Application restart introduced.

When processing a restart request, the router sends a QUIT message to all
existing processes of the application.  Then, a new shared application port is
created to ensure that new requests won't be handled by the old processes of
the application.

docs/changes.xml

@@ -43,6 +43,12 @@ process and thread lifecycle hooks in Ruby.
 </para>
 </change>
 
+<change type="feature">
+<para>
+application restart control.
+</para>
+</change>
+
 <change type="bugfix">
 <para>
 TLS connection was rejected for configuration with more than one

src/nxt_controller.c

@@ -92,6 +92,10 @@ static nxt_bool_t nxt_controller_cert_in_use(nxt_str_t *name);
 static void nxt_controller_cert_cleanup(nxt_task_t *task, void *obj,
     void *data);
 #endif
+static void nxt_controller_process_control(nxt_task_t *task,
+    nxt_controller_request_t *req, nxt_str_t *path);
+static void nxt_controller_app_restart_handler(nxt_task_t *task,
+    nxt_port_recv_msg_t *msg, void *data);
 static void nxt_controller_conf_handler(nxt_task_t *task,
     nxt_port_recv_msg_t *msg, void *data);
 static void nxt_controller_conf_store(nxt_task_t *task,
@@ -1022,6 +1026,14 @@ nxt_controller_process_request(nxt_task_t *task, nxt_controller_request_t *req)
 
 #endif
 
+    if (nxt_str_start(&path, "/control/", 9)) {
+        path.length -= 9;
+        path.start += 9;
+
+        nxt_controller_process_control(task, req, &path);
+        return;
+    }
+
     nxt_memzero(&resp, sizeof(nxt_controller_response_t));
 
     if (path.length == 1 && path.start[0] == '/') {
@@ -1683,6 +1695,155 @@ nxt_controller_conf_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg,
 }
 
 
+static void
+nxt_controller_process_control(nxt_task_t *task,
+    nxt_controller_request_t *req, nxt_str_t *path)
+{
+    uint32_t                   stream;
+    nxt_buf_t                  *b;
+    nxt_int_t                  rc;
+    nxt_port_t                 *router_port, *controller_port;
+    nxt_runtime_t              *rt;
+    nxt_conf_value_t           *value;
+    nxt_controller_response_t  resp;
+
+    static nxt_str_t applications = nxt_string("applications");
+
+    nxt_memzero(&resp, sizeof(nxt_controller_response_t));
+
+    if (!nxt_str_eq(&req->parser.method, "GET", 3)) {
+        goto not_allowed;
+    }
+
+    if (!nxt_str_start(path, "applications/", 13)
+        || nxt_memcmp(path->start + path->length - 8, "/restart", 8) != 0)
+    {
+        goto not_found;
+    }
+
+    path->start += 13;
+    path->length -= 13 + 8;
+
+    if (nxt_controller_check_postpone_request(task)) {
+        nxt_queue_insert_tail(&nxt_controller_waiting_requests, &req->link);
+        return;
+    }
+
+    value = nxt_controller_conf.root;
+    if (value == NULL) {
+        goto not_found;
+    }
+
+    value = nxt_conf_get_object_member(value, &applications, NULL);
+    if (value == NULL) {
+        goto not_found;
+    }
+
+    value = nxt_conf_get_object_member(value, path, NULL);
+    if (value == NULL) {
+        goto not_found;
+    }
+
+    b = nxt_buf_mem_alloc(req->conn->mem_pool, path->length, 0);
+    if (nxt_slow_path(b == NULL)) {
+        goto alloc_fail;
+    }
+
+    b->mem.free = nxt_cpymem(b->mem.pos, path->start, path->length);
+
+    rt = task->thread->runtime;
+
+    controller_port = rt->port_by_type[NXT_PROCESS_CONTROLLER];
+    router_port = rt->port_by_type[NXT_PROCESS_ROUTER];
+
+    stream = nxt_port_rpc_register_handler(task, controller_port,
+                                           nxt_controller_app_restart_handler,
+                                           nxt_controller_app_restart_handler,
+                                           router_port->pid, req);
+    if (nxt_slow_path(stream == 0)) {
+        goto alloc_fail;
+    }
+
+    rc = nxt_port_socket_write(task, router_port, NXT_PORT_MSG_APP_RESTART,
+                               -1, stream, 0, b);
+    if (nxt_slow_path(rc != NXT_OK)) {
+        nxt_port_rpc_cancel(task, controller_port, stream);
+
+        goto fail;
+    }
+
+    nxt_queue_insert_head(&nxt_controller_waiting_requests, &req->link);
+
+    return;
+
+not_allowed:
+
+    resp.status = 405;
+    resp.title = (u_char *) "Method isn't allowed.";
+    resp.offset = -1;
+
+    nxt_controller_response(task, req, &resp);
+    return;
+
+not_found:
+
+    resp.status = 404;
+    resp.title = (u_char *) "Value doesn't exist.";
+    resp.offset = -1;
+
+    nxt_controller_response(task, req, &resp);
+    return;
+
+alloc_fail:
+
+    resp.status = 500;
+    resp.title = (u_char *) "Memory allocation failed.";
+    resp.offset = -1;
+
+    nxt_controller_response(task, req, &resp);
+    return;
+
+fail:
+
+    resp.status = 500;
+    resp.title = (u_char *) "Send restart failed.";
+    resp.offset = -1;
+
+    nxt_controller_response(task, req, &resp);
+}
+
+
+static void
+nxt_controller_app_restart_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg,
+    void *data)
+{
+    nxt_controller_request_t   *req;
+    nxt_controller_response_t  resp;
+
+    req = data;
+
+    nxt_debug(task, "controller app restart handler");
+
+    nxt_queue_remove(&req->link);
+
+    nxt_memzero(&resp, sizeof(nxt_controller_response_t));
+
+    if (msg->port_msg.type == NXT_PORT_MSG_RPC_READY) {
+        resp.status = 200;
+        resp.title = (u_char *) "Ok";
+
+    } else {
+        resp.status = 500;
+        resp.title = (u_char *) "Failed to restart app.";
+        resp.offset = -1;
+    }
+
+    nxt_controller_response(task, req, &resp);
+
+    nxt_controller_flush_requests(task);
+}
+
+
 static void
 nxt_controller_conf_store(nxt_task_t *task, nxt_conf_value_t *conf)
 {

src/nxt_port.h

@@ -50,6 +50,7 @@ struct nxt_port_handlers_s {
 
     /* Various data. */
     nxt_port_handler_t  data;
+    nxt_port_handler_t  app_restart;
 
     nxt_port_handler_t  oosm;
     nxt_port_handler_t  shm_ack;
@@ -100,6 +101,7 @@ typedef enum {
     _NXT_PORT_MSG_WEBSOCKET       = nxt_port_handler_idx(websocket_frame),
 
     _NXT_PORT_MSG_DATA            = nxt_port_handler_idx(data),
+    _NXT_PORT_MSG_APP_RESTART     = nxt_port_handler_idx(app_restart),
 
     _NXT_PORT_MSG_OOSM            = nxt_port_handler_idx(oosm),
     _NXT_PORT_MSG_SHM_ACK         = nxt_port_handler_idx(shm_ack),
@@ -139,6 +141,7 @@ typedef enum {
 
     NXT_PORT_MSG_DATA             = _NXT_PORT_MSG_DATA,
     NXT_PORT_MSG_DATA_LAST        = nxt_msg_last(_NXT_PORT_MSG_DATA),
+    NXT_PORT_MSG_APP_RESTART      = nxt_msg_last(_NXT_PORT_MSG_APP_RESTART),
 
     NXT_PORT_MSG_OOSM             = nxt_msg_last(_NXT_PORT_MSG_OOSM),
     NXT_PORT_MSG_SHM_ACK          = nxt_msg_last(_NXT_PORT_MSG_SHM_ACK),

src/nxt_router.c

@@ -18,6 +18,8 @@
 #include <nxt_app_queue.h>
 #include <nxt_port_queue.h>
 
+#define NXT_SHARED_PORT_ID  0xFFFFu
+
 typedef struct {
     nxt_str_t         type;
     uint32_t          processes;
@@ -67,6 +69,12 @@ typedef struct {
 } nxt_app_rpc_t;
 
 
+typedef struct {
+    nxt_app_joint_t         *app_joint;
+    uint32_t                generation;
+} nxt_app_joint_rpc_t;
+
+
 static nxt_int_t nxt_router_prefork(nxt_task_t *task, nxt_process_t *process,
     nxt_mp_t *mp);
 static nxt_int_t nxt_router_start(nxt_task_t *task, nxt_process_data_t *data);
@@ -79,6 +87,8 @@ static void nxt_router_new_port_handler(nxt_task_t *task,
     nxt_port_recv_msg_t *msg);
 static void nxt_router_conf_data_handler(nxt_task_t *task,
     nxt_port_recv_msg_t *msg);
+static void nxt_router_app_restart_handler(nxt_task_t *task,
+    nxt_port_recv_msg_t *msg);
 static void nxt_router_remove_pid_handler(nxt_task_t *task,
     nxt_port_recv_msg_t *msg);
 static void nxt_router_access_log_reopen_handler(nxt_task_t *task,
@@ -281,6 +291,7 @@ static const nxt_port_handlers_t  nxt_router_process_port_handlers = {
     .mmap         = nxt_port_mmap_handler,
     .get_mmap     = nxt_router_get_mmap_handler,
     .data         = nxt_router_conf_data_handler,
+    .app_restart  = nxt_router_app_restart_handler,
     .remove_pid   = nxt_router_remove_pid_handler,
     .access_log   = nxt_router_access_log_reopen_handler,
     .rpc_ready    = nxt_port_rpc_handler,
@@ -387,6 +398,7 @@ nxt_router_start_app_process_handler(nxt_task_t *task, nxt_port_t *port,
     nxt_buf_t            *b;
     nxt_port_t           *main_port;
     nxt_runtime_t        *rt;
+    nxt_app_joint_rpc_t  *app_joint_rpc;
 
     app = data;
 
@@ -407,30 +419,29 @@ nxt_router_start_app_process_handler(nxt_task_t *task, nxt_port_t *port,
     *b->mem.free++ = '\0';
     nxt_buf_cpystr(b, &app->conf);
 
-    nxt_router_app_joint_use(task, app->joint, 1);
+    app_joint_rpc = nxt_port_rpc_register_handler_ex(task, port,
-
-    stream = nxt_port_rpc_register_handler(task, port,
                                                      nxt_router_app_port_ready,
                                                      nxt_router_app_port_error,
-                                           -1, app->joint);
+                                                   sizeof(nxt_app_joint_rpc_t));
-
+    if (nxt_slow_path(app_joint_rpc == NULL)) {
-    if (nxt_slow_path(stream == 0)) {
-        nxt_router_app_joint_use(task, app->joint, -1);
-
         goto failed;
     }
 
+    stream = nxt_port_rpc_ex_stream(app_joint_rpc);
+
     ret = nxt_port_socket_write(task, main_port, NXT_PORT_MSG_START_PROCESS,
                                 -1, stream, port->id, b);
-
     if (nxt_slow_path(ret != NXT_OK)) {
         nxt_port_rpc_cancel(task, port, stream);
 
-        nxt_router_app_joint_use(task, app->joint, -1);
-
         goto failed;
     }
 
+    app_joint_rpc->app_joint = app->joint;
+    app_joint_rpc->generation = app->generation;
+
+    nxt_router_app_joint_use(task, app->joint, 1);
+
     nxt_router_app_use(task, app, -1);
 
     return;
@@ -504,6 +515,7 @@ nxt_router_msg_cancel(nxt_task_t *task, nxt_request_rpc_data_t *req_rpc_data)
 {
     nxt_buf_t       *b, *next;
     nxt_bool_t      cancelled;
+    nxt_port_t      *app_port;
     nxt_msg_info_t  *msg_info;
 
     msg_info = &req_rpc_data->msg_info;
@@ -512,7 +524,10 @@ nxt_router_msg_cancel(nxt_task_t *task, nxt_request_rpc_data_t *req_rpc_data)
         return 0;
     }
 
-    cancelled = nxt_app_queue_cancel(req_rpc_data->app->shared_port->queue,
+    app_port = req_rpc_data->app_port;
+
+    if (app_port != NULL && app_port->id == NXT_SHARED_PORT_ID) {
+        cancelled = nxt_app_queue_cancel(app_port->queue,
                                          msg_info->tracking_cookie,
                                          req_rpc_data->stream);
 
@@ -521,6 +536,10 @@ nxt_router_msg_cancel(nxt_task_t *task, nxt_request_rpc_data_t *req_rpc_data)
                       req_rpc_data->stream);
         }
 
+    } else {
+        cancelled = 0;
+    }
+
     for (b = msg_info->buf; b != NULL; b = next) {
         next = b->next;
         b->next = NULL;
@@ -793,6 +812,90 @@ cleanup:
 }
 
 
+static void
+nxt_router_app_restart_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
+{
+    nxt_app_t            *app;
+    nxt_int_t            ret;
+    nxt_str_t            app_name;
+    nxt_port_t           *port, *reply_port, *shared_port, *old_shared_port;
+    nxt_port_msg_type_t  reply;
+
+    reply_port = nxt_runtime_port_find(task->thread->runtime,
+                                       msg->port_msg.pid,
+                                       msg->port_msg.reply_port);
+    if (nxt_slow_path(reply_port == NULL)) {
+        nxt_alert(task, "app_restart_handler: reply port not found");
+        return;
+    }
+
+    app_name.length = nxt_buf_mem_used_size(&msg->buf->mem);
+    app_name.start = msg->buf->mem.pos;
+
+    nxt_debug(task, "app_restart_handler: %V", &app_name);
+
+    app = nxt_router_app_find(&nxt_router->apps, &app_name);
+
+    if (nxt_fast_path(app != NULL)) {
+        shared_port = nxt_port_new(task, NXT_SHARED_PORT_ID, nxt_pid,
+                                   NXT_PROCESS_APP);
+        if (nxt_slow_path(shared_port == NULL)) {
+            goto fail;
+        }
+
+        ret = nxt_port_socket_init(task, shared_port, 0);
+        if (nxt_slow_path(ret != NXT_OK)) {
+            nxt_port_use(task, shared_port, -1);
+            goto fail;
+        }
+
+        ret = nxt_router_app_queue_init(task, shared_port);
+        if (nxt_slow_path(ret != NXT_OK)) {
+            nxt_port_write_close(shared_port);
+            nxt_port_read_close(shared_port);
+            nxt_port_use(task, shared_port, -1);
+            goto fail;
+        }
+
+        nxt_port_write_enable(task, shared_port);
+
+        nxt_thread_mutex_lock(&app->mutex);
+
+        nxt_queue_each(port, &app->ports, nxt_port_t, app_link) {
+
+            (void) nxt_port_socket_write(task, port, NXT_PORT_MSG_QUIT, -1,
+                                         0, 0, NULL);
+
+        } nxt_queue_loop;
+
+        app->generation++;
+
+        shared_port->app = app;
+
+        old_shared_port = app->shared_port;
+        old_shared_port->app = NULL;
+
+        app->shared_port = shared_port;
+
+        nxt_thread_mutex_unlock(&app->mutex);
+
+        nxt_port_close(task, old_shared_port);
+        nxt_port_use(task, old_shared_port, -1);
+
+        reply = NXT_PORT_MSG_RPC_READY_LAST;
+
+    } else {
+
+fail:
+
+        reply = NXT_PORT_MSG_RPC_ERROR;
+    }
+
+    nxt_port_socket_write(task, reply_port, reply, -1, msg->port_msg.stream,
+                          0, NULL);
+}
+
+
 static void
 nxt_router_app_process_remove_pid(nxt_task_t *task, nxt_port_t *port,
     void *data)
@@ -1607,7 +1710,7 @@ nxt_router_conf_create(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
             app_joint->free_app_work.task = &engine->task;
             app_joint->free_app_work.obj = app_joint;
 
-            port = nxt_port_new(task, (nxt_port_id_t) -1, nxt_pid,
+            port = nxt_port_new(task, NXT_SHARED_PORT_ID, nxt_pid,
                                 NXT_PROCESS_APP);
             if (nxt_slow_path(port == NULL)) {
                 return NXT_ERROR;
@@ -4234,10 +4337,15 @@ nxt_router_app_port_ready(nxt_task_t *task, nxt_port_recv_msg_t *msg,
     void *data)
 {
     nxt_app_t            *app;
+    nxt_bool_t           start_process;
     nxt_port_t           *port;
     nxt_app_joint_t      *app_joint;
+    nxt_app_joint_rpc_t  *app_joint_rpc;
 
-    app_joint = data;
+    nxt_assert(data != NULL);
+
+    app_joint_rpc = data;
+    app_joint = app_joint_rpc->app_joint;
     port = msg->u.new_port;
 
     nxt_assert(app_joint != NULL);
@@ -4257,14 +4365,37 @@ nxt_router_app_port_ready(nxt_task_t *task, nxt_port_recv_msg_t *msg,
         return;
     }
 
-    port->app = app;
-    port->main_app_port = port;
-
     nxt_thread_mutex_lock(&app->mutex);
 
     nxt_assert(app->pending_processes != 0);
 
     app->pending_processes--;
+
+    if (nxt_slow_path(app->generation != app_joint_rpc->generation)) {
+        nxt_debug(task, "new port ready for restarted app, send QUIT");
+
+        start_process = !task->thread->engine->shutdown
+                        && nxt_router_app_can_start(app)
+                        && nxt_router_app_need_start(app);
+
+        if (start_process) {
+            app->pending_processes++;
+        }
+
+        nxt_thread_mutex_unlock(&app->mutex);
+
+        nxt_port_socket_write(task, port, NXT_PORT_MSG_QUIT, -1, 0, 0, NULL);
+
+        if (start_process) {
+            nxt_router_start_app_process(task, app);
+        }
+
+        return;
+    }
+
+    port->app = app;
+    port->main_app_port = port;
+
     app->processes++;
     nxt_port_hash_add(&app->port_hash, port);
     app->port_hash_count++;
@@ -4322,8 +4453,12 @@ nxt_router_app_port_error(nxt_task_t *task, nxt_port_recv_msg_t *msg,
     nxt_app_joint_t      *app_joint;
     nxt_queue_link_t     *link;
     nxt_http_request_t   *r;
+    nxt_app_joint_rpc_t  *app_joint_rpc;
 
-    app_joint = data;
+    nxt_assert(data != NULL);
+
+    app_joint_rpc = data;
+    app_joint = app_joint_rpc->app_joint;
 
     nxt_assert(app_joint != NULL);
 
@@ -4490,7 +4625,7 @@ nxt_router_app_port_release(nxt_task_t *task, nxt_port_t *port,
               port->pid, port->id,
               (int) inc_use, (int) got_response);
 
-    if (port == app->shared_port) {
+    if (port->id == NXT_SHARED_PORT_ID) {
         nxt_thread_mutex_lock(&app->mutex);
 
         app->active_requests -= got_response + dec_requests;
@@ -4860,6 +4995,8 @@ nxt_router_free_app(nxt_task_t *task, void *obj, void *data)
         app->shared_port->app = NULL;
         nxt_port_close(task, app->shared_port);
         nxt_port_use(task, app->shared_port, -1);
+
+        app->shared_port = NULL;
     }
 
     nxt_thread_mutex_destroy(&app->mutex);

src/nxt_router.h

@@ -125,6 +125,8 @@ struct nxt_app_s {
     uint32_t               max_pending_processes;
     uint32_t               max_requests;
 
+    uint32_t               generation;
+
     nxt_msec_t             timeout;
     nxt_msec_t             idle_timeout;
 

test/python/restart/longstart.py

@@ -0,0 +1,10 @@
+import os
+import time
+
+time.sleep(2)
+
+def application(environ, start_response):
+    body = str(os.getpid()).encode()
+
+    start_response('200', [('Content-Length', str(len(body)))])
+    return [body]

test/python/restart/v1.py

@@ -0,0 +1,7 @@
+import os
+
+def application(environ, start_response):
+    body = "v1".encode()
+
+    start_response('200', [('Content-Length', str(len(body)))])
+    return [body]

test/python/restart/v2.py

@@ -0,0 +1,7 @@
+import os
+
+def application(environ, start_response):
+    body = "v2".encode()
+
+    start_response('200', [('Content-Length', str(len(body)))])
+    return [body]

test/test_python_procman.py

@@ -1,4 +1,5 @@
 import re
+import shutil
 import subprocess
 import time
 
@@ -201,3 +202,81 @@ class TestPythonProcman(TestApplicationPython):
         assert 'success' in self.conf({"listeners": {}, "applications": {}})
 
         assert len(self.pids_for_process()) == 0, 'stop all'
+
+    def test_python_restart(self, temp_dir):
+        shutil.copyfile(
+            option.test_dir + '/python/restart/v1.py', temp_dir + '/wsgi.py'
+        )
+
+        self.load(
+            temp_dir,
+            name=self.app_name,
+            processes=1,
+            environment={'PYTHONDONTWRITEBYTECODE': '1'},
+        )
+
+        b = self.get()['body']
+        assert b == "v1", 'process started'
+
+        shutil.copyfile(
+            option.test_dir + '/python/restart/v2.py', temp_dir + '/wsgi.py'
+        )
+
+        b = self.get()['body']
+        assert b == "v1", 'still old process'
+
+        assert 'success' in self.conf_get(
+            '/control/applications/' + self.app_name + '/restart'
+        ), 'restart processes'
+
+        b = self.get()['body']
+        assert b == "v2", 'new process started'
+
+        assert 'error' in self.conf_get(
+            '/control/applications/blah/restart'
+        ), 'application incorrect'
+
+        assert 'error' in self.conf_delete(
+            '/control/applications/' + self.app_name + '/restart'
+        ), 'method incorrect'
+
+    def test_python_restart_multi(self):
+        self.conf_proc('2')
+
+        pids = self.pids_for_process()
+        assert len(pids) == 2, 'restart 2 started'
+
+        assert 'success' in self.conf_get(
+            '/control/applications/' + self.app_name + '/restart'
+        ), 'restart processes'
+
+        new_pids = self.pids_for_process()
+        assert len(new_pids) == 2, 'restart still 2'
+
+        assert len(new_pids.intersection(pids)) == 0, 'restart all new'
+
+    def test_python_restart_longstart(self):
+        self.load(
+            'restart',
+            name=self.app_name,
+            module="longstart",
+            processes={"spare": 1, "max": 2, "idle_timeout": 5},
+        )
+
+        assert len(self.pids_for_process()) == 1, 'longstarts == 1'
+
+        pid = self.get()['body']
+        pids = self.pids_for_process()
+        assert len(pids) == 2, 'longstarts == 2'
+
+        assert 'success' in self.conf_get(
+            '/control/applications/' + self.app_name + '/restart'
+        ), 'restart processes'
+
+        # wait for longstarted app
+        time.sleep(2)
+
+        new_pids = self.pids_for_process()
+        assert len(new_pids) == 1, 'restart 1'
+
+        assert len(new_pids.intersection(pids)) == 0, 'restart all new'

test/unit/applications/lang/python.py

@@ -44,6 +44,7 @@ class TestApplicationPython(TestApplicationProto):
 
         for attr in (
             'callable',
+            'environment',
             'home',
             'limits',
             'path',