From 3cf37fe21c7b9247c6c5f2c5a93f5480b2ad4f7c Mon Sep 17 00:00:00 2001
From: Fred Hebert <mononcqc@ferd.ca>
Date: Fri, 6 Jul 2012 08:13:13 -0400
Subject: [PATCH] Attempt at fixing a possible process leak

Yoshihiro Tanaka found that when lhttpc:request closes a worker
due to a timeout, it's possible that it happens after the port
is unlinked in prim_inet:close, but before it is properly closed.

This results in orphaned sockets/ports being left hanging in the
ether.

This fix attempts to wrap lhttpc_sock:close commands around a safe
build that should resolve it.

A potential fix would have been to have the manager monitor the
sockets itself, but this wouldn't have worked if the socket is new
and the manager has never seen it before, hence the current fix.
---
 src/lhttpc.app.src  |  2 +-
 src/lhttpc_sock.erl | 26 ++++++++++++++++++++++++--
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/lhttpc.app.src b/src/lhttpc.app.src
index 0603b2bd..75f17ef8 100644
--- a/src/lhttpc.app.src
+++ b/src/lhttpc.app.src
@@ -29,7 +29,7 @@
 %%% @end
 {application, lhttpc,
     [{description, "Lightweight HTTP Client"},
-        {vsn, "1.2.7"},
+        {vsn, "1.2.8"},
         {modules, [lhttpc,lhttpc_sup,lhttpc_client,lhttpc_sock,lhttp_lb]},
         {registered, [lhttpc_sup]},
         {applications, [kernel, stdlib, ssl, crypto]},
diff --git a/src/lhttpc_sock.erl b/src/lhttpc_sock.erl
index 63c3124b..429517c3 100644
--- a/src/lhttpc_sock.erl
+++ b/src/lhttpc_sock.erl
@@ -154,6 +154,28 @@ setopts(Socket, Options, false) ->
 %% @end
 -spec close(socket(), boolean()) -> ok | {error, atom()}.
 close(Socket, true) ->
-    ssl:close(Socket);
+    %% Safer exiting. Yoshihiro Tanaka from OpenX figured out
+    %% that we had potential race conditions while closing the
+    %% socket and timing out. This process flagging aims to
+    %% wrap some safety around this in case of a timeout
+    Flag = process_flag(trap_exit, true),
+    Res = ssl:close(Socket),
+    receive
+        {'EXIT',_Pid,timeout} -> exit(timeout)
+    after 0 ->
+            process_flag(trap_exit, Flag),
+            Res
+    end;
 close(Socket, false) ->
-    gen_tcp:close(Socket).
+    %% Safer exiting. Yoshihiro Tanaka from OpenX figured out
+    %% that we had potential race conditions while closing the
+    %% socket and timing out. This process flagging aims to
+    %% wrap some safety around this in case of a timeout
+    Flag = process_flag(trap_exit, true),
+    Res = gen_tcp:close(Socket),
+    receive
+        {'EXIT',_Pid,timeout} -> exit(timeout)
+    after 0 ->
+            process_flag(trap_exit, Flag),
+            Res
+    end.