From 2100b4498daa1d89e2850196dca19bae1b4a6151 Mon Sep 17 00:00:00 2001
From: Alan Conway <aconway@apache.org>
Date: Thu, 7 Aug 2008 20:46:18 +0000
Subject: Check CPG flow control.

git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@683711 13f79535-47bb-0310-9956-ffa450edef68
---
 cpp/src/qpid/cluster/Cpg.cpp | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

(limited to 'cpp/src/qpid/cluster/Cpg.cpp')

diff --git a/cpp/src/qpid/cluster/Cpg.cpp b/cpp/src/qpid/cluster/Cpg.cpp
index 674781ac06..6b01d73197 100644
--- a/cpp/src/qpid/cluster/Cpg.cpp
+++ b/cpp/src/qpid/cluster/Cpg.cpp
@@ -77,6 +77,46 @@ Cpg::~Cpg() {
     }
 }
 
+void Cpg::join(const Name& group) {
+    check(cpg_join(handle, const_cast<Name*>(&group)),cantJoinMsg(group));
+}
+    
+void Cpg::leave(const Name& group) {
+    check(cpg_leave(handle,const_cast<Name*>(&group)),cantLeaveMsg(group));
+}
+
+bool Cpg::isFlowControlEnabled() {
+    cpg_flow_control_state_t flowState;
+    check(cpg_flow_control_state_get(handle, &flowState), "Cannot get CPG flow control status.");
+    return flowState == CPG_FLOW_CONTROL_ENABLED;
+}
+
+// TODO aconway 2008-08-07: better handling of flow control.
+// Wait for flow control to be disabled.
+void Cpg::waitForFlowControl() {
+    int delayNs=1000;           // one millisecond
+    int tries=8;                // double the delay on each try.
+    while (isFlowControlEnabled() && tries > 0) {
+        QPID_LOG(warning, "CPG flow control enabled, retry in " << delayNs << "ns");
+        ::usleep(delayNs);
+        --tries;
+        delayNs *= 2;
+    };
+    if (tries == 0) {
+        // FIXME aconway 2008-08-07: this is a fatal leave-the-cluster condition.
+        throw Cpg::Exception("CPG flow control enabled, failed to send.");
+    }
+}
+
+void Cpg::mcast(const Name& group, const iovec* iov, int iovLen) {
+    waitForFlowControl();
+    cpg_error_t result;
+    do {
+        result = cpg_mcast_joined(handle, CPG_TYPE_AGREED, const_cast<iovec*>(iov), iovLen);
+        if (result != CPG_ERR_TRY_AGAIN) check(result, cantMcastMsg(group));
+    } while(result == CPG_ERR_TRY_AGAIN);
+}
+
 void Cpg::shutdown() {
     if (!isShutdown) {
         QPID_LOG(debug,"Shutting down CPG");
-- 
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