Adding upstream version 7.0.6-dfsg.upstream/7.0.6-dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 137 insertions, 0 deletions

diff --git a/include/iprt/queueatomic.h b/include/iprt/queueatomic.h
new file mode 100644
index 00000000..72b188e1
--- /dev/null
+++ b/include/iprt/queueatomic.h
@@ -0,0 +1,137 @@
+/** @file
+ * IPRT - Generic Work Queue with concurrent atomic access.
+ */
+
+/*
+ * Copyright (C) 2013-2022 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+#ifndef IPRT_INCLUDED_queueatomic_h
+#define IPRT_INCLUDED_queueatomic_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/types.h>
+#include <iprt/asm.h>
+
+/** @defgroup grp_rt_queueatomic RTQueueAtomic - Generic Work Queue
+ * @ingroup grp_rt
+ *
+ * Implementation of a lockless work queue for threaded environments.
+ * @{
+ */
+
+RT_C_DECLS_BEGIN
+
+/**
+ * A work item
+ */
+typedef struct RTQUEUEATOMICITEM
+{
+    /** Pointer to the next work item in the list. */
+    struct RTQUEUEATOMICITEM * volatile pNext;
+} RTQUEUEATOMICITEM;
+/** Pointer to a work item. */
+typedef RTQUEUEATOMICITEM *PRTQUEUEATOMICITEM;
+/** Pointer to a work item pointer. */
+typedef PRTQUEUEATOMICITEM *PPRTQUEUEATOMICITEM;
+
+/**
+ * Work queue.
+ */
+typedef struct RTQUEUEATOMIC
+{
+    /* Head of the work queue. */
+    volatile PRTQUEUEATOMICITEM        pHead;
+} RTQUEUEATOMIC;
+/** Pointer to a work queue. */
+typedef RTQUEUEATOMIC *PRTQUEUEATOMIC;
+
+/**
+ * Initialize a work queue.
+ *
+ * @param   pWorkQueue          Pointer to an unitialised work queue.
+ */
+DECLINLINE(void) RTQueueAtomicInit(PRTQUEUEATOMIC pWorkQueue)
+{
+    ASMAtomicWriteNullPtr(&pWorkQueue->pHead);
+}
+
+/**
+ * Insert a new item into the work queue.
+ *
+ * @param   pWorkQueue          The work queue to insert into.
+ * @param   pItem               The item to insert.
+ */
+DECLINLINE(void) RTQueueAtomicInsert(PRTQUEUEATOMIC pWorkQueue, PRTQUEUEATOMICITEM pItem)
+{
+    PRTQUEUEATOMICITEM pNext = ASMAtomicUoReadPtrT(&pWorkQueue->pHead, PRTQUEUEATOMICITEM);
+    PRTQUEUEATOMICITEM pHeadOld;
+    pItem->pNext = pNext;
+    while (!ASMAtomicCmpXchgExPtr(&pWorkQueue->pHead, pItem, pNext, &pHeadOld))
+    {
+        pNext = pHeadOld;
+        Assert(pNext != pItem);
+        pItem->pNext = pNext;
+        ASMNopPause();
+    }
+}
+
+/**
+ * Remove all items from the given work queue and return them in the inserted order.
+ *
+ * @returns Pointer to the first item.
+ * @param   pWorkQueue          The work queue.
+ */
+DECLINLINE(PRTQUEUEATOMICITEM) RTQueueAtomicRemoveAll(PRTQUEUEATOMIC pWorkQueue)
+{
+    PRTQUEUEATOMICITEM pHead = ASMAtomicXchgPtrT(&pWorkQueue->pHead, NULL, PRTQUEUEATOMICITEM);
+
+    /* Reverse it. */
+    PRTQUEUEATOMICITEM pCur = pHead;
+    pHead = NULL;
+    while (pCur)
+    {
+        PRTQUEUEATOMICITEM pInsert = pCur;
+        pCur = pCur->pNext;
+        pInsert->pNext = pHead;
+        pHead = pInsert;
+    }
+
+    return pHead;
+}
+
+RT_C_DECLS_END
+
+/** @} */
+
+#endif /* !IPRT_INCLUDED_queueatomic_h */
+