QPID-6021: avoid waking up the io thread unnecessarily, improves receive rate a bit

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1618914 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 18 insertions, 2 deletions

diff --git a/qpid/cpp/src/qpid/messaging/amqp/ConnectionContext.cpp b/qpid/cpp/src/qpid/messaging/amqp/ConnectionContext.cpp
index 5aba00fc50..e08b387e85 100644
--- a/qpid/cpp/src/qpid/messaging/amqp/ConnectionContext.cpp
+++ b/qpid/cpp/src/qpid/messaging/amqp/ConnectionContext.cpp
@@ -272,7 +272,11 @@ bool ConnectionContext::get(boost::shared_ptr<SessionContext> ssn, boost::shared
             pn_link_advance(lnk->receiver);
             if (lnk->capacity) {
                 pn_link_flow(lnk->receiver, 1);
-                wakeupDriver();//TODO: wakeup less frequently
+                if (lnk->wakeupToIssueCredit()) {
+                    wakeupDriver();
+                } else {
+                    haveOutput = true;
+                }
             }
             return true;
         } else if (until > qpid::sys::now()) {
diff --git a/qpid/cpp/src/qpid/messaging/amqp/ReceiverContext.cpp b/qpid/cpp/src/qpid/messaging/amqp/ReceiverContext.cpp
index 7eaa1c068b..08cc130a9e 100644
--- a/qpid/cpp/src/qpid/messaging/amqp/ReceiverContext.cpp
+++ b/qpid/cpp/src/qpid/messaging/amqp/ReceiverContext.cpp
@@ -36,7 +36,7 @@ ReceiverContext::ReceiverContext(pn_session_t* session, const std::string& n, co
     address(a),
     helper(address),
     receiver(pn_receiver(session, name.c_str())),
-    capacity(0) {}
+    capacity(0), used(0) {}
 ReceiverContext::~ReceiverContext()
 {
     //pn_link_free(receiver);
@@ -125,4 +125,14 @@ bool ReceiverContext::hasCurrent()
     return pn_link_current(receiver);
 }
 
+bool ReceiverContext::wakeupToIssueCredit()
+{
+    if (++used >= (capacity/2)) {
+        used = 0;
+        return true;
+    } else {
+        return false;
+    }
+}
+
 }}} // namespace qpid::messaging::amqp
diff --git a/qpid/cpp/src/qpid/messaging/amqp/ReceiverContext.h b/qpid/cpp/src/qpid/messaging/amqp/ReceiverContext.h
index d185ae3146..2b4e8e1986 100644
--- a/qpid/cpp/src/qpid/messaging/amqp/ReceiverContext.h
+++ b/qpid/cpp/src/qpid/messaging/amqp/ReceiverContext.h
@@ -67,8 +67,10 @@ class ReceiverContext
     AddressHelper helper;
     pn_link_t* receiver;
     uint32_t capacity;
+    uint32_t used;
     qpid::sys::AtomicCount fetching;
     void configure(pn_terminus_t*);
+    bool wakeupToIssueCredit();
 };
 }}} // namespace qpid::messaging::amqp