Implicit port read buffer completion.

To disable implicit completion, handler should reset msg->buf field.

src/nxt_master_process.c

@@ -141,8 +141,6 @@ nxt_port_master_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
     b = msg->buf;
 
     nxt_debug(task, "master data: %*s", b->mem.free - b->mem.pos, b->mem.pos);
-
-    b->mem.pos = b->mem.free;
 }
 
 
@@ -175,7 +173,6 @@ nxt_port_master_start_worker_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
     start += app_conf.name.length + 1;
 
     conf = nxt_conf_json_parse(mp, start, b->mem.free);
-    b->mem.pos = b->mem.free;
 
     if (conf == NULL) {
         nxt_log(task, NXT_LOG_CRIT, "configuration parsing error");

src/nxt_port.c

@@ -225,7 +225,6 @@ nxt_port_new_port_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
     rt = task->thread->runtime;
 
     new_port_msg = (nxt_port_msg_new_port_t *) msg->buf->mem.pos;
-    msg->buf->mem.pos = msg->buf->mem.free;
 
     nxt_debug(task, "new port %d received for process %PI:%d",
               msg->fd, new_port_msg->pid, new_port_msg->id);
@@ -405,8 +404,6 @@ nxt_port_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
     }
 
     nxt_debug(task, "data: %*s", dump_size, b->mem.pos);
-
-    b->mem.pos = b->mem.free;
 }
 
 

src/nxt_port_socket.c

@@ -415,7 +415,11 @@ nxt_port_read_handler(nxt_task_t *task, void *obj, void *data)
 
             nxt_port_read_msg_process(task, port, &msg);
 
-            if (b->mem.pos == b->mem.free) {
+            /*
+             * To disable instant completion or buffer re-usage,
+             * handler should reset 'msg.buf'.
+             */
+            if (msg.buf == b) {
                 nxt_port_buf_free(port, b);
             }
 
@@ -469,14 +473,23 @@ nxt_port_read_msg_process(nxt_task_t *task, nxt_port_t *port,
     port->handler(task, msg);
 
     if (msg->port_msg.mmap && orig_b != b) {
-        /* complete used mmap buffers */
-        for (; b && nxt_buf_used_size(b) == 0;
-            b = b->next) {
-            nxt_debug(task, "complete buffer %p", b);
 
-            nxt_work_queue_add(port->socket.read_work_queue,
-                b->completion_handler, task, b, b->parent);
+        /*
+         * To disable instant buffer completion,
+         * handler should reset 'msg->buf'.
+         */
+        if (msg->buf == b) {
+            /* complete mmap buffers */
+            for (; b != NULL; b = b->next) {
+                nxt_debug(task, "complete buffer %p", b);
+
+                nxt_work_queue_add(port->socket.read_work_queue,
+                    b->completion_handler, task, b, b->parent);
+            }
         }
+
+        /* restore original buf */
+        msg->buf = orig_b;
     }
 
     return;

src/nxt_router.c

@@ -333,8 +333,6 @@ nxt_router_conf_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
 
     ret = nxt_router_conf_new(task, tmcf, b->mem.pos, b->mem.free);
 
-    b->mem.pos = b->mem.free;
-
     if (ret == NXT_OK) {
         nxt_router_conf_success(task, tmcf);
         return;
@@ -1735,7 +1733,7 @@ static void
 nxt_router_app_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
 {
     size_t               dump_size;
-    nxt_buf_t            *b, *i, *last;
+    nxt_buf_t            *b, *last;
     nxt_conn_t           *c;
     nxt_req_conn_link_t  *rc;
     nxt_event_engine_t   *engine;
@@ -1748,11 +1746,6 @@ nxt_router_app_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
 
         nxt_debug(task, "request id %08uxD not found", msg->port_msg.stream);
 
-        /* Mark buffers as read. */
-        for (i = b; i != NULL; i = i->next) {
-            i->mem.pos = i->mem.free;
-        }
-
         return;
     }
 
@@ -1793,6 +1786,9 @@ nxt_router_app_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
         return;
     }
 
+    /* Disable instant buffer completion/re-using by port. */
+    msg->buf = NULL;
+
     if (c->write == NULL) {
         c->write = b;
         c->write_state = &nxt_router_conn_write_state;