Allocate request object from its own pool.

Previously, it was allocated from a connection pool and
was selectively freed for an idle keepalive connection.

The goal is to put coupled things in one chunk of memory,
and to simplify handling of request objects.

src/http/ngx_http_request.c

@@ -365,6 +365,7 @@ ngx_http_init_connection(ngx_connection_t *c)
 static void
 ngx_http_init_request(ngx_event_t *rev)
 {
+    ngx_pool_t                 *pool;
     ngx_time_t                 *tp;
     ngx_connection_t           *c;
     ngx_http_request_t         *r;
@@ -387,27 +388,25 @@ ngx_http_init_request(ngx_event_t *rev)
 
     hc = c->data;
 
-    r = hc->request;
+    cscf = ngx_http_get_module_srv_conf(hc->conf_ctx, ngx_http_core_module);
 
-    if (r) {
+    pool = ngx_create_pool(cscf->request_pool_size, c->log);
-        ngx_memzero(r, sizeof(ngx_http_request_t));
+    if (pool == NULL) {
-
-        r->pipeline = hc->pipeline;
-
-        if (hc->nbusy) {
-            r->header_in = hc->busy[0];
-        }
-
-    } else {
-        r = ngx_pcalloc(c->pool, sizeof(ngx_http_request_t));
-        if (r == NULL) {
         ngx_http_close_connection(c);
         return;
     }
 
-        hc->request = r;
+    r = ngx_pcalloc(pool, sizeof(ngx_http_request_t));
+    if (r == NULL) {
+        ngx_destroy_pool(pool);
+        ngx_http_close_connection(c);
+        return;
     }
 
+    r->pool = pool;
+
+    r->pipeline = hc->pipeline;
+
     c->data = r;
     r->http_connection = hc;
 
@@ -426,27 +425,17 @@ ngx_http_init_request(ngx_event_t *rev)
 
     ngx_http_set_connection_log(r->connection, clcf->error_log);
 
-    cscf = ngx_http_get_module_srv_conf(r, ngx_http_core_module);
-
     if (c->buffer == NULL) {
         c->buffer = ngx_create_temp_buf(c->pool,
                                         cscf->client_header_buffer_size);
         if (c->buffer == NULL) {
+            ngx_destroy_pool(r->pool);
             ngx_http_close_connection(c);
             return;
         }
     }
 
-    if (r->header_in == NULL) {
+    r->header_in = hc->nbusy ? hc->busy[0] : c->buffer;
-        r->header_in = c->buffer;
-    }
-
-    r->pool = ngx_create_pool(cscf->request_pool_size, c->log);
-    if (r->pool == NULL) {
-        ngx_http_close_connection(c);
-        return;
-    }
-
 
     if (ngx_list_init(&r->headers_out.headers, r->pool, 20,
                       sizeof(ngx_table_elt_t))
@@ -2663,6 +2652,7 @@ ngx_http_set_keepalive(ngx_http_request_t *r)
         }
     }
 
+    /* guard against recursive call from ngx_http_finalize_connection() */
     r->keepalive = 0;
 
     ngx_http_free_request(r, 0);
@@ -2694,17 +2684,12 @@ ngx_http_set_keepalive(ngx_http_request_t *r)
     hc->pipeline = 0;
 
     /*
-     * To keep a memory footprint as small as possible for an idle
+     * To keep a memory footprint as small as possible for an idle keepalive
-     * keepalive connection we try to free the ngx_http_request_t and
+     * connection we try to free c->buffer's memory if it was allocated outside
-     * c->buffer's memory if they were allocated outside the c->pool.
+     * the c->pool.  The large header buffers are always allocated outside the
-     * The large header buffers are always allocated outside the c->pool and
+     * c->pool and are freed too.
-     * are freed too.
      */
 
-    if (ngx_pfree(c->pool, r) == NGX_OK) {
-        hc->request = NULL;
-    }
-
     b = c->buffer;
 
     if (ngx_pfree(c->pool, b->start) == NGX_OK) {
@@ -3155,6 +3140,7 @@ static void
 ngx_http_free_request(ngx_http_request_t *r, ngx_int_t rc)
 {
     ngx_log_t                 *log;
+    ngx_pool_t                *pool;
     struct linger              linger;
     ngx_http_cleanup_t        *cln;
     ngx_http_log_ctx_t        *ctx;
@@ -3221,7 +3207,15 @@ ngx_http_free_request(ngx_http_request_t *r, ngx_int_t rc)
 
     r->connection->destroyed = 1;
 
-    ngx_destroy_pool(r->pool);
+    /*
+     * Setting r->pool to NULL will increase probability to catch double close
+     * of request since the request object is allocated from its own pool.
+     */
+
+    pool = r->pool;
+    r->pool = NULL;
+
+    ngx_destroy_pool(pool);
 }
 
 

src/http/ngx_http_request.h

@@ -302,8 +302,6 @@ typedef struct {
 #endif
 #endif
 
-    ngx_http_request_t               *request;
-
     ngx_buf_t                       **busy;
     ngx_int_t                         nbusy;