Changes between Version 3 and Version 4 of Documentation/SystemQueue

Timestamp:

Dec 17, 2008, 11:43:42 AM (16 years ago)

Author:

Christoph Mayer

Comment:

--

Documentation/SystemQueue

@@ -18 +18 @@
 == !SystemQueue Internals == 
 
+The !SystemQueue class has one main thread that uses {{{boost::condition}}} with the {{{wait}}} and {{{signal}}} functionality to implement a queue. The thread blocks and waits until a new event is inserted into the queue. It then executes this event and calls the event handler that is assigned to this event. The insertion and execution of an event therefore are decoupled in terms of threading and run asynchronous. 
+
+One example of events are imcoming network messages. When a packet comes in from the network a new event is generated and the packet attacked to this event. The event is inserted into the !SystemQueue and gets processed asynchronous from the !SystemQueue thread. 
+
 == Using the !SystemQueue == 
 
+Every mechanisms that gets triggered by some external event must get synchronized with the main !SystemQueue thread. If you e.g. observe the network card and want to execute some stuff on network changes, you must synchronized with the !SystemQueue. Why? Because a network packet might get processed and call some code that you would maybe call, too. Therefore producing parallel access to some code and causing threading problems. 
+
+Synchronizing with the main Ariba thread is easy, thanks to the !SystemQueue. We will not explain step-by-step how to use the !SystemQueue in your code:
+
+ 1. In you {{{.h}}} file integrate the !SystemQueue header and some {{{using declerations}}};
+
+{{{
+#!cpp
+#include "spovnet/common/system/SystemQueue.h"
+using spovnet::common::SystemQueue;
+using spovnet::common::SystemEvent;
+using spovnet::common::SystemEventType;
+using spovnet::common::SystemEventListener;
+}}}
+
+ 2. Derive your class from from a {{{SystemEventListener}}} to be able to receive events:
+
+{{{
+#!cpp
+class MyClass : public SystemEventListener
+}}}
+
+ 3. Redefine the {{{SystemEventListener}}} interface:
+
+{{{
+#!cpp
+protected:
+    virtual void handleSystemEvent( const SystemEvent& event );
+}}}
+
+
 == Using Blocking Code == 
+
+