[core] keep pool of (request_st *) for HTTP/2

src/connections.c

@@ -458,7 +458,7 @@ static connection *connection_init(server *srv) {
 	con->config_data_base = srv->config_data_base;
 
 	request_st * const r = &con->request;
-	request_init(r, con, srv);
+	request_init_data(r, con, srv);
 	config_reset_config(r);
 	con->write_queue = r->write_queue;
 	con->read_queue = r->read_queue;
@@ -482,7 +482,7 @@ void connections_free(server *srv) {
 			chunkqueue_free(con->write_queue);
 		if (con->read_queue != r->read_queue)
 			chunkqueue_free(con->read_queue);
-		request_free(r);
+		request_free_data(r);
 
 		free(con->plugin_ctx);
 		buffer_free(con->dst_addr_buf);

src/reqpool.c

@@ -19,7 +19,7 @@
 
 
 void
-request_init (request_st * const r, connection * const con, server * const srv)
+request_init_data (request_st * const r, connection * const con, server * const srv)
 {
     r->write_queue = chunkqueue_init();
     r->read_queue = chunkqueue_init();
@@ -166,7 +166,7 @@ request_reset_ex (request_st * const r)
 
 
 void
-request_free (request_st * const r)
+request_free_data (request_st * const r)
 {
     chunkqueue_free(r->reqbody_queue);
     chunkqueue_free(r->write_queue);
@@ -200,6 +200,32 @@ request_free (request_st * const r)
 }
 
 
+/* linked list of (request_st *) cached for reuse */
+static request_st *reqpool;
+/* max num of (request_st *) to cache */
+static uint32_t reqspace;
+
+
+void
+request_pool_init (uint32_t sz)
+{
+    reqspace = sz;
+}
+
+
+void
+request_pool_free (void)
+{
+    while (reqpool) {
+        request_st * const r = reqpool;
+        reqpool = (request_st *)r->con; /*(reuse r->con as next ptr)*/
+        request_free_data(r);
+        free(r);
+        ++reqspace;
+    }
+}
+
+
 void
 request_release (request_st * const r)
 {
@@ -217,19 +243,31 @@ request_release (request_st * const r)
     request_reset_ex(r);
     r->state = CON_STATE_CONNECT;
 
-    /* future: might keep a pool of reusable (request_st *) */
-    request_free(r);
-    free(r);
+    if (reqspace) {
+        --reqspace;
+        r->con = (connection *)reqpool; /*(reuse r->con as next ptr)*/
+        reqpool = r;
+    }
+    else {
+        request_free_data(r);
+        free(r);
+    }
 }
 
 
 request_st *
 request_acquire (connection * const con)
 {
-    /* future: might keep a pool of reusable (request_st *) */
-    request_st * const r = calloc(1, sizeof(request_st));
-    force_assert(r);
-    request_init(r, con, con->srv);
+    request_st *r = reqpool;
+    if (r) {
+        reqpool = (request_st *)r->con; /*(reuse r->con as next ptr)*/
+        ++reqspace;
+    }
+    else {
+        r = calloc(1, sizeof(request_st));
+        force_assert(r);
+        request_init_data(r, con, con->srv);
+    }
 
     r->con = con;
     r->tmp_buf = con->srv->tmp_buf;

src/reqpool.h

@@ -4,11 +4,19 @@
 
 #include "base_decls.h"
 
-void request_init (request_st *r, connection *con, server *srv);
+void request_init_data (request_st *r, connection *con, server *srv);
 void request_reset (request_st *r);
 void request_reset_ex (request_st *r);
-void request_free (request_st *r);
 void request_release (request_st *r);
 request_st * request_acquire (connection *con);
 
+__attribute_cold__
+void request_free_data (request_st *r);
+
+__attribute_cold__
+void request_pool_init (uint32_t sz);
+
+__attribute_cold__
+void request_pool_free (void);
+
 #endif

src/server.c

@@ -14,6 +14,7 @@
 #include "stat_cache.h"
 #include "plugin.h"
 #include "network_write.h"  /* network_write_show_handlers() */
+#include "reqpool.h"        /* request_pool_init() request_pool_free() */
 #include "response.h"       /* strftime_cache_reset() */
 
 #ifdef HAVE_VERSIONSTAMP_H
@@ -1356,6 +1357,8 @@ static int server_main_setup (server * const srv, int argc, char **argv) {
 		srv->max_conns = srv->max_fds/3;
 	}
 
+	request_pool_init(srv->max_conns);
+
 	/* libev backend overwrites our SIGCHLD handler and calls waitpid on SIGCHLD; we want our own SIGCHLD handling. */
 #ifdef HAVE_SIGACTION
 	sigaction(SIGCHLD, &act, NULL);
@@ -1627,6 +1630,7 @@ int main (int argc, char **argv) {
             server_sockets_save(srv);
         else
             network_close(srv);
+        request_pool_free();
         connections_free(srv);
         plugins_free(srv);
         server_free(srv);