- Added OutputTask::hasOutput() test.

 - Cluster only sends doOutput events when hasOutput()


git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@683416 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 17 insertions, 0 deletions

diff --git a/cpp/src/qpid/sys/AggregateOutput.cpp b/cpp/src/qpid/sys/AggregateOutput.cpp
index 57cc0c5a33..2fad28c381 100644
--- a/cpp/src/qpid/sys/AggregateOutput.cpp
+++ b/cpp/src/qpid/sys/AggregateOutput.cpp
@@ -31,6 +31,12 @@ void AggregateOutput::activateOutput()
     control.activateOutput();
 }
 
+bool AggregateOutput::hasOutput() {
+    for (TaskList::const_iterator i = tasks.begin(); i != tasks.end(); ++i) 
+        if ((*i)->hasOutput()) return true;
+    return false;
+}
+
 bool AggregateOutput::doOutput()
 {
     bool result = false;
diff --git a/cpp/src/qpid/sys/AggregateOutput.h b/cpp/src/qpid/sys/AggregateOutput.h
index a870fcb95a..02a53ed50b 100644
--- a/cpp/src/qpid/sys/AggregateOutput.h
+++ b/cpp/src/qpid/sys/AggregateOutput.h
@@ -43,6 +43,7 @@ namespace sys {
         void activateOutput();
         //all the following will be called on the same thread
         bool doOutput();
+        bool hasOutput();
         void addOutputTask(OutputTask* t);
         void removeOutputTask(OutputTask* t);
     };
diff --git a/cpp/src/qpid/sys/OutputTask.h b/cpp/src/qpid/sys/OutputTask.h
index 109765b8c3..005ae7dbc4 100644
--- a/cpp/src/qpid/sys/OutputTask.h
+++ b/cpp/src/qpid/sys/OutputTask.h
@@ -28,7 +28,17 @@ namespace sys {
     {
     public:
         virtual ~OutputTask() {}
+        /** Generate some  output.
+         *@return true if output was generated, false if there is no work to do.
+         */
         virtual bool doOutput() = 0;
+
+        /** Check if there may be work to do, but don't do it.
+         * @return True if there may be work to do, false if there is none.
+         * Can to return a false positive, to allow implementations to do a
+         * faster check than doOutput(). Must never return a false negative.
+         */
+        virtual bool hasOutput() = 0;
     };
 
 }