FairMQ: Introduce callbacks for the FairMQUnmanagedRegion.

Callbacks are called when the data buffer of the message assiciated
with the corresponding region is no longer needed by the transport.
Example in examples/advanced/Region/

examples/advanced/Region/FairMQExampleRegionSampler.cxx

@@ -16,29 +16,54 @@
 #include "FairMQLogger.h"
 #include "FairMQProgOptions.h" // device->fConfig
 
+#include <thread>
+#include <atomic>
+
 using namespace std;
 
 FairMQExampleRegionSampler::FairMQExampleRegionSampler()
     : fMsgSize(10000)
+    , fRegion(nullptr)
+    , fNumUnackedMsgs(0)
 {
 }
 
 void FairMQExampleRegionSampler::InitTask()
 {
     fMsgSize = fConfig->GetValue<int>("msg-size");
+
+    fRegion = FairMQUnmanagedRegionPtr(NewUnmanagedRegionFor("data",
+                                                             0,
+                                                             10000000,
+                                                             [this](void* data, size_t size) { --fNumUnackedMsgs; } // callback to be called when message buffers no longer needed by transport
+                                                             ));
 }
 
-void FairMQExampleRegionSampler::Run()
+bool FairMQExampleRegionSampler::ConditionalRun()
 {
-    FairMQChannel& dataOutChannel = fChannels.at("data").at(0);
-
-    FairMQUnmanagedRegionPtr region(NewUnmanagedRegionFor("data", 0, 10000000));
-
-    while (CheckCurrentState(RUNNING))
+    FairMQMessagePtr msg(NewMessageFor("data", // channel
+                                        0, // sub-channel
+                                        fRegion, // region
+                                        fRegion->GetData(), // ptr within region
+                                        fMsgSize // offset from ptr
+                                        ));
+    if (Send(msg, "data", 0) > 0)
     {
-        FairMQMessagePtr msg(NewMessageFor("data", 0, region, region->GetData(), fMsgSize));
-        dataOutChannel.Send(msg);
+        ++fNumUnackedMsgs;
     }
+
+    return true;
+}
+
+void FairMQExampleRegionSampler::ResetTask()
+{
+    // if not all messages acknowledged, wait for a bit. But only once, since receiver could be already dead.
+    if (fNumUnackedMsgs != 0)
+    {
+        LOG(DEBUG) << "waiting for all acknowledgements... (" << fNumUnackedMsgs << ")";
+        this_thread::sleep_for(chrono::milliseconds(500));
+    }
+    fRegion.reset();
 }
 
 FairMQExampleRegionSampler::~FairMQExampleRegionSampler()

examples/advanced/Region/FairMQExampleRegionSampler.h

@@ -16,6 +16,7 @@
 #define FAIRMQEXAMPLEREGIONSAMPLER_H_
 
 #include <string>
+#include <atomic>
 
 #include "FairMQDevice.h"
 
@@ -26,10 +27,14 @@ class FairMQExampleRegionSampler : public FairMQDevice
     virtual ~FairMQExampleRegionSampler();
 
   protected:
-    int fMsgSize;
-
     virtual void InitTask();
-    virtual void Run();
+    virtual bool ConditionalRun();
+    virtual void ResetTask();
+
+  private:
+    int fMsgSize;
+    FairMQUnmanagedRegionPtr fRegion;
+    std::atomic<uint64_t> fNumUnackedMsgs;
 };
 
 #endif /* FAIRMQEXAMPLEREGIONSAMPLER_H_ */

examples/advanced/Region/FairMQExampleRegionSink.cxx

@@ -29,6 +29,7 @@ void FairMQExampleRegionSink::Run()
     {
         FairMQMessagePtr msg(dataInChannel.Transport()->CreateMessage());
         dataInChannel.Receive(msg);
+        void* ptr = msg->GetData();
     }
 }
 

examples/advanced/Region/startMQExRegion.sh.in

@@ -10,6 +10,7 @@ fi
 SAMPLER="ex-region-sampler"
 SAMPLER+=" --id sampler1"
 SAMPLER+=" --msg-size $msgSize"
+# SAMPLER+=" --rate 10"
 SAMPLER+=" --transport shmem"
 SAMPLER+=" --mq-config $exRegionConfig"
 xterm -geometry 80x23+0+0 -hold -e @CMAKE_BINARY_DIR@/bin/examples/advanced/Region/$SAMPLER &