QPID-1170 - Provide a better factory for creation and deletion of the management agent

git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@677408 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 43 insertions, 10 deletions

diff --git a/cpp/src/qpid/agent/ManagementAgent.h b/cpp/src/qpid/agent/ManagementAgent.h
index 97fc827f2a..e7379e6c94 100644
--- a/cpp/src/qpid/agent/ManagementAgent.h
+++ b/cpp/src/qpid/agent/ManagementAgent.h
@@ -22,6 +22,7 @@
 
 #include "qpid/management/ManagementObject.h"
 #include "qpid/management/Manageable.h"
+#include "qpid/sys/Mutex.h"
 
 namespace qpid { 
 namespace management {
@@ -30,11 +31,21 @@ class ManagementAgent
 {
   public:
 
+    class Singleton {
+    public:
+        Singleton(bool disableManagement = false);
+        ~Singleton();
+        static ManagementAgent* getInstance();
+    private:
+        static sys::Mutex lock;
+        static bool disabled;
+        static int refCount;
+        static ManagementAgent* agent;
+    };
+
     ManagementAgent () {}
     virtual ~ManagementAgent () {}
 
-    static ManagementAgent* getAgent();
-
     virtual int getMaxThreads() = 0;
 
     // Connect to a management broker
diff --git a/cpp/src/qpid/agent/ManagementAgentImpl.cpp b/cpp/src/qpid/agent/ManagementAgentImpl.cpp
index 3c079a5a0a..5894aad404 100644
--- a/cpp/src/qpid/agent/ManagementAgentImpl.cpp
+++ b/cpp/src/qpid/agent/ManagementAgentImpl.cpp
@@ -33,14 +33,36 @@ using std::string;
 using std::cout;
 using std::endl;
 
-ManagementAgent* ManagementAgent::getAgent()
+Mutex            ManagementAgent::Singleton::lock;
+bool             ManagementAgent::Singleton::disabled = false;
+ManagementAgent* ManagementAgent::Singleton::agent    = 0;
+int              ManagementAgent::Singleton::refCount = 0;
+
+ManagementAgent::Singleton::Singleton(bool disableManagement)
 {
-    //static ManagementAgent* agent = 0;
+    Mutex::ScopedLock _lock(lock);
+    if (disableManagement && !disabled) {
+        disabled = true;
+        assert(refCount == 0); // can't disable after agent has been allocated
+    }
+    if (refCount == 0 && !disabled)
+        agent = new ManagementAgentImpl();
+    refCount++;
+}
 
-    //if (agent == 0)
-    //    agent = new ManagementAgentImpl();
-    //return agent;
-    return 0;
+ManagementAgent::Singleton::~Singleton()
+{
+    Mutex::ScopedLock _lock(lock);
+    refCount--;
+    if (refCount == 0 && !disabled) {
+        delete agent;
+        agent = 0;
+    }
+}
+
+ManagementAgent* ManagementAgent::Singleton::getInstance()
+{
+    return agent;
 }
 
 ManagementAgentImpl::ManagementAgentImpl() :
diff --git a/cpp/src/qpid/agent/ManagementAgentImpl.h b/cpp/src/qpid/agent/ManagementAgentImpl.h
index b7572fe833..2ecf63cd5d 100644
--- a/cpp/src/qpid/agent/ManagementAgentImpl.h
+++ b/cpp/src/qpid/agent/ManagementAgentImpl.h
@@ -41,8 +41,8 @@ class ManagementAgentImpl : public ManagementAgent, public client::MessageListen
 {
   public:
 
-    ManagementAgentImpl ();
-    virtual ~ManagementAgentImpl ();
+    ManagementAgentImpl();
+    virtual ~ManagementAgentImpl();
 
     int getMaxThreads() { return 1; }
     void init(std::string brokerHost        = "localhost",