From da85d39c0cce2aef20a8dc0c4fdaf3e87e9f5459 Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Mon, 2 Apr 2018 10:40:50 -0700
Subject: [PATCH] codec: const-ify socket

Avoid possible data race of changing _channel
before worker threads are joined.
Was just using this as a boolean flag for a method
which is already guarded in BlockingTCPTransportCodec::close()
from being called twice.
---
 src/remote/codec.cpp  | 4 +---
 src/remote/pv/codec.h | 2 +-
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/remote/codec.cpp b/src/remote/codec.cpp
index 6e4cb4f..f50ffbc 100644
--- a/src/remote/codec.cpp
+++ b/src/remote/codec.cpp
@@ -1060,7 +1060,7 @@ void BlockingTCPTransportCodec::waitJoin()
 
 void BlockingTCPTransportCodec::internalClose(bool /*force*/)
 {
-    if(_channel != INVALID_SOCKET) {
+    {
 
         epicsSocketSystemCallInterruptMechanismQueryInfo info  =
             epicsSocketSystemCallInterruptMechanismQuery ();
@@ -1090,8 +1090,6 @@ void BlockingTCPTransportCodec::internalClose(bool /*force*/)
         default:
             epicsSocketDestroy(_channel);
         }
-
-        _channel = INVALID_SOCKET; //TODO: mutex to guard _channel
     }
 
     Transport::shared_pointer thisSharedPtr = this->shared_from_this();
diff --git a/src/remote/pv/codec.h b/src/remote/pv/codec.h
index 5b75baa..92c5017 100644
--- a/src/remote/pv/codec.h
+++ b/src/remote/pv/codec.h
@@ -466,8 +466,8 @@ private:
     AtomicValue<bool> _isOpen;
     epics::pvData::Thread _readThread, _sendThread;
     epics::pvData::Event _shutdownEvent;
+    const SOCKET _channel;
 protected:
-    SOCKET _channel;
     osiSockAddr _socketAddress;
     std::string _socketName;
 protected: