108 lines
4.2 KiB
C#
108 lines
4.2 KiB
C#
// <copyright file="MemoryMonitor.cs" company="Microsoft">
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// Copyright (c) 2009 Microsoft Corporation. All rights reserved.
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// </copyright>
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using System;
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using System.Collections.Specialized;
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using System.Security;
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namespace System.Runtime.Caching {
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// MemoryMonitor is the base class for memory monitors. The MemoryCache has two
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// types of monitors: PhysicalMemoryMonitor and CacheMemoryMonitor. The first monitors
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// the amount of physical memory used on the machine, and helps determine when we should
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// drop cache entries to avoid paging. The second monitors the amount of memory used by
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// the cache itself, and helps determine when we should drop cache entries to avoid
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// exceeding the cache's memory limit. Both are configurable (see ConfigUtil.cs).
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internal abstract class MemoryMonitor {
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protected const int TERABYTE_SHIFT = 40;
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protected const long TERABYTE = 1L << TERABYTE_SHIFT;
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protected const int GIGABYTE_SHIFT = 30;
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protected const long GIGABYTE = 1L << GIGABYTE_SHIFT;
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protected const int MEGABYTE_SHIFT = 20;
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protected const long MEGABYTE = 1L << MEGABYTE_SHIFT; // 1048576
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protected const int KILOBYTE_SHIFT = 10;
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protected const long KILOBYTE = 1L << KILOBYTE_SHIFT; // 1024
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protected const int HISTORY_COUNT = 6;
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protected int _pressureHigh; // high pressure level
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protected int _pressureLow; // low pressure level - slow growth here
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protected int _i0;
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protected int[] _pressureHist;
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protected int _pressureTotal;
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private static long s_totalPhysical;
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private static long s_totalVirtual;
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[SecuritySafeCritical]
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static MemoryMonitor() {
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#if MONO
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var pc = new System.Diagnostics.PerformanceCounter ("Mono Memory", "Total Physical Memory");
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s_totalPhysical = pc.RawValue;
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// We should set the the total virtual memory with a system value.
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// But Mono has no such PerformanceCounter and the total virtual memory has little relevance
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// for the rest of the System.Runtime.Caching code.
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s_totalVirtual = 0;
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#else
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MEMORYSTATUSEX memoryStatusEx = new MEMORYSTATUSEX();
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memoryStatusEx.Init();
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if (UnsafeNativeMethods.GlobalMemoryStatusEx(ref memoryStatusEx) != 0) {
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s_totalPhysical = memoryStatusEx.ullTotalPhys;
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s_totalVirtual = memoryStatusEx.ullTotalVirtual;
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}
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#endif
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}
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internal static long TotalPhysical { get { return s_totalPhysical; } }
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internal static long TotalVirtual { get { return s_totalVirtual; } }
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internal int PressureLast { get { return _pressureHist[_i0]; } }
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internal int PressureHigh { get { return _pressureHigh; } }
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internal int PressureLow { get { return _pressureLow; } }
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internal bool IsAboveHighPressure() {
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return PressureLast >= PressureHigh;
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}
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protected abstract int GetCurrentPressure();
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internal abstract int GetPercentToTrim(DateTime lastTrimTime, int lastTrimPercent);
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protected void InitHistory() {
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Dbg.Assert(_pressureHigh > 0, "_pressureHigh > 0");
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Dbg.Assert(_pressureLow > 0, "_pressureLow > 0");
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Dbg.Assert(_pressureLow <= _pressureHigh, "_pressureLow <= _pressureHigh");
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int pressure = GetCurrentPressure();
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_pressureHist = new int[HISTORY_COUNT];
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for (int i = 0; i < HISTORY_COUNT; i++) {
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_pressureHist[i] = pressure;
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_pressureTotal += pressure;
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}
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}
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// Get current pressure and update history
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internal void Update() {
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int pressure = GetCurrentPressure();
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_i0 = (_i0 + 1) % HISTORY_COUNT;
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_pressureTotal -= _pressureHist[_i0];
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_pressureTotal += pressure;
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_pressureHist[_i0] = pressure;
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#if DBG
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Dbg.Trace("MemoryCacheStats", this.GetType().Name + ".Update: last=" + pressure
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+ ",high=" + PressureHigh
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+ ",low=" + PressureLow
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+ " " + Dbg.FormatLocalDate(DateTime.Now));
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#endif
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}
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}
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}
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