TAO_Leader_Follower Class Reference

TAO_Leader_Follower. More...

#include <Leader_Follower.h>

Collaboration diagram for TAO_Leader_Follower:

Collaboration graph
[legend]
List of all members.

Public Member Functions

 TAO_Leader_Follower (TAO_ORB_Core *orb_core, TAO_New_Leader_Generator *new_leader_generator=0)
 Constructor.
 ~TAO_Leader_Follower (void)
 Destructor.
int set_event_loop_thread (ACE_Time_Value *max_wait_time)
void reset_event_loop_thread (void)
void set_upcall_thread (void)
int leader_available (void) const
 Is there any thread running as a leader?
void set_client_thread (void)
 A server thread is making a request.
void reset_client_thread (void)
 A server thread has finished is making a request.
int wait_for_event (TAO_LF_Event *event, TAO_Transport *transport, ACE_Time_Value *max_wait_time)
 Wait on the Leader/Followers loop until one event happens.
void set_client_leader_thread (void)
void reset_client_leader_thread (void)
void set_client_leader_thread (ACE_thread_t thread_ID)
int is_client_leader_thread (void) const
 checks if we are a leader thread
int elect_new_leader (void)
TAO_SYNCH_MUTEX & lock (void)
 Get a reference to the underlying mutex.
ACE_Reverse_Lock< TAO_SYNCH_MUTEX > & reverse_lock (void)
int has_clients (void) const
 Check if there are any client threads running.
ACE_Reactorreactor (void)
 Accesor to the reactor.
void no_leaders_available (void)
 Called when we are out of leaders.
Follower creation/destructions
The Leader/Followers set acts as a factory for the Follower objects. Followers are used to represent a thread blocked waiting in the Follower set.

The Leader/Followers abstraction keeps a list of the waiting followers, so it can wake up one when the leader thread stops handling events.

For performance reasons the Leader/Followers set uses a pool (or free-list) to keep Follower objects unattached to any thread. It could be tempting to use TSS to keep such followers, after all a thread can only need one such Follower object, however, that does not work with multiple Leader/Followers sets, consult this bug report for more details:

http://ace.cs.wustl.edu/bugzilla/show_bug.cgi?id=296

TAO_LF_Followerallocate_follower (void)
 Allocate a new follower to the caller.
void release_follower (TAO_LF_Follower *)
 The caller has finished using a follower.
Follower Set Operations
void add_follower (TAO_LF_Follower *follower)
 Add a new follower to the set.
void remove_follower (TAO_LF_Follower *follower)
 Removes a follower from the leader-follower set.
int follower_available (void) const
 Checks if there are any followers available.

Private Types

typedef ACE_Intrusive_List<
TAO_LF_Follower
Follower_Set
 Implement the Leader/Followers set using an intrusive list.

Private Member Functions

TAO_ORB_Core_TSS_Resourcesget_tss_resources (void) const
 Shortcut to obtain the TSS resources of the orb core.
int wait_for_client_leader_to_complete (ACE_Time_Value *max_wait_time)
 Wait for the client leader to complete.
void reset_event_loop_thread_i (TAO_ORB_Core_TSS_Resources *tss)
Follower Set Operations
int elect_new_leader_i (void)

Private Attributes

TAO_ORB_Coreorb_core_
 The orb core.
TAO_SYNCH_MUTEX lock_
 To synchronize access to the members.
ACE_Reverse_Lock< TAO_SYNCH_MUTEX > reverse_lock_
 do protect the access to the following three members
Follower_Set follower_set_
Follower_Set follower_free_list_
 Use a free list to allocate and release Follower objects.
int leaders_
int clients_
ACE_Reactorreactor_
 The reactor.
int client_thread_is_leader_
 Is a client thread the current leader?
int event_loop_threads_waiting_
 Are server threads waiting for the client leader to complete?
TAO_SYNCH_CONDITION event_loop_threads_condition_
TAO_New_Leader_Generatornew_leader_generator_

Detailed Description

TAO_Leader_Follower.

TAO_Leader_Follower


Member Typedef Documentation

typedef ACE_Intrusive_List<TAO_LF_Follower> TAO_Leader_Follower::Follower_Set [private]
 

Implement the Leader/Followers set using an intrusive list.


Constructor & Destructor Documentation

ACE_INLINE TAO_Leader_Follower::TAO_Leader_Follower TAO_ORB_Core orb_core,
TAO_New_Leader_Generator new_leader_generator = 0
 

Constructor.

TAO_Leader_Follower::~TAO_Leader_Follower void   ) 
 

Destructor.


Member Function Documentation

ACE_INLINE void TAO_Leader_Follower::add_follower TAO_LF_Follower follower  ) 
 

Add a new follower to the set.

TAO_LF_Follower * TAO_Leader_Follower::allocate_follower void   ) 
 

Allocate a new follower to the caller.

ACE_INLINE int TAO_Leader_Follower::elect_new_leader void   ) 
 

A leader thread is relinquishing its role, unless there are more leader threads running pick up a follower (if there is any) to play the leader role.

int TAO_Leader_Follower::elect_new_leader_i void   )  [private]
 

This is a helper routine for elect_new_leader(), after verifying that all the pre-conditions are satisfied the Follower set is changed and the promoted Follower is signaled.

ACE_INLINE int TAO_Leader_Follower::follower_available void   )  const
 

Checks if there are any followers available.

Returns:
1 if there follower set is not empty

ACE_INLINE TAO_ORB_Core_TSS_Resources * TAO_Leader_Follower::get_tss_resources void   )  const [private]
 

Shortcut to obtain the TSS resources of the orb core.

ACE_INLINE int TAO_Leader_Follower::has_clients void   )  const
 

Check if there are any client threads running.

ACE_INLINE int TAO_Leader_Follower::is_client_leader_thread void   )  const
 

checks if we are a leader thread

ACE_INLINE int TAO_Leader_Follower::leader_available void   )  const
 

Is there any thread running as a leader?

ACE_INLINE TAO_SYNCH_MUTEX & TAO_Leader_Follower::lock void   ) 
 

Get a reference to the underlying mutex.

ACE_INLINE void TAO_Leader_Follower::no_leaders_available void   ) 
 

Called when we are out of leaders.

ACE_Reactor * TAO_Leader_Follower::reactor void   ) 
 

Accesor to the reactor.

void TAO_Leader_Follower::release_follower TAO_LF_Follower  ) 
 

The caller has finished using a follower.

ACE_INLINE void TAO_Leader_Follower::remove_follower TAO_LF_Follower follower  ) 
 

Removes a follower from the leader-follower set.

ACE_INLINE void TAO_Leader_Follower::reset_client_leader_thread void   ) 
 

The current thread is no longer the leader thread in the client side leader-follower set.

void TAO_Leader_Follower::reset_client_thread void   ) 
 

A server thread has finished is making a request.

ACE_INLINE void TAO_Leader_Follower::reset_event_loop_thread void   ) 
 

The current thread is not a server thread anymore, reset any flags and counters.

ACE_INLINE void TAO_Leader_Follower::reset_event_loop_thread_i TAO_ORB_Core_TSS_Resources tss  )  [private]
 

Implement the reset_event_loop_thread() method, once the TSS resources have been acquired. Also used in the set_upcall_thread.

ACE_INLINE ACE_Reverse_Lock< TAO_SYNCH_MUTEX > & TAO_Leader_Follower::reverse_lock void   ) 
 

The Leader/Followers set mutex must be release during some long running operations. This helper class simplifies the process of releasing and reacquiring said mutex.

void TAO_Leader_Follower::set_client_leader_thread ACE_thread_t  thread_ID  ) 
 

sets the thread ID of the leader thread in the leader-follower model

ACE_INLINE void TAO_Leader_Follower::set_client_leader_thread void   ) 
 

The current thread has become the leader thread in the client side leader-follower set.

void TAO_Leader_Follower::set_client_thread void   ) 
 

A server thread is making a request.

ACE_INLINE int TAO_Leader_Follower::set_event_loop_thread ACE_Time_Value max_wait_time  ) 
 

The current thread has become a server thread (i.e. called ORB::run), update any flags and counters.

ACE_INLINE void TAO_Leader_Follower::set_upcall_thread void   ) 
 

This thread is going to perform an upcall, it will no longer be an event loop thread.

int TAO_Leader_Follower::wait_for_client_leader_to_complete ACE_Time_Value max_wait_time  )  [private]
 

Wait for the client leader to complete.

int TAO_Leader_Follower::wait_for_event TAO_LF_Event event,
TAO_Transport transport,
ACE_Time_Value max_wait_time
 

Wait on the Leader/Followers loop until one event happens.

Parameters:
event The event we wait for, the loop iterates until the event is sucessful, or it fails due to timeout, and error or a connection closed.
transport The transport attached to the event
max_wait_time Limit the time spent on the loop
Todo:
Document this better, split the Follower code to the TAO_LF_Follower class, we probably don't need the transport object.


Member Data Documentation

int TAO_Leader_Follower::client_thread_is_leader_ [private]
 

Is a client thread the current leader?

int TAO_Leader_Follower::clients_ [private]
 

Count the number of active clients, this is useful to know when to deactivate the reactor

TAO_SYNCH_CONDITION TAO_Leader_Follower::event_loop_threads_condition_ [private]
 

Condition variable for server threads waiting for the client leader to complete.

int TAO_Leader_Follower::event_loop_threads_waiting_ [private]
 

Are server threads waiting for the client leader to complete?

Follower_Set TAO_Leader_Follower::follower_free_list_ [private]
 

Use a free list to allocate and release Follower objects.

Follower_Set TAO_Leader_Follower::follower_set_ [private]
 

int TAO_Leader_Follower::leaders_ [private]
 

Count the number of active leaders. There could be many leaders in the thread pool (i.e. calling ORB::run), and the same leader could show up multiple times as it receives nested upcalls and sends more requests.

TAO_SYNCH_MUTEX TAO_Leader_Follower::lock_ [private]
 

To synchronize access to the members.

TAO_New_Leader_Generator* TAO_Leader_Follower::new_leader_generator_ [private]
 

Leader/Follower class uses this method to notify the system that we are out of leaders.

TAO_ORB_Core* TAO_Leader_Follower::orb_core_ [private]
 

The orb core.

ACE_Reactor* TAO_Leader_Follower::reactor_ [private]
 

The reactor.

ACE_Reverse_Lock<TAO_SYNCH_MUTEX> TAO_Leader_Follower::reverse_lock_ [private]
 

do protect the access to the following three members


The documentation for this class was generated from the following files:
Generated on Wed Nov 23 16:03:00 2005 for TAO by  doxygen 1.4.5