332 lines
11 KiB
C++
332 lines
11 KiB
C++
|
//+-------------------------------------------------------------------
|
||
|
|
//
|
||
|
|
// File: RWLock.hxx
|
||
|
|
//
|
||
|
|
// Contents: Reader writer lock implementation that supports the
|
||
|
|
// following features
|
||
|
|
// 1. Cheap enough to be used in large numbers
|
||
|
|
// such as per object synchronization.
|
||
|
|
// 2. Supports timeout. This is a valuable feature
|
||
|
|
// to detect deadlocks
|
||
|
|
// 3. Supports caching of events. The allows
|
||
|
|
// the events to be moved from least contentious
|
||
|
|
// regions to the most contentious regions.
|
||
|
|
// In other words, the number of events needed by
|
||
|
|
// Reader-Writer lockls is bounded by the number
|
||
|
|
// of threads in the process.
|
||
|
|
// 4. Supports nested locks by readers and writers
|
||
|
|
// 5. Supports spin counts for avoiding context switches
|
||
|
|
// on multi processor machines.
|
||
|
|
// 6. Supports functionality for upgrading to a writer
|
||
|
|
// lock with a return argument that indicates
|
||
|
|
// intermediate writes. Downgrading from a writer
|
||
|
|
// lock restores the state of the lock.
|
||
|
|
// 7. Supports functionality to Release Lock for calling
|
||
|
|
// app code. RestoreLock restores the lock state and
|
||
|
|
// indicates intermediate writes.
|
||
|
|
// 8. Recovers from most common failures such as creation of
|
||
|
|
// events. In other words, the lock mainitains consistent
|
||
|
|
// internal state and remains usable
|
||
|
|
//
|
||
|
|
// Classes: CRWLock,
|
||
|
|
// CStaticRWLock
|
||
|
|
//
|
||
|
|
// History: 19-Aug-98 Gopalk Created
|
||
|
|
//
|
||
|
|
//--------------------------------------------------------------------
|
||
|
|
#ifndef _RWLOCK_HXX_
|
||
|
|
#define _RWLOCK_HXX_
|
||
|
|
|
||
|
|
#if LOCK_PERF==1
|
||
|
|
#define RWLOCK_STATISTICS 1
|
||
|
|
#endif
|
||
|
|
|
||
|
|
extern DWORD gdwDefaultTimeout;
|
||
|
|
extern DWORD gdwDefaultSpinCount;
|
||
|
|
extern DWORD gdwNumberOfProcessors;
|
||
|
|
|
||
|
|
typedef struct {
|
||
|
|
DWORD dwFlags;
|
||
|
|
DWORD dwWriterSeqNum;
|
||
|
|
WORD *pwReaderLevel;
|
||
|
|
WORD wReaderLevel;
|
||
|
|
WORD wWriterLevel;
|
||
|
|
} LockCookie;
|
||
|
|
typedef DWORD WriterCookie;
|
||
|
|
|
||
|
|
//+-------------------------------------------------------------------
|
||
|
|
//
|
||
|
|
// Class: CRWLock
|
||
|
|
//
|
||
|
|
// Synopsis: Abstract base class the implements the locking
|
||
|
|
// functionality. It supports nested read locks and
|
||
|
|
// guarantees progress when the derived class is capable
|
||
|
|
// of creating ReaderSlot
|
||
|
|
//
|
||
|
|
// History: 21-Aug-98 Gopalk Created
|
||
|
|
//
|
||
|
|
//+-------------------------------------------------------------------
|
||
|
|
#define RWLOCKFLAG_INITIALIZED 1
|
||
|
|
|
||
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
||
|
|
#define RWLOCKFLAG_CACHEEVENTS 2
|
||
|
|
#define RWLOCKFLAG_RETURNERRORS 4
|
||
|
|
#endif
|
||
|
|
|
||
|
|
class CRWLock
|
||
|
|
{
|
||
|
|
public:
|
||
|
|
// Constuctor
|
||
|
|
CRWLock() :
|
||
|
|
_hWriterEvent(NULL),
|
||
|
|
_hReaderEvent(NULL),
|
||
|
|
_dwState(0),
|
||
|
|
_dwWriterID(0),
|
||
|
|
_dwWriterSeqNum(1),
|
||
|
|
_wFlags(0),
|
||
|
|
_wWriterLevel(0)
|
||
|
|
#ifdef RWLOCK_STATISTICS
|
||
|
|
,
|
||
|
|
_dwReaderEntryCount(0),
|
||
|
|
_dwReaderContentionCount(0),
|
||
|
|
_dwWriterEntryCount(0),
|
||
|
|
_dwWriterContentionCount(0)
|
||
|
|
#endif
|
||
|
|
{
|
||
|
|
}
|
||
|
|
|
||
|
|
// Initialize
|
||
|
|
virtual void Initialize() { _wFlags |= RWLOCKFLAG_INITIALIZED; }
|
||
|
|
BOOL IsInitialized() { return(_wFlags & RWLOCKFLAG_INITIALIZED); }
|
||
|
|
|
||
|
|
// Cleanup
|
||
|
|
virtual void Cleanup();
|
||
|
|
|
||
|
|
// Lock functions
|
||
|
|
HRESULT AcquireReaderLock(
|
||
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
||
|
|
BOOL fReturnErrors = FALSE,
|
||
|
|
DWORD dwDesiredTimeout = gdwDefaultTimeout
|
||
|
|
#if LOCK_PERF==1
|
||
|
|
,
|
||
|
|
#endif
|
||
|
|
#endif
|
||
|
|
#if LOCK_PERF==1
|
||
|
|
const char *pszFile = "Unknown File",
|
||
|
|
DWORD dwLine = 0,
|
||
|
|
const char *pszLockName = "Unknown RWLock"
|
||
|
|
#endif
|
||
|
|
);
|
||
|
|
HRESULT AcquireWriterLock(
|
||
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
||
|
|
BOOL fReturnErrors = FALSE,
|
||
|
|
DWORD dwDesiredTimeout = gdwDefaultTimeout
|
||
|
|
#if LOCK_PERF==1
|
||
|
|
,
|
||
|
|
#endif
|
||
|
|
#endif
|
||
|
|
#if LOCK_PERF==1
|
||
|
|
const char *pszFile = "Unknown File",
|
||
|
|
DWORD dwLine = 0,
|
||
|
|
const char *pszLockName = "Unknown RWLock"
|
||
|
|
#endif
|
||
|
|
);
|
||
|
|
|
||
|
|
HRESULT ReleaseReaderLock();
|
||
|
|
HRESULT ReleaseWriterLock();
|
||
|
|
HRESULT UpgradeToWriterLock(LockCookie *pLockCookie,
|
||
|
|
BOOL *pfInterveningWrites = NULL
|
||
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
||
|
|
,
|
||
|
|
BOOL fReturnErrors = FALSE,
|
||
|
|
DWORD dwDesiredTimeout = gdwDefaultTimeout
|
||
|
|
#endif
|
||
|
|
#if LOCK_PERF==1
|
||
|
|
,
|
||
|
|
const char *pszFile = "Unknown File",
|
||
|
|
DWORD dwLine = 0,
|
||
|
|
const char *pszLockName = "Unknown RWLock"
|
||
|
|
#endif
|
||
|
|
);
|
||
|
|
HRESULT DowngradeFromWriterLock(LockCookie *pLockCookie
|
||
|
|
#if LOCK_PERF==1
|
||
|
|
,
|
||
|
|
const char *pszFile = "Unknown File",
|
||
|
|
DWORD dwLine = 0,
|
||
|
|
const char *pszLockName = "Unknown RWLock"
|
||
|
|
#endif
|
||
|
|
);
|
||
|
|
HRESULT ReleaseLock(LockCookie *pLockCookie);
|
||
|
|
HRESULT RestoreLock(LockCookie *pLockCookie,
|
||
|
|
BOOL *pfInterveningWrites = NULL
|
||
|
|
#if LOCK_PERF==1
|
||
|
|
,
|
||
|
|
const char *pszFile = "Unknown File",
|
||
|
|
DWORD dwLine = 0,
|
||
|
|
const char *pszLockName = "Unknown RWLock"
|
||
|
|
#endif
|
||
|
|
);
|
||
|
|
// Assert functions
|
||
|
|
#if DBG==1
|
||
|
|
BOOL AssertWriterLockHeld();
|
||
|
|
BOOL AssertWriterLockNotHeld();
|
||
|
|
BOOL AssertReaderLockHeld();
|
||
|
|
BOOL AssertReaderLockNotHeld();
|
||
|
|
BOOL AssertReaderOrWriterLockHeld();
|
||
|
|
void AssertHeld() { AssertWriterLockHeld(); }
|
||
|
|
void AssertNotHeld() { AssertWriterLockNotHeld();
|
||
|
|
AssertReaderLockNotHeld(); }
|
||
|
|
#else
|
||
|
|
void AssertWriterLockHeld() { }
|
||
|
|
void AssertWriterLockNotHeld() { }
|
||
|
|
void AssertReaderLockHeld() { }
|
||
|
|
void AssertReaderLockNotHeld() { }
|
||
|
|
void AssertReaderOrWriterLockHeld() { }
|
||
|
|
void AssertHeld() { }
|
||
|
|
void AssertNotHeld() { }
|
||
|
|
#endif
|
||
|
|
|
||
|
|
// Helper functions
|
||
|
|
WriterCookie GetWriterCookie() { return(_dwWriterSeqNum); }
|
||
|
|
BOOL IntermediateWrites(WriterCookie cookie) { return((cookie+1) != _dwWriterSeqNum); }
|
||
|
|
BOOL HeldExclusive() { return _dwWriterID == GetCurrentThreadId(); }
|
||
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
||
|
|
void ReturnErrors() { _wFlags |= RWLOCKFLAG_RETURNERRORS; }
|
||
|
|
void CacheEvents() { _wFlags |= RWLOCKFLAG_CACHEEVENTS; }
|
||
|
|
#endif
|
||
|
|
#ifdef RWLOCK_STATISTICS
|
||
|
|
DWORD GetReaderEntryCount() { return(_dwReaderEntryCount); }
|
||
|
|
DWORD GetReaderContentionCount() { return(_dwReaderContentionCount); }
|
||
|
|
DWORD GetWriterEntryCount() { return(_dwWriterEntryCount); }
|
||
|
|
DWORD GetWriterContentionCount() { return(_dwWriterContentionCount); }
|
||
|
|
#endif
|
||
|
|
// Static functions
|
||
|
|
static void InitDefaults();
|
||
|
|
static void SetTimeout(DWORD dwTimeout) { gdwDefaultTimeout = dwTimeout; }
|
||
|
|
static DWORD GetTimeout() { return(gdwDefaultTimeout); }
|
||
|
|
static void SetSpinCount(DWORD dwSpinCount) { gdwDefaultSpinCount = gdwNumberOfProcessors > 1
|
||
|
|
? dwSpinCount
|
||
|
|
: 0; }
|
||
|
|
static DWORD GetSpinCount() { return(gdwDefaultSpinCount); }
|
||
|
|
|
||
|
|
private:
|
||
|
|
virtual HRESULT GetTLSLockData(WORD **ppwReaderLevel) = 0;
|
||
|
|
|
||
|
|
HANDLE GetReaderEvent();
|
||
|
|
HANDLE GetWriterEvent();
|
||
|
|
ULONG ModifyState(ULONG dwModifyState);
|
||
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
||
|
|
void ReleaseEvents();
|
||
|
|
#endif
|
||
|
|
static void RWSetEvent(HANDLE event);
|
||
|
|
static void RWResetEvent(HANDLE event);
|
||
|
|
static void RWSleep(DWORD dwTime);
|
||
|
|
|
||
|
|
HANDLE _hWriterEvent;
|
||
|
|
HANDLE _hReaderEvent;
|
||
|
|
DWORD _dwState;
|
||
|
|
DWORD _dwWriterID;
|
||
|
|
DWORD _dwWriterSeqNum;
|
||
|
|
WORD _wFlags;
|
||
|
|
WORD _wWriterLevel;
|
||
|
|
#ifdef RWLOCK_STATISTICS
|
||
|
|
DWORD _dwReaderEntryCount;
|
||
|
|
DWORD _dwReaderContentionCount;
|
||
|
|
DWORD _dwWriterEntryCount;
|
||
|
|
DWORD _dwWriterContentionCount;
|
||
|
|
#endif
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
//+-------------------------------------------------------------------
|
||
|
|
//
|
||
|
|
// Class: CStaticRWLock
|
||
|
|
//
|
||
|
|
// Synopsis: Instances of this class are statically created. It
|
||
|
|
// manages creation and allocation of ReaderSlots
|
||
|
|
//
|
||
|
|
// History: 21-Aug-98 Gopalk Created
|
||
|
|
//
|
||
|
|
//+-------------------------------------------------------------------
|
||
|
|
class CStaticRWLock : public CRWLock
|
||
|
|
{
|
||
|
|
public:
|
||
|
|
// Constructor
|
||
|
|
CStaticRWLock() :
|
||
|
|
_dwLockNum(-1)
|
||
|
|
{
|
||
|
|
}
|
||
|
|
|
||
|
|
// Initialize
|
||
|
|
void Initialize();
|
||
|
|
|
||
|
|
// Compatibility functions
|
||
|
|
void Request(
|
||
|
|
#if LOCK_PERF==1 || DBG==1
|
||
|
|
const char *pszFile = "Unknown File",
|
||
|
|
DWORD dwLine = 0,
|
||
|
|
const char* pszLockName = "Unknown RWLock"
|
||
|
|
#endif
|
||
|
|
)
|
||
|
|
{
|
||
|
|
AcquireWriterLock(
|
||
|
|
#if LOCK_PERF==1
|
||
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
||
|
|
FALSE, gdwDefaultTimeout,
|
||
|
|
#endif
|
||
|
|
pszFile, dwLine, pszLockName
|
||
|
|
#endif
|
||
|
|
);
|
||
|
|
}
|
||
|
|
void Release()
|
||
|
|
{
|
||
|
|
ReleaseWriterLock();
|
||
|
|
}
|
||
|
|
|
||
|
|
private:
|
||
|
|
HRESULT GetTLSLockData(WORD **ppwReaderLevel);
|
||
|
|
|
||
|
|
DWORD _dwLockNum;
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
//+-------------------------------------------------------------------
|
||
|
|
//
|
||
|
|
// Class: CStaticWriteLock
|
||
|
|
//
|
||
|
|
// Synopsis: Helper class that simulates acquiring/releasing
|
||
|
|
// write lock as constructing/destroying an object
|
||
|
|
// on the stack
|
||
|
|
//
|
||
|
|
// History: 21-Aug-98 Gopalk Created
|
||
|
|
//
|
||
|
|
//+-------------------------------------------------------------------
|
||
|
|
class CStaticWriteLock
|
||
|
|
{
|
||
|
|
public:
|
||
|
|
CStaticWriteLock(CStaticRWLock &rwLock
|
||
|
|
#if LOCK_PERF==1 || DBG==1
|
||
|
|
,
|
||
|
|
const char *pszFile = "Unknown File",
|
||
|
|
DWORD dwLine = 0,
|
||
|
|
const char *pszLockName = "Unknown RWLock"
|
||
|
|
#endif
|
||
|
|
) :
|
||
|
|
_rwLock(rwLock)
|
||
|
|
{
|
||
|
|
_rwLock.Request(
|
||
|
|
#if LOCK_PERF==1 || DBG==1
|
||
|
|
pszFile, dwLine, pszLockName
|
||
|
|
#endif
|
||
|
|
);
|
||
|
|
}
|
||
|
|
~CStaticWriteLock()
|
||
|
|
{
|
||
|
|
_rwLock.Release();
|
||
|
|
}
|
||
|
|
|
||
|
|
private:
|
||
|
|
CStaticRWLock &_rwLock;
|
||
|
|
};
|
||
|
|
#endif // _RWLOCK_HXX_
|