track workers by Pid instead of name

3 files changed, 37 insertions, 59 deletions

diff --git a/src/worker_pool.erl b/src/worker_pool.erl
index 268c703f..db8c4e96 100644
--- a/src/worker_pool.erl
+++ b/src/worker_pool.erl
@@ -42,7 +42,7 @@
 -spec(start_link/0 :: () -> {'ok', pid()} | {'error', any()}).
 -spec(submit/1 :: (fun (() -> A) | mfargs()) -> A).
 -spec(submit_async/1 :: (fun (() -> any()) | mfargs()) -> 'ok').
--spec(idle/1 :: (any()) -> 'ok').
+-spec(idle/1 :: (pid()) -> 'ok').
 
 -endif.
 
@@ -56,9 +56,8 @@
 
 %%----------------------------------------------------------------------------
 
-start_link() ->
-    gen_server2:start_link({local, ?SERVER}, ?MODULE, [],
-                           [{timeout, infinity}]).
+start_link() -> gen_server2:start_link({local, ?SERVER}, ?MODULE, [],
+                                       [{timeout, infinity}]).
 
 submit(Fun) ->
     case get(worker_pool_worker) of
@@ -67,11 +66,9 @@ submit(Fun) ->
                 worker_pool_worker:submit(Pid, Fun)
     end.
 
-submit_async(Fun) ->
-    gen_server2:cast(?SERVER, {run_async, Fun}).
+submit_async(Fun) -> gen_server2:cast(?SERVER, {run_async, Fun}).
 
-idle(WId) ->
-    gen_server2:cast(?SERVER, {idle, WId}).
+idle(WPid) -> gen_server2:cast(?SERVER, {idle, WPid}).
 
 %%----------------------------------------------------------------------------
 
@@ -84,27 +81,25 @@ handle_call({next_free, CPid}, From, State = #state { available = [],
     {noreply, State#state{pending = queue:in({next_free, From, CPid}, Pending)},
      hibernate};
 handle_call({next_free, CPid}, _From, State = #state { available =
-                                                           [WId | Avail1] }) ->
-    WPid = get_worker_pid(WId),
+                                                           [WPid | Avail1] }) ->
     worker_pool_worker:next_job_from(WPid, CPid),
     {reply, WPid, State #state { available = Avail1 }, hibernate};
 
 handle_call(Msg, _From, State) ->
     {stop, {unexpected_call, Msg}, State}.
 
-handle_cast({idle, WId}, State = #state { available = Avail,
-                                          pending   = Pending }) ->
+handle_cast({idle, WPid}, State = #state { available = Avail,
+                                           pending   = Pending }) ->
     {noreply,
      case queue:out(Pending) of
          {empty, _Pending} ->
-             State #state { available = ordsets:add_element(WId, Avail) };
+             State #state { available = ordsets:add_element(WPid, Avail) };
          {{value, {next_free, From, CPid}}, Pending1} ->
-             WPid = get_worker_pid(WId),
              worker_pool_worker:next_job_from(WPid, CPid),
              gen_server2:reply(From, WPid),
              State #state { pending = Pending1 };
          {{value, {run_async, Fun}}, Pending1} ->
-             worker_pool_worker:submit_async(get_worker_pid(WId), Fun),
+             worker_pool_worker:submit_async(WPid, Fun),
              State #state { pending = Pending1 }
      end, hibernate};
 
@@ -112,8 +107,8 @@ handle_cast({run_async, Fun}, State = #state { available = [],
                                                pending   = Pending }) ->
     {noreply, State #state { pending = queue:in({run_async, Fun}, Pending)},
      hibernate};
-handle_cast({run_async, Fun}, State = #state { available = [WId | Avail1] }) ->
-    worker_pool_worker:submit_async(get_worker_pid(WId), Fun),
+handle_cast({run_async, Fun}, State = #state { available = [WPid | Avail1] }) ->
+    worker_pool_worker:submit_async(WPid, Fun),
     {noreply, State #state { available = Avail1 }, hibernate};
 
 handle_cast(Msg, State) ->
@@ -127,14 +122,3 @@ code_change(_OldVsn, State, _Extra) ->
 
 terminate(_Reason, State) ->
     State.
-
-%%----------------------------------------------------------------------------
-
-get_worker_pid(WId) ->
-    [{WId, Pid, _Type, _Modules} | _] =
-        lists:dropwhile(fun ({Id, _Pid, _Type, _Modules})
-                              when Id =:= WId -> false;
-                            (_)               -> true
-                        end,
-                        supervisor:which_children(worker_pool_sup)),
-    Pid.
diff --git a/src/worker_pool_sup.erl b/src/worker_pool_sup.erl
index 16c359a0..89d2ed46 100644
--- a/src/worker_pool_sup.erl
+++ b/src/worker_pool_sup.erl
@@ -49,5 +49,5 @@ init([WCount]) ->
     {ok, {{one_for_one, 10, 10},
           [{worker_pool, {worker_pool, start_link, []}, transient,
             16#ffffffff, worker, [worker_pool]} |
-           [{N, {worker_pool_worker, start_link, [N]}, transient, 16#ffffffff,
+           [{N, {worker_pool_worker, start_link, []}, transient, 16#ffffffff,
              worker, [worker_pool_worker]} || N <- lists:seq(1, WCount)]]}}.
diff --git a/src/worker_pool_worker.erl b/src/worker_pool_worker.erl
index 43673cb2..ef6f115a 100644
--- a/src/worker_pool_worker.erl
+++ b/src/worker_pool_worker.erl
@@ -18,7 +18,7 @@
 
 -behaviour(gen_server2).
 
--export([start_link/1, next_job_from/2, submit/2, submit_async/2, run/1]).
+-export([start_link/0, next_job_from/2, submit/2, submit_async/2, run/1]).
 
 -export([set_maximum_since_use/2]).
 
@@ -31,7 +31,7 @@
 
 -type(mfargs() :: {atom(), atom(), [any()]}).
 
--spec(start_link/1 :: (any()) -> {'ok', pid()} | {'error', any()}).
+-spec(start_link/0 :: () -> {'ok', pid()} | {'error', any()}).
 -spec(next_job_from/2 :: (pid(), pid()) -> 'ok').
 -spec(submit/2 :: (pid(), fun (() -> A) | mfargs()) -> A).
 -spec(submit_async/2 :: (pid(), fun (() -> any()) | mfargs()) -> 'ok').
@@ -45,12 +45,10 @@
 -define(HIBERNATE_AFTER_MIN, 1000).
 -define(DESIRED_HIBERNATE, 10000).
 
--record(state, {id, next}).
-
 %%----------------------------------------------------------------------------
 
-start_link(WId) ->
-    gen_server2:start_link(?MODULE, [WId], [{timeout, infinity}]).
+start_link() ->
+    gen_server2:start_link(?MODULE, [], [{timeout, infinity}]).
 
 next_job_from(Pid, CPid) ->
     gen_server2:cast(Pid, {next_job_from, CPid}).
@@ -71,45 +69,43 @@ run(Fun) ->
 
 %%----------------------------------------------------------------------------
 
-init([WId]) ->
+init([]) ->
     ok = file_handle_cache:register_callback(?MODULE, set_maximum_since_use,
                                              [self()]),
-    ok = worker_pool:idle(WId),
+    ok = worker_pool:idle(self()),
     put(worker_pool_worker, true),
-    {ok, #state{id = WId}, hibernate,
+    {ok, undefined, hibernate,
      {backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}.
 
 prioritise_cast({set_maximum_since_use, _Age}, _Len, _State) -> 8;
 prioritise_cast({next_job_from, _CPid},        _Len, _State) -> 7;
 prioritise_cast(_Msg,                          _Len, _State) -> 0.
 
-handle_call({submit, Fun, CPid}, From, State = #state{next = undefined}) ->
-    {noreply, State#state{next = {job, CPid, From, Fun}}, hibernate};
+handle_call({submit, Fun, CPid}, From, undefined) ->
+    {noreply, {job, CPid, From, Fun}, hibernate};
 
-handle_call({submit, Fun, CPid}, From, State = #state{next = {from, CPid, MRef},
-                                                      id   = WId}) ->
+handle_call({submit, Fun, CPid}, From, {from, CPid, MRef}) ->
     erlang:demonitor(MRef),
     gen_server2:reply(From, run(Fun)),
-    ok = worker_pool:idle(WId),
-    {noreply, State#state{next = undefined}, hibernate};
+    ok = worker_pool:idle(self()),
+    {noreply, undefined, hibernate};
 
 handle_call(Msg, _From, State) ->
     {stop, {unexpected_call, Msg}, State}.
 
-handle_cast({next_job_from, CPid}, State = #state{next = undefined}) ->
+handle_cast({next_job_from, CPid}, undefined) ->
     MRef = erlang:monitor(process, CPid),
-    {noreply, State#state{next = {from, CPid, MRef}}, hibernate};
+    {noreply, {from, CPid, MRef}, hibernate};
 
-handle_cast({next_job_from, CPid}, State = #state{next = {job, CPid, From, Fun},
-                                                  id   = WId}) ->
+handle_cast({next_job_from, CPid}, {job, CPid, From, Fun}) ->
     gen_server2:reply(From, run(Fun)),
-    ok = worker_pool:idle(WId),
-    {noreply, State#state{next = undefined}, hibernate};
+    ok = worker_pool:idle(self()),
+    {noreply, undefined, hibernate};
 
-handle_cast({submit_async, Fun}, State = #state{id = WId}) ->
+handle_cast({submit_async, Fun}, undefined) ->
     run(Fun),
-    ok = worker_pool:idle(WId),
-    {noreply, State, hibernate};
+    ok = worker_pool:idle(self()),
+    {noreply, undefined, hibernate};
 
 handle_cast({set_maximum_since_use, Age}, State) ->
     ok = file_handle_cache:set_maximum_since_use(Age),
@@ -118,14 +114,12 @@ handle_cast({set_maximum_since_use, Age}, State) ->
 handle_cast(Msg, State) ->
     {stop, {unexpected_cast, Msg}, State}.
 
-handle_info({'DOWN', MRef, process, CPid, _Reason},
-            State = #state{id            = WId,
-                           next = {from, CPid, MRef}}) ->
-    ok = worker_pool:idle(WId),
-    {noreply, State#state{next = undefined}};
+handle_info({'DOWN', MRef, process, CPid, _Reason}, {from, CPid, MRef}) ->
+    ok = worker_pool:idle(self()),
+    {noreply, undefined, hibernate};
 
 handle_info({'DOWN', _MRef, process, _Pid, _Reason}, State) ->
-    {noreply, State};
+    {noreply, State, hibernate};
 
 handle_info(Msg, State) ->
     {stop, {unexpected_info, Msg}, State}.