6.ngx_pool_t

ngx pool 相关结构

struct ngx_pool_large_s {
   ngx_pool_large_t     *next;
   void                 *alloc;
};


typedef struct {
   u_char               *last;     /* 最新内存池数据空闲地址 */
   u_char               *end;      /* 最终内存池数据地址 */
   ngx_pool_t           *next;     /* 下一个内存池指针 */
   ngx_uint_t            failed;   /* 分配失败次数，当>3时，将更新 current = d.next */
} ngx_pool_data_t;


struct ngx_pool_s {
   ngx_pool_data_t       d;        /* 内存池数据地址 */
   size_t                max;      /* 内存池可容纳的最大数据大小 */
   ngx_pool_t           *current;  /* 指向当前内存池的指针 */
   ngx_chain_t          *chain;
   ngx_pool_large_t     *large;    /* 当分配的 size 大于 max时，使用该结构 */
   ngx_pool_cleanup_t   *cleanup;
   ngx_log_t            *log;      /* 日志指针 */
};

#define ngx_align_ptr(p, a)                                                   \
   (u_char *) (((uintptr_t) (p) + ((uintptr_t) a - 1)) & ~((uintptr_t) a - 1))

实例

#include <stdio.h>
#include <ngx_config.h>
#include <ngx_conf_file.h>
#include <nginx.h>
#include <ngx_core.h>
#include <ngx_string.h>
#include <ngx_palloc.h>

volatile ngx_cycle_t *ngx_cycle;

void ngx_log_error_core(ngx_uint_t level, ngx_log_t *log, ngx_err_t err,
    const char *fmt, ...)
{
}

void dump_pool(ngx_pool_t *pool);


int
main(int argc, char *argv[])
{
    // 创建 pool, 并初始化
    ngx_log_t *log = NULL;
    ngx_pool_t *pool;

    printf("size of pool: %lu\n", sizeof(ngx_pool_t));
    printf("size of pool_large: %lu\n", sizeof(ngx_pool_large_t));
    printf("size of pool_data: %lu\n", sizeof(ngx_pool_data_t));
    printf("size of alignment: %lu\n", sizeof(unsigned long));

    pool = ngx_create_pool(1024, log);
    dump_pool(pool);

    ngx_palloc(pool, 900);
    dump_pool(pool);

    ngx_palloc(pool, 50);
    dump_pool(pool);
    ngx_palloc(pool, 10);
    dump_pool(pool);
    ngx_palloc(pool, 10);
    dump_pool(pool);
    ngx_palloc(pool, 10);
    dump_pool(pool);

    // 销毁 pool
    ngx_destroy_pool(pool);

    return 0;
}

void
dump_pool(ngx_pool_t *pool)
{
    printf("\x1b[32m > dump pool: \x1b[0m\n");

    printf("%10s : %-p\n", "d", &(pool->d));
    printf("%10s : %-p\n", "d->last", pool->d.last);
    printf("%10s : %-p\n", "d->end", pool->d.end);
    printf("%10s : %-p\n\n", "d->next", pool->d.next);
    printf("%10s : %-lu\n", "d->failed", pool->d.failed);
    
    if (pool->d.next) {
        printf("next: \n");
        dump_pool(pool->d.next);
        printf("------------------------------------\n");
    }
    
    printf("%10s : %-lu\n", "max", pool->max);
    printf("%10s : %-p\n", "current", pool->current);
    printf("%10s : %-p\n", "chain", pool->chain);
    printf("%10s : %-p\n", "large", pool->large);
    printf("%10s : %-p\n", "cleanup", pool->cleanup);
    printf("%10s : %-p\n", "log", pool->log);
    printf("\n");

    return;
}

执行

gcc -c -O -pipe -O -W -Wall -Wpointer-arith -Wno-unused-parameter -Wunused-function -Wunused-variable -Wunused-value -Werror -g  -I ../../objs/  -I ../os/unix/  -I../core/  -I /usr/local/opt/pcre/include/  -I../event/  -I../os/  ./t_ngx_pool.c

gcc -o ./t_ngx_pool ./t_ngx_pool.o ../../objs/src/core/ngx_string.o ../../objs/src/os/unix/ngx_alloc.o  ../../objs/src/core/ngx_palloc.o

结果

size of pool: 80
size of pool_large: 16
size of pool_data: 32
size of alignment: 8



 1.> dump pool: 
         d : 0x7fd57f802000
   d->last : 0x7fd57f802050
    d->end : 0x7fd57f802400
   d->next : 0x0

 d->failed : 0
       max : 944
   current : 0x7fd57f802000
     chain : 0x0
     large : 0x0
   cleanup : 0x0
       log : 0x0



 2.> dump pool: 
         d : 0x7fd57f802000
   d->last : 0x7fd57f8023d4
    d->end : 0x7fd57f802400
   d->next : 0x0

 d->failed : 0
       max : 944
   current : 0x7fd57f802000
     chain : 0x0
     large : 0x0
   cleanup : 0x0
       log : 0x0



 3.> dump pool: 
         d : 0x7fd57f802000
   d->last : 0x7fd57f8023d4
    d->end : 0x7fd57f802400
   d->next : 0x7fd57f802400

 d->failed : 0
next: 
 > dump pool: 
         d : 0x7fd57f802400
   d->last : 0x7fd57f802452
    d->end : 0x7fd57f802800
   d->next : 0x0

 d->failed : 0
       max : 0
   current : 0x0
     chain : 0x0
     large : 0x0
   cleanup : 0x0
       log : 0x0

------------------------------------
       max : 944
   current : 0x7fd57f802000
     chain : 0x0
     large : 0x0
   cleanup : 0x0
       log : 0x0



 4.> dump pool: 
         d : 0x7fd57f802000
   d->last : 0x7fd57f8023e2
    d->end : 0x7fd57f802400
   d->next : 0x7fd57f802400

 d->failed : 0
next: 
 > dump pool: 
         d : 0x7fd57f802400
   d->last : 0x7fd57f802452
    d->end : 0x7fd57f802800
   d->next : 0x0

 d->failed : 0
       max : 0
   current : 0x0
     chain : 0x0
     large : 0x0
   cleanup : 0x0
       log : 0x0

------------------------------------
       max : 944
   current : 0x7fd57f802000
     chain : 0x0
     large : 0x0
   cleanup : 0x0
       log : 0x0




 5.> dump pool: 
         d : 0x7fd57f802000
   d->last : 0x7fd57f8023f2
    d->end : 0x7fd57f802400
   d->next : 0x7fd57f802400

 d->failed : 0
next: 
 > dump pool: 
         d : 0x7fd57f802400
   d->last : 0x7fd57f802452
    d->end : 0x7fd57f802800
   d->next : 0x0

 d->failed : 0
       max : 0
   current : 0x0
     chain : 0x0
     large : 0x0
   cleanup : 0x0
       log : 0x0

------------------------------------
       max : 944
   current : 0x7fd57f802000
     chain : 0x0
     large : 0x0
   cleanup : 0x0
       log : 0x0



 6.> dump pool: 
         d : 0x7fd57f802000
   d->last : 0x7fd57f8023f2
    d->end : 0x7fd57f802400
   d->next : 0x7fd57f802400

 d->failed : 0
next: 
 > dump pool: 
         d : 0x7fd57f802400
   d->last : 0x7fd57f802462
    d->end : 0x7fd57f802800
   d->next : 0x0

 d->failed : 0
       max : 0
   current : 0x0
     chain : 0x0
     large : 0x0
   cleanup : 0x0
       log : 0x0

------------------------------------
       max : 944
   current : 0x7fd57f802000
     chain : 0x0
     large : 0x0
   cleanup : 0x0
       log : 0x0