MCOL-4675 DMLProc now automatically and gracefully shutdowns when a cluster state is set to

SS_SHUTDOWN_PENDING | SS_ROLLBACK

dmlproc/dmlproc.cpp

@@ -686,6 +686,8 @@ int ServiceDMLProc::Child()
 
     dmlserver.start();
 
+    // WIP the rc looks misguiding b/c DMLProc now can legitimately quits from DMLServer::start()
+    // so Child() should return dmlserver.start().
     return 1;
 }
 

dmlproc/dmlprocessor.cpp

@@ -98,7 +98,7 @@ boost::mutex PackageHandler::tableOidMutex;
 // If FORCE is set, we can't rollback.
 struct CancellationThread
 {
-    CancellationThread(DBRM* aDbrm) : fDbrm(aDbrm)
+    CancellationThread(DBRM* aDbrm, DMLServer& aServer) : fDbrm(aDbrm), fServer(aServer)
     {}
     void operator()()
     {
@@ -118,6 +118,9 @@ struct CancellationThread
             // Check to see if someone has ordered a shutdown or suspend with rollback.
             (void)fDbrm->getSystemShutdownPending(bRollback, bForce);
 
+            if (bForce)
+                break;
+
             if (bDoingRollback && bRollback)
             {
                 continue;
@@ -162,6 +165,7 @@ struct CancellationThread
                     DMLProcessor::log(oss1.str(), logging::LOG_TYPE_INFO);
                 }
 
+                // WIP Need to set cluster to read-only via CMAPI before shutting the cluster down.
                 if (fDbrm->isReadWrite())
                 {
                     continue;
@@ -288,10 +292,15 @@ struct CancellationThread
                     oss2 << "DMLProc has rolled back " << idleTransCount << " idle transactions.";
                     DMLProcessor::log(oss2.str(), logging::LOG_TYPE_INFO);
                 }
+                // Here is the end of the rollback if so DMLProc rollbacks what it can.
+                break;
             }
         }
+        // Setting the flag to tell DMLServer to exit.
+        fServer.startShutdown();
     }
     DBRM* fDbrm;
+    DMLServer& fServer;
 };
 
 PackageHandler::PackageHandler(const messageqcpp::IOSocket& ios,
@@ -1195,7 +1204,7 @@ void added_a_pm(int)
 }
 
 DMLServer::DMLServer(int packageMaxThreads, int packageWorkQueueSize, DBRM* dbrm) :
-    fPackageMaxThreads(packageMaxThreads), fPackageWorkQueueSize(packageWorkQueueSize), fDbrm(dbrm)
+    fPackageMaxThreads(packageMaxThreads), fPackageWorkQueueSize(packageWorkQueueSize), fDbrm(dbrm), fShutdownFlag(false)
 {
     fMqServer.reset(new MessageQueueServer("DMLProc"));
 
@@ -1214,14 +1223,24 @@ void DMLServer::start()
         // CancellationThread is for telling all active transactions
         // to quit working because the system is either going down
         // or going into write suspend mode
-        CancellationThread cancelObject(fDbrm);
+        CancellationThread cancelObject(fDbrm, *this);
         boost::thread cancelThread(cancelObject);
 
         cout << "DMLProc is ready..." << endl;
 
+        const static struct timespec timeout = {1, 100}; // roughly 1 second TO
         for (;;)
         {
-            ios = fMqServer->accept();
+            ios = fMqServer->accept(&timeout);
+            // MCS polls in a loop watching for a pending shutdown
+            // that is signalled via fShutdownFlag set in a
+            // CancellationThread. CT sets the flag if a cluster state
+            // has SS_SHUTDOWNPENDING value set.
+            while (!ios.hasSocketDescriptor() && !pendingShutdown())
+                ios = fMqServer->accept(&timeout);
+
+            if (pendingShutdown())
+                break;
             ios.setSockID(nextID++);
             fDmlPackagepool.invoke(DMLProcessor(ios, fDbrm));
         }

dmlproc/dmlprocessor.h

@@ -146,6 +146,16 @@ public:
         fPackageWorkQueueSize = workQueueSize;
     }
 
+    inline bool pendingShutdown() const
+    {
+        return fShutdownFlag;
+    }
+
+    inline void startShutdown()
+    {
+        fShutdownFlag = true;
+    }
+
 private:
     //not copyable
     DMLServer(const DMLServer& rhs);
@@ -156,6 +166,7 @@ private:
 
     boost::scoped_ptr<messageqcpp::MessageQueueServer> fMqServer;
     BRM::DBRM* fDbrm;
+    bool fShutdownFlag;
 
 public:
     /** @brief the thread pool for processing dml packages

utils/messageqcpp/iosocket.h

@@ -42,6 +42,7 @@
 #include "socket.h"
 #include "socketparms.h"
 #include "bytestream.h"
+#include "checks.h"
 
 class MessageQTestSuite;
 
@@ -198,6 +199,7 @@ public:
 
     inline virtual bool isConnected() const;
     inline virtual bool hasData() const;
+    inline bool hasSocketDescriptor() const;
 
     friend class ::MessageQTestSuite;
 
@@ -217,6 +219,12 @@ inline const sockaddr IOSocket::sa() const
 {
     return fSa;
 }
+
+inline bool IOSocket::hasSocketDescriptor() const
+{
+    return fSocket && utils::is_nonnegative(fSocket->socketParms().sd());
+}
+
 inline void IOSocket::sa(const sockaddr* sa)
 {
     fSa = *sa;