Add Beast fork from JUCE commit 265fb0e8ebc26e1469d6edcc68d2ca9acefeb508

modules/beast_core/threads/beast_ReadWriteLock.cpp

@@ -0,0 +1,153 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of Beast: https://github.com/vinniefalco/Beast
+    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
+
+    Portions of this file are from JUCE.
+    Copyright (c) 2013 - Raw Material Software Ltd.
+    Please visit http://www.juce.com
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+ReadWriteLock::ReadWriteLock() noexcept
+    : numWaitingWriters (0),
+      numWriters (0),
+      writerThreadId (0)
+{
+    readerThreads.ensureStorageAllocated (16);
+}
+
+ReadWriteLock::~ReadWriteLock() noexcept
+{
+    bassert (readerThreads.size() == 0);
+    bassert (numWriters == 0);
+}
+
+//==============================================================================
+void ReadWriteLock::enterRead() const noexcept
+{
+    while (! tryEnterRead())
+        waitEvent.wait (100);
+}
+
+bool ReadWriteLock::tryEnterRead() const noexcept
+{
+    const Thread::ThreadID threadId = Thread::getCurrentThreadId();
+
+    const SpinLock::ScopedLockType sl (accessLock);
+
+    for (int i = 0; i < readerThreads.size(); ++i)
+    {
+        ThreadRecursionCount& trc = readerThreads.getReference(i);
+
+        if (trc.threadID == threadId)
+        {
+            trc.count++;
+            return true;
+        }
+    }
+
+    if (numWriters + numWaitingWriters == 0
+         || (threadId == writerThreadId && numWriters > 0))
+    {
+        ThreadRecursionCount trc = { threadId, 1 };
+        readerThreads.add (trc);
+        return true;
+    }
+
+    return false;
+}
+
+void ReadWriteLock::exitRead() const noexcept
+{
+    const Thread::ThreadID threadId = Thread::getCurrentThreadId();
+    const SpinLock::ScopedLockType sl (accessLock);
+
+    for (int i = 0; i < readerThreads.size(); ++i)
+    {
+        ThreadRecursionCount& trc = readerThreads.getReference(i);
+
+        if (trc.threadID == threadId)
+        {
+            if (--(trc.count) == 0)
+            {
+                readerThreads.remove (i);
+                waitEvent.signal();
+            }
+
+            return;
+        }
+    }
+
+    jassertfalse; // unlocking a lock that wasn't locked..
+}
+
+//==============================================================================
+void ReadWriteLock::enterWrite() const noexcept
+{
+    const Thread::ThreadID threadId = Thread::getCurrentThreadId();
+    const SpinLock::ScopedLockType sl (accessLock);
+
+    for (;;)
+    {
+        if (readerThreads.size() + numWriters == 0
+             || threadId == writerThreadId
+             || (readerThreads.size() == 1
+                  && readerThreads.getReference(0).threadID == threadId))
+        {
+            writerThreadId = threadId;
+            ++numWriters;
+            break;
+        }
+
+        ++numWaitingWriters;
+        accessLock.exit();
+        waitEvent.wait (100);
+        accessLock.enter();
+        --numWaitingWriters;
+    }
+}
+
+bool ReadWriteLock::tryEnterWrite() const noexcept
+{
+    const Thread::ThreadID threadId = Thread::getCurrentThreadId();
+    const SpinLock::ScopedLockType sl (accessLock);
+
+    if (readerThreads.size() + numWriters == 0
+         || threadId == writerThreadId
+         || (readerThreads.size() == 1
+              && readerThreads.getReference(0).threadID == threadId))
+    {
+        writerThreadId = threadId;
+        ++numWriters;
+        return true;
+    }
+
+    return false;
+}
+
+void ReadWriteLock::exitWrite() const noexcept
+{
+    const SpinLock::ScopedLockType sl (accessLock);
+
+    // check this thread actually had the lock..
+    bassert (numWriters > 0 && writerThreadId == Thread::getCurrentThreadId());
+
+    if (--numWriters == 0)
+    {
+        writerThreadId = 0;
+        waitEvent.signal();
+    }
+}