Special pipe between monitor and server for clients using force_dorma…

…nt_start option

Summary:
We want to prevent accepting clients, but there are also special clients (using `--force-dormant-start` flag) that need to be accepted. The easiest way I could think to do it (without rewriting entire client handling code, which we should do at some point), is to send them through a special channel.

(Note: this ignores all push blocking failures!)

Differential Revision: D10515469

fbshipit-source-id: f63d5e6bd0661530b9d522cfb7b239c477adb53a

hphp/hack/src/server/clientProvider_sig.ml

@@ -13,7 +13,7 @@ module type S = sig
 
   exception Client_went_away
 
-  val provider_from_file_descriptors : (Unix.file_descr * Unix.file_descr) -> t
+  val provider_from_file_descriptors : (Unix.file_descr * Unix.file_descr * Unix.file_descr) -> t
   val provider_for_test : unit -> t
 
   val sleep_and_check : t ->
@@ -22,7 +22,7 @@ module type S = sig
     (* Whether the most recent message received from persistent client
      * was IDE_IDLE *)
     ide_idle:bool ->
-    [`Any | `Priority] ->
+    [`Any | `Priority | `Force_dormant_start_only] ->
     (** Returns an optional new client, and a boolean for whether there is
      * a request on the persistent client. *)
     client option * bool

hphp/hack/src/server/hhServerMonitorConfig.ml

@@ -14,10 +14,12 @@ module SP = ServerProcess
 type pipe_type =
   | Default
   | Priority
+  | Force_dormant_start_only
 
 let pipe_type_to_string = function
   | Default -> "default"
   | Priority -> "priority"
+  | Force_dormant_start_only -> "force_dormant_start_only"
 
 let start_server_daemon ~informant_managed options log_link daemon_entry =
   let log_fds =
@@ -43,13 +45,20 @@ let start_server_daemon ~informant_managed options log_link daemon_entry =
   let () = Unix.set_close_on_exec parent_priority_fd in
   let () = Unix.clear_close_on_exec child_priority_fd in
 
+  let parent_force_dormant_start_only_fd, child_force_dormant_start_only_force_fd =
+    Unix.socketpair Unix.PF_UNIX Unix.SOCK_STREAM 0 in
+  let () = Unix.set_close_on_exec parent_force_dormant_start_only_fd in
+  let () = Unix.clear_close_on_exec child_force_dormant_start_only_force_fd in
+
   let {Daemon.pid; Daemon.channels = (ic, oc)} =
     Daemon.spawn
       ~channel_mode:`socket
       log_fds
       daemon_entry
-      (informant_managed, state, options, monitor_pid, child_priority_fd) in
+      (informant_managed, state, options, monitor_pid,
+        child_priority_fd, child_force_dormant_start_only_force_fd) in
   Unix.close child_priority_fd;
+  Unix.close child_force_dormant_start_only_force_fd;
   Hh_logger.log "Just started typechecker server with pid: %d." pid;
   let server =
     SP.({
@@ -58,6 +67,7 @@ let start_server_daemon ~informant_managed options log_link daemon_entry =
       out_fds = [
         pipe_type_to_string Default, Daemon.descr_of_out_channel oc;
         pipe_type_to_string Priority, parent_priority_fd;
+        pipe_type_to_string Force_dormant_start_only, parent_force_dormant_start_only_fd;
       ];
       start_t = start_t;
       last_request_handoff = ref (Unix.time());

hphp/hack/src/server/serverClientProvider.ml

@@ -12,8 +12,8 @@ open ServerCommandTypes
 
 exception Client_went_away
 
-(* default pipe, priority pipe *)
-type t = Unix.file_descr * Unix.file_descr
+(* default pipe, priority pipe, force formant start only pipe *)
+type t = Unix.file_descr * Unix.file_descr * Unix.file_descr
 type client =
   | Non_persistent_client of Timeout.in_channel * Out_channel.t
   | Persistent_client of Unix.file_descr
@@ -40,14 +40,15 @@ let accept_client_opt parent_in_fd =
 (* - If we should read from persistent_client, then (None, true)            *)
 (* - If we should read from in_fd, then (Some (Non_persist in_fd)), false)  *)
 (* - If there's nothing to read, then (None, false)                         *)
-let sleep_and_check (default_in_fd, priority_in_fd) persistent_client_opt
+let sleep_and_check (default_in_fd, priority_in_fd, force_dormant_start_only) persistent_client_opt
     ~ide_idle kind =
-  let in_fds = [default_in_fd; priority_in_fd] in
+  let in_fds = [default_in_fd; priority_in_fd; force_dormant_start_only] in
   let is_persistent x = match persistent_client_opt with
     | Some (Persistent_client fd) when fd = x -> true
     | _ -> false
   in
   let l = match kind, persistent_client_opt with
+    | `Force_dormant_start_only, _ -> [force_dormant_start_only]
     | `Priority, _ -> [priority_in_fd]
     | `Any, Some (Persistent_client fd) ->
       (* If we are not sure that there are no more IDE commands, do not even
@@ -73,7 +74,7 @@ let has_persistent_connection_request = function
     ready <> []
   | _ -> false
 
-let priority_fd (_, x) = Some x
+let priority_fd (_, x, _) = Some x
 
 let get_client_fd = function
   | Persistent_client fd -> Some fd

hphp/hack/src/server/serverMain.ml

@@ -909,10 +909,13 @@ let daemon_main_exn ~informant_managed options monitor_pid in_fds =
   let env = MainInit.go genv options init_id (fun () -> program_init genv) in
   serve genv env in_fds
 
-let daemon_main (informant_managed, state, options, monitor_pid, priority_in_fd)
-  (default_ic, _) =
+let daemon_main
+    (informant_managed, state, options,
+      monitor_pid, priority_in_fd, force_dormant_start_only_in_fd)
+    (default_ic, _) =
   (* Avoid leaking this fd further *)
   let () = Unix.set_close_on_exec priority_in_fd in
+  let () = Unix.set_close_on_exec force_dormant_start_only_in_fd in
   let default_in_fd = Daemon.descr_of_in_channel default_ic in
   (* Restore the root directory and other global states from monitor *)
   ServerGlobalState.restore state;
@@ -922,7 +925,7 @@ let daemon_main (informant_managed, state, options, monitor_pid, priority_in_fd)
 
   ServerUtils.with_exit_on_exception @@ fun () ->
   daemon_main_exn ~informant_managed options monitor_pid
-    (default_in_fd, priority_in_fd)
+    (default_in_fd, priority_in_fd, force_dormant_start_only_in_fd)
 
 
 let entry =

hphp/hack/src/server/serverMain.mli

@@ -12,7 +12,7 @@
  * these phantom types because OCaml doesn't allow polymorphic values that
  * are not functions. *)
 val entry:
-  (bool * ServerGlobalState.t * ServerArgs.options * int * Unix.file_descr,
+  (bool * ServerGlobalState.t * ServerArgs.options * int * Unix.file_descr * Unix.file_descr,
     unit, unit) Daemon.entry
 
 val run_once: ServerArgs.options -> SharedMem.handle -> 'a