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430 lines
11 KiB
430 lines
11 KiB
/*===================================================================
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Microsoft IIS 5.0 (ASP)
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Microsoft Confidential.
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Copyright 1998 Microsoft Corporation. All Rights Reserved.
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Component: Thread Gate
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The thread gate limits number of threads executing at the
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moment by sleeping some of them.
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File: thrdgate.cpp
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Owner: DmitryR
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This file contains the code for the Thread Gate
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===================================================================*/
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#include "denpre.h"
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#pragma hdrstop
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#include "thrdgate.h"
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#include "memchk.h"
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/*===================================================================
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Constants for tuning
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===================================================================*/
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/*===================================================================
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Class to track the processor load
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===================================================================*/
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inline DWORD GetNumberOfProcessors() {
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SYSTEM_INFO si;
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GetSystemInfo(&si);
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return si.dwNumberOfProcessors;
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}
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inline LONG GetPercentage(LARGE_INTEGER part, LARGE_INTEGER total) {
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if (total.HighPart == 0 && total.LowPart == 0) {
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return 100;
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}
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ULONG ul;
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LARGE_INTEGER t1, t2, t3;
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if (total.HighPart == 0) {
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t1 = RtlEnlargedIntegerMultiply(part.LowPart, 100);
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t2 = RtlExtendedLargeIntegerDivide(t1, total.LowPart, &ul);
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} else {
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t1 = RtlExtendedLargeIntegerDivide(total, 100, &ul);
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t2 = RtlLargeIntegerDivide(part, t1, &t3);
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}
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return t2.LowPart;
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}
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class CCPULoad {
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private:
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DWORD m_cCPU;
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DWORD m_cbData; // data struct length
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SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION *m_psppiOld;
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SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION *m_psppiNew;
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public:
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/*===================================================================
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Constructor
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===================================================================*/
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CCPULoad() {
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// get the CPU count
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m_cCPU = GetNumberOfProcessors();
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m_cbData = m_cCPU * sizeof(SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION);
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m_psppiOld = new SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION[m_cCPU];
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m_psppiNew = new SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION[m_cCPU];
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if (m_psppiOld == NULL || m_psppiNew == NULL) {
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return;
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}
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// get the original snapshot
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NtQuerySystemInformation(
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SystemProcessorPerformanceInformation,
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m_psppiOld,
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m_cbData,
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NULL
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);
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}
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/*===================================================================
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Destructor
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===================================================================*/
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~CCPULoad() {
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if (m_psppiOld != NULL) {
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delete m_psppiOld;
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}
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if (m_psppiNew != NULL) {
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delete m_psppiNew;
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}
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}
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/*===================================================================
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GetReading
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get the current reading as a percentage of CPU load
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averaged across processors
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===================================================================*/
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DWORD GetReading() {
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if (m_psppiOld == NULL || m_psppiNew == NULL) {
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return 0;
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}
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// get the new snapshot
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NtQuerySystemInformation(
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SystemProcessorPerformanceInformation,
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m_psppiNew,
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m_cbData,
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NULL
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);
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// calculate
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LARGE_INTEGER cpuIdleTime, cpuUserTime, cpuKernelTime,
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cpuBusyTime, cpuTotalTime,
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sumBusyTime = RtlConvertLongToLargeInteger(0),
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sumTotalTime = RtlConvertLongToLargeInteger(0);
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for (DWORD i = 0; i < m_cCPU; i++) {
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cpuIdleTime = RtlLargeIntegerSubtract(m_psppiNew[i].IdleTime, m_psppiOld[i].IdleTime);
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cpuUserTime = RtlLargeIntegerSubtract(m_psppiNew[i].UserTime, m_psppiOld[i].UserTime);
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cpuKernelTime = RtlLargeIntegerSubtract(m_psppiNew[i].KernelTime, m_psppiOld[i].KernelTime);
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cpuTotalTime = RtlLargeIntegerAdd(cpuUserTime, cpuKernelTime);
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cpuBusyTime = RtlLargeIntegerSubtract(cpuTotalTime, cpuIdleTime);
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IF_DEBUG(THREADGATE)
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{
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LONG p = GetPercentage(cpuBusyTime, cpuTotalTime);
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DBGPRINTF((DBG_CONTEXT, "ThreadGate: load(%d)=%d", i+1, p));
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}
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sumBusyTime = RtlLargeIntegerAdd(sumBusyTime, cpuBusyTime);
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sumTotalTime = RtlLargeIntegerAdd(sumTotalTime, cpuTotalTime);
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}
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LONG nPercentage = GetPercentage(sumBusyTime, sumTotalTime);
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IF_DEBUG(THREADGATE)
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{
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DBGPRINTF((DBG_CONTEXT, "ThreadGate: **** load = %d\r\n", nPercentage));
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}
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// move new to old
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memcpy(m_psppiOld, m_psppiNew, m_cbData);
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return nPercentage;
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}
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/*=================================================================*/
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}; // class CCPULoad
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/*===================================================================
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The thread gate class
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===================================================================*/
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class CThreadGate {
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private:
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DWORD m_msSlice; // granularity
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DWORD m_msSleep; // sleep length
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DWORD m_cSleepsMax; // max wait 50 sleeps
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LONG m_nLowLoad; // low CPU load is < 75%
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LONG m_nHighLoad; // hight CPU load is > 90%
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LONG m_cThreadLimitMin; // hunting range low
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LONG m_cThreadLimitMax; // hunting range high
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LONG m_cThreadLimit; // current limit
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LONG m_nTrend; // last change
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DWORD m_msT0; // starting time
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LONG m_iCurrentSlice; // current time slice index
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LONG m_nRequests; // number of active requests
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CCPULoad m_CPULoad; // track the CPU load
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public:
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/*===================================================================
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Constructor
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===================================================================*/
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CThreadGate(
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DWORD msSlice,
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DWORD msSleep,
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DWORD cSleepsMax,
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DWORD nLowLoad,
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DWORD nHighLoad,
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DWORD cLimitMin,
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DWORD cLimitMax
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) {
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m_msSlice = msSlice;
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m_msSleep = msSleep;
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m_cSleepsMax = cSleepsMax;
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m_nLowLoad = nLowLoad,
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m_nHighLoad = nHighLoad;
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m_cThreadLimitMin = cLimitMin;
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m_cThreadLimitMax = cLimitMax;
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m_cThreadLimit = m_cThreadLimitMin;
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m_nTrend = 0;
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m_msT0 = GetTickCount();
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m_iCurrentSlice = 0;
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m_nRequests = 0;
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}
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/*===================================================================
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Destructor
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===================================================================*/
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~CThreadGate() {
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}
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/*===================================================================
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HuntLoad
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Do the load hunting
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===================================================================*/
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void HuntLoad() {
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LONG nLoad = m_CPULoad.GetReading();
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if (m_nRequests == 0) {
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// no requests - don't change
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m_nTrend = 0;
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return;
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}
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LONG cThreadLimit = m_cThreadLimit;
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LONG nTrend = m_nTrend;
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if (nLoad < m_nLowLoad) {
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nTrend = nTrend <= 0 ? 1 : nTrend+3; // grow faster
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cThreadLimit += nTrend;
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if (cThreadLimit >= m_cThreadLimitMax) {
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cThreadLimit = m_cThreadLimitMax;
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nTrend = 0;
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}
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}
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else if (nLoad > m_nHighLoad) {
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nTrend = nTrend > 0 ? -1 : nTrend-1;
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cThreadLimit += nTrend;
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if (cThreadLimit <= m_cThreadLimitMin) {
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cThreadLimit = m_cThreadLimitMin;
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nTrend = 0;
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}
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}
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// set the new limit and trend
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m_cThreadLimit = cThreadLimit;
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m_nTrend = nTrend;
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}
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/*===================================================================
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Enter
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Pass through the gate. Can make the thread sleep
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Returns
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Thread Gate Pass
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===================================================================*/
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void Enter(DWORD msCurrentTickCount) {
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DWORD cSleeps = 0;
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while (cSleeps++ < m_cSleepsMax) {
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// if shutting down, let the request go. Later it will find
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// out again that the server is shutting down and not actually
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// fire the request.
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if (IsShutDownInProgress()) {
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break;
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}
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// calculate the current time slice
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DWORD msElapsedSinceT0 = (msCurrentTickCount >= m_msT0) ?
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(msCurrentTickCount - m_msT0) :
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((0xffffffff - m_msT0) + msCurrentTickCount);
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LONG iSlice = msElapsedSinceT0 / m_msSlice;
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if (iSlice > m_iCurrentSlice) {
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// set it as the new one
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if (InterlockedExchange(&m_iCurrentSlice, iSlice) != iSlice) {
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// this is the first thread to jump the time slice - go hunting
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HuntLoad();
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}
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}
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// enforce the gate limit
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if (m_nRequests < m_cThreadLimit) {
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break;
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}
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// Too many active threads -- sleep
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Sleep(m_msSleep);
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}
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// let it through
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InterlockedIncrement(&m_nRequests);
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}
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/*===================================================================
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Leave
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Return. The user lets us know that the request finished.
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===================================================================*/
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void Leave() {
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InterlockedDecrement(&m_nRequests);
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}
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/*=================================================================*/
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}; // class CThreadGate
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// Pointer to the sole instance of the above
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static CThreadGate *gs_pThreadGate = NULL;
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/*===================================================================
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E x t e r n a l A P I
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===================================================================*/
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/*===================================================================
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InitThreadGate
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Initialization
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Parameters
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ptgc configuration
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Returns:
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HRESULT
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===================================================================*/
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HRESULT InitThreadGate(THREADGATE_CONFIG *ptgc) {
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DWORD cCPU = GetNumberOfProcessors();
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if (ptgc->fEnabled) {
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gs_pThreadGate = new CThreadGate(
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ptgc->msTimeSlice,
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ptgc->msSleepDelay,
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ptgc->nSleepMax,
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ptgc->nLoadLow,
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ptgc->nLoadHigh,
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ptgc->nMinProcessorThreads * cCPU,
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ptgc->nMaxProcessorThreads * cCPU
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);
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return (gs_pThreadGate != NULL) ? S_OK : E_OUTOFMEMORY;
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}
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gs_pThreadGate = NULL;
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return S_OK;
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}
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/*===================================================================
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UnInitThreadGate
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To be called from DllUnInit()
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Parameters
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Returns:
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n/a
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===================================================================*/
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void UnInitThreadGate() {
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if (gs_pThreadGate) {
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delete gs_pThreadGate;
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gs_pThreadGate = NULL;
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}
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}
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/*===================================================================
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PassThroughThreadGate
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Pass through the gate. The current thread could be delayed in
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case there are too many running threads at this moment
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Parameters
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msCurrentTickCount current tick count
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===================================================================*/
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void EnterThreadGate(DWORD msCurrentTickCount) {
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if (gs_pThreadGate) {
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gs_pThreadGate->Enter(msCurrentTickCount);
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}
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}
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/*===================================================================
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LeaveThreadGate
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Request done executing
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===================================================================*/
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void LeaveThreadGate() {
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if (gs_pThreadGate) {
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gs_pThreadGate->Leave();
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}
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}
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