ACE_RW_Token Class Reference

Class that acquires, renews, and releases a process-local synchronization token. More...

#include <Local_Tokens.h>

Inheritance diagram for ACE_RW_Token:

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Collaboration diagram for ACE_RW_Token:

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List of all members.

Public Types

enum  PROXY_TYPE { READER, WRITER }
 These are the types that proxies can be. More...

Public Member Functions

 ACE_RW_Token (const ACE_TCHAR *name)
 Constructor.
virtual ~ACE_RW_Token (void)
 Destructor.
virtual int acquire (ACE_TPQ_Entry *caller, int ignore_deadlock, int notify)
virtual int tryacquire (ACE_TPQ_Entry *caller)
 Same as acquire except fails on would block.
virtual int renew (ACE_TPQ_Entry *caller, int requeue_position)
virtual int release (ACE_TPQ_Entry *caller)
void dump (void) const
 Dump the state of the class.
virtual int type (void) const
 Returns READER or WRITER.
virtual int owners (OWNER_STACK &o, const ACE_TCHAR *id)
virtual int is_waiting_for (const ACE_TCHAR *id)
 Returns 1 if <id> is waiting for this token. 0 otherwise.
virtual int is_owner (const ACE_TCHAR *id)
 Returns 1 if <id> is an owner of this token. 0 otherwise.

Protected Member Functions

void notify_new_owner (ACE_TPQ_Entry *caller)
 Sets the new owner.

Protected Attributes

int num_writers_
 The number of waiting writers.
ACE_TOKEN_CONST::MUTEX lock_
 ACE_Mutex_Token used to lock internal data structures.

Detailed Description

Class that acquires, renews, and releases a process-local synchronization token.

Not a public interface. This class is a more general-purpose synchronization mechanism than SunOS 5.x mutexes. For example, it implements "recursive mutex" semantics, where a thread that owns the token can reacquire it without deadlocking. In addition, threads that are blocked awaiting the token are serviced in strict FIFO order as other threads release the token (SunOS 5.x mutexes don't strictly enforce an acquisition order).


Member Enumeration Documentation

enum ACE_RW_Token::PROXY_TYPE
 

These are the types that proxies can be.

Enumerator:
READER 
WRITER 


Constructor & Destructor Documentation

ACE_RW_Token::ACE_RW_Token const ACE_TCHAR name  )  [explicit]
 

Constructor.

ACE_RW_Token::~ACE_RW_Token void   )  [virtual]
 

Destructor.


Member Function Documentation

int ACE_RW_Token::acquire ACE_TPQ_Entry caller,
int  ignore_deadlock,
int  notify
[virtual]
 

Returns 0 on success, -1 on failure with <ACE_Log_Msg::errnum> as the reason. If errnum == EWOULDBLOCK, and notify == 1, <ACE_Token_Proxy::sleep_hook> has been called on the current owner of the token. If ignore_deadlock is passed as 1 and errnum == EDEADLK, then deadlock was detected via ACE_Token_Manager.

Implements ACE_Tokens.

void ACE_RW_Token::dump void   )  const
 

Dump the state of the class.

Reimplemented from ACE_Tokens.

int ACE_RW_Token::is_owner const ACE_TCHAR id  )  [virtual]
 

Returns 1 if <id> is an owner of this token. 0 otherwise.

Implements ACE_Tokens.

int ACE_RW_Token::is_waiting_for const ACE_TCHAR id  )  [virtual]
 

Returns 1 if <id> is waiting for this token. 0 otherwise.

Implements ACE_Tokens.

void ACE_RW_Token::notify_new_owner ACE_TPQ_Entry caller  )  [protected]
 

Sets the new owner.

int ACE_RW_Token::owners OWNER_STACK o,
const ACE_TCHAR id
[virtual]
 

Returns a stack of the current owners. Returns -1 on error, 0 on success. If <id> is non-zero, returns 1 if id is an owner.

int ACE_RW_Token::release ACE_TPQ_Entry caller  )  [virtual]
 

Relinquish the token. If there are any waiters then the next one in line gets it. If the caller is not the owner, caller is removed from the waiter list.

Implements ACE_Tokens.

int ACE_RW_Token::renew ACE_TPQ_Entry caller,
int  requeue_position
[virtual]
 

An optimized method that efficiently reacquires the token if no other threads are waiting. This is useful for situations where you don't want to degrade the quality of service if there are other threads waiting to get the token. If <requeue_position> == -1 and there are other threads waiting to obtain the token we are queued at the end of the list of waiters. If <requeue_position> > -1 then it indicates how many entries to skip over before inserting our thread into the list of waiters (e.g., <requeue_position> == 0 means "insert at front of the queue"). Renew has the rather odd semantics such that if there are other waiting threads it will give up the token even if the nesting_level_ > 1. I'm not sure if this is really the right thing to do (since it makes it possible for shared data to be changed unexpectedly) so use with caution... Returns 0 on success, -1 on failure with <ACE_Log_Msg::errnum> as the reason. If errnum == EWOULDBLOCK, and notify == 1, <ACE_Token_Proxy::sleep_hook> has been called on the current owner of the token.

Implements ACE_Tokens.

int ACE_RW_Token::tryacquire ACE_TPQ_Entry caller  )  [virtual]
 

Same as acquire except fails on would block.

Implements ACE_Tokens.

virtual int ACE_RW_Token::type void   )  const [virtual]
 

Returns READER or WRITER.

Implements ACE_Tokens.


Member Data Documentation

ACE_TOKEN_CONST::MUTEX ACE_RW_Token::lock_ [protected]
 

ACE_Mutex_Token used to lock internal data structures.

int ACE_RW_Token::num_writers_ [protected]
 

The number of waiting writers.


The documentation for this class was generated from the following files:
Generated on Wed Nov 23 15:50:18 2005 for ACE by  doxygen 1.4.5