX_POOL_ALIGNMENT)
//ngx_pool_cleanup_pt 为函数指针
typedef void (*ngx_pool_cleanup_pt)(void *data);
typedef struct ngx_pool_cleanup_s ngx_pool_cleanup_t;
//这个结构用来表示内存池中的数据的清理handler
//handler表示清理函数，data表示传递给清理函数的数据，next表示下一个清理handler,
//也就是说当destroy这个pool的时候会遍历清理handler链表，然后调用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;
//该结构表示大块内存，这个结构很简单，就是一个指针指向下一块large，一个alloc指向数据
struct ngx_pool_large_s {
ngx_pool_large_t *next;
void *alloc;
};
//数据区的指针ngx_pool_data_t。其中last表示当前的数据区的已经使用的数据的结尾。
//end表示当前的内存池的结尾。也就是说end-last就是内存池未使用的大小。
typedef struct {
u_char *last;
u_char *end;
//指向下一块内存池
ngx_pool_t *next;
//申请该内存池失败的标记
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_ */