add worker_pook:submit_async/1

This was on the todo list and got cherry-picked from the bug21673 branch.

2 files changed, 34 insertions, 6 deletions

diff --git a/src/worker_pool.erl b/src/worker_pool.erl
index 1ee958af..97e07545 100644
--- a/src/worker_pool.erl
+++ b/src/worker_pool.erl
@@ -40,12 +40,10 @@
 %%
 %% 1. Allow priorities (basically, change the pending queue to a
 %% priority_queue).
-%%
-%% 2. Allow the submission to the pool_worker to be async.
 
 -behaviour(gen_server2).
 
--export([start_link/0, submit/1, idle/1]).
+-export([start_link/0, submit/1, submit_async/1, idle/1]).
 
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
          terminate/2, code_change/3]).
@@ -56,6 +54,8 @@
 
 -spec(start_link/0 :: () -> {'ok', pid()} | 'ignore' | {'error', any()}).
 -spec(submit/1 :: (fun (() -> A) | {atom(), atom(), [any()]}) -> A).
+-spec(submit_async/1 ::
+      (fun (() -> any()) | {atom(), atom(), [any()]}) -> 'ok').
 
 -endif.
 
@@ -80,6 +80,9 @@ submit(Fun) ->
                 worker_pool_worker:submit(Pid, Fun)
     end.
 
+submit_async(Fun) ->
+    gen_server2:cast(?SERVER, {run_async, Fun}).
+
 idle(WId) ->
     gen_server2:cast(?SERVER, {idle, WId}).
 
@@ -93,7 +96,8 @@ handle_call(next_free, From, State = #state { available = Avail,
                                               pending = Pending }) ->
     case queue:out(Avail) of
         {empty, _Avail} ->
-            {noreply, State #state { pending = queue:in(From, Pending) },
+            {noreply,
+             State #state { pending = queue:in({next_free, From}, Pending) },
              hibernate};
         {{value, WId}, Avail1} ->
             {reply, get_worker_pid(WId), State #state { available = Avail1 },
@@ -108,11 +112,25 @@ handle_cast({idle, WId}, State = #state { available = Avail,
     {noreply, case queue:out(Pending) of
                   {empty, _Pending} ->
                       State #state { available = queue:in(WId, Avail) };
-                  {{value, From}, Pending1} ->
+                  {{value, {next_free, From}}, Pending1} ->
                       gen_server2:reply(From, get_worker_pid(WId)),
+                      State #state { pending = Pending1 };
+                  {{value, {run_async, Fun}}, Pending1} ->
+                      worker_pool_worker:submit_async(get_worker_pid(WId), Fun),
                       State #state { pending = Pending1 }
               end, hibernate};
 
+handle_cast({run_async, Fun}, State = #state { available = Avail,
+                                               pending = Pending }) ->
+    {noreply,
+     case queue:out(Avail) of
+         {empty, _Avail} ->
+             State #state { pending = queue:in({run_async, Fun}, Pending)};
+         {{value, WId}, Avail1} ->
+             worker_pool_worker:submit_async(get_worker_pid(WId), Fun),
+             State #state { available = Avail1 }
+     end, hibernate};
+
 handle_cast(Msg, State) ->
     {stop, {unexpected_cast, Msg}, State}.
 
diff --git a/src/worker_pool_worker.erl b/src/worker_pool_worker.erl
index 3bfcc2d9..d3a48119 100644
--- a/src/worker_pool_worker.erl
+++ b/src/worker_pool_worker.erl
@@ -33,7 +33,7 @@
 
 -behaviour(gen_server2).
 
--export([start_link/1, submit/2, run/1]).
+-export([start_link/1, submit/2, submit_async/2, run/1]).
 
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
          terminate/2, code_change/3]).
@@ -44,6 +44,8 @@
 
 -spec(start_link/1 :: (any()) -> {'ok', pid()} | 'ignore' | {'error', any()}).
 -spec(submit/2 :: (pid(), fun (() -> A) | {atom(), atom(), [any()]}) -> A).
+-spec(submit_async/2 ::
+      (pid(), fun (() -> any()) | {atom(), atom(), [any()]}) -> 'ok').
 
 -endif.
 
@@ -60,6 +62,9 @@ start_link(WId) ->
 submit(Pid, Fun) ->
     gen_server2:call(Pid, {submit, Fun}, infinity).
 
+submit_async(Pid, Fun) ->
+    gen_server2:cast(Pid, {submit_async, Fun}).
+
 init([WId]) ->
     ok = worker_pool:idle(WId),
     put(worker_pool_worker, true),
@@ -74,6 +79,11 @@ handle_call({submit, Fun}, From, WId) ->
 handle_call(Msg, _From, State) ->
     {stop, {unexpected_call, Msg}, State}.
 
+handle_cast({submit_async, Fun}, WId) ->
+    run(Fun),
+    ok = worker_pool:idle(WId),
+    {noreply, WId, hibernate};
+
 handle_cast(Msg, State) ->
     {stop, {unexpected_cast, Msg}, State}.