Filtering process to keep connection.

- Main process should be connected to all other processes.
- Controller should be connected to Router.
- Router should be connected to Controller and all Workers.
- Workers should be connected to Router worker thread ports only.

This filtering helps to avoid unnecessary communication and various errors
during massive application workers stop / restart.

src/nxt_main_process.c

@@ -764,6 +764,7 @@ nxt_main_cleanup_worker_process(nxt_task_t *task, nxt_pid_t pid)
     nxt_port_t          *port;
     nxt_runtime_t       *rt;
     nxt_process_t       *process;
+    nxt_process_type_t  ptype;
     nxt_process_init_t  *init;
 
     rt = task->thread->runtime;
@@ -773,6 +774,8 @@ nxt_main_cleanup_worker_process(nxt_task_t *task, nxt_pid_t pid)
     if (process) {
         init = process->init;
 
+        ptype = nxt_process_type(process);
+
         nxt_process_close_ports(task, process);
 
         if (!nxt_exiting) {
@@ -787,6 +790,10 @@ nxt_main_cleanup_worker_process(nxt_task_t *task, nxt_pid_t pid)
 
                 port = nxt_process_port_first(process);
 
+                if (nxt_proc_remove_notify_martix[ptype][port->type] == 0) {
+                    continue;
+                }
+
                 buf = nxt_buf_mem_ts_alloc(task, task->thread->engine->mem_pool,
                                            sizeof(pid));
                 buf->mem.free = nxt_cpymem(buf->mem.free, &pid, sizeof(pid));

src/nxt_port.c

@@ -177,7 +177,7 @@ nxt_port_quit_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
 }
 
 
-void
+nxt_inline void
 nxt_port_send_new_port(nxt_task_t *task, nxt_runtime_t *rt,
     nxt_port_t *new_port, uint32_t stream)
 {
@@ -195,10 +195,7 @@ nxt_port_send_new_port(nxt_task_t *task, nxt_runtime_t *rt,
 
         port = nxt_process_port_first(process);
 
-        if (port->type == NXT_PROCESS_MAIN
-            || port->type == NXT_PROCESS_CONTROLLER
-            || port->type == NXT_PROCESS_ROUTER)
-        {
+        if (nxt_proc_conn_martix[port->type][new_port->type]) {
             (void) nxt_port_send_port(task, port, new_port, stream);
         }
 

src/nxt_port.h

@@ -227,8 +227,6 @@ nxt_int_t nxt_port_socket_write(nxt_task_t *task, nxt_port_t *port,
 
 void nxt_port_enable(nxt_task_t *task, nxt_port_t *port,
     nxt_port_handlers_t *handlers);
-void nxt_port_send_new_port(nxt_task_t *task, nxt_runtime_t *rt,
-    nxt_port_t *port, uint32_t stream);
 nxt_int_t nxt_port_send_port(nxt_task_t *task, nxt_port_t *port,
     nxt_port_t *new_port, uint32_t stream);
 void nxt_port_change_log_file(nxt_task_t *task, nxt_runtime_t *rt,

src/nxt_process.c

@@ -18,13 +18,31 @@ nxt_pid_t  nxt_pid;
 /* An original parent process pid. */
 nxt_pid_t  nxt_ppid;
 
+nxt_bool_t  nxt_proc_conn_martix[NXT_PROCESS_MAX][NXT_PROCESS_MAX] = {
+    { 0, 0, 0, 0, 0, 0 },
+    { 0, 1, 1, 1, 1, 1 },
+    { 0, 1, 0, 0, 0, 0 },
+    { 0, 1, 0, 0, 1, 0 },
+    { 0, 1, 0, 1, 0, 1 },
+    { 0, 1, 0, 0, 0, 0 },
+};
+
+nxt_bool_t  nxt_proc_remove_notify_martix[NXT_PROCESS_MAX][NXT_PROCESS_MAX] = {
+    { 0, 0, 0, 0, 0, 0 },
+    { 0, 0, 0, 0, 0, 0 },
+    { 0, 0, 0, 0, 0, 0 },
+    { 0, 0, 0, 0, 1, 0 },
+    { 0, 0, 0, 1, 0, 1 },
+    { 0, 0, 0, 0, 1, 0 },
+};
 
 nxt_pid_t
 nxt_process_create(nxt_task_t *task, nxt_process_t *process)
 {
-    nxt_pid_t      pid;
-    nxt_process_t  *p;
-    nxt_runtime_t  *rt;
+    nxt_pid_t           pid;
+    nxt_process_t       *p;
+    nxt_runtime_t       *rt;
+    nxt_process_type_t  ptype;
 
     rt = task->thread->runtime;
 
@@ -48,6 +66,8 @@ nxt_process_create(nxt_task_t *task, nxt_process_t *process)
 
         rt->types = 0;
 
+        ptype = process->init->type;
+
         nxt_port_reset_next_id();
 
         nxt_event_engine_thread_adopt(task->thread->engine);
@@ -55,16 +75,25 @@ nxt_process_create(nxt_task_t *task, nxt_process_t *process)
         /* Remove not ready processes */
         nxt_runtime_process_each(rt, p) {
 
+            if (nxt_proc_conn_martix[ptype][nxt_process_type(p)] == 0) {
+                nxt_debug(task, "remove not required process %PI", p->pid);
+
+                nxt_process_close_ports(task, p);
+
+                continue;
+            }
+
             if (!p->ready) {
                 nxt_debug(task, "remove not ready process %PI", p->pid);
 
                 nxt_process_close_ports(task, p);
 
-            } else {
-                nxt_port_mmaps_destroy(&p->incoming, 0);
-                nxt_port_mmaps_destroy(&p->outgoing, 0);
+                continue;
             }
 
+            nxt_port_mmaps_destroy(&p->incoming, 0);
+            nxt_port_mmaps_destroy(&p->outgoing, 0);
+
         } nxt_runtime_process_loop;
 
         nxt_runtime_process_add(task, process);
@@ -598,6 +627,14 @@ nxt_process_port_add(nxt_task_t *task, nxt_process_t *process, nxt_port_t *port)
 }
 
 
+nxt_process_type_t
+nxt_process_type(nxt_process_t *process)
+{
+    return nxt_queue_is_empty(&process->ports) ? 0 :
+        (nxt_process_port_first(process))->type;
+}
+
+
 void
 nxt_process_close_ports(nxt_task_t *task, nxt_process_t *process)
 {

src/nxt_process.h

@@ -70,6 +70,10 @@ typedef struct {
 } nxt_process_t;
 
 
+extern nxt_bool_t  nxt_proc_conn_martix[NXT_PROCESS_MAX][NXT_PROCESS_MAX];
+extern nxt_bool_t
+          nxt_proc_remove_notify_martix[NXT_PROCESS_MAX][NXT_PROCESS_MAX];
+
 NXT_EXPORT nxt_pid_t nxt_process_create(nxt_task_t *task,
     nxt_process_t *process);
 NXT_EXPORT nxt_pid_t nxt_process_execute(nxt_task_t *task, char *name,
@@ -95,6 +99,8 @@ NXT_EXPORT void nxt_process_port_add(nxt_task_t *task, nxt_process_t *process,
 #define nxt_process_port_loop                                                 \
     nxt_queue_loop
 
+nxt_process_type_t nxt_process_type(nxt_process_t *process);
+
 void nxt_process_close_ports(nxt_task_t *task, nxt_process_t *process);
 
 void nxt_process_connected_port_add(nxt_process_t *process, nxt_port_t *port);