540 lines
10 KiB
C
540 lines
10 KiB
C
/*++
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Copyright (c) 1995 Microsoft Corporation
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Module Name:
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lookasid.c
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Abstract:
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This module implements heap lookaside list function.
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Author:
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David N. Cutler (davec) 19-Feb-1995
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Revision History:
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--*/
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#include "ntrtlp.h"
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#include "heap.h"
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#include "heappriv.h"
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// begin_ntslist
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#if !defined(NTSLIST_ASSERT)
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#define NTSLIST_ASSERT(x) ASSERT(x)
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#endif // !defined(NTSLIST_ASSERT)
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#ifdef _NTSLIST_DIRECT_
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#define INLINE_SLIST __inline
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#define RtlInitializeSListHead _RtlInitializeSListHead
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#define _RtlFirstEntrySList FirstEntrySList
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PSINGLE_LIST_ENTRY
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FirstEntrySList (
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const SLIST_HEADER *ListHead
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);
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#define RtlInterlockedPopEntrySList _RtlInterlockedPopEntrySList
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#define RtlInterlockedPushEntrySList _RtlInterlockedPushEntrySList
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#define RtlInterlockedFlushSList _RtlInterlockedFlushSList
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#define _RtlQueryDepthSList RtlpQueryDepthSList
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#else
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#define INLINE_SLIST
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#endif // _NTSLIST_DIRECT_
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// end_ntslist
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//
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// Define minimum allocation threshold.
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//
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#define MINIMUM_ALLOCATION_THRESHOLD 25
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// begin_ntslist
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//
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// Define forward referenced function prototypes.
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//
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VOID
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RtlpInitializeSListHead (
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IN PSLIST_HEADER ListHead
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);
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PSINGLE_LIST_ENTRY
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FASTCALL
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RtlpInterlockedPopEntrySList (
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IN PSLIST_HEADER ListHead
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);
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PSINGLE_LIST_ENTRY
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FASTCALL
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RtlpInterlockedPushEntrySList (
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IN PSLIST_HEADER ListHead,
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IN PSINGLE_LIST_ENTRY ListEntry
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);
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PSINGLE_LIST_ENTRY
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FASTCALL
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RtlpInterlockedFlushSList (
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IN PSLIST_HEADER ListHead
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);
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USHORT
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RtlpQueryDepthSList (
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IN PSLIST_HEADER SListHead
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);
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// end_ntslist
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VOID
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RtlpInitializeHeapLookaside (
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IN PHEAP_LOOKASIDE Lookaside,
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IN USHORT Depth
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)
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/*++
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Routine Description:
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This function initializes a heap lookaside list structure
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Arguments:
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Lookaside - Supplies a pointer to a heap lookaside list structure.
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Allocate - Supplies a pointer to an allocate function.
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Free - Supplies a pointer to a free function.
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HeapHandle - Supplies a pointer to the heap that backs this lookaside list
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Flags - Supplies a set of heap flags.
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Size - Supplies the size for the lookaside list entries.
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Depth - Supplies the maximum depth of the lookaside list.
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Return Value:
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None.
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--*/
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{
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//
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// Initialize the lookaside list structure.
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//
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RtlInitializeSListHead(&Lookaside->ListHead);
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Lookaside->Depth = MINIMUM_LOOKASIDE_DEPTH;
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Lookaside->MaximumDepth = 256; //Depth;
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Lookaside->TotalAllocates = 0;
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Lookaside->AllocateMisses = 0;
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Lookaside->TotalFrees = 0;
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Lookaside->FreeMisses = 0;
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Lookaside->LastTotalAllocates = 0;
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Lookaside->LastAllocateMisses = 0;
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return;
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}
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VOID
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RtlpDeleteHeapLookaside (
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IN PHEAP_LOOKASIDE Lookaside
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)
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/*++
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Routine Description:
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This function frees any entries specified by the lookaside structure.
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Arguments:
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Lookaside - Supplies a pointer to a heap lookaside list structure.
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Return Value:
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None.
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--*/
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{
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PVOID Entry;
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return;
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}
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VOID
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RtlpAdjustHeapLookasideDepth (
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IN PHEAP_LOOKASIDE Lookaside
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)
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/*++
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Routine Description:
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This function is called periodically to adjust the maximum depth of
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a single heap lookaside list.
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Arguments:
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Lookaside - Supplies a pointer to a heap lookaside list structure.
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Return Value:
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None.
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--*/
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{
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ULONG Allocates;
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ULONG Misses;
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//
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// Compute the total number of allocations and misses for this scan
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// period.
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//
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Allocates = Lookaside->TotalAllocates - Lookaside->LastTotalAllocates;
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Lookaside->LastTotalAllocates = Lookaside->TotalAllocates;
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Misses = Lookaside->AllocateMisses - Lookaside->LastAllocateMisses;
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Lookaside->LastAllocateMisses = Lookaside->AllocateMisses;
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//
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// Compute target depth of lookaside list.
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//
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{
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ULONG Ratio;
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ULONG Target;
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//
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// If the allocate rate is less than the mimimum threshold, then lower
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// the maximum depth of the lookaside list. Otherwise, if the miss rate
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// is less than .5%, then lower the maximum depth. Otherwise, raise the
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// maximum depth based on the miss rate.
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//
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if (Misses >= Allocates) {
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Misses = Allocates;
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}
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if (Allocates == 0) {
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Allocates = 1;
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}
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Ratio = (Misses * 1000) / Allocates;
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Target = Lookaside->Depth;
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if (Allocates < MINIMUM_ALLOCATION_THRESHOLD) {
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if (Target > (MINIMUM_LOOKASIDE_DEPTH + 10)) {
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Target -= 10;
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} else {
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Target = MINIMUM_LOOKASIDE_DEPTH;
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}
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} else if (Ratio < 5) {
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if (Target > (MINIMUM_LOOKASIDE_DEPTH + 1)) {
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Target -= 1;
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} else {
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Target = MINIMUM_LOOKASIDE_DEPTH;
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}
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} else {
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Target += ((Ratio * Lookaside->MaximumDepth) / (1000 * 2)) + 5;
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if (Target > Lookaside->MaximumDepth) {
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Target = Lookaside->MaximumDepth;
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}
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}
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Lookaside->Depth = (USHORT)Target;
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}
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return;
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}
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PVOID
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RtlpAllocateFromHeapLookaside (
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IN PHEAP_LOOKASIDE Lookaside
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)
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/*++
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Routine Description:
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This function removes (pops) the first entry from the specified
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heap lookaside list.
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Arguments:
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Lookaside - Supplies a pointer to a paged lookaside list structure.
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Return Value:
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If an entry is removed from the specified lookaside list, then the
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address of the entry is returned as the function value. Otherwise,
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NULL is returned.
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--*/
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{
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PVOID Entry;
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Lookaside->TotalAllocates += 1;
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//
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// We need to protect ourselves from a second thread that can cause us
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// to fault on the pop. If we do fault then we'll just do a regular pop
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// operation
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//
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__try {
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Entry = RtlpInterlockedPopEntrySList(&Lookaside->ListHead);
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} __except (EXCEPTION_EXECUTE_HANDLER) {
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Entry = NULL;
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}
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if (Entry != NULL) {
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return Entry;
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}
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Lookaside->AllocateMisses += 1;
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return NULL;
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}
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BOOLEAN
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RtlpFreeToHeapLookaside (
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IN PHEAP_LOOKASIDE Lookaside,
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IN PVOID Entry
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)
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/*++
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Routine Description:
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This function inserts (pushes) the specified entry into the specified
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paged lookaside list.
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Arguments:
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Lookaside - Supplies a pointer to a paged lookaside list structure.
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Entry - Supples a pointer to the entry that is inserted in the
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lookaside list.
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Return Value:
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BOOLEAN - TRUE if the entry was put on the lookaside list and FALSE
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otherwise.
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--*/
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{
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Lookaside->TotalFrees += 1;
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if (RtlpQueryDepthSList(&Lookaside->ListHead) < Lookaside->Depth) {
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RtlpInterlockedPushEntrySList(&Lookaside->ListHead,
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(PSINGLE_LIST_ENTRY)Entry);
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return TRUE;
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}
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Lookaside->FreeMisses += 1;
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return FALSE;
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}
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// begin_ntslist
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INLINE_SLIST
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VOID
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RtlInitializeSListHead (
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IN PSLIST_HEADER SListHead
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)
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/*++
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Routine Description:
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This function initializes a sequenced singly linked listhead.
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Arguments:
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SListHead - Supplies a pointer to a sequenced singly linked listhead.
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Return Value:
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None.
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--*/
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{
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RtlpInitializeSListHead(SListHead);
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return;
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}
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INLINE_SLIST
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PSINGLE_LIST_ENTRY
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RtlInterlockedPopEntrySList (
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IN PSLIST_HEADER ListHead
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)
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/*++
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Routine Description:
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This function removes an entry from the front of a sequenced singly
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linked list so that access to the list is synchronized in a MP system.
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If there are no entries in the list, then a value of NULL is returned.
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Otherwise, the address of the entry that is removed is returned as the
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function value.
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Arguments:
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ListHead - Supplies a pointer to the sequenced listhead from which
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an entry is to be removed.
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Return Value:
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The address of the entry removed from the list, or NULL if the list is
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empty.
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--*/
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{
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ULONG Count;
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//
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// It is posible during the pop of the sequenced list that an access
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// violation can occur if a stale pointer is dereferenced. This is an
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// acceptable result and the operation can be retried.
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//
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// N.B. The count is used to distinguish the case where the list head
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// itself causes the access violation and therefore no progress
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// can be made by repeating the operation.
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//
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Count = 0;
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do {
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__try {
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return RtlpInterlockedPopEntrySList(ListHead);
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} __except (Count++ < 20 ? EXCEPTION_EXECUTE_HANDLER : EXCEPTION_CONTINUE_SEARCH) {
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continue;
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}
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} while (TRUE);
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}
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INLINE_SLIST
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PSINGLE_LIST_ENTRY
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RtlInterlockedPushEntrySList (
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IN PSLIST_HEADER ListHead,
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IN PSINGLE_LIST_ENTRY ListEntry
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)
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/*++
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Routine Description:
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This function inserts an entry at the head of a sequenced singly linked
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list so that access to the list is synchronized in an MP system.
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Arguments:
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ListHead - Supplies a pointer to the sequenced listhead into which
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an entry is to be inserted.
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ListEntry - Supplies a pointer to the entry to be inserted at the
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head of the list.
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Return Value:
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The address of the previous firt entry in the list. NULL implies list
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went from empty to not empty.
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--*/
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{
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NTSLIST_ASSERT(((ULONG_PTR)ListEntry & 0x7) == 0);
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return RtlpInterlockedPushEntrySList(ListHead, ListEntry);
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}
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INLINE_SLIST
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PSINGLE_LIST_ENTRY
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RtlInterlockedFlushSList (
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IN PSLIST_HEADER ListHead
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)
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/*++
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Routine Description:
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This function flushes the entire list of entries on a sequenced singly
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linked list so that access to the list is synchronized in a MP system.
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If there are no entries in the list, then a value of NULL is returned.
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Otherwise, the address of the firt entry on the list is returned as the
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function value.
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Arguments:
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ListHead - Supplies a pointer to the sequenced listhead from which
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an entry is to be removed.
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Return Value:
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The address of the entry removed from the list, or NULL if the list is
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empty.
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--*/
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{
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return RtlpInterlockedFlushSList(ListHead);
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}
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// end_ntslist
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USHORT
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RtlQueryDepthSList (
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IN PSLIST_HEADER SListHead
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)
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/*++
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Routine Description:
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This function queries the depth of the specified SLIST.
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Arguments:
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SListHead - Supplies a pointer to a sequenced singly linked listhead.
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Return Value:
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The current depth of the specified SLIST is returned as the function
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value.
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--*/
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{
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return RtlpQueryDepthSList(SListHead);
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}
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