1840 lines
60 KiB
C++
1840 lines
60 KiB
C++
//+-------------------------------------------------------------------
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//
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// File: RWLock.cxx
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//
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// Contents: Reader writer lock implementation that supports the
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// following features
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// 1. Cheap enough to be used in large numbers
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// such as per object synchronization.
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// 2. Supports timeout. This is a valuable feature
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// to detect deadlocks
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// 3. Supports caching of events. This allows
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// the events to be moved from least contentious
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// regions to the most contentious regions.
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// In other words, the number of events needed by
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// Reader-Writer lockls is bounded by the number
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// of threads in the process.
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// 4. Supports nested locks by readers and writers
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// 5. Supports spin counts for avoiding context switches
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// on multi processor machines.
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// 6. Supports functionality for upgrading to a writer
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// lock with a return argument that indicates
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// intermediate writes. Downgrading from a writer
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// lock restores the state of the lock.
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// 7. Supports functionality to Release Lock for calling
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// app code. RestoreLock restores the lock state and
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// indicates intermediate writes.
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// 8. Recovers from most common failures such as creation of
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// events. In other words, the lock mainitains consistent
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// internal state and remains usable
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//
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//
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// Classes: CRWLock
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// CStaticRWLock
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//
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// History: 19-Aug-98 Gopalk Created
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//
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//--------------------------------------------------------------------
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#include <ole2int.h>
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#include "RWLock.hxx"
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// Reader increment
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#define READER 0x00000001
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// Max number of readers
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#define READERS_MASK 0x000003FF
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// Reader being signaled
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#define READER_SIGNALED 0x00000400
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// Writer being signaled
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#define WRITER_SIGNALED 0x00000800
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#define WRITER 0x00001000
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// Waiting reader increment
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#define WAITING_READER 0x00002000
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// Note size of waiting readers must be less
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// than or equal to size of readers
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#define WAITING_READERS_MASK 0x007FE000
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#define WAITING_READERS_SHIFT 13
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// Waiting writer increment
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#define WAITING_WRITER 0x00800000
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// Max number of waiting writers
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#define WAITING_WRITERS_MASK 0xFF800000
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// Events are being cached
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#define CACHING_EVENTS (READER_SIGNALED | WRITER_SIGNALED)
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// Reader lock was upgraded
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#define INVALID_COOKIE 0x01
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#define UPGRADE_COOKIE 0x02
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#define RELEASE_COOKIE 0x04
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#define COOKIE_NONE 0x10
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#define COOKIE_WRITER 0x20
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#define COOKIE_READER 0x40
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DWORD gdwDefaultTimeout = INFINITE;
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DWORD gdwDefaultSpinCount = 0;
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DWORD gdwNumberOfProcessors = 1;
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DWORD gdwLockSeqNum = 0;
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BOOL fBreakOnErrors = FALSE;
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const DWORD gdwReasonableTimeout = 120000;
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const DWORD gdwMaxReaders = READERS_MASK;
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const DWORD gdwMaxWaitingReaders = (WAITING_READERS_MASK >> WAITING_READERS_SHIFT);
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#ifdef __NOOLETLS__
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DWORD gLockTlsIdx;
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#endif
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#define RWLOCK_FATALFAILURE 1000
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#define HEAP_SERIALIZE 0
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::InitDefaults public
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//
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// Synopsis: Reads default values from registry
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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void CRWLock::InitDefaults()
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{
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SYSTEM_INFO system;
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// Obtain number of processors on the system
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GetSystemInfo(&system);
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gdwNumberOfProcessors = system.dwNumberOfProcessors;
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gdwDefaultSpinCount = (gdwNumberOfProcessors > 1) ? 500 : 0;
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// Obtain system wide timeout value
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HKEY hKey;
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LONG lRetVal = RegOpenKeyExA(HKEY_LOCAL_MACHINE,
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"SYSTEM\\CurrentControlSet\\Control\\Session Manager",
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NULL,
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KEY_READ,
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&hKey);
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if(lRetVal == ERROR_SUCCESS)
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{
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DWORD dwTimeout, dwSize = sizeof(dwTimeout);
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lRetVal = RegQueryValueExA(hKey,
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"CriticalSectionTimeout",
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NULL,
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NULL,
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(LPBYTE) &dwTimeout,
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&dwSize);
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if(lRetVal == ERROR_SUCCESS)
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{
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gdwDefaultTimeout = dwTimeout * 2000;
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}
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RegCloseKey(hKey);
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}
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return;
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}
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::Cleanup public
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//
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// Synopsis: Cleansup state
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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void CRWLock::Cleanup()
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{
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#if DBG==1
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if (g_fDllState != DLL_STATE_PROCESS_DETACH)
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{
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// Perform sanity checks if we're not shutting down
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Win4Assert(_dwState == 0);
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Win4Assert(_dwWriterID == 0);
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Win4Assert(_wWriterLevel == 0);
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}
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#endif
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if(_hWriterEvent)
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CloseHandle(_hWriterEvent);
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if(_hReaderEvent)
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CloseHandle(_hReaderEvent);
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#if LOCK_PERF==1
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gLockTracker.ReportContention(this,
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_dwWriterEntryCount,
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_dwWriterContentionCount,
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_dwReaderEntryCount,
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_dwReaderContentionCount);
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#endif
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return;
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}
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::AssertWriterLockHeld public
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//
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// Synopsis: Asserts that writer lock is held
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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#if DBG==1
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BOOL CRWLock::AssertWriterLockHeld()
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{
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DWORD dwThreadID = GetCurrentThreadId();
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if(_dwWriterID != dwThreadID)
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Win4Assert(!"Writer lock not held by the current thread");
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return(_dwWriterID == dwThreadID);
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}
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#endif
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::AssertWriterLockNotHeld public
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//
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// Synopsis: Asserts that writer lock is not held
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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#if DBG==1
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BOOL CRWLock::AssertWriterLockNotHeld()
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{
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DWORD dwThreadID = GetCurrentThreadId();
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if(_dwWriterID == dwThreadID)
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Win4Assert(!"Writer lock held by the current thread");
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return(_dwWriterID != dwThreadID);
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}
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#endif
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::AssertReaderLockHeld public
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//
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// Synopsis: Asserts that reader lock is held
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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#if DBG==1
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BOOL CRWLock::AssertReaderLockHeld()
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{
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HRESULT hr;
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WORD *pwReaderLevel;
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BOOL fLockHeld = FALSE;
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hr = GetTLSLockData(&pwReaderLevel);
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if((hr == S_OK) && (*pwReaderLevel != 0))
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fLockHeld = TRUE;
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if(fLockHeld == FALSE)
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Win4Assert(!"Reader lock not held by the current thread");
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return(fLockHeld);
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}
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#endif
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::AssertReaderLockNotHeld public
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//
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// Synopsis: Asserts that writer lock is not held
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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#if DBG==1
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BOOL CRWLock::AssertReaderLockNotHeld()
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{
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HRESULT hr;
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WORD *pwReaderLevel;
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BOOL fLockHeld = FALSE;
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hr = GetTLSLockData(&pwReaderLevel);
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if((hr == S_OK) && (*pwReaderLevel != 0))
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fLockHeld = TRUE;
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if(fLockHeld == TRUE)
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Win4Assert(!"Reader lock held by the current thread");
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return(fLockHeld == FALSE);
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}
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#endif
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::AssertReaderOrWriterLockHeld public
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//
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// Synopsis: Asserts that writer lock is not held
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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#if DBG==1
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BOOL CRWLock::AssertReaderOrWriterLockHeld()
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{
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BOOL fLockHeld;
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if(_dwWriterID == GetCurrentThreadId())
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{
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fLockHeld = TRUE;
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}
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else
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{
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HRESULT hr;
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WORD *pwReaderLevel;
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hr = GetTLSLockData(&pwReaderLevel);
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if((hr == S_OK) && (*pwReaderLevel != 0))
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fLockHeld = TRUE;
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}
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Win4Assert(fLockHeld && "Neither Reader nor Writer lock held");
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return(fLockHeld);
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}
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#endif
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::ModifyState public
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//
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// Synopsis: Helper function for updating the state inside the lock
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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inline DWORD CRWLock::ModifyState(DWORD dwModifyState)
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{
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return(InterlockedExchangeAdd((LONG *) &_dwState, dwModifyState));
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}
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::RWSetEvent public
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//
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// Synopsis: Helper function for setting an event
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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inline void CRWLock::RWSetEvent(HANDLE event)
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{
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if(!SetEvent(event))
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{
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Win4Assert(!"SetEvent failed");
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if(fBreakOnErrors)
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DebugBreak();
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TerminateProcess(GetCurrentProcess(), RWLOCK_FATALFAILURE);
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}
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}
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::RWResetEvent public
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//
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// Synopsis: Helper function for resetting an event
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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inline void CRWLock::RWResetEvent(HANDLE event)
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{
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if(!ResetEvent(event))
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{
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Win4Assert(!"ResetEvent failed");
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if(fBreakOnErrors)
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DebugBreak();
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TerminateProcess(GetCurrentProcess(), RWLOCK_FATALFAILURE);
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}
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}
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::RWSleep public
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//
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// Synopsis: Helper function for calling Sleep. Useful for debugging
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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inline void CRWLock::RWSleep(DWORD dwTime)
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{
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Sleep(dwTime);
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}
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::ReleaseEvents public
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//
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// Synopsis: Helper function for caching events
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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#ifdef RWLOCK_FULL_FUNCTIONALITY
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void CRWLock::ReleaseEvents()
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{
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// Sanity check
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Win4Assert(_wFlags & RWLOCKFLAG_CACHEEVENTS);
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// Ensure that reader and writers have been stalled
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Win4Assert((_dwState & CACHING_EVENTS) == CACHING_EVENTS);
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// Save writer event
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HANDLE hWriterEvent = _hWriterEvent;
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_hWriterEvent = NULL;
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// Save reader event
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HANDLE hReaderEvent = _hReaderEvent;
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_hReaderEvent = NULL;
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// Allow readers and writers to continue
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ModifyState(-(CACHING_EVENTS));
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// Cache events
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// REVIEW: I am closing events for now. What is needed
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// is an event cache to which the events are
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// released using InterlockedCompareExchange64
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if(hWriterEvent)
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{
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ComDebOut((DEB_TRACE, "Releasing writer event\n"));
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CloseHandle(hWriterEvent);
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}
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if(hReaderEvent)
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{
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ComDebOut((DEB_TRACE, "Releasing reader event\n"));
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CloseHandle(hReaderEvent);
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}
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return;
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}
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#endif
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::GetWriterEvent public
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//
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// Synopsis: Helper function for obtaining a auto reset event used
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// for serializing writers. It utilizes event cache
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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HANDLE CRWLock::GetWriterEvent()
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{
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if(_hWriterEvent == NULL)
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{
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HANDLE hWriterEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
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if(hWriterEvent)
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{
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if(InterlockedCompareExchangePointer(&_hWriterEvent, hWriterEvent, NULL))
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{
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CloseHandle(hWriterEvent);
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}
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}
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}
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return(_hWriterEvent);
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}
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::GetReaderEvent public
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//
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// Synopsis: Helper function for obtaining a manula reset event used
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// by readers to wait when a writer holds the lock.
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// It utilizes event cache
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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HANDLE CRWLock::GetReaderEvent()
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{
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if(_hReaderEvent == NULL)
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{
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HANDLE hReaderEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
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if(hReaderEvent)
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{
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if(InterlockedCompareExchangePointer(&_hReaderEvent, hReaderEvent, NULL))
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{
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CloseHandle(hReaderEvent);
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}
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}
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}
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return(_hReaderEvent);
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}
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//+-------------------------------------------------------------------
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//
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// Method: CRWLock::AcquireReaderLock public
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//
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// Synopsis: Makes the thread a reader. Supports nested reader locks.
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//
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// History: 21-Aug-98 Gopalk Created
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//
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//+-------------------------------------------------------------------
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HRESULT CRWLock::AcquireReaderLock(
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#ifdef RWLOCK_FULL_FUNCTIONALITY
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BOOL fReturnErrors,
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DWORD dwDesiredTimeout
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#if LOCK_PERF==1
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,
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#endif
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#endif
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#if LOCK_PERF==1
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const char *pszFile,
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DWORD dwLine,
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const char *pszLockName
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#endif
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)
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{
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HRESULT hr;
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#ifndef RWLOCK_FULL_FUNCTIONALITY
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DWORD dwDesiredTimeout = gdwDefaultTimeout;
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#endif
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// Ensure that the lock was initialized
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if(!IsInitialized())
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Initialize();
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// Check if the thread already has writer lock
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if(_dwWriterID == GetCurrentThreadId())
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{
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hr = AcquireWriterLock();
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}
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else
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{
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WORD *pwReaderLevel;
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hr = GetTLSLockData(&pwReaderLevel);
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if(SUCCEEDED(hr))
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{
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if(*pwReaderLevel != 0)
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{
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++(*pwReaderLevel);
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}
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else
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{
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DWORD dwCurrentState, dwKnownState;
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DWORD dwSpinCount;
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// Initialize
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hr = S_OK;
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dwSpinCount = 0;
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dwCurrentState = _dwState;
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do
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{
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dwKnownState = dwCurrentState;
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// Reader need not wait if there are only readers and no writer
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if((dwKnownState < READERS_MASK) ||
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(((dwKnownState & READER_SIGNALED) && ((dwKnownState & WRITER) == 0)) &&
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(((dwKnownState & READERS_MASK) +
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((dwKnownState & WAITING_READERS_MASK) >> WAITING_READERS_SHIFT)) <=
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(READERS_MASK - 2))))
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{
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// Add to readers
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dwCurrentState = InterlockedCompareExchange((LONG *) &_dwState,
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(dwKnownState + READER),
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dwKnownState);
|
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if(dwCurrentState == dwKnownState)
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{
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// One more reader
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break;
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}
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}
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// Check for too many Readers, or waiting readers
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else if(((dwKnownState & READERS_MASK) == READERS_MASK) ||
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((dwKnownState & WAITING_READERS_MASK) == WAITING_READERS_MASK) ||
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((dwKnownState & CACHING_EVENTS) == READER_SIGNALED))
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{
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RWSleep(1000);
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dwSpinCount = 0;
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dwCurrentState = _dwState;
|
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}
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// Check if events are being cached
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#ifdef RWLOCK_FULL_FUNCTIONALITY
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else if((dwKnownState & CACHING_EVENTS) == CACHING_EVENTS)
|
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{
|
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if(++dwSpinCount > gdwDefaultSpinCount)
|
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{
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RWSleep(10);
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dwSpinCount = 0;
|
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}
|
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dwCurrentState = _dwState;
|
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}
|
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#endif
|
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// Check spin count
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else if(++dwSpinCount > gdwDefaultSpinCount)
|
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{
|
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// Add to waiting readers
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dwCurrentState = InterlockedCompareExchange((LONG *) &_dwState,
|
|
(dwKnownState + WAITING_READER),
|
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dwKnownState);
|
|
if(dwCurrentState == dwKnownState)
|
|
{
|
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HANDLE hReaderEvent;
|
|
DWORD dwStatus;
|
|
DWORD dwModifyState;
|
|
|
|
// One more waiting reader
|
|
#ifdef RWLOCK_STATISTICS
|
|
InterlockedIncrement((LONG *) &_dwReaderContentionCount);
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
gLockTracker.ReaderWaiting(pszFile, dwLine, pszLockName, this);
|
|
#endif
|
|
|
|
hReaderEvent = GetReaderEvent();
|
|
if(hReaderEvent)
|
|
{
|
|
dwStatus = WaitForSingleObject(hReaderEvent, dwDesiredTimeout);
|
|
}
|
|
else
|
|
{
|
|
ComDebOut((DEB_WARN,
|
|
"AcquireReaderLock failed to create reader "
|
|
"event for RWLock 0x%x\n", this));
|
|
dwStatus = WAIT_FAILED;
|
|
hr = RPC_E_OUT_OF_RESOURCES;
|
|
}
|
|
|
|
if(dwStatus == WAIT_OBJECT_0)
|
|
{
|
|
Win4Assert(_dwState & READER_SIGNALED);
|
|
Win4Assert((_dwState & READERS_MASK) < READERS_MASK);
|
|
dwModifyState = READER - WAITING_READER;
|
|
}
|
|
else
|
|
{
|
|
dwModifyState = -WAITING_READER;
|
|
if(dwStatus == WAIT_TIMEOUT)
|
|
{
|
|
ComDebOut((DEB_WARN,
|
|
"Timed out trying to acquire reader lock "
|
|
"for RWLock 0x%x\n", this));
|
|
hr = RPC_E_TIMEOUT;
|
|
}
|
|
else if(SUCCEEDED(hr))
|
|
{
|
|
ComDebOut((DEB_ERROR,
|
|
"WaitForSingleObject Failed for "
|
|
"RWLock 0x%x\n", this));
|
|
hr = HRESULT_FROM_WIN32(GetLastError());
|
|
}
|
|
}
|
|
|
|
// One less waiting reader and he may have become a reader
|
|
dwKnownState = ModifyState(dwModifyState);
|
|
|
|
// Check for last signaled waiting reader
|
|
if(((dwKnownState & WAITING_READERS_MASK) == WAITING_READER) &&
|
|
(dwKnownState & READER_SIGNALED))
|
|
{
|
|
dwModifyState = -READER_SIGNALED;
|
|
if(dwStatus != WAIT_OBJECT_0)
|
|
{
|
|
if(hReaderEvent == NULL)
|
|
hReaderEvent = GetReaderEvent();
|
|
Win4Assert(hReaderEvent);
|
|
dwStatus = WaitForSingleObject(hReaderEvent, INFINITE);
|
|
Win4Assert(dwStatus == WAIT_OBJECT_0);
|
|
Win4Assert((_dwState & READERS_MASK) < READERS_MASK);
|
|
dwModifyState += READER;
|
|
hr = S_OK;
|
|
}
|
|
|
|
RWResetEvent(hReaderEvent);
|
|
dwKnownState = ModifyState(dwModifyState);
|
|
}
|
|
|
|
// Check if the thread became a reader
|
|
if(dwStatus == WAIT_OBJECT_0)
|
|
{
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
dwCurrentState = _dwState;
|
|
}
|
|
} while(SUCCEEDED(hr));
|
|
|
|
// Sanity checks
|
|
if(SUCCEEDED(hr))
|
|
{
|
|
Win4Assert((_dwState & WRITER) == 0);
|
|
Win4Assert(_dwState & READERS_MASK);
|
|
*pwReaderLevel = 1;
|
|
#ifdef RWLOCK_STATISTICS
|
|
InterlockedIncrement((LONG *) &_dwReaderEntryCount);
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
gLockTracker.ReaderEntered(pszFile, dwLine, pszLockName, this);
|
|
#endif
|
|
}
|
|
}
|
|
}
|
|
|
|
// Check failure return
|
|
#if RWLOCK_FULL_FUNCTIONALITY
|
|
if(FAILED(hr) && (fReturnErrors == FALSE))
|
|
#else
|
|
if(FAILED(hr))
|
|
#endif
|
|
{
|
|
Win4Assert(!"Failed to acquire reader lock");
|
|
if(fBreakOnErrors)
|
|
DebugBreak();
|
|
TerminateProcess(GetCurrentProcess(), RWLOCK_FATALFAILURE);
|
|
}
|
|
}
|
|
|
|
return(hr);
|
|
}
|
|
|
|
|
|
//+-------------------------------------------------------------------
|
|
//
|
|
// Method: CRWLock::AcquireWriterLock public
|
|
//
|
|
// Synopsis: Makes the thread a writer. Supports nested writer
|
|
// locks
|
|
//
|
|
// History: 21-Aug-98 Gopalk Created
|
|
//
|
|
//+-------------------------------------------------------------------
|
|
HRESULT CRWLock::AcquireWriterLock(
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
BOOL fReturnErrors,
|
|
DWORD dwDesiredTimeout
|
|
#if LOCK_PERF==1
|
|
,
|
|
#endif
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
const char *pszFile,
|
|
DWORD dwLine,
|
|
const char *pszLockName
|
|
#endif
|
|
)
|
|
{
|
|
HRESULT hr = S_OK;
|
|
DWORD dwThreadID = GetCurrentThreadId();
|
|
#ifndef RWLOCK_FULL_FUNCTIONALITY
|
|
DWORD dwDesiredTimeout = gdwDefaultTimeout;
|
|
#endif
|
|
|
|
// Ensure that the lock was initialized
|
|
if(!IsInitialized())
|
|
Initialize();
|
|
|
|
// Check if the thread already has writer lock
|
|
if(_dwWriterID == dwThreadID)
|
|
{
|
|
++_wWriterLevel;
|
|
}
|
|
else
|
|
{
|
|
DWORD dwCurrentState, dwKnownState;
|
|
DWORD dwSpinCount = 0;
|
|
|
|
dwCurrentState = _dwState;
|
|
do
|
|
{
|
|
dwKnownState = dwCurrentState;
|
|
|
|
// Writer need not wait if there are no readers and writer
|
|
if(dwKnownState == 0)
|
|
{
|
|
// Can be a writer
|
|
dwCurrentState = InterlockedCompareExchange((LONG *) &_dwState,
|
|
WRITER,
|
|
dwKnownState);
|
|
if(dwCurrentState == dwKnownState)
|
|
{
|
|
// Only writer
|
|
break;
|
|
}
|
|
}
|
|
// Check for too many waiting writers
|
|
else if(((dwKnownState & WAITING_WRITERS_MASK) == WAITING_WRITERS_MASK))
|
|
{
|
|
RWSleep(1000);
|
|
dwSpinCount = 0;
|
|
dwCurrentState = _dwState;
|
|
}
|
|
// Check if events are being cached
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
else if((dwKnownState & CACHING_EVENTS) == CACHING_EVENTS)
|
|
{
|
|
if(++dwSpinCount > gdwDefaultSpinCount)
|
|
{
|
|
RWSleep(10);
|
|
dwSpinCount = 0;
|
|
}
|
|
dwCurrentState = _dwState;
|
|
}
|
|
#endif
|
|
// Check spin count
|
|
else if(++dwSpinCount > gdwDefaultSpinCount)
|
|
{
|
|
// Add to waiting writers
|
|
dwCurrentState = InterlockedCompareExchange((LONG *) &_dwState,
|
|
(dwKnownState + WAITING_WRITER),
|
|
dwKnownState);
|
|
if(dwCurrentState == dwKnownState)
|
|
{
|
|
HANDLE hWriterEvent;
|
|
DWORD dwStatus;
|
|
DWORD dwModifyState;
|
|
BOOL fLoopback;
|
|
|
|
// One more waiting writer
|
|
#ifdef RWLOCK_STATISTICS
|
|
InterlockedIncrement((LONG *) &_dwWriterContentionCount);
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
gLockTracker.WriterWaiting(pszFile, dwLine, pszLockName, this);
|
|
#endif
|
|
|
|
do
|
|
{
|
|
fLoopback = FALSE;
|
|
hr = S_OK;
|
|
hWriterEvent = GetWriterEvent();
|
|
if(hWriterEvent)
|
|
{
|
|
dwStatus = WaitForSingleObject(hWriterEvent, dwDesiredTimeout);
|
|
}
|
|
else
|
|
{
|
|
ComDebOut((DEB_WARN,
|
|
"AcquireWriterLock failed to create writer "
|
|
"event for RWLock 0x%x\n", this));
|
|
dwStatus = WAIT_FAILED;
|
|
hr = RPC_E_OUT_OF_RESOURCES;
|
|
}
|
|
|
|
if(dwStatus == WAIT_OBJECT_0)
|
|
{
|
|
Win4Assert(_dwState & WRITER_SIGNALED);
|
|
dwModifyState = WRITER - WAITING_WRITER - WRITER_SIGNALED;
|
|
}
|
|
else
|
|
{
|
|
dwModifyState = -WAITING_WRITER;
|
|
if(dwStatus == WAIT_TIMEOUT)
|
|
{
|
|
ComDebOut((DEB_WARN,
|
|
"Timed out trying to acquire writer "
|
|
"lock for RWLock 0x%x\n", this));
|
|
hr = RPC_E_TIMEOUT;
|
|
}
|
|
else if(SUCCEEDED(hr))
|
|
{
|
|
ComDebOut((DEB_ERROR,
|
|
"WaitForSingleObject Failed for "
|
|
"RWLock 0x%x\n", this));
|
|
hr = HRESULT_FROM_WIN32(GetLastError());
|
|
}
|
|
}
|
|
|
|
// One less waiting writer and he may have become a writer
|
|
dwKnownState = ModifyState(dwModifyState);
|
|
|
|
// Check for last timing out signaled waiting writer
|
|
if((dwStatus != WAIT_OBJECT_0) &&
|
|
(dwKnownState & WRITER_SIGNALED) &&
|
|
((dwKnownState & WAITING_WRITERS_MASK) == WAITING_WRITER))
|
|
{
|
|
fLoopback = TRUE;
|
|
dwCurrentState = _dwState;
|
|
do
|
|
{
|
|
dwKnownState = dwCurrentState;
|
|
if(((dwKnownState & WAITING_WRITERS_MASK) == 0) &&
|
|
(dwKnownState & WRITER_SIGNALED))
|
|
{
|
|
dwCurrentState = InterlockedCompareExchange((LONG *) &_dwState,
|
|
(dwKnownState + WAITING_WRITER),
|
|
dwKnownState);
|
|
}
|
|
else
|
|
{
|
|
Win4Assert(FAILED(hr));
|
|
fLoopback = FALSE;
|
|
break;
|
|
}
|
|
} while(dwCurrentState != dwKnownState);
|
|
}
|
|
|
|
if(fLoopback)
|
|
{
|
|
ComDebOut((DEB_WARN,
|
|
"Retry of timing out writer for RWLock 0x%x\n",
|
|
this));
|
|
// Reduce the timeout value for retries
|
|
dwDesiredTimeout = 100;
|
|
}
|
|
} while(fLoopback);
|
|
|
|
// Check if the thread became a writer
|
|
if(dwStatus == WAIT_OBJECT_0)
|
|
break;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
dwCurrentState = _dwState;
|
|
}
|
|
} while(SUCCEEDED(hr));
|
|
|
|
// Sanity checks
|
|
if(SUCCEEDED(hr))
|
|
{
|
|
Win4Assert(_dwState & WRITER);
|
|
Win4Assert((_dwState & WRITER_SIGNALED) == 0);
|
|
Win4Assert((_dwState & READERS_MASK) == 0);
|
|
Win4Assert(_dwWriterID == 0);
|
|
|
|
// Save threadid of the writer
|
|
_dwWriterID = dwThreadID;
|
|
_wWriterLevel = 1;
|
|
++_dwWriterSeqNum;
|
|
#ifdef RWLOCK_STATISTICS
|
|
++_dwWriterEntryCount;
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
gLockTracker.WriterEntered(pszFile, dwLine, pszLockName, this);
|
|
#endif
|
|
}
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
else if(fReturnErrors == FALSE)
|
|
#else
|
|
else
|
|
#endif
|
|
{
|
|
Win4Assert(!"Failed to acquire writer lock");
|
|
if(fBreakOnErrors)
|
|
DebugBreak();
|
|
TerminateProcess(GetCurrentProcess(), RWLOCK_FATALFAILURE);
|
|
}
|
|
}
|
|
|
|
return(hr);
|
|
}
|
|
|
|
|
|
//+-------------------------------------------------------------------
|
|
//
|
|
// Method: CRWLock::ReleaseWriterLock public
|
|
//
|
|
// Synopsis: Removes the thread as a writer if not a nested
|
|
// call to release the lock
|
|
//
|
|
// History: 21-Aug-98 Gopalk Created
|
|
//
|
|
//+-------------------------------------------------------------------
|
|
HRESULT CRWLock::ReleaseWriterLock()
|
|
{
|
|
HRESULT hr = S_OK;
|
|
DWORD dwThreadID = GetCurrentThreadId();
|
|
|
|
// Check validity of caller
|
|
if(_dwWriterID == dwThreadID)
|
|
{
|
|
// Sanity check
|
|
Win4Assert(IsInitialized());
|
|
|
|
// Check for nested release
|
|
if(--_wWriterLevel == 0)
|
|
{
|
|
DWORD dwCurrentState, dwKnownState, dwModifyState;
|
|
BOOL fCacheEvents;
|
|
HANDLE hReaderEvent = NULL, hWriterEvent = NULL;
|
|
|
|
// Not a writer any more
|
|
#if LOCK_PERF==1
|
|
gLockTracker.WriterLeaving(this);
|
|
#endif
|
|
_dwWriterID = 0;
|
|
dwCurrentState = _dwState;
|
|
do
|
|
{
|
|
dwKnownState = dwCurrentState;
|
|
dwModifyState = -WRITER;
|
|
fCacheEvents = FALSE;
|
|
if(dwKnownState & WAITING_READERS_MASK)
|
|
{
|
|
hReaderEvent = GetReaderEvent();
|
|
if(hReaderEvent == NULL)
|
|
{
|
|
ComDebOut((DEB_WARN,
|
|
"ReleaseWriterLock failed to create "
|
|
"reader event for RWLock 0x%x\n", this));
|
|
RWSleep(100);
|
|
dwCurrentState = _dwState;
|
|
dwKnownState = 0;
|
|
Win4Assert(dwCurrentState != dwKnownState);
|
|
continue;
|
|
}
|
|
dwModifyState += READER_SIGNALED;
|
|
}
|
|
else if(dwKnownState & WAITING_WRITERS_MASK)
|
|
{
|
|
hWriterEvent = GetWriterEvent();
|
|
if(hWriterEvent == NULL)
|
|
{
|
|
ComDebOut((DEB_WARN,
|
|
"ReleaseWriterLock failed to create "
|
|
"writer event for RWLock 0x%x\n", this));
|
|
RWSleep(100);
|
|
dwCurrentState = _dwState;
|
|
dwKnownState = 0;
|
|
Win4Assert(dwCurrentState != dwKnownState);
|
|
continue;
|
|
}
|
|
dwModifyState += WRITER_SIGNALED;
|
|
}
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
else if((_wFlags & RWLOCKFLAG_CACHEEVENTS) &&
|
|
(dwKnownState == WRITER) &&
|
|
(_hReaderEvent || _hWriterEvent) &&
|
|
((dwKnownState & CACHING_EVENTS) == 0))
|
|
{
|
|
fCacheEvents = TRUE;
|
|
dwModifyState += CACHING_EVENTS;
|
|
}
|
|
#endif
|
|
|
|
// Sanity checks
|
|
Win4Assert((dwKnownState & CACHING_EVENTS) == 0);
|
|
Win4Assert((dwKnownState & READERS_MASK) == 0);
|
|
|
|
dwCurrentState = InterlockedCompareExchange((LONG *) &_dwState,
|
|
(dwKnownState + dwModifyState),
|
|
dwKnownState);
|
|
} while(dwCurrentState != dwKnownState);
|
|
|
|
// Check for waiting readers
|
|
if(dwKnownState & WAITING_READERS_MASK)
|
|
{
|
|
Win4Assert(_dwState & READER_SIGNALED);
|
|
Win4Assert(hReaderEvent);
|
|
RWSetEvent(hReaderEvent);
|
|
}
|
|
// Check for waiting writers
|
|
else if(dwKnownState & WAITING_WRITERS_MASK)
|
|
{
|
|
Win4Assert(_dwState & WRITER_SIGNALED);
|
|
Win4Assert(hWriterEvent);
|
|
RWSetEvent(hWriterEvent);
|
|
}
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
// Check for the need to release events
|
|
else if(fCacheEvents)
|
|
{
|
|
ReleaseEvents();
|
|
}
|
|
#endif
|
|
}
|
|
}
|
|
else
|
|
{
|
|
hr = HRESULT_FROM_WIN32(ERROR_NOT_OWNER);
|
|
Win4Assert(!"Attempt to release writer lock on a wrong thread");
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
if((_wFlags & RWLOCKFLAG_RETURNERRORS) == 0)
|
|
#endif
|
|
{
|
|
if(fBreakOnErrors)
|
|
DebugBreak();
|
|
TerminateProcess(GetCurrentProcess(), RWLOCK_FATALFAILURE);
|
|
}
|
|
}
|
|
|
|
return(hr);
|
|
}
|
|
|
|
|
|
//+-------------------------------------------------------------------
|
|
//
|
|
// Method: CRWLock::ReleaseReaderLock public
|
|
//
|
|
// Synopsis: Removes the thread as a reader
|
|
//
|
|
// History: 21-Aug-98 Gopalk Created
|
|
//
|
|
//+-------------------------------------------------------------------
|
|
HRESULT CRWLock::ReleaseReaderLock()
|
|
{
|
|
HRESULT hr = S_OK;
|
|
|
|
// Check if the thread has writer lock
|
|
if(_dwWriterID == GetCurrentThreadId())
|
|
{
|
|
hr = ReleaseWriterLock();
|
|
}
|
|
else
|
|
{
|
|
WORD *pwReaderLevel;
|
|
|
|
hr = GetTLSLockData(&pwReaderLevel);
|
|
if(SUCCEEDED(hr))
|
|
{
|
|
if(*pwReaderLevel > 1)
|
|
{
|
|
--(*pwReaderLevel);
|
|
}
|
|
else if(*pwReaderLevel == 1)
|
|
{
|
|
DWORD dwCurrentState, dwKnownState, dwModifyState;
|
|
BOOL fLastReader, fCacheEvents;
|
|
HANDLE hReaderEvent = NULL, hWriterEvent = NULL;
|
|
|
|
// Sanity checks
|
|
Win4Assert((_dwState & WRITER) == 0);
|
|
Win4Assert(_dwState & READERS_MASK);
|
|
|
|
// Not a reader any more
|
|
*pwReaderLevel = 0;
|
|
dwCurrentState = _dwState;
|
|
do
|
|
{
|
|
dwKnownState = dwCurrentState;
|
|
dwModifyState = -READER;
|
|
if((dwKnownState & (READERS_MASK | READER_SIGNALED)) == READER)
|
|
{
|
|
fLastReader = TRUE;
|
|
fCacheEvents = FALSE;
|
|
if(dwKnownState & WAITING_WRITERS_MASK)
|
|
{
|
|
hWriterEvent = GetWriterEvent();
|
|
if(hWriterEvent == NULL)
|
|
{
|
|
ComDebOut((DEB_WARN,
|
|
"ReleaseReaderLock failed to create "
|
|
"writer event for RWLock 0x%x\n", this));
|
|
RWSleep(100);
|
|
dwCurrentState = _dwState;
|
|
dwKnownState = 0;
|
|
Win4Assert(dwCurrentState != dwKnownState);
|
|
continue;
|
|
}
|
|
dwModifyState += WRITER_SIGNALED;
|
|
}
|
|
else if(dwKnownState & WAITING_READERS_MASK)
|
|
{
|
|
hReaderEvent = GetReaderEvent();
|
|
if(hReaderEvent == NULL)
|
|
{
|
|
ComDebOut((DEB_WARN,
|
|
"ReleaseReaderLock failed to create "
|
|
"reader event\n", this));
|
|
RWSleep(100);
|
|
dwCurrentState = _dwState;
|
|
dwKnownState = 0;
|
|
Win4Assert(dwCurrentState != dwKnownState);
|
|
continue;
|
|
}
|
|
dwModifyState += READER_SIGNALED;
|
|
}
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
else if((_wFlags & RWLOCKFLAG_CACHEEVENTS) &&
|
|
(dwKnownState == READER) &&
|
|
(_hReaderEvent || _hWriterEvent))
|
|
{
|
|
fCacheEvents = TRUE;
|
|
dwModifyState += (WRITER_SIGNALED + READER_SIGNALED);
|
|
}
|
|
#endif
|
|
}
|
|
else
|
|
{
|
|
fLastReader = FALSE;
|
|
}
|
|
|
|
// Sanity checks
|
|
Win4Assert((dwKnownState & WRITER) == 0);
|
|
Win4Assert(dwKnownState & READERS_MASK);
|
|
|
|
dwCurrentState = InterlockedCompareExchange((LONG *) &_dwState,
|
|
(dwKnownState + dwModifyState),
|
|
dwKnownState);
|
|
} while(dwCurrentState != dwKnownState);
|
|
|
|
#if LOCK_PERF==1
|
|
gLockTracker.ReaderLeaving(this);
|
|
#endif
|
|
// Check for last reader
|
|
if(fLastReader)
|
|
{
|
|
// Check for waiting writers
|
|
if(dwKnownState & WAITING_WRITERS_MASK)
|
|
{
|
|
Win4Assert(_dwState & WRITER_SIGNALED);
|
|
Win4Assert(hWriterEvent);
|
|
RWSetEvent(hWriterEvent);
|
|
}
|
|
// Check for waiting readers
|
|
else if(dwKnownState & WAITING_READERS_MASK)
|
|
{
|
|
Win4Assert(_dwState & READER_SIGNALED);
|
|
Win4Assert(hReaderEvent);
|
|
RWSetEvent(hReaderEvent);
|
|
}
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
// Check for the need to release events
|
|
else if(fCacheEvents)
|
|
{
|
|
ReleaseEvents();
|
|
}
|
|
#endif
|
|
}
|
|
}
|
|
else
|
|
{
|
|
hr = HRESULT_FROM_WIN32(ERROR_NOT_OWNER);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
hr = HRESULT_FROM_WIN32(ERROR_NOT_OWNER);
|
|
}
|
|
|
|
if(FAILED(hr))
|
|
{
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
if((_wFlags & RWLOCKFLAG_RETURNERRORS) == 0)
|
|
#endif
|
|
{
|
|
Win4Assert(!"Attempt to release reader lock on a wrong thread");
|
|
if(fBreakOnErrors)
|
|
DebugBreak();
|
|
TerminateProcess(GetCurrentProcess(), RWLOCK_FATALFAILURE);
|
|
}
|
|
}
|
|
}
|
|
|
|
return(hr);
|
|
}
|
|
|
|
|
|
//+-------------------------------------------------------------------
|
|
//
|
|
// Method: CRWLock::UpgradeToWriterLock public
|
|
//
|
|
// Synopsis: Upgrades to a writer lock. It returns a BOOL that
|
|
// indicates intervening writes.
|
|
//
|
|
// History: 21-Aug-98 Gopalk Created
|
|
//
|
|
//+-------------------------------------------------------------------
|
|
HRESULT CRWLock::UpgradeToWriterLock(LockCookie *pLockCookie,
|
|
BOOL *pfInterveningWrites
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
,
|
|
BOOL fReturnErrors,
|
|
DWORD dwDesiredTimeout
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
,
|
|
const char *pszFile,
|
|
DWORD dwLine,
|
|
const char *pszLockName
|
|
#endif
|
|
)
|
|
{
|
|
HRESULT hr;
|
|
DWORD dwThreadID;
|
|
|
|
// Initialize the cookie
|
|
memset(pLockCookie, 0, sizeof(LockCookie));
|
|
if(pfInterveningWrites)
|
|
*pfInterveningWrites = TRUE;
|
|
dwThreadID = GetCurrentThreadId();
|
|
|
|
// Check if the thread is already a writer
|
|
if(_dwWriterID == dwThreadID)
|
|
{
|
|
// Update cookie state
|
|
pLockCookie->dwFlags = UPGRADE_COOKIE | COOKIE_WRITER;
|
|
pLockCookie->wWriterLevel = _wWriterLevel;
|
|
|
|
// No intevening writes
|
|
if(pfInterveningWrites)
|
|
*pfInterveningWrites = FALSE;
|
|
|
|
// Acquire the writer lock again
|
|
hr = AcquireWriterLock();
|
|
}
|
|
else
|
|
{
|
|
WORD *pwReaderLevel;
|
|
|
|
// Ensure that the lock was initialized
|
|
if(!IsInitialized())
|
|
Initialize();
|
|
|
|
hr = GetTLSLockData(&pwReaderLevel);
|
|
if(SUCCEEDED(hr))
|
|
{
|
|
BOOL fAcquireWriterLock;
|
|
DWORD dwWriterSeqNum = 0;
|
|
|
|
// Check if the thread is a reader
|
|
if(*pwReaderLevel != 0)
|
|
{
|
|
// Sanity check
|
|
Win4Assert(_dwState & READERS_MASK);
|
|
|
|
// Save lock state in the cookie
|
|
pLockCookie->dwFlags = UPGRADE_COOKIE | COOKIE_READER;
|
|
pLockCookie->pwReaderLevel = pwReaderLevel;
|
|
pLockCookie->wReaderLevel = *pwReaderLevel;
|
|
|
|
// If there is only one reader, try to convert reader to a writer
|
|
DWORD dwKnownState = InterlockedCompareExchange((LONG *) &_dwState,
|
|
WRITER,
|
|
READER);
|
|
if(dwKnownState == READER)
|
|
{
|
|
// Thread is no longer a reader
|
|
*pwReaderLevel = 0;
|
|
|
|
// Save threadid of the writer
|
|
_dwWriterID = dwThreadID;
|
|
_wWriterLevel = 1;
|
|
++_dwWriterSeqNum;
|
|
fAcquireWriterLock = FALSE;
|
|
|
|
// No intevening writes
|
|
if(pfInterveningWrites)
|
|
*pfInterveningWrites = FALSE;
|
|
#if RWLOCK_STATISTICS
|
|
++_dwWriterEntryCount;
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
gLockTracker.ReaderLeaving(this);
|
|
gLockTracker.WriterEntered(pszFile, dwLine, pszLockName, this);
|
|
#endif
|
|
}
|
|
else
|
|
{
|
|
// Note the current sequence number of the writer lock
|
|
dwWriterSeqNum = _dwWriterSeqNum;
|
|
|
|
// Release the reader lock
|
|
*pwReaderLevel = 1;
|
|
hr = ReleaseReaderLock();
|
|
Win4Assert(SUCCEEDED(hr));
|
|
fAcquireWriterLock = TRUE;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
fAcquireWriterLock = TRUE;
|
|
pLockCookie->dwFlags = UPGRADE_COOKIE | COOKIE_NONE;
|
|
}
|
|
|
|
// Check for the need to acquire the writer lock
|
|
if(fAcquireWriterLock)
|
|
{
|
|
hr = AcquireWriterLock(
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
TRUE, dwDesiredTimeout
|
|
#if LOCK_PERF==1
|
|
,
|
|
#endif
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
pszFile, dwLine, pszLockName
|
|
#endif
|
|
);
|
|
if(SUCCEEDED(hr))
|
|
{
|
|
// Check for intevening writes
|
|
if((_dwWriterSeqNum == (dwWriterSeqNum + 1)) &&
|
|
pfInterveningWrites)
|
|
*pfInterveningWrites = FALSE;
|
|
}
|
|
else
|
|
{
|
|
if(pLockCookie->dwFlags & COOKIE_READER)
|
|
{
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
DWORD dwTimeout = (dwDesiredTimeout > gdwReasonableTimeout)
|
|
? dwDesiredTimeout
|
|
: gdwReasonableTimeout;
|
|
#endif
|
|
|
|
HRESULT hr1 = AcquireReaderLock(
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
FALSE, dwTimeout
|
|
#if LOCK_PERF==1
|
|
,
|
|
#endif
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
pszFile, dwLine, pszLockName
|
|
#endif
|
|
);
|
|
if(SUCCEEDED(hr1))
|
|
{
|
|
*pwReaderLevel = pLockCookie->wReaderLevel;
|
|
}
|
|
else
|
|
{
|
|
Win4Assert(!"Failed to reacquire reader lock");
|
|
if(fBreakOnErrors)
|
|
DebugBreak();
|
|
TerminateProcess(GetCurrentProcess(), RWLOCK_FATALFAILURE);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Check failure return
|
|
if(FAILED(hr))
|
|
{
|
|
pLockCookie->dwFlags = INVALID_COOKIE;
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
if(fReturnErrors == FALSE)
|
|
{
|
|
Win4Assert(!"Failed to upgrade the lock");
|
|
if(fBreakOnErrors)
|
|
DebugBreak();
|
|
TerminateProcess(GetCurrentProcess(), RWLOCK_FATALFAILURE);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
return(hr);
|
|
}
|
|
|
|
|
|
//+-------------------------------------------------------------------
|
|
//
|
|
// Method: CRWLock::DowngradeFromWriterLock public
|
|
//
|
|
// Synopsis: Downgrades from a writer lock.
|
|
//
|
|
// History: 21-Aug-98 Gopalk Created
|
|
//
|
|
//+-------------------------------------------------------------------
|
|
HRESULT CRWLock::DowngradeFromWriterLock(LockCookie *pLockCookie
|
|
#if LOCK_PERF==1
|
|
,
|
|
const char *pszFile,
|
|
DWORD dwLine,
|
|
const char *pszLockName
|
|
#endif
|
|
)
|
|
{
|
|
HRESULT hr = S_OK;
|
|
|
|
// Ensure that the cookie is valid
|
|
if(pLockCookie->dwFlags & UPGRADE_COOKIE)
|
|
{
|
|
DWORD dwThreadID = GetCurrentThreadId();
|
|
|
|
// Sanity check
|
|
Win4Assert((pLockCookie->pwReaderLevel == NULL) ||
|
|
(*pLockCookie->pwReaderLevel == 0));
|
|
|
|
// Ensure that the thread is a writer
|
|
if(_dwWriterID == dwThreadID)
|
|
{
|
|
// Release the writer lock
|
|
hr = ReleaseWriterLock();
|
|
if(SUCCEEDED(hr))
|
|
{
|
|
// Check if the thread was a writer
|
|
if(_dwWriterID == dwThreadID)
|
|
{
|
|
// Ensure that the thread was a writer and that
|
|
// nesting level was restored to the previous
|
|
// value
|
|
if(((pLockCookie->dwFlags & COOKIE_WRITER) == 0) ||
|
|
(pLockCookie->wWriterLevel != _wWriterLevel))
|
|
{
|
|
Win4Assert(!"Writer lock incorrectly nested");
|
|
hr = E_FAIL;
|
|
}
|
|
}
|
|
// Check if the thread was a reader
|
|
else if(pLockCookie->dwFlags & COOKIE_READER)
|
|
{
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
DWORD dwTimeout = (gdwDefaultTimeout > gdwReasonableTimeout)
|
|
? gdwDefaultTimeout
|
|
: gdwReasonableTimeout;
|
|
#endif
|
|
hr = AcquireReaderLock(
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
TRUE, dwTimeout
|
|
#if LOCK_PERF==1
|
|
,
|
|
#endif
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
pszFile, dwLine, pszLockName
|
|
#endif
|
|
);
|
|
if(SUCCEEDED(hr))
|
|
{
|
|
*pLockCookie->pwReaderLevel = pLockCookie->wReaderLevel;
|
|
}
|
|
else
|
|
{
|
|
Win4Assert(!"Failed to reacquire reader lock");
|
|
}
|
|
}
|
|
else
|
|
{
|
|
Win4Assert(pLockCookie->dwFlags & COOKIE_NONE);
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
Win4Assert(!"Attempt to downgrade writer lock on a wrong thread");
|
|
hr = HRESULT_FROM_WIN32(ERROR_NOT_OWNER);
|
|
}
|
|
|
|
// Check failure return
|
|
if(FAILED(hr))
|
|
{
|
|
if(fBreakOnErrors)
|
|
DebugBreak();
|
|
TerminateProcess(GetCurrentProcess(), RWLOCK_FATALFAILURE);
|
|
}
|
|
}
|
|
|
|
return(hr);
|
|
}
|
|
|
|
|
|
//+-------------------------------------------------------------------
|
|
//
|
|
// Method: CRWLock::ReleaseLock public
|
|
//
|
|
// Synopsis: Releases the lock held by the current thread
|
|
//
|
|
// History: 21-Aug-98 Gopalk Created
|
|
//
|
|
//+-------------------------------------------------------------------
|
|
HRESULT CRWLock::ReleaseLock(LockCookie *pLockCookie)
|
|
{
|
|
HRESULT hr;
|
|
|
|
// Initialize the cookie
|
|
memset(pLockCookie, 0, sizeof(LockCookie));
|
|
|
|
// Check if the thread is a writer
|
|
if(_dwWriterID == GetCurrentThreadId())
|
|
{
|
|
// Save lock state in the cookie
|
|
pLockCookie->dwFlags = RELEASE_COOKIE | COOKIE_WRITER;
|
|
pLockCookie->dwWriterSeqNum = _dwWriterSeqNum;
|
|
pLockCookie->wWriterLevel = _wWriterLevel;
|
|
|
|
// Release the writer lock
|
|
_wWriterLevel = 1;
|
|
hr = ReleaseWriterLock();
|
|
Win4Assert(SUCCEEDED(hr));
|
|
}
|
|
else
|
|
{
|
|
WORD *pwReaderLevel;
|
|
|
|
// Ensure that the lock was initialized
|
|
if(!IsInitialized())
|
|
Initialize();
|
|
|
|
hr = GetTLSLockData(&pwReaderLevel);
|
|
if(SUCCEEDED(hr))
|
|
{
|
|
// Check if the thread is a reader
|
|
if(*pwReaderLevel != 0)
|
|
{
|
|
// Save lock state in the cookie
|
|
pLockCookie->dwFlags = RELEASE_COOKIE | COOKIE_READER;
|
|
pLockCookie->pwReaderLevel = pwReaderLevel;
|
|
pLockCookie->wReaderLevel = *pwReaderLevel;
|
|
pLockCookie->dwWriterSeqNum = _dwWriterSeqNum;
|
|
|
|
// Release the reader lock
|
|
*pwReaderLevel = 1;
|
|
hr = ReleaseReaderLock();
|
|
Win4Assert(SUCCEEDED(hr));
|
|
}
|
|
else
|
|
{
|
|
pLockCookie->dwFlags = RELEASE_COOKIE | COOKIE_NONE;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
hr = S_OK;
|
|
pLockCookie->dwFlags = RELEASE_COOKIE | COOKIE_NONE;
|
|
}
|
|
}
|
|
|
|
return(hr);
|
|
}
|
|
|
|
|
|
//+-------------------------------------------------------------------
|
|
//
|
|
// Method: CRWLock::RestoreLock public
|
|
//
|
|
// Synopsis: Restore the lock held by the current thread
|
|
//
|
|
// History: 21-Aug-98 Gopalk Created
|
|
//
|
|
//+-------------------------------------------------------------------
|
|
HRESULT CRWLock::RestoreLock(LockCookie *pLockCookie,
|
|
BOOL *pfInterveningWrites
|
|
#if LOCK_PERF==1
|
|
,
|
|
const char *pszFile,
|
|
DWORD dwLine,
|
|
const char *pszLockName
|
|
#endif
|
|
)
|
|
{
|
|
HRESULT hr = S_OK;
|
|
|
|
// Initialize
|
|
if(pfInterveningWrites)
|
|
*pfInterveningWrites = TRUE;
|
|
|
|
// Ensure that the cookie is valid
|
|
if(pLockCookie->dwFlags & RELEASE_COOKIE)
|
|
{
|
|
DWORD dwThreadID = GetCurrentThreadId();
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
DWORD dwTimeout = (gdwDefaultTimeout > gdwReasonableTimeout)
|
|
? gdwDefaultTimeout
|
|
: gdwReasonableTimeout;
|
|
#endif
|
|
|
|
// Check if the thread holds reader or writer lock
|
|
if(((pLockCookie->pwReaderLevel != NULL) && (*pLockCookie->pwReaderLevel > 0)) ||
|
|
(_dwWriterID == dwThreadID))
|
|
{
|
|
Win4Assert(!"Thread holds reader or writer lock");
|
|
if(fBreakOnErrors)
|
|
DebugBreak();
|
|
TerminateProcess(GetCurrentProcess(), RWLOCK_FATALFAILURE);
|
|
}
|
|
// Check if the thread was a writer
|
|
else if(pLockCookie->dwFlags & COOKIE_WRITER)
|
|
{
|
|
// Acquire writer lock
|
|
hr = AcquireWriterLock(
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
FALSE, dwTimeout
|
|
#if LOCK_PERF==1
|
|
,
|
|
#endif
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
pszFile, dwLine, pszLockName
|
|
#endif
|
|
);
|
|
Win4Assert(SUCCEEDED(hr));
|
|
_wWriterLevel = pLockCookie->wWriterLevel;
|
|
if((_dwWriterSeqNum == (pLockCookie->dwWriterSeqNum + 1)) &&
|
|
pfInterveningWrites)
|
|
*pfInterveningWrites = FALSE;
|
|
}
|
|
// Check if the thread was a reader
|
|
else if(pLockCookie->dwFlags & COOKIE_READER)
|
|
{
|
|
hr = AcquireReaderLock(
|
|
#ifdef RWLOCK_FULL_FUNCTIONALITY
|
|
FALSE, dwTimeout
|
|
#if LOCK_PERF==1
|
|
,
|
|
#endif
|
|
#endif
|
|
#if LOCK_PERF==1
|
|
pszFile, dwLine, pszLockName
|
|
#endif
|
|
);
|
|
Win4Assert(SUCCEEDED(hr));
|
|
*pLockCookie->pwReaderLevel = pLockCookie->wReaderLevel;
|
|
if((_dwWriterSeqNum == (pLockCookie->dwWriterSeqNum + 1)) &&
|
|
pfInterveningWrites)
|
|
*pfInterveningWrites = FALSE;
|
|
}
|
|
else
|
|
{
|
|
Win4Assert(pLockCookie->dwFlags & COOKIE_NONE);
|
|
}
|
|
}
|
|
|
|
return(hr);
|
|
}
|
|
|
|
|
|
//+-------------------------------------------------------------------
|
|
//
|
|
// Method: CStaticRWLock::Initialize public
|
|
//
|
|
// Synopsis: Initializes state. It is important that the
|
|
// default constructor only Zero out the memory
|
|
//
|
|
// History: 21-Aug-98 Gopalk Created
|
|
//
|
|
//+-------------------------------------------------------------------
|
|
extern CRITICAL_SECTION g_OleMutexCreationSem;
|
|
void CStaticRWLock::Initialize()
|
|
{
|
|
// Acquire lock creation critical section
|
|
EnterCriticalSection (&g_OleMutexCreationSem);
|
|
|
|
// Prevent second initialization
|
|
if(!IsInitialized())
|
|
{
|
|
_dwLockNum = gdwLockSeqNum++;
|
|
#if LOCK_PERF==1
|
|
gLockTracker.RegisterLock(this, TRUE);
|
|
#endif
|
|
|
|
// The initialization should be complete
|
|
// before delegating to the base class
|
|
CRWLock::Initialize();
|
|
}
|
|
|
|
// Release lock creation critical section
|
|
LeaveCriticalSection (&g_OleMutexCreationSem);
|
|
|
|
return;
|
|
}
|
|
|
|
|
|
LockEntry * GetLockEntryFromTLS()
|
|
{
|
|
LockEntry *pLockEntry = NULL;
|
|
#ifdef __NOOLETLS__
|
|
pLockEntry = (LockEntry *) TlsGetValue(gLockTlsIdx);
|
|
if (!pLockEntry)
|
|
{
|
|
pLockEntry = (LockEntry *) PrivMemAlloc(sizeof(LockEntry));
|
|
if (pLockEntry)
|
|
{
|
|
memset(pLockEntry, 0, sizeof(LockEntry));
|
|
TlsSetValue(gLockTlsIdx, pLockEntry);
|
|
}
|
|
|
|
}
|
|
#else
|
|
HRESULT hr;
|
|
COleTls Tls(hr);
|
|
|
|
if(SUCCEEDED(hr))
|
|
{
|
|
pLockEntry = &(Tls->lockEntry);
|
|
}
|
|
#endif
|
|
return pLockEntry;
|
|
}
|
|
|
|
|
|
//+-------------------------------------------------------------------
|
|
//
|
|
// Method: CStaticRWLock::GetTLSLockData private
|
|
//
|
|
// Synopsis: Obtains the data mainitained in TLS for the lock
|
|
//
|
|
// History: 21-Aug-98 Gopalk Created
|
|
//
|
|
//+-------------------------------------------------------------------
|
|
HRESULT CStaticRWLock::GetTLSLockData(WORD **ppwReaderLevel)
|
|
{
|
|
HRESULT hr = E_OUTOFMEMORY;
|
|
|
|
// Ensure that the lock was initialized
|
|
if(IsInitialized())
|
|
{
|
|
LockEntry *pLockEntry = GetLockEntryFromTLS();
|
|
if (pLockEntry)
|
|
{
|
|
// Compute the quotient and remainder
|
|
DWORD dwSkip = _dwLockNum / LOCKS_PER_ENTRY;
|
|
DWORD dwIndex = _dwLockNum % LOCKS_PER_ENTRY;
|
|
|
|
|
|
// Skip quotient entries
|
|
while(dwSkip && pLockEntry)
|
|
{
|
|
// Allocate the lock entries if needed
|
|
if(pLockEntry->pNext == NULL)
|
|
{
|
|
LockEntry *pEntry;
|
|
pEntry = (LockEntry *) HeapAlloc(g_hHeap, HEAP_SERIALIZE, sizeof(LockEntry));
|
|
if(pEntry)
|
|
{
|
|
memset(pEntry, 0 , sizeof(LockEntry));
|
|
pEntry = (LockEntry *) InterlockedCompareExchangePointer((void **) &(pLockEntry->pNext),
|
|
pEntry,
|
|
NULL);
|
|
if(pEntry)
|
|
HeapFree(g_hHeap, HEAP_SERIALIZE, pEntry);
|
|
}
|
|
}
|
|
|
|
// Skip to next lock entry
|
|
pLockEntry = pLockEntry->pNext;
|
|
--dwSkip;
|
|
}
|
|
|
|
// Check for OOM
|
|
if(pLockEntry)
|
|
{
|
|
*ppwReaderLevel = &(pLockEntry->wReaderLevel[dwIndex]);
|
|
hr = S_OK;
|
|
}
|
|
else
|
|
{
|
|
*ppwReaderLevel = NULL;
|
|
hr = E_OUTOFMEMORY;
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
*ppwReaderLevel = NULL;
|
|
hr = S_FALSE;
|
|
}
|
|
|
|
return(hr);
|
|
}
|
|
|