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diff --git a/TAO/docs/leader_follower.html b/TAO/docs/leader_follower.html deleted file mode 100644 index beb09eb92b3..00000000000 --- a/TAO/docs/leader_follower.html +++ /dev/null @@ -1,60 +0,0 @@ -<html> - <!-- $Id $ --> - <head> - <title>Implementation of leader follower model for global resources</title> - </head> - - <BODY text = "#000000" - link="#0000ff" - vlink="#cc0000" - bgcolor="#ffffff"> - - <body> - <HR> - <h1>Leader follower model for global resources</h1> - <HR> - <h2>Context</h2> - Global resources in TAO mean one ORB and using the reactive strategy - one Reactor. TAO uses the ACE Select Reactor for this purpose. - One main problem with multithreading and only one Reactor is that - only one thread can wait in handle_events at a time. - Handle_events is called, when a thread expects input, meaning - it is blocking to wait for it. - - <h2>Idea</h2> - One solution to this problem is to use a leader-follower model, - which partitions the set of threads wanting to wait for input - into one leader and followers. Every thread is eligible to become - a leader. A thread wanting to wait while nobody else is waiting - becomes the leader. If the leader gets its input, which is in - this case its response, it will select a new leader out of the - set of followers. The followers wait on a condition variable they - own and register it with the ORB core. The ORB core is thereby - responsible for making this access thread-save by providing - a lock for the list of followers with some flags, like - leader_available. - - <h2>Implementation</h2> - The above mentioned condition variables are owned by the - connection handlers, because reponses are expected per connection, - not necessarily, thinking about other resource models, per thread. - <p> - The involved classes are TAO_ORB_Core, TAO_Client_Connection_Handler - and TAO_ORB. In the TAO_ORB_Core class the list of followers, a lock, - a leader reference counter and a leader thread ID were added. - The handle_input and send_request methods on the TAO_Client_Connection_Handler - contain 95% of the code used for implementing the leader-follower - model. Care has to be taken, that the connection handlers are - suspended and resumed, properly. A special concern is that - no deadlocking occurs. - - <HR> - For more details and questions, - <p> - - <address><a href="mailto:mk1@cs.wustl.edu">Michael Kircher</a></address> - <p> - <address><a href="mailto:irfan1@cs.wustl.edu">Irfan Pyarali</a></address> - </body> -</html> - |