Nginx Dynamic Array ngx_array_t

ngx_array_t is a dynamic array designed in Nginx, similar to the vector in STL . Below we combine the example analysis.

First, the example

#include
  
   
#include "ngx_config.h" #include "ngx_conf_file.h" #include "nginx.h" #include "ngx_core.h" #include "ngx_string.h" # Include "Ngx_palloc.h" #include "ngx_queue.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) {while (pool) {printf ("pool = 0x%x\n", pool);        printf (". d\n");        printf (". Last =0x%x\n", pool->d.last);        printf (". End =0x%x\n", pool->d.end);        printf (". Next =0x%x\n", Pool->d.next);        printf (". Failed =%d\n", pool->d.failed);        printf (". Max =%d\n", Pool->max);        printf (". Current =0x%x\n", pool->current);        printf (". Chain =0x%x\n", Pool->chain);        printf (". Large =0x%x\n", pool->large);        printf (". Cleanup =0x%x\n", pool->cleanup);        printf (". Log =0x%x\n", Pool->log); printf ("Available pool memory =%d\n\n", Pool->d.end-Pool->d.last);       Ngx_pool_large_t*large = pool->large;       printf ("*****large_pool*******\n");            while (Large) {printf ("%p->", Large);       Large= large->next;                    } printf ("\ n");   Pool = pool->d.next; }} typedef struct {intarray[128];//* 4 = 512}testnode;     int main () {ngx_pool_t *pool;    printf ("--------------------------------\ n");    printf ("Create a new pool:\n");    printf ("--------------------------------\ n");    Pool = Ngx_create_pool (1024x768, NULL);              Dump_pool (pool);       Ngx_array_t*myarray = Ngx_array_create (pool, 1, sizeof (Testnode));   printf ("******ngx_array_create**********\n");             Dump_pool (pool);       TESTNODE*T1 = Ngx_array_push (MyArray);       Testnode*t2 = Ngx_array_push (MyArray);   printf ("******ngx_array_push**********\n");             Dump_pool (pool);   Ngx_array_destroy (MyArray);//There is nothing to do here dump_pool (pool);    Ngx_destroy_pool (pool);return 0; }
  

Operation Result:

--------------------------------Create a new pool:--------------------------------pool = 0x95ae020. D. Last = 0x95ae048 . end = 0x95ae420. Next = 0x0. Failed = 0. Max = 984. Current = 0x95ae020. chain= 0x0. Large = 0x0. Cleanup = 0x0. Log = 0x0available Pool memory = 984 *****large_pool*******null******ngx_array_create**********pool = 0x95ae020. D. Las t = 0x95ae25c. End = 0x95ae420. Next = 0x0. Failed = 0. Max = 984. Current = 0x95ae020. Chain = 0x0. Large = 0x0. Cl   Eanup = 0x0. log = 0x0available pool memory = 452 *****large_pool*******null******ngx_array_push**********pool = 0x95ae020 . d. Last = 0x95ae264. End = 0x95ae420. Next = 0x0. Failed = 0. Max = 984. Current = 0x95ae020. Chain = 0x0. Lar GE = 0x95ae25c. Cleanup = 0x0. log = 0x0available pool memory = 444 *****large_pool*******0x95ae25c->null******ngx_arra  Y_destroy******pool = 0x95ae020. D. last = 0x95ae264. End = 0x95ae420. Next = 0x0. Failed = 0. Max = 984. Current = 0x95ae020. Chain = 0x0. Large = 0x95ae25c. Cleanup = 0x0. log = 0x0available pool memory = 444 *****large_pool*******0x95ae25c->null 

1, from the available pool memory changes can be learned that the ngx_array_t, ngx_pool_large_t structure of the body itself is allocated memory on the memory pool.

From the source can be proven:

ngx_array_t *

Ngx_array_create (Ngx_pool_t*p, ngx_uint_t N, size_t size)

{

A = Ngx_palloc (p, sizeof (ngx_array_t));

}

static void *

Ngx_palloc_large (Ngx_pool_t*pool, size_t size)

{

Allocated on the memory pool.

Large = Ngx_palloc (pool,sizeof (ngx_pool_large_t));

}

2, Ngx_array_push if the expansion, and will not release the original occupied memory. can refer to the source code of Ngx_array_push, not posted here.

3. If the size of the allocated dynamic array exceeds the capacity of a memory pool (in this case, 1024), Ngx_palloc_large is called to allocate large chunks of memory.

4, if the dynamic array of memory is a chunk of memory, Ngx_array_destroy will not do anything, and the API in the Nginx kernel source code has not been called.

Compiling can refer to the previous analysis of the ngx_queue_t structure of the article.

Second, reference materials:

"Deep understanding of Nginx" Tao Hui

http://blog.csdn.net/livelylittlefish/article/details/6586946

The above describes the Nginx dynamic array ngx_array_t, including the aspects of the content, I hope that the PHP tutorial interested in a friend helpful.

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