1087 lines
44 KiB
C#
1087 lines
44 KiB
C#
/*******************************************************************/
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/* WARNING */
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/* This file should be identical in the Bartok and Singularity */
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/* depots. Master copy resides in Bartok Depot. Changes should be */
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/* made to Bartok Depot and propagated to Singularity Depot. */
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/*******************************************************************/
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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#define OVERLAPPING_PHASES
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namespace System.GCs {
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using Microsoft.Bartok.Runtime;
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using System.Runtime.CompilerServices;
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using System.Threading;
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#if SINGULARITY
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using Microsoft.Singularity;
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#if SINGULARITY_PROCESS
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using Microsoft.Singularity.V1.Services; // Used for timing, only
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#elif SINGULARITY_KERNEL
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using Microsoft.Singularity.Scheduling;
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using Microsoft.Singularity.X86;
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#endif
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#endif
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/// <summary>
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/// This class implements a semi-concurrent version of MarkSweep.
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///
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/// The goal for this collector is to perform as much of the processing
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/// as possible during mutator time, and also have a fixed upper bound
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/// on pause times.
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///
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/// Additionally, the collector will be required in the future to
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/// communicate with the scheduler to prevent real time applications
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/// from competing with the GC.
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///
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///
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/// BUGBUG: NEED TO REPLICATE THE ALLOCATION COLOR LOGIC TO THE INLINED
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/// ALLOCATION SEQUENCE. [T-DANIF 12/3/2004]
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/// </summary>
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[NoCCtor]
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[RequiredByBartok]
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internal class ConcurrentMSCollector: BaseCollector
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{
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internal enum MarkingPhase {
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Dummy, // Not used!
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Idle, // No marking is occurring
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Requested, // No marking, but will be soon
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ComputingRoots, // Marking the roots
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Tracing, // Tracing gray objects
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}
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internal enum ReclamationPhase {
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Dummy, // Not used!
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Idle, // No reclamation is in progress
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Reclaiming, // Reclamation is in progress
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}
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internal static MarkingPhase CurrentMarkingPhase {
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get { return (MarkingPhase) currentMarkingPhase; }
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set { currentMarkingPhase = (int) value; }
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}
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internal static int currentMarkingPhase;
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internal static ReclamationPhase CurrentReclamationPhase;
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#if SINGULARITY
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private static TimeSpan infiniteWait;
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#else
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private static int infiniteWait;
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#endif
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/// <summary>
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/// Current mark state. This is flipped between collections.
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/// </summary>
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internal static UIntPtr markedColor;
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internal static UIntPtr unmarkedColor;
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internal static UIntPtr reclamationColor;
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private const uint markOne = 1U;
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private const uint markTwo = 2U;
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private const uint markThree = 3U;
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/// <summary>
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/// Amount of memory to allocate between collections.
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/// BUGBUG: This heuristic is not very good for CMS.
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/// </summary>
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private static UIntPtr collectionTrigger;
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internal static ConcurrentMSCollector instance;
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// Pointer visitors used for marking, etc
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private static MarkReferenceVisitor markReferenceVisitor;
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private static UpdateReferenceVisitor updateReferenceVisitor;
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private static StackMarkReferenceVisitor stackMarkReferenceVisitor;
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// Object visitors used for sweeping, etc
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private static SweepVisitor sweepVisitor;
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// Which threads are in what marking stage?
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private static UIntPtr[] threadColor;
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// Threads waiting for a particular collection to finish
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private static int[] waitingThreads;
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private static int firstWaitingThread;
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private const int waitingThreadsNullValue = -1;
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private const int waitingThreadsUnusedValue = -2;
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private const uint noColor = 0xffffffff;
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// The threads that performs the collection work
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private static Thread markThread;
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private static Thread workerThread1;
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private static Thread workerThread2;
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private static AutoResetEvent sweepPhaseMutex;
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/// <summary>
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/// Does this collector compute a root set with threads running?
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/// </summary>
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internal override bool IsOnTheFlyCollector {
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get {
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return true;
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}
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}
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/// <summary>
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/// Initialise the collector and allow allocations to commence.
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/// </summary>
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[PreInitRefCounts]
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public static void Initialize() {
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GC.Initialize();
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SegregatedFreeList.Initialize();
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unmarkedColor = (UIntPtr) markOne;
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markedColor = (UIntPtr) markTwo;
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reclamationColor = (UIntPtr) markThree;
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// instance = new ConcurrentMSCollector();
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ConcurrentMSCollector.instance = (ConcurrentMSCollector)
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BootstrapMemory.Allocate(typeof(ConcurrentMSCollector));
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// markReferenceVisitor = new MarkReferenceVisitor();
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markReferenceVisitor = (MarkReferenceVisitor)
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BootstrapMemory.Allocate(typeof(MarkReferenceVisitor));
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// updateReferenceVisitor = new UpdateReferenceVisitor();
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updateReferenceVisitor = (UpdateReferenceVisitor)
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BootstrapMemory.Allocate(typeof(UpdateReferenceVisitor));
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// stackMarkReferenceVisitor = new StackMarkReferenceVisitor();
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stackMarkReferenceVisitor = (StackMarkReferenceVisitor)
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BootstrapMemory.Allocate(typeof(StackMarkReferenceVisitor));
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// sweepVisitor = new SweepVisitor();
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sweepVisitor = (SweepVisitor)
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BootstrapMemory.Allocate(typeof(SweepVisitor));
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// threadColor = new UIntPtr[Thread.maxThreads];
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threadColor = (UIntPtr[])
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BootstrapMemory.Allocate(typeof(UIntPtr[]), Thread.maxThreads);
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for (int i = 0; i < threadColor.Length; i++) {
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threadColor[i] = (UIntPtr) noColor;
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}
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collectionTrigger = (UIntPtr) (1 << 24);
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CurrentMarkingPhase = MarkingPhase.Idle;
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CurrentReclamationPhase = ReclamationPhase.Idle;
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#if SINGULARITY
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infiniteWait = TimeSpan.Infinite;
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#else
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infiniteWait = Timeout.Infinite;
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#endif
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}
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/// <summary>
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/// Perform a collection. Depending on the current phase of collection
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/// this method will either:
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///
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/// 1. Start a new collection and schedule the mark thread
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/// 2. Notice that a collection is underway and exit
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/// 3. Clean up after a collection
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///
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/// BUGBUG: The interaction between the collector needs work!
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/// </summary>
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internal override void Collect(int currentThreadIndex,
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int generation)
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{
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if (Transitions.HasGCRequest(currentThreadIndex)) {
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// We are GC safe, so we may do this
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Transitions.TakeDormantControlNoGC(currentThreadIndex);
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if (Transitions.TakeGCControl(currentThreadIndex)) {
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MutatorHandshake(currentThreadIndex);
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Transitions.ReleaseGCControl(currentThreadIndex);
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Thread.SignalGCEvent(markThread.threadIndex);
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}
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Transitions.TakeMutatorControlNoGC(currentThreadIndex);
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} else {
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if (generation >= 0) {
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AddThreadToWaitList(currentThreadIndex);
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}
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AddCollectionRequest();
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if (generation >= 0) {
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Thread currentThread =
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Thread.threadTable[currentThreadIndex];
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while (ThreadIsWaiting(currentThreadIndex)) {
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currentThread.WaitForEvent(infiniteWait);
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}
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}
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}
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}
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internal override void CheckForNeededGCWork(Thread currentThread) {
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if (Transitions.HasGCRequest(currentThread.threadIndex)) {
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GC.InvokeCollection(currentThread);
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}
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}
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private static void CollectorHandshake(Thread collectorThread)
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{
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Transitions.MakeGCRequests(collectorThread.threadIndex);
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// Handshake with all the (other) threads.
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for(int i=0; i < Thread.threadTable.Length; i++) {
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#if SINGULARITY_KERNEL
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if (Scheduler.IsIdleThread(i)) {
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continue;
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}
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#endif
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// Is there an unscanned thread here?
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while (Transitions.HasGCRequest(i)) {
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if (Transitions.TakeGCControl(i)) {
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MutatorHandshake(i);
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Transitions.ReleaseGCControl(i);
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Thread.SignalGCEvent(i);
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} else if (Thread.threadTable[i] == null) {
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// The thread must have terminated but the
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// state hasn't yet changed to DormantState.
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break;
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} else {
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Thread.WaitForGCEvent(collectorThread.threadIndex);
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}
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}
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}
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if (CurrentMarkingPhase == MarkingPhase.ComputingRoots &&
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!WriteBarrierCMS.InSnoopingPhase) {
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MultiUseWord.CollectFromPreviousCollections(false);
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}
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}
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private static void MutatorHandshake(int threadIndex)
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{
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if (CurrentMarkingPhase == MarkingPhase.ComputingRoots &&
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!WriteBarrierCMS.InSnoopingPhase) {
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Thread thread = Thread.threadTable[threadIndex];
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if (thread != null) {
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ScanThreadRoots(thread);
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MultiUseWord.CollectFromThread(thread);
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}
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}
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}
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private static void ScanThreadRoots(Thread thread) {
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long start = CollectorStatistics.PerformanceCounter;
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CollectorStatistics.Event(GCEvent.StackScanStart,
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thread.threadIndex);
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CallStack.ScanStack(thread, stackMarkReferenceVisitor,
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stackMarkReferenceVisitor);
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threadColor[thread.threadIndex] = markedColor;
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// Report the pause
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long pause =
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CollectorStatistics.PerformanceCounter - start;
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CollectorStatistics.Event(GCEvent.StackScanComplete,
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pause);
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}
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private static bool terminateCollectorThreads;
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private static void TraceThreadNotification() {
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terminateCollectorThreads = true;
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GC.Collect();
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}
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/// <summary>
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/// This method is run by the collector threads.
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/// </summary>
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private static void CollectionLoop() {
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Thread currentThread = Thread.CurrentThread;
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#if SINGULARITY_PROCESS
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currentThread.MakeServiceThread(new Thread.StopServiceNotice(TraceThreadNotification));
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#endif
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while (!terminateCollectorThreads) {
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// Wait to be told to start working.
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while (!TakeChargeOfTraceRequest()) {
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currentThread.WaitForEvent(infiniteWait);
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}
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#if SINGULARITY
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#if DEBUG
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DebugStub.WriteLine("~~~~~ Start Concurrent Marking [data={0:x8}, pid={1:x3}]",
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__arglist(SegregatedFreeList.TotalBytes,
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PageTable.processTag >> 16));
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#endif
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int startTicks = Environment.TickCount;
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#endif
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markThread = currentThread;
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advanceMarkColors();
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// Construct the root set.
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CollectorStatistics.Event(GCEvent.ComputeRootSet);
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StartRootMarkingPhase();
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WriteBarrierCMS.EnterSnoopingPhase();
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// Start the process of recycling pages
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SegregatedFreeList.RecycleGlobalPagesPhase1();
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// One handshake to ensure that everyone starts snooping
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CollectorHandshake(currentThread);
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// Complete the process of recycling pages
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SegregatedFreeList.RecycleGlobalPagesPhase2();
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// Another handshake to ensure that all updates started by
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// other threads prior to their handshake are done and
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// snooping will affect all new updates.
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CollectorHandshake(currentThread);
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WriteBarrierCMS.LeaveSnoopingPhase();
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ScanThreadRoots(currentThread);
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// A third handshake to get the threads to process their
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// own roots.
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CollectorHandshake(currentThread);
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Finalizer.PrepareCollectFinalizers();
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Thread.VisitBootstrapData(markReferenceVisitor);
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#if SINGULARITY_KERNEL
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Kernel.VisitSpecialData(markReferenceVisitor);
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#endif
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MultiUseWord.VisitStrongRefs(markReferenceVisitor,
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false /* Don't use shadows */);
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#if !VC
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TryAllManager.VisitStrongRefs(markReferenceVisitor);
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#endif
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StaticData.ScanStaticData(markReferenceVisitor);
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CollectorStatistics.Event(GCEvent.RootSetComputed);
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int waitingThreadList = StealWaitingThreadsList();
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// We are now in the concurrent tracing phase.
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ResetCollectorRequests();
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StartTracingPhase();
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CollectorStatistics.Event(GCEvent.TraceStart,
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ReservedMemory);
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// Trace live objects from the root set.
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markReferenceVisitor.ProcessScheduledObjects();
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CollectorStatistics.Event(GCEvent.TraceSpecial);
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// Mark weak references that do not track resurrection as dead.
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WeakReference.Process(updateReferenceVisitor, true, true);
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// Resurrect any finalization candidates.
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Finalizer.ResurrectCandidates(updateReferenceVisitor,
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markReferenceVisitor, true);
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// Complete closure from finalized objects.
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markReferenceVisitor.ProcessScheduledObjects();
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// Mark appropriate weak references as dead
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WeakReference.Process(updateReferenceVisitor, true, false);
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MultiUseWord.VisitWeakRefs(updateReferenceVisitor,
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false /* Don't use shadows */);
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#if !VC
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TryAllManager.VisitWeakRefs(updateReferenceVisitor);
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#endif
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MultiUseWord.PostGCHook();
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// Reset thread queues. They should all be empty.
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markReferenceVisitor.Cleanup();
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#if SINGULARITY
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#if DEBUG
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int middleTicks = Environment.TickCount;
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DebugStub.WriteLine("~~~~~ Finish Concurrent Marking [data={0:x8}, pid={1:x3} ms={2:d6}]",
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__arglist(SegregatedFreeList.TotalBytes,
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PageTable.processTag >> 16,
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middleTicks - startTicks));
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#endif
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#endif
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markThread = nextWorkerThread(currentThread);
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sweepPhaseMutex.WaitOne();
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try {
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reclamationColor = unmarkedColor;
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FinishTracingPhase();
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SatisfyCollectorRequest(); // May start another trace phase
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// Sweep garbage objects
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StartReclamationPhase();
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CollectorStatistics.Event(GCEvent.SweepStart,
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ReservedMemory);
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Sweep();
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// Clean up after the collection
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CollectorStatistics.Event(GCEvent.SweepSpecial,
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ReservedMemory);
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Finalizer.ReleaseCollectFinalizers();
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CollectorStatistics.Event(GCEvent.SweepPreCommit,
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ReservedMemory);
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// Commit accounting changes
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CommitSweep();
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CollectorStatistics.Event(GCEvent.CollectionComplete,
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ReservedMemory);
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// TODO: Determine a new collection trigger?
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SignalWaitingThreads(waitingThreadList);
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FinishReclamationPhase();
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} finally {
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sweepPhaseMutex.Set();
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}
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#if SINGULARITY
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#if DEBUG
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int endTicks = Environment.TickCount;
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DebugStub.WriteLine("~~~~~ Finish Concurrent Reclamation [data={0:x8}, pid={1:x3} ms={2:d6}]",
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__arglist(ReservedMemory,
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PageTable.processTag >> 16,
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endTicks - middleTicks));
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#endif
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#endif
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}
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}
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/// <summary>
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/// Allocate memory for a new object, potentially triggering a
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/// collection.
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/// </summary>
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[Inline]
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internal override UIntPtr AllocateObjectMemory(UIntPtr numBytes,
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uint alignment,
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Thread currentThread)
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{
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UIntPtr resultAddr =
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SegregatedFreeList.AllocateFast(currentThread,
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numBytes, alignment);
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if (resultAddr == UIntPtr.Zero) {
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resultAddr = AllocateObjectMemorySlow(numBytes, alignment,
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currentThread);
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}
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return resultAddr;
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}
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[NoInline]
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private UIntPtr AllocateObjectMemorySlow(UIntPtr numBytes,
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uint alignment,
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Thread currentThread)
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{
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if (GC.newBytesSinceGC > collectionTrigger) {
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if (CurrentMarkingPhase == MarkingPhase.Idle ||
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Transitions.HasGCRequest(currentThread.threadIndex)) {
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GC.InvokeCollection(currentThread);
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} else if (GC.newBytesSinceGC > (collectionTrigger<<1)) {
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// Slow down the allocating thread a bit
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Thread.Yield();
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}
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}
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return SegregatedFreeList.AllocateSlow(currentThread,
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numBytes, alignment);
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}
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[Inline]
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protected override void CreateObject(Object obj, VTable vtable,
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Thread currentThread)
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{
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// We expect the color to be assigned before the vtable field
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// is initialized. This ensures that every real object has a
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// valid color.
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UIntPtr markBits = threadColor[currentThread.threadIndex];
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ThreadHeaderQueue.SetGcMark(obj, markBits);
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// The vtable field must be initialized before the object is
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// inserted into a list of objects to be scanned.
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base.CreateObject(obj, vtable, currentThread);
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// If necessary, mark the object for future scanning
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if (CurrentMarkingPhase == MarkingPhase.ComputingRoots &&
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Transitions.HasGCRequest(currentThread.threadIndex)) {
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ThreadHeaderQueue.PushUnsafe(currentThread, obj, markBits);
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}
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}
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/// <summary>
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/// Return the generation for an object. We only have one
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/// generation so we always return generation zero.
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/// </summary>
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internal override int GetGeneration(Object obj) {
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Verifier.genericObjectVisitor.Visit(obj);
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return MinGeneration;
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}
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/// <summary>
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/// The maximum generation. For MarkSweep this is generation zero.
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/// </summary>
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internal override int MaxGeneration {
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get { return (int)PageType.Owner0; }
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}
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/// <summary>
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/// The minimum generation. For MarkSweep this is generation zero.
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/// </summary>
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internal override int MinGeneration {
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get { return (int)PageType.Owner0; }
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}
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/// <summary>
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/// This returns the total amount of memory that is allocated within
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/// the collected heap.
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/// </summary>
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internal override long TotalMemory {
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get {
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return ReservedMemory;
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}
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}
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private static long ReservedMemory {
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get {
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return (long)SegregatedFreeList.TotalBytes;
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}
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}
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internal override void EnableHeap() {
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// waitingThreads = new int[Thread.maxThreads]
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waitingThreads = new int[Thread.maxThreads];
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for (int i = 0; i < waitingThreads.Length; i++) {
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waitingThreads[i] = waitingThreadsUnusedValue;
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}
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firstWaitingThread = -1;
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// Construct the collector thread(s)
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#if SINGULARITY_KERNEL
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workerThread1 =
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Thread.CreateThread(Process.kernelProcess,
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new ThreadStart(CollectionLoop));
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workerThread2 =
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Thread.CreateThread(Process.kernelProcess,
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new ThreadStart(CollectionLoop));
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#else
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workerThread1 = new Thread(new ThreadStart(CollectionLoop));
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workerThread2 = new Thread(new ThreadStart(CollectionLoop));
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#endif
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workerThread1.Start();
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workerThread2.Start();
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markThread = workerThread1;
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sweepPhaseMutex = new AutoResetEvent(true);
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}
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/// <summary>
|
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/// Destroy the heap. Nothing to do here.
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/// </summary>
|
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internal override void DestructHeap() {
|
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// Do nothing
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while (CurrentMarkingPhase != MarkingPhase.Idle &&
|
|
CurrentReclamationPhase != ReclamationPhase.Idle) {
|
|
Thread.Yield();
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Verify the heap.
|
|
/// </summary>
|
|
internal override void VerifyHeap(bool beforeCollection) {
|
|
SegregatedFreeList.VisitAllObjects(VerifyVisitor.visitor);
|
|
Verifier.segregatedFreeListVerifier.VerifyHeap();
|
|
}
|
|
|
|
private static char ToHexDigit(int number, int position) {
|
|
int digit = (number >> (position * 4)) & 0xf;
|
|
return (char) (digit + ((digit <= 9) ? '0' : ('A' - 10)));
|
|
}
|
|
private static int flag; // = 0;
|
|
private static void DebugTrace(String text, int threadIndex) {
|
|
while (Interlocked.CompareExchange(ref flag, 1, 0) != 0) { }
|
|
VTable.DebugPrint(text+" "+
|
|
ToHexDigit(threadIndex, 2)+
|
|
ToHexDigit(threadIndex, 1)+
|
|
ToHexDigit(threadIndex, 0)+
|
|
"\n");
|
|
Interlocked.Exchange(ref flag, 0);
|
|
}
|
|
|
|
/// Routines to keep track of requests for collection work
|
|
|
|
private static int collectorStack; // 0:idle, 1:work, 2+:work+pending
|
|
|
|
private static void AddCollectionRequest() {
|
|
int stackHeight = Interlocked.Increment(ref collectorStack);
|
|
VTable.Assert(stackHeight > 0);
|
|
if (stackHeight == 1) {
|
|
MakeTraceRequest();
|
|
}
|
|
}
|
|
|
|
private static void ResetCollectorRequests() {
|
|
Interlocked.Exchange(ref collectorStack, 1);
|
|
}
|
|
|
|
private static void SatisfyCollectorRequest() {
|
|
int stackHeight = Interlocked.Decrement(ref collectorStack);
|
|
VTable.Assert(stackHeight >= 0);
|
|
if (stackHeight > 0 ) {
|
|
MakeTraceRequest();
|
|
}
|
|
}
|
|
|
|
/// Routines to control the commencement of the tracing phase
|
|
|
|
private static void MakeTraceRequest() {
|
|
CurrentMarkingPhase = MarkingPhase.Requested;
|
|
markThread.SignalEvent();
|
|
}
|
|
|
|
private static bool TakeChargeOfTraceRequest() {
|
|
return
|
|
(Interlocked.CompareExchange(ref currentMarkingPhase,
|
|
(int) MarkingPhase.ComputingRoots,
|
|
(int) MarkingPhase.Requested) ==
|
|
(int) MarkingPhase.Requested);
|
|
}
|
|
|
|
/// Routines to keep track of threads that must be notified when
|
|
/// a collection has been completed.
|
|
|
|
private static void AddThreadToWaitList(int threadIndex) {
|
|
int listHead = firstWaitingThread;
|
|
waitingThreads[threadIndex] = listHead;
|
|
while (Interlocked.CompareExchange(ref firstWaitingThread,
|
|
threadIndex, listHead) !=
|
|
listHead) {
|
|
listHead = firstWaitingThread;
|
|
waitingThreads[threadIndex] = listHead;
|
|
}
|
|
}
|
|
|
|
private static bool ThreadIsWaiting(int threadIndex) {
|
|
return (waitingThreads[threadIndex] != waitingThreadsUnusedValue);
|
|
}
|
|
|
|
private static int StealWaitingThreadsList() {
|
|
return Interlocked.Exchange(ref firstWaitingThread,
|
|
waitingThreadsNullValue);
|
|
}
|
|
|
|
private static void SignalWaitingThreads(int listHead) {
|
|
while (listHead != waitingThreadsNullValue) {
|
|
int threadIndex = listHead;
|
|
listHead = waitingThreads[threadIndex];
|
|
waitingThreads[threadIndex] = waitingThreadsUnusedValue;
|
|
Thread.threadTable[threadIndex].SignalEvent();
|
|
}
|
|
}
|
|
|
|
// Routines to keep track of what phases the collector threads are in.
|
|
|
|
private static void StartRootMarkingPhase() {
|
|
CurrentMarkingPhase = MarkingPhase.ComputingRoots;
|
|
}
|
|
|
|
private static void StartTracingPhase() {
|
|
CurrentMarkingPhase = MarkingPhase.Tracing;
|
|
}
|
|
|
|
private static void FinishTracingPhase() {
|
|
CurrentMarkingPhase = MarkingPhase.Idle;
|
|
}
|
|
|
|
private static void StartReclamationPhase() {
|
|
CurrentReclamationPhase = ReclamationPhase.Reclaiming;
|
|
}
|
|
|
|
private static void FinishReclamationPhase() {
|
|
CurrentReclamationPhase = ReclamationPhase.Idle;
|
|
}
|
|
|
|
// Routines to manage marking colors
|
|
|
|
private static void advanceMarkColors()
|
|
{
|
|
unmarkedColor = markedColor;
|
|
markedColor = nextColor(markedColor);
|
|
}
|
|
|
|
private static UIntPtr nextColor(UIntPtr originalColor)
|
|
{
|
|
switch ((uint) originalColor) {
|
|
case markOne: return (UIntPtr) markTwo;
|
|
case markTwo: return (UIntPtr) markThree;
|
|
case markThree: return (UIntPtr) markOne;
|
|
default: throw new Exception("advanceColor failure!");
|
|
}
|
|
}
|
|
|
|
private static Thread nextWorkerThread(Thread currentThread) {
|
|
#if OVERLAPPING_PHASES
|
|
return ((currentThread == workerThread1) ?
|
|
workerThread2 :
|
|
workerThread1);
|
|
#else
|
|
return currentThread;
|
|
#endif
|
|
}
|
|
|
|
/// <summary>
|
|
/// Walk the allocation structures and reclaim any free cells.
|
|
/// </summary>
|
|
private static void Sweep() {
|
|
SegregatedFreeList.VisitAllObjects(sweepVisitor);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Update alloc heap to account for data just freed.
|
|
/// </summary>
|
|
private static void CommitSweep() {
|
|
SegregatedFreeList.CommitFreedData();
|
|
}
|
|
|
|
/// <summary>
|
|
/// Routines for updating pointers to new locations of marked objects
|
|
/// No objects are resurrected using this mechanism.
|
|
/// As this is mark sweep the value does not need to be updated.
|
|
/// </summary>
|
|
private class UpdateReferenceVisitor: NonNullReferenceVisitor
|
|
{
|
|
|
|
internal unsafe override void Visit(UIntPtr *loc) {
|
|
UIntPtr addr = *loc;
|
|
// Ignore pointers out of our memory area
|
|
if (PageTable.IsForeignAddr(addr)) {
|
|
return;
|
|
}
|
|
UIntPtr page = PageTable.Page(addr);
|
|
PageType pageType = PageTable.Type(page);
|
|
if (!PageTable.IsGcPage(pageType)) {
|
|
VTable.Assert((PageTable.IsNonGcPage(pageType) &&
|
|
PageTable.IsMyPage(page)) ||
|
|
PageTable.IsStackPage(pageType),
|
|
"update.visit invalid page");
|
|
return;
|
|
}
|
|
VTable.Assert(PageTable.IsMyPage(page));
|
|
Object obj = Magic.fromAddress(addr);
|
|
if (ThreadHeaderQueue.GcMark(obj) == unmarkedColor) {
|
|
// The object was not live
|
|
*loc = UIntPtr.Zero;
|
|
}
|
|
VTable.Assert(obj.vtable != null, "update.visit null vtable");
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Select the generation to collect (always generation 0)
|
|
/// </summary>
|
|
internal override int CollectionGeneration(int genRequest) {
|
|
return MinGeneration;
|
|
}
|
|
|
|
|
|
/// <summary>
|
|
/// This visitor is the core of the tracing functionality.
|
|
/// It builds up a buffer of references (the root set), and
|
|
/// then at a later point the tracing thread processes these
|
|
/// buffers.
|
|
/// </summary>
|
|
private class MarkReferenceVisitor : NonNullReferenceVisitor
|
|
{
|
|
|
|
/// <summary>
|
|
/// Visit an object reference.
|
|
/// </summary>
|
|
internal unsafe override void Visit(UIntPtr *loc) {
|
|
UIntPtr addr = *loc;
|
|
if (addr == UIntPtr.Zero) return;
|
|
VisitValue(addr);
|
|
}
|
|
|
|
|
|
public void VisitValue(UIntPtr addr) {
|
|
// Ignore pointers out of our memory area
|
|
if (PageTable.IsForeignAddr(addr)) {
|
|
return;
|
|
}
|
|
UIntPtr page = PageTable.Page(addr);
|
|
PageType pageType = PageTable.Type(page);
|
|
if (!PageTable.IsGcPage(pageType)) {
|
|
VTable.Assert((PageTable.IsNonGcPage(pageType) &&
|
|
PageTable.IsMyPage(page)) ||
|
|
PageTable.IsStackPage(pageType),
|
|
"value.visit invalid page");
|
|
return;
|
|
}
|
|
VTable.Assert(PageTable.IsMyPage(page));
|
|
Object obj = Magic.fromAddress(addr);
|
|
VTable.Assert(obj.vtable != null,
|
|
"value.visit null vtable");
|
|
WriteBarrierCMS.MarkObject(obj);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Process all marked objects from queues stored in
|
|
/// thread objects.
|
|
/// </summary>
|
|
public void ProcessScheduledObjects() {
|
|
Thread currentThread = Thread.CurrentThread;
|
|
StealWork();
|
|
do {
|
|
while (!ThreadHeaderQueue.IsEmpty(currentThread)) {
|
|
// Pop the next value
|
|
Object obj =
|
|
ThreadHeaderQueue.Pop(currentThread, markedColor);
|
|
// Visit Fields
|
|
this.VisitReferenceFields(obj);
|
|
}
|
|
} while (StealWork());
|
|
}
|
|
|
|
/// <summary>
|
|
/// Look through other threads and see if any have some values on
|
|
/// their queues that we can steal.
|
|
/// </summary>
|
|
private bool StealWork() {
|
|
Thread[] threadTable = Thread.threadTable;
|
|
Thread me = Thread.CurrentThread;
|
|
bool foundWork = false;
|
|
// Attempt to steal work from live threads
|
|
for (int i = 0; i < threadTable.Length; i++) {
|
|
Thread t = threadTable[i];
|
|
if (t != null && t != me &&
|
|
ThreadHeaderQueue.Steal(me, t, markedColor)) {
|
|
foundWork = true;
|
|
}
|
|
}
|
|
return foundWork;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Clean up after processing all queues. This involves calling
|
|
/// reset on each thread's queue.
|
|
/// </summary>
|
|
internal void Cleanup() {
|
|
Thread[] threadTable = Thread.threadTable;
|
|
for (int i = 0; i < threadTable.Length; i++) {
|
|
Thread t = threadTable[i];
|
|
if (t != null) {
|
|
if (!ThreadHeaderQueue.IsEmpty(t)) {
|
|
// The queues may contain new objects allocated
|
|
// during the root-set computation phase but added
|
|
// to the queue after the scanning has completed.
|
|
// This is benign and we can clear the queues.
|
|
do {
|
|
Object head =
|
|
ThreadHeaderQueue.Pop(t, markedColor);
|
|
VTable.Assert(ThreadHeaderQueue.GcMark(head) ==
|
|
markedColor);
|
|
} while (!ThreadHeaderQueue.IsEmpty(t));
|
|
}
|
|
ThreadHeaderQueue.Reset(t);
|
|
}
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
/// <summary>
|
|
/// This class maps an interior pointer back to the containing object
|
|
/// pointer and then passes it on to the object marking visitor.
|
|
/// </summary>
|
|
private class StackMarkReferenceVisitor : NonNullReferenceVisitor
|
|
{
|
|
|
|
/// <summary>
|
|
/// Visit an interior pointer stored in loc.
|
|
/// </summary>
|
|
internal unsafe override void Visit(UIntPtr *loc) {
|
|
UIntPtr addr = *loc;
|
|
// Ignore pointers out of our memory area
|
|
if (PageTable.IsForeignAddr(addr)) {
|
|
return;
|
|
}
|
|
UIntPtr page = PageTable.Page(addr);
|
|
PageType pageType = PageTable.Type(page);
|
|
if (!PageTable.IsGcPage(pageType)) {
|
|
VTable.Assert((PageTable.IsNonGcPage(pageType) &&
|
|
PageTable.IsMyPage(page)) ||
|
|
PageTable.IsStackPage(pageType) ||
|
|
PageTable.IsSharedPage(pageType),
|
|
"interior.visit invalid page");
|
|
return;
|
|
}
|
|
UIntPtr realPtr = SegregatedFreeList.Find(addr);
|
|
VTable.Assert(Magic.fromAddress(realPtr).vtable != null,
|
|
"interior.visit null vtable");
|
|
markReferenceVisitor.VisitValue(realPtr);
|
|
}
|
|
|
|
}
|
|
|
|
|
|
/// <summary>
|
|
/// This class is used to visit every small object, determine if it
|
|
/// is marked and free it if not.
|
|
/// </summary>
|
|
private class SweepVisitor : SegregatedFreeList.ObjectVisitor
|
|
{
|
|
|
|
private SegregatedFreeList.TempList tempList;
|
|
|
|
internal override void VisitSmall(Object obj, UIntPtr memAddr)
|
|
{
|
|
if (ThreadHeaderQueue.GcMark(obj) == reclamationColor) {
|
|
// Not marked.
|
|
tempList.Add(memAddr);
|
|
}
|
|
}
|
|
|
|
internal override void VisitSmallPageEnd() {
|
|
SegregatedFreeList.FreeSmallList(ref tempList);
|
|
}
|
|
|
|
internal override UIntPtr VisitLarge(Object obj)
|
|
{
|
|
UIntPtr objectSize = ObjectLayout.Sizeof(obj);
|
|
if (ThreadHeaderQueue.GcMark(obj) == reclamationColor) {
|
|
// Not marked.
|
|
SegregatedFreeList.FreeLarge(obj);
|
|
}
|
|
return objectSize;
|
|
}
|
|
|
|
}
|
|
|
|
/// <summary>
|
|
/// Find the object address for a given interior pointer.
|
|
/// </summary>
|
|
internal override UIntPtr FindObjectAddr(UIntPtr interiorPtr) {
|
|
return SegregatedFreeList.Find(interiorPtr);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Visit all objects in the heap with a specified visitor.
|
|
/// </summary>
|
|
internal override
|
|
void VisitObjects(ObjectLayout.ObjectVisitor objectVisitor,
|
|
UIntPtr lowAddr, UIntPtr highAddr)
|
|
{
|
|
VTable.Assert(PageTable.PageAligned(lowAddr),
|
|
"low not page aligned");
|
|
VTable.Assert(PageTable.PageAligned(highAddr),
|
|
"high not page aligned");
|
|
UIntPtr lowPage = PageTable.Page(lowAddr);
|
|
UIntPtr highPage = PageTable.Page(highAddr);
|
|
SegregatedFreeList.VisitObjects(lowPage, highPage, objectVisitor);
|
|
}
|
|
|
|
/// <summary>
|
|
/// A new thread has been created, set any allocator/collector state.
|
|
/// </summary>
|
|
internal override void NewThreadNotification(Thread newThread,
|
|
bool initial)
|
|
{
|
|
base.NewThreadNotification(newThread, initial);
|
|
threadColor[newThread.threadIndex] = markedColor;
|
|
ThreadHeaderQueue.Reset(newThread);
|
|
SegregatedFreeList.NewThreadNotification(newThread, initial);
|
|
if (CurrentMarkingPhase == MarkingPhase.ComputingRoots) {
|
|
Transitions.MakeGCRequest(newThread.threadIndex);
|
|
}
|
|
}
|
|
|
|
internal override void DeadThreadNotification(Thread deadThread)
|
|
{
|
|
MultiUseWord.CollectFromThread(deadThread);
|
|
SegregatedFreeList.DeadThreadNotification(deadThread);
|
|
ThreadHeaderQueue.DeadThreadNotification(deadThread, markedColor);
|
|
threadColor[deadThread.threadIndex] = (UIntPtr) noColor;
|
|
base.DeadThreadNotification(deadThread);
|
|
}
|
|
|
|
internal override void ThreadStartNotification(int currentThreadIndex)
|
|
{
|
|
base.ThreadStartNotification(currentThreadIndex);
|
|
threadColor[currentThreadIndex] = markedColor;
|
|
if (CurrentMarkingPhase == MarkingPhase.ComputingRoots) {
|
|
Transitions.MakeGCRequest(currentThreadIndex);
|
|
}
|
|
}
|
|
|
|
internal override void ThreadDormantGCNotification(int threadIndex) {
|
|
// We could scan our own stack, but instead we try to get
|
|
// some work done while the Trace thread scans our stack.
|
|
Thread.SignalGCEvent(markThread.threadIndex);
|
|
}
|
|
|
|
/// <summary>
|
|
/// This class is used to verify that there are no dangling pointers.
|
|
/// </summary>
|
|
private class VerifyVisitor : SegregatedFreeList.ObjectVisitor
|
|
{
|
|
|
|
internal static VerifyVisitor visitor = new VerifyVisitor();
|
|
|
|
internal override void VisitSmall(Object obj, UIntPtr memAddr) {
|
|
if (ThreadHeaderQueue.GcMark(obj) == markedColor) {
|
|
VerifyMarkVisitor.visitor.VisitReferenceFields(obj);
|
|
} else {
|
|
VTable.Assert(ThreadHeaderQueue.GcMark(obj) ==
|
|
unmarkedColor);
|
|
}
|
|
}
|
|
|
|
internal override UIntPtr VisitLarge(Object obj) {
|
|
UIntPtr size;
|
|
if (ThreadHeaderQueue.GcMark(obj) == markedColor) {
|
|
// The object has the mark color, so it should only
|
|
// reference other objects with the mark color.
|
|
size = VerifyMarkVisitor.visitor.VisitReferenceFields(obj);
|
|
} else {
|
|
VTable.Assert(ThreadHeaderQueue.GcMark(obj) ==
|
|
unmarkedColor);
|
|
size = ObjectLayout.Sizeof(obj);
|
|
}
|
|
return size;
|
|
}
|
|
|
|
}
|
|
|
|
/// <summary>
|
|
/// This class is used to check that all the pointers within a marked
|
|
/// object point into other marked objects.
|
|
/// </summary>
|
|
private class VerifyMarkVisitor : NonNullReferenceVisitor
|
|
{
|
|
|
|
internal static VerifyMarkVisitor visitor
|
|
= new VerifyMarkVisitor();
|
|
|
|
internal unsafe override void Visit(UIntPtr *loc) {
|
|
UIntPtr addr = *loc;
|
|
UIntPtr page = PageTable.Page(addr);
|
|
if (PageTable.IsGcPage(page)) {
|
|
Object obj = Magic.fromAddress(addr);
|
|
|
|
VTable.Assert(ThreadHeaderQueue.GcMark(obj) == markedColor,
|
|
"dangling pointer!");
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
/// <summary>
|
|
/// This method loops through all non-null threads and asserts that
|
|
/// no thread has any work on its marking queue.
|
|
/// </summary>
|
|
private void VerifyEmptyQueues() {
|
|
Thread[] threadTable = Thread.threadTable;
|
|
for (int i = 0; i < threadTable.Length; i++) {
|
|
Thread t = threadTable[i];
|
|
if (t != null) {
|
|
VTable.Assert(ThreadHeaderQueue.IsEmpty(t),
|
|
"Non-empty Queue!");
|
|
}
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// This method walks through all objects in the heap to ensure
|
|
/// that no objects have values in their queue header field
|
|
/// </summary>
|
|
private void VerifyQueueHeaders() {
|
|
SegregatedFreeList.VisitAllObjects(VerifyHeaderVisitor.visitor);
|
|
}
|
|
|
|
/// <summary>
|
|
/// This visitor trivially asserts that the objects queue header
|
|
/// field is zero.
|
|
/// </summary>
|
|
private class VerifyHeaderVisitor : SegregatedFreeList.ObjectVisitor
|
|
{
|
|
|
|
internal static VerifyHeaderVisitor visitor
|
|
= new VerifyHeaderVisitor();
|
|
|
|
/// <summary>
|
|
/// Visit small objects, checking queue header.
|
|
/// </summary>
|
|
internal unsafe override void VisitSmall(Object obj,
|
|
UIntPtr memAddr)
|
|
{
|
|
VTable.Deny(ThreadHeaderQueue.IsInQueue(obj),
|
|
"Object in ThreadHeaderQueue");
|
|
}
|
|
|
|
internal override UIntPtr VisitLarge(Object obj) {
|
|
VTable.Deny(ThreadHeaderQueue.IsInQueue(obj),
|
|
"Object in ThreadHeaderQueue");
|
|
return ObjectLayout.Sizeof(obj);
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|