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/*++
Copyright (C) 2001 Microsoft Corporation
Module Name:
THRPOOL.H
Abstract:
General purpose thread pool.
History:
raymcc 25-Feb-99 Created
--*/
#ifndef _THRPOOL_H_
#define _THRPOOL_H_
class POLARITY CThreadPool{ // User-defined control parms.
// ===========================
DWORD m_dwMsMaxIdle; // Max idle milliseconds before letting thread terminate
LONG m_lMaxThreads; // Max threads in pool, -1 = no limit.
LONG m_lIdleThreadLimit; // No more than this number of idle threads
// Thread status info. These may become out-of-date as soon as they
// are read, but they are statistically useful.
// =================================================================
LONG m_lIdleThreads; // How many threads available
LONG m_lTotalThreads; // How many threads created
// Other stuff.
// ============
HANDLE m_hReleaseThread; // Signaled to release a blocked thread
HANDLE m_hBeginRendezvous; // Signaled to indicate a rendezvous
HANDLE m_hParmXfer; // Signaled to begin interthread transfer of parms
HANDLE m_hEndRendezvous; // Signaled when parameter transfer is completed
CRITICAL_SECTION m_cs_dispatch; // Protects dispatcher rendezvous
CRITICAL_SECTION m_cs_pool; // Protects thread pool rendezvous
bool m_bShutdown; bool m_bPendingRequest; // Used to signal that a parm transfer
// is taking place via the two Xfer members
// following this.
// These are used for interthread parameter transfers.
// ====================================================
LPVOID m_pXferUserParms; // Used to copy user-supplied thread parms
LPTHREAD_START_ROUTINE m_pXferUserProc; // Used to copy the user-supplied
// thread entry point
LPDWORD m_pXferReturnCode; // Receives user's return code
LPDWORD m_pXferElapsedTime; // Receives elapsed dispatch time
HANDLE m_hXferThreadCompleted; // Signaled when thread is done
// Internal functions.
// ===================
bool CreateNewThread(); static DWORD WINAPI _ThreadEntry(LPVOID pArg); void Pool(); public: enum { NoError, ExceededPool, ThreadCreationFailure, ShutdownInProgress, Failed, TimedOut };
CThreadPool( DWORD dwMsMaxIdleBeforeDie = 5000, // 5 sec
LONG lIdleThreadLimit = 8, // No more than this number of idle threads, -1=no limit
LONG lMaxThreads = -1 // No limit
); ~CThreadPool();
void IncrementMaxThreads() { InterlockedIncrement(&m_lMaxThreads); } void DecrementMaxThreads() { InterlockedDecrement(&m_lMaxThreads); } LONG GetCurrentMaxThreads() { return m_lMaxThreads; }
bool Shutdown(DWORD dwMaxWait = 5000); // Stops dispatching and lets thread pool return to
// zero. New requests via DispatchThread() will be denied
// with a <Shutdown> error code.
// If this returns while there still threads due to timeout,
// <false> is returned.
bool Restart(); // Allows thread pool to start again.
// All of these can become out of date before the call even returns!
// They are primarily for load analysis and don't have to be exact.
// =================================================================
LONG GetTotalThreadCount() { return m_lTotalThreads; } LONG GetIdleThreadCount() { return m_lIdleThreads; }
// Dispatches a thread to the user's entry point.
// ==============================================
int DispatchThread( IN DWORD dwMaxPreferredWait, IN DWORD dwMaxWaitBeforeFail, IN LPTHREAD_START_ROUTINE pEntry, IN LPVOID pArg = 0, IN DWORD *pdwReturnCode = 0, IN DWORD *pdwElapsedTime = 0, IN HANDLE hThreadCompleted = 0 ); /*
dwMaxPreferredWait -- How long to wait while attempting to reuse a thread which has just become idle. Typically, no more than 250 msec. Once this expires, if no threads are available, one will be created, if the max thread limit hasn't been reached. If it has, then dwMaxWaitBeforeFail kicks in. dwMaxWaitBeforeFail -- The maximum wait time to acquire or create a thread. If a thread cannot be dispatched within this time, ExceededPool is returned. pEntry -- The user's entry point. pdwReturnCode -- If not NULL, receives the thread return code. pdwElapsedTime -- If not NULL, receives the elapsed running time of the dispatch. hThreadCompleted If not NULL, a user event handle to be signaled when thread is done
Return value -- One of the enum error codes */};
#endif
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