[45723] | 1 | /** @file
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[46185] | 2 | * IPRT - Generic Work Queue with concurrent atomic access.
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[45723] | 3 | */
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| 4 |
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| 5 | /*
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[76553] | 6 | * Copyright (C) 2013-2019 Oracle Corporation
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[45723] | 7 | *
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| 8 | * This file is part of VirtualBox Open Source Edition (OSE), as
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| 9 | * available from http://www.virtualbox.org. This file is free software;
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| 10 | * you can redistribute it and/or modify it under the terms of the GNU
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| 11 | * General Public License (GPL) as published by the Free Software
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| 12 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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| 13 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 14 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 15 | *
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| 16 | * The contents of this file may alternatively be used under the terms
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| 17 | * of the Common Development and Distribution License Version 1.0
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| 18 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 19 | * VirtualBox OSE distribution, in which case the provisions of the
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| 20 | * CDDL are applicable instead of those of the GPL.
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| 21 | *
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| 22 | * You may elect to license modified versions of this file under the
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| 23 | * terms and conditions of either the GPL or the CDDL or both.
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| 24 | */
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| 25 |
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[76557] | 26 | #ifndef IPRT_INCLUDED_queueatomic_h
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| 27 | #define IPRT_INCLUDED_queueatomic_h
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[76507] | 28 | #ifndef RT_WITHOUT_PRAGMA_ONCE
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| 29 | # pragma once
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| 30 | #endif
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[45723] | 31 |
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| 32 | #include <iprt/types.h>
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| 33 | #include <iprt/asm.h>
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| 34 |
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[53615] | 35 | /** @defgroup grp_rt_queueatomic RTQueueAtomic - Generic Work Queue
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[45723] | 36 | * @ingroup grp_rt
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| 37 | *
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| 38 | * Implementation of a lockless work queue for threaded environments.
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| 39 | * @{
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| 40 | */
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| 41 |
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| 42 | RT_C_DECLS_BEGIN
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| 43 |
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| 44 | /**
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| 45 | * A work item
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| 46 | */
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[46185] | 47 | typedef struct RTQUEUEATOMICITEM
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[45723] | 48 | {
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| 49 | /** Pointer to the next work item in the list. */
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[46185] | 50 | struct RTQUEUEATOMICITEM * volatile pNext;
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| 51 | } RTQUEUEATOMICITEM;
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[45723] | 52 | /** Pointer to a work item. */
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[46185] | 53 | typedef RTQUEUEATOMICITEM *PRTQUEUEATOMICITEM;
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[45723] | 54 | /** Pointer to a work item pointer. */
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[46185] | 55 | typedef PRTQUEUEATOMICITEM *PPRTQUEUEATOMICITEM;
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[45723] | 56 |
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| 57 | /**
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| 58 | * Work queue.
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| 59 | */
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[46185] | 60 | typedef struct RTQUEUEATOMIC
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[45723] | 61 | {
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| 62 | /* Head of the work queue. */
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[46185] | 63 | volatile PRTQUEUEATOMICITEM pHead;
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| 64 | } RTQUEUEATOMIC;
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[45723] | 65 | /** Pointer to a work queue. */
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[46185] | 66 | typedef RTQUEUEATOMIC *PRTQUEUEATOMIC;
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[45723] | 67 |
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| 68 | /**
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| 69 | * Initialize a work queue.
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| 70 | *
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| 71 | * @param pWorkQueue Pointer to an unitialised work queue.
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| 72 | */
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[46185] | 73 | DECLINLINE(void) RTQueueAtomicInit(PRTQUEUEATOMIC pWorkQueue)
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[45723] | 74 | {
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| 75 | ASMAtomicWriteNullPtr(&pWorkQueue->pHead);
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| 76 | }
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| 77 |
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| 78 | /**
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| 79 | * Insert a new item into the work queue.
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| 80 | *
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| 81 | * @param pWorkQueue The work queue to insert into.
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| 82 | * @param pItem The item to insert.
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| 83 | */
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[46185] | 84 | DECLINLINE(void) RTQueueAtomicInsert(PRTQUEUEATOMIC pWorkQueue, PRTQUEUEATOMICITEM pItem)
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[45723] | 85 | {
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[46185] | 86 | PRTQUEUEATOMICITEM pNext = ASMAtomicUoReadPtrT(&pWorkQueue->pHead, PRTQUEUEATOMICITEM);
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| 87 | PRTQUEUEATOMICITEM pHeadOld;
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[45723] | 88 | pItem->pNext = pNext;
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| 89 | while (!ASMAtomicCmpXchgExPtr(&pWorkQueue->pHead, pItem, pNext, &pHeadOld))
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| 90 | {
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| 91 | pNext = pHeadOld;
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| 92 | Assert(pNext != pItem);
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| 93 | pItem->pNext = pNext;
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| 94 | ASMNopPause();
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| 95 | }
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| 96 | }
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| 97 |
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| 98 | /**
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| 99 | * Remove all items from the given work queue and return them in the inserted order.
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| 100 | *
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| 101 | * @returns Pointer to the first item.
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| 102 | * @param pWorkQueue The work queue.
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| 103 | */
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[46185] | 104 | DECLINLINE(PRTQUEUEATOMICITEM) RTQueueAtomicRemoveAll(PRTQUEUEATOMIC pWorkQueue)
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[45723] | 105 | {
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[46185] | 106 | PRTQUEUEATOMICITEM pHead = ASMAtomicXchgPtrT(&pWorkQueue->pHead, NULL, PRTQUEUEATOMICITEM);
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[45723] | 107 |
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| 108 | /* Reverse it. */
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[46185] | 109 | PRTQUEUEATOMICITEM pCur = pHead;
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[45723] | 110 | pHead = NULL;
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| 111 | while (pCur)
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| 112 | {
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[46185] | 113 | PRTQUEUEATOMICITEM pInsert = pCur;
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[45723] | 114 | pCur = pCur->pNext;
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| 115 | pInsert->pNext = pHead;
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| 116 | pHead = pInsert;
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| 117 | }
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| 118 |
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| 119 | return pHead;
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| 120 | }
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| 121 |
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| 122 | RT_C_DECLS_END
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| 123 |
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| 124 | /** @} */
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| 125 |
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[76585] | 126 | #endif /* !IPRT_INCLUDED_queueatomic_h */
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[53615] | 127 |
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