SG_RWLock Class Reference

#include <SG_RWLock.h>

List of all members.

Public Member Functions
	SG_RWLock ()
void	enter_read ()
void	leave_read ()
void	enter_write ()
void	leave_write ()
Static Public Member Functions
static const char *	name ()
Private Attributes
volatile int	readers
volatile int	writers
SystemLock	l

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Detailed Description

Definition at line 9 of file SG_RWLock.h.

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Constructor & Destructor Documentation

SG_RWLock::SG_RWLock

(

)

[inline]

Definition at line 13 of file SG_RWLock.h.

References readers, and writers.

        {
                readers = writers = 0;
        }

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Member Function Documentation

static const char* SG_RWLock::name

(

)

[inline, static]

Definition at line 12 of file SG_RWLock.h.

{ return "SG_Lock"; }

void SG_RWLock::enter_read

(

void

)

[inline]

Definition at line 17 of file SG_RWLock.h.

References atomic_inc(), readers, thread_yield(), and writers.

        {
                atomic_inc(&readers);

        // Wait until all writers have left
                while(writers > 0) thread_yield();
        }

void SG_RWLock::leave_read

(

void

)

[inline]

Definition at line 24 of file SG_RWLock.h.

References atomic_dec(), and readers.

        {
                atomic_dec(&readers);
        }

void SG_RWLock::enter_write

(

void

)

[inline]

Definition at line 28 of file SG_RWLock.h.

References atomic_dec(), atomic_inc(), l, SystemLock::lock(), readers, thread_yield(), and writers.

        {
                // Use a critsec for mutual exclusion between writers
                l.lock();
                // We must now wait until all readers have left the lock
                atomic_inc(&writers);
// -BUG         writers++; // Assume there are no readers
                while (readers > 0) 
                {
                        // Readers in the lock
                        // Decrement writers again to avoid deadlocking with readers that
                        // are interrupted immediately after incrementing readers
                        atomic_dec(&writers);
// - BUG                        writers--;
                        thread_yield();
                        atomic_inc(&writers);
// --BUG                        writers++; // Try again
                }
        }

void SG_RWLock::leave_write

(

void

)

[inline]

Definition at line 47 of file SG_RWLock.h.

References atomic_dec(), l, SystemLock::unlock(), and writers.

        {   
                atomic_dec(&writers);
                l.unlock();
        }

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Member Data Documentation

volatile int SG_RWLock::readers [private]

Definition at line 53 of file SG_RWLock.h.

Referenced by enter_read(), enter_write(), leave_read(), and SG_RWLock().

volatile int SG_RWLock::writers [private]

Definition at line 54 of file SG_RWLock.h.

Referenced by enter_read(), enter_write(), leave_write(), and SG_RWLock().

SystemLock SG_RWLock::l [private]

Definition at line 55 of file SG_RWLock.h.

Referenced by enter_write(), and leave_write().

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

• C:/rwlock/SG_RWLock.h