143 lines
2.7 KiB
C++
143 lines
2.7 KiB
C++
|
/*++
|
||
|
|
|
||
|
|
Copyright (c) 1995 Microsoft Corporation
|
||
|
|
|
||
|
|
Module Name:
|
||
|
|
|
||
|
|
Locks.hxx
|
||
|
|
|
||
|
|
Abstract:
|
||
|
|
|
||
|
|
Several small class (CInterlockedInteger, CMutexLock and CSharedLock
|
||
|
|
which are wrappers for Win32 APIs.
|
||
|
|
|
||
|
|
CInterlockedInteger is a simple wrapper for win32 interlockedm integer APis.
|
||
|
|
|
||
|
|
CMutexLock is a wrapper designed to automatically constructed around
|
||
|
|
win32 critical sections. They never forget to release the lock.
|
||
|
|
|
||
|
|
CSharedLocks are similar to NT resources, they allow shared (multiple readers)
|
||
|
|
and exclusive (single writer) access to the resource. They are different
|
||
|
|
in the following ways:
|
||
|
|
CSharedLocks don't starve exclusive threads.
|
||
|
|
Exclusive threads spin (Sleep(0)) while waiting for readers to finish.
|
||
|
|
Exclusive threads will deadlock trying to gain shared access.
|
||
|
|
Exclusive threads trying to recursively take the lock may deadlock.
|
||
|
|
They always block if they can't get access.
|
||
|
|
|
||
|
|
Author:
|
||
|
|
|
||
|
|
Mario Goertzel [MarioGo]
|
||
|
|
|
||
|
|
Revision History:
|
||
|
|
|
||
|
|
MarioGo 03-14-95 Moved from misc.?xx
|
||
|
|
|
||
|
|
--*/
|
||
|
|
|
||
|
|
#ifndef __LOCKS_HXX
|
||
|
|
#define __LOCKS_HXX
|
||
|
|
|
||
|
|
class CInterlockedInteger
|
||
|
|
{
|
||
|
|
private:
|
||
|
|
LONG i;
|
||
|
|
|
||
|
|
public:
|
||
|
|
|
||
|
|
CInterlockedInteger(LONG i = 0) : i(i) {}
|
||
|
|
|
||
|
|
LONG operator++(int)
|
||
|
|
{
|
||
|
|
return(InterlockedIncrement(&i));
|
||
|
|
}
|
||
|
|
|
||
|
|
LONG operator--(int)
|
||
|
|
{
|
||
|
|
return(InterlockedDecrement(&i));
|
||
|
|
}
|
||
|
|
|
||
|
|
operator LONG()
|
||
|
|
{
|
||
|
|
return(i);
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
class CMutexLock
|
||
|
|
{
|
||
|
|
private:
|
||
|
|
|
||
|
|
CRITICAL_SECTION *pCurrentLock;
|
||
|
|
int owned;
|
||
|
|
|
||
|
|
public:
|
||
|
|
|
||
|
|
CMutexLock(CRITICAL_SECTION *pLock) : owned(0), pCurrentLock(pLock) {
|
||
|
|
Lock();
|
||
|
|
}
|
||
|
|
|
||
|
|
~CMutexLock() {
|
||
|
|
if (owned)
|
||
|
|
Unlock();
|
||
|
|
#if DBG
|
||
|
|
pCurrentLock = 0;
|
||
|
|
#endif
|
||
|
|
}
|
||
|
|
|
||
|
|
void Lock()
|
||
|
|
{
|
||
|
|
ASSERT(!owned);
|
||
|
|
EnterCriticalSection(pCurrentLock);
|
||
|
|
owned = 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
void Unlock()
|
||
|
|
{
|
||
|
|
ASSERT(owned);
|
||
|
|
owned = 0;
|
||
|
|
LeaveCriticalSection(pCurrentLock);
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
class CSharedLock
|
||
|
|
{
|
||
|
|
private:
|
||
|
|
CRITICAL_SECTION lock;
|
||
|
|
HANDLE hevent;
|
||
|
|
CInterlockedInteger readers;
|
||
|
|
CInterlockedInteger writers;
|
||
|
|
DWORD exclusive_owner;
|
||
|
|
|
||
|
|
public:
|
||
|
|
|
||
|
|
CSharedLock(ORSTATUS &status);
|
||
|
|
|
||
|
|
~CSharedLock();
|
||
|
|
|
||
|
|
void LockShared(void);
|
||
|
|
|
||
|
|
void UnlockShared(void);
|
||
|
|
|
||
|
|
void LockExclusive(void);
|
||
|
|
|
||
|
|
void UnlockExclusive(void);
|
||
|
|
|
||
|
|
void Unlock(void);
|
||
|
|
|
||
|
|
void ConvertToExclusive(void);
|
||
|
|
|
||
|
|
BOOL HeldExclusive()
|
||
|
|
{
|
||
|
|
return(exclusive_owner == GetCurrentThreadId());
|
||
|
|
}
|
||
|
|
|
||
|
|
BOOL NotHeldExclusiveByAnyone()
|
||
|
|
{
|
||
|
|
return(exclusive_owner == 0);
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
#endif // __LOCKS_HXX
|
||
|
|
|