job control: add 'detach' option to jobstart

runtime/doc/eval.txt

@@ -4194,6 +4194,10 @@ jobstart({cmd}[, {opts}])				{Nvim} *jobstart()*
 		  - width: Width of the terminal screen(only if pty is set)
 		  - height: Height of the terminal screen(only if pty is set)
 		  - TERM: $TERM environment variable(only if pty is set)
+		  - detach: Detach the job process from the nvim process. The
+		    process won't get killed when nvim exists. If the process
+		    dies before nvim exits, on_exit will still be invoked.
+		    This option is only allowed for non-pty jobs.
 		Either funcrefs or function names can be passed as event
 		handlers. The {opts} object is also used as the "self"
 		argument for the callback, so the caller may pass arbitrary

src/nvim/eval.c

@@ -11771,8 +11771,9 @@ static void f_jobstart(typval_T *argvars, typval_T *rettv)
   }
 
   bool pty = job_opts && get_dict_number(job_opts, (uint8_t *)"pty") != 0;
+  bool detach = job_opts && get_dict_number(job_opts, (uint8_t *)"detach") != 0;
   TerminalJobData *data = common_job_init(argv, on_stdout, on_stderr, on_exit,
-      job_opts, pty);
+                                          job_opts, pty, detach);
   Process *proc = (Process *)&data->proc;
 
   if (pty) {
@@ -16776,7 +16777,7 @@ static void f_termopen(typval_T *argvars, typval_T *rettv)
   }
 
   TerminalJobData *data = common_job_init(argv, on_stdout, on_stderr, on_exit,
-      job_opts, true);
+                                          job_opts, true, false);
   data->proc.pty.width = curwin->w_width;
   data->proc.pty.height = curwin->w_height;
   data->proc.pty.term_name = xstrdup("xterm-256color");
@@ -21782,8 +21783,13 @@ char_u *do_string_sub(char_u *str, char_u *pat, char_u *sub, char_u *flags)
   return ret;
 }
 
-static inline TerminalJobData *common_job_init(char **argv, ufunc_T *on_stdout,
-    ufunc_T *on_stderr, ufunc_T *on_exit, dict_T *self, bool pty)
+static inline TerminalJobData *common_job_init(char **argv,
+                                               ufunc_T *on_stdout,
+                                               ufunc_T *on_stderr,
+                                               ufunc_T *on_exit,
+                                               dict_T *self,
+                                               bool pty,
+                                               bool detach)
 {
   TerminalJobData *data = xcalloc(1, sizeof(TerminalJobData));
   data->stopped = false;
@@ -21806,6 +21812,7 @@ static inline TerminalJobData *common_job_init(char **argv, ufunc_T *on_stdout,
   }
   proc->cb = on_process_exit;
   proc->events = data->events;
+  proc->detach = detach;
   return data;
 }
 
@@ -21833,8 +21840,13 @@ static inline bool common_job_callbacks(dict_T *vopts, ufunc_T **on_stdout,
 
 static inline bool common_job_start(TerminalJobData *data, typval_T *rettv)
 {
-  data->refcount++;
   Process *proc = (Process *)&data->proc;
+  if (proc->type == kProcessTypePty && proc->detach) {
+    EMSG2(_(e_invarg2), "terminal/pty job cannot be detached");
+    return false;
+  }
+
+  data->refcount++;
   char *cmd = xstrdup(proc->argv[0]);
   if (!process_spawn(proc)) {
     EMSG2(_(e_jobspawn), cmd);

src/nvim/event/libuv_process.c

@@ -21,6 +21,9 @@ bool libuv_process_spawn(LibuvProcess *uvproc)
   uvproc->uvopts.args = proc->argv;
   uvproc->uvopts.flags = UV_PROCESS_WINDOWS_HIDE
                   | UV_PROCESS_WINDOWS_VERBATIM_ARGUMENTS;
+  if (proc->detach) {
+      uvproc->uvopts.flags |= UV_PROCESS_DETACHED;
+  }
   uvproc->uvopts.exit_cb = exit_cb;
   uvproc->uvopts.cwd = NULL;
   uvproc->uvopts.env = NULL;

src/nvim/event/process.c

@@ -29,6 +29,7 @@
     }                                                               \
   } while (0)
 
+static bool process_is_tearing_down = false;
 
 bool process_spawn(Process *proc) FUNC_ATTR_NONNULL_ALL
 {
@@ -112,11 +113,17 @@ bool process_spawn(Process *proc) FUNC_ATTR_NONNULL_ALL
 
 void process_teardown(Loop *loop) FUNC_ATTR_NONNULL_ALL
 {
+  process_is_tearing_down = true;
   kl_iter(WatcherPtr, loop->children, current) {
     Process *proc = (*current)->data;
-    uv_kill(proc->pid, SIGTERM);
-    proc->term_sent = true;
-    process_stop(proc);
+    if (proc->detach) {
+      // Close handles to process without killing it.
+      CREATE_EVENT(loop->events, process_close_handles, 1, proc);
+    } else {
+      uv_kill(proc->pid, SIGTERM);
+      proc->term_sent = true;
+      process_stop(proc);
+    }
   }
 
   // Wait until all children exit
@@ -303,6 +310,10 @@ static void decref(Process *proc)
 static void process_close(Process *proc)
   FUNC_ATTR_NONNULL_ARG(1)
 {
+  if (process_is_tearing_down && proc->detach && proc->closed) {
+    // If a detached process dies while tearing down it might get closed twice.
+    return;
+  }
   assert(!proc->closed);
   proc->closed = true;
   switch (proc->type) {
@@ -333,6 +344,7 @@ static void on_process_exit(Process *proc)
     DLOG("Stopping process kill timer");
     uv_timer_stop(&loop->children_kill_timer);
   }
+
   // Process handles are closed in the next event loop tick. This is done to
   // give libuv more time to read data from the OS after the process exits(If
   // process_close_streams is called with data still in the OS buffer, we lose

src/nvim/event/process.h

@@ -25,7 +25,7 @@ struct process {
   Stream *in, *out, *err;
   process_exit_cb cb;
   internal_process_cb internal_exit_cb, internal_close_cb;
-  bool closed, term_sent;
+  bool closed, term_sent, detach;
   Queue *events;
 };
 
@@ -48,7 +48,8 @@ static inline Process process_init(Loop *loop, ProcessType type, void *data)
     .closed = false,
     .term_sent = false,
     .internal_close_cb = NULL,
-    .internal_exit_cb = NULL
+    .internal_exit_cb = NULL,
+    .detach = false
   };
 }