ucommon
Data Structures | Public Member Functions | Static Public Member Functions | Protected Member Functions | Protected Attributes
ucommon::ThreadLock Class Reference

A generic and portable implimentation of Read/Write locking. More...

#include <thread.h>

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Data Structures

class  gaurd_reader
 Gaurd class to apply scope based access locking to objects. More...
class  gaurd_writer
 Gaurd class to apply scope based exclusive locking to objects. More...

Public Member Functions

bool access (timeout_t timeout=Timer::inf)
 Request shared (read) access through the lock.
unsigned getAccess (void)
 Get the number of threads in shared access mode.
unsigned getModify (void)
 Get the number of threads waiting to modify the lock.
unsigned getWaiting (void)
 Get the number of threads waiting to access after writer completes.
bool modify (timeout_t timeout=Timer::inf)
 Request modify (write) access through the lock.
void release (void)
 Release the lock.
 ThreadLock ()
 Create an instance of a rwlock.

Static Public Member Functions

static bool access (ThreadLock &lock, timeout_t timeout=Timer::inf)
 Convenience function to access (read lock) a rwlock.
static void indexing (unsigned size)
 Specify hash table size for gaurd protection.
static bool modify (ThreadLock &lock, timeout_t timeout=Timer::inf)
 Convenience function to modify (write lock) a rwlock.
static bool reader (void *object, timeout_t timeout=Timer::inf)
 Shared access to an arbitrary object.
static void release (void *object)
 Release an arbitrary object that has been protected by a rwlock.
static void release (ThreadLock &lock)
 Convenience function to release a rwlock.
static bool writer (void *object, timeout_t timeout=Timer::inf)
 Write protect access to an arbitrary object.

Protected Member Functions

void Exlock (void)
 Protocol interface to exclusive lock the object.
void Shlock (void)
 Protocol interface to share lock the object.
void Unlock (void)
 Protocol interface to release a lock.

Protected Attributes

pthread_t writeid
unsigned writers

Detailed Description

A generic and portable implimentation of Read/Write locking.

This class impliments classical read/write locking, including "timed" locks. Support for scheduling threads to avoid writer starvation is also provided for. By building read/write locks from a conditional, we make them available on pthread implimetations and other platforms which do not normally include optional pthread rwlock's. We also do not restrict the number of threads that may use the lock. Finally, both the exclusive and shared protocols are implimented to support exclusive_lock and shared_lock referencing.

Author:
David Sugar <dyfet@gnutelephony.org>

Definition at line 547 of file thread.h.


Member Function Documentation

Request shared (read) access through the lock.

Parameters:
timeoutin milliseconds to wait for lock.
Returns:
true if locked, false if timeout.
static bool ucommon::ThreadLock::access ( ThreadLock lock,
timeout_t  timeout = Timer::inf 
) [inline, static]

Convenience function to access (read lock) a rwlock.

Parameters:
lockto access.
timeoutto wait for lock.
Returns:
true if successful, false if timeout.

Definition at line 749 of file thread.h.

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unsigned ucommon::ThreadLock::getAccess ( void  )

Get the number of threads in shared access mode.

Returns:
number of accessing threads.
unsigned ucommon::ThreadLock::getModify ( void  )

Get the number of threads waiting to modify the lock.

Returns:
number of pending write threads.
unsigned ucommon::ThreadLock::getWaiting ( void  )

Get the number of threads waiting to access after writer completes.

Returns:
number of waiting access threads.
static void ucommon::ThreadLock::indexing ( unsigned  size) [static]

Specify hash table size for gaurd protection.

The default is 1. This should be called at initialization time from the main thread of the application before any other threads are created.

Parameters:
sizeof hash table used for gaurding.

Request modify (write) access through the lock.

Parameters:
timeoutin milliseconds to wait for lock.
Returns:
true if locked, false if timeout.
static bool ucommon::ThreadLock::modify ( ThreadLock lock,
timeout_t  timeout = Timer::inf 
) [inline, static]

Convenience function to modify (write lock) a rwlock.

Parameters:
lockto modify.
timeoutto wait for lock.
Returns:
true if successful, false if timeout.

Definition at line 740 of file thread.h.

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static bool ucommon::ThreadLock::reader ( void *  object,
timeout_t  timeout = Timer::inf 
) [static]

Shared access to an arbitrary object.

This is based on the protect function of mutex.

Parameters:
objectto share.
timeoutin milliseconds to wait for lock.
Returns:
true if shared, false if timeout.
static void ucommon::ThreadLock::release ( void *  object) [static]

Release an arbitrary object that has been protected by a rwlock.

Parameters:
objectto release.
static void ucommon::ThreadLock::release ( ThreadLock lock) [inline, static]

Convenience function to release a rwlock.

Parameters:
lockto release.

Definition at line 756 of file thread.h.

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static bool ucommon::ThreadLock::writer ( void *  object,
timeout_t  timeout = Timer::inf 
) [static]

Write protect access to an arbitrary object.

This is like the protect function of mutex.

Parameters:
objectto protect.
timeoutin milliseconds to wait for lock.
Returns:
true if locked, false if timeout.

The documentation for this class was generated from the following file: