From fac07c7f3acba58d739813d0a1fd8d91dfca2df4 Mon Sep 17 00:00:00 2001
From: mrkraimer <mrkraimer@comcast.net>
Date: Fri, 24 Jun 2016 15:03:19 -0400
Subject: [PATCH] added stateChangeRequester; improve semantics for unlisten
 and channelStateChange

---
 src/pv/pvaClient.h       | 39 ++++++++++++++++++++++++++++++++++++++-
 src/pvaClientChannel.cpp | 13 ++++++++++++-
 src/pvaClientMonitor.cpp | 11 ++++++++++-
 3 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/src/pv/pvaClient.h b/src/pv/pvaClient.h
index 1327462..bc668c6 100644
--- a/src/pv/pvaClient.h
+++ b/src/pv/pvaClient.h
@@ -53,6 +53,9 @@ class PvaClientPutData;
 typedef std::tr1::shared_ptr<PvaClientPutData> PvaClientPutDataPtr;
 class PvaClientMonitorData;
 typedef std::tr1::shared_ptr<PvaClientMonitorData> PvaClientMonitorDataPtr;
+class PvaClientChannelStateChangeRequester;
+typedef std::tr1::shared_ptr<PvaClientChannelStateChangeRequester> PvaClientChannelStateChangeRequesterPtr;
+typedef std::tr1::weak_ptr<PvaClientChannelStateChangeRequester> PvaClientChannelStateChangeRequesterWPtr;
 class PvaClientChannel;
 typedef std::tr1::shared_ptr<PvaClientChannel> PvaClientChannelPtr;
 class PvaClientField;
@@ -194,13 +197,35 @@ typedef std::tr1::shared_ptr<PvaClientPutCache> PvaClientPutCachePtr;
 class ChannelRequesterImpl;
 typedef std::tr1::shared_ptr<ChannelRequesterImpl> ChannelRequesterImplPtr;
 
+/** 
+ * @brief An easy to be notified of a change in connection status.
+ *
+ * @author mrk
+ */
+class epicsShareClass PvaClientChannelStateChangeRequester
+{
+public:
+    POINTER_DEFINITIONS(PvaClientChannelStateChangeRequester);
+    /**
+     * Destructor
+     */
+    virtual ~PvaClientChannelStateChangeRequester(){}
+    /**
+     * A channel connection state change has occurred.
+     * @param channel The channel.
+     * @param isConnected The new connection status.
+     */
+    virtual void channelStateChange(PvaClientChannelPtr const & channel, bool isConnected) = 0;
+};
+
 /** 
  * @brief An easy to use alternative to directly calling the Channel methods of pvAccess.
  *
  * @author mrk
  */
 
-class epicsShareClass PvaClientChannel 
+class epicsShareClass PvaClientChannel :
+   public std::tr1::enable_shared_from_this<PvaClientChannel>
 {
 public:
     POINTER_DEFINITIONS(PvaClientChannel);
@@ -208,6 +233,7 @@ public:
      * Destructor
      */
     ~PvaClientChannel();
+    void setStateChangeRequester(PvaClientChannelStateChangeRequesterPtr const &stateChangeRequester);
     /** Get the name of the channel to which PvaClientChannel is connected.
      * @return The channel name.
      */
@@ -421,9 +447,11 @@ private:
     epics::pvData::Mutex mutex;
     epics::pvData::Event waitForConnect;
     epics::pvAccess::Channel::shared_pointer channel;
+    PvaClientChannelStateChangeRequesterWPtr stateChangeRequester;
     ChannelRequesterImplPtr channelRequester;
     friend class PvaClient;
     friend class ChannelRequesterImpl;
+
 };
 
 /** 
@@ -1312,6 +1340,15 @@ public:
      * @param monitor The PvaClientMonitor that received the event.
      */
     virtual void event(PvaClientMonitorPtr const & monitor) = 0;
+    /**
+     * The data source is no longer available.
+     */
+
+    virtual void unlisten()
+    {
+         std::cerr << "PvaClientMonitorRequester::unlisten called"
+                 << " but no PvaClientMonitorRequester::unlisten\n";
+    }
 };
 
 
diff --git a/src/pvaClientChannel.cpp b/src/pvaClientChannel.cpp
index 52c032b..fb2c901 100644
--- a/src/pvaClientChannel.cpp
+++ b/src/pvaClientChannel.cpp
@@ -213,7 +213,6 @@ PvaClientChannel::~PvaClientChannel()
     if(PvaClient::getDebug()) showCache();
 }
 
-
 void PvaClientChannel::channelCreated(const Status& status, Channel::shared_pointer const & channel)
 {
     if(PvaClient::getDebug()) {
@@ -252,6 +251,12 @@ void PvaClientChannel::channelStateChange(
         << " " << Channel::ConnectionStateNames[connectionState]
         << endl;
     }
+    PvaClientChannelStateChangeRequesterPtr req(stateChangeRequester.lock());
+    if(req) {
+         bool value = (connectionState==Channel::CONNECTED ? true :  false);
+         req->channelStateChange(shared_from_this(),value);
+    }
+   
     Lock xx(mutex);
     bool waitingForConnect = false;
     if(connectState==connectActive) waitingForConnect = true;
@@ -293,6 +298,12 @@ Channel::shared_pointer PvaClientChannel::getChannel()
     return channel;
 }
 
+void PvaClientChannel::setStateChangeRequester(
+    PvaClientChannelStateChangeRequesterPtr const & stateChangeRequester)
+{
+    this->stateChangeRequester = stateChangeRequester;
+}
+
 void PvaClientChannel::connect(double timeout)
 {
     if(PvaClient::getDebug()) {
diff --git a/src/pvaClientMonitor.cpp b/src/pvaClientMonitor.cpp
index 6b58d5c..5c472f7 100644
--- a/src/pvaClientMonitor.cpp
+++ b/src/pvaClientMonitor.cpp
@@ -219,9 +219,18 @@ void PvaClientMonitor::monitorEvent(MonitorPtr const & monitor)
 void PvaClientMonitor::unlisten(MonitorPtr const & monitor)
 {
     if(PvaClient::getDebug()) cout << "PvaClientMonitor::unlisten\n";
-    throw std::runtime_error("pvaClientMonitor::unlisten called but do not know what to do");
+    PvaClientMonitorRequesterPtr req = pvaClientMonitorRequester.lock();
+    if(req) {
+        req->unlisten();
+        return;
+    }
+    string channelName("disconnected");
+    Channel::shared_pointer chan(channel.lock());
+    if(chan) channelName = chan->getChannelName();
+    cerr << channelName + "pvaClientMonitor::unlisten called but no PvaClientMonitorRequester\n";
 }
 
+
 void PvaClientMonitor::connect()
 {
     if(PvaClient::getDebug()) cout << "PvaClientMonitor::connect\n";