JUCE/modules/juce_core/threads/juce_Thread.cpp

/*
  ==============================================================================

   This file is part of the JUCE library - "Jules' Utility Class Extensions"
   Copyright 2004-11 by Raw Material Software Ltd.

  ------------------------------------------------------------------------------

   JUCE can be redistributed and/or modified under the terms of the GNU General
   Public License (Version 2), as published by the Free Software Foundation.
   A copy of the license is included in the JUCE distribution, or can be found
   online at www.gnu.org/licenses.

   JUCE 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.

  ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.rawmaterialsoftware.com/juce for more information.

  ==============================================================================
*/

Thread::Thread (const String& threadName_)
    : threadName (threadName_),
      threadHandle (nullptr),
      threadId (0),
      threadPriority (5),
      affinityMask (0),
      shouldExit (false)
{
}

Thread::~Thread()
{
    /* If your thread class's destructor has been called without first stopping the thread, that
       means that this partially destructed object is still performing some work - and that's
       probably a Bad Thing!

       To avoid this type of nastiness, always make sure you call stopThread() before or during
       your subclass's destructor.
    */
    jassert (! isThreadRunning());

    stopThread (100);
}

//==============================================================================
// Use a ref-counted object to hold this shared data, so that it can outlive its static
// shared pointer when threads are still running during static shutdown.
struct CurrentThreadHolder   : public ReferenceCountedObject
{
    CurrentThreadHolder() noexcept {}

    typedef ReferenceCountedObjectPtr <CurrentThreadHolder> Ptr;
    ThreadLocalValue<Thread*> value;

    JUCE_DECLARE_NON_COPYABLE (CurrentThreadHolder);
};

static char currentThreadHolderLock [sizeof (SpinLock)]; // (statically initialised to zeros).

static CurrentThreadHolder::Ptr getCurrentThreadHolder()
{
    static CurrentThreadHolder::Ptr currentThreadHolder;
    SpinLock::ScopedLockType lock (*reinterpret_cast <SpinLock*> (currentThreadHolderLock));

    if (currentThreadHolder == nullptr)
        currentThreadHolder = new CurrentThreadHolder();

    return currentThreadHolder;
}

void Thread::threadEntryPoint()
{
    const CurrentThreadHolder::Ptr currentThreadHolder (getCurrentThreadHolder());
    currentThreadHolder->value = this;

    JUCE_TRY
    {
        if (threadName.isNotEmpty())
            setCurrentThreadName (threadName);

        if (startSuspensionEvent.wait (10000))
        {
            jassert (getCurrentThreadId() == threadId);

            if (affinityMask != 0)
                setCurrentThreadAffinityMask (affinityMask);

            run();
        }
    }
    JUCE_CATCH_ALL_ASSERT

    currentThreadHolder->value.releaseCurrentThreadStorage();
    closeThreadHandle();
}

// used to wrap the incoming call from the platform-specific code
void JUCE_API juce_threadEntryPoint (void* userData)
{
    static_cast <Thread*> (userData)->threadEntryPoint();
}

//==============================================================================
void Thread::startThread()
{
    const ScopedLock sl (startStopLock);

    shouldExit = false;

    if (threadHandle == nullptr)
    {
        launchThread();
        setThreadPriority (threadHandle, threadPriority);
        startSuspensionEvent.signal();
    }
}

void Thread::startThread (const int priority)
{
    const ScopedLock sl (startStopLock);

    if (threadHandle == nullptr)
    {
        threadPriority = priority;
        startThread();
    }
    else
    {
        setPriority (priority);
    }
}

bool Thread::isThreadRunning() const
{
    return threadHandle != nullptr;
}

Thread* Thread::getCurrentThread()
{
    return getCurrentThreadHolder()->value.get();
}

//==============================================================================
void Thread::signalThreadShouldExit()
{
    shouldExit = true;
}

bool Thread::waitForThreadToExit (const int timeOutMilliseconds) const
{
    // Doh! So how exactly do you expect this thread to wait for itself to stop??
    jassert (getThreadId() != getCurrentThreadId() || getCurrentThreadId() == 0);

    const int sleepMsPerIteration = 5;
    int count = timeOutMilliseconds / sleepMsPerIteration;

    while (isThreadRunning())
    {
        if (timeOutMilliseconds >= 0 && --count < 0)
            return false;

        sleep (sleepMsPerIteration);
    }

    return true;
}

void Thread::stopThread (const int timeOutMilliseconds)
{
    // agh! You can't stop the thread that's calling this method! How on earth
    // would that work??
    jassert (getCurrentThreadId() != getThreadId());

    const ScopedLock sl (startStopLock);

    if (isThreadRunning())
    {
        signalThreadShouldExit();
        notify();

        if (timeOutMilliseconds != 0)
            waitForThreadToExit (timeOutMilliseconds);

        if (isThreadRunning())
        {
            // very bad karma if this point is reached, as there are bound to be
            // locks and events left in silly states when a thread is killed by force..
            jassertfalse;
            Logger::writeToLog ("!! killing thread by force !!");

            killThread();

            threadHandle = nullptr;
            threadId = 0;
        }
    }
}

//==============================================================================
bool Thread::setPriority (const int newPriority)
{
    // NB: deadlock possible if you try to set the thread prio from the thread itself,
    // so using setCurrentThreadPriority instead in that case.
    if (getCurrentThreadId() == getThreadId())
        return setCurrentThreadPriority (newPriority);

    const ScopedLock sl (startStopLock);

    if (setThreadPriority (threadHandle, newPriority))
    {
        threadPriority = newPriority;
        return true;
    }

    return false;
}

bool Thread::setCurrentThreadPriority (const int newPriority)
{
    return setThreadPriority (0, newPriority);
}

void Thread::setAffinityMask (const uint32 newAffinityMask)
{
    affinityMask = newAffinityMask;
}

//==============================================================================
bool Thread::wait (const int timeOutMilliseconds) const
{
    return defaultEvent.wait (timeOutMilliseconds);
}

void Thread::notify() const
{
    defaultEvent.signal();
}

//==============================================================================
void SpinLock::enter() const noexcept
{
    if (! tryEnter())
    {
        for (int i = 20; --i >= 0;)
            if (tryEnter())
                return;

        while (! tryEnter())
            Thread::yield();
    }
}

//==============================================================================
#if JUCE_UNIT_TESTS

class AtomicTests  : public UnitTest
{
public:
    AtomicTests() : UnitTest ("Atomics") {}

    void runTest()
    {
        beginTest ("Misc");

        char a1[7];
        expect (numElementsInArray(a1) == 7);
        int a2[3];
        expect (numElementsInArray(a2) == 3);

        expect (ByteOrder::swap ((uint16) 0x1122) == 0x2211);
        expect (ByteOrder::swap ((uint32) 0x11223344) == 0x44332211);
        expect (ByteOrder::swap ((uint64) literal64bit (0x1122334455667788)) == literal64bit (0x8877665544332211));

        beginTest ("Atomic int");
        AtomicTester <int>::testInteger (*this);
        beginTest ("Atomic unsigned int");
        AtomicTester <unsigned int>::testInteger (*this);
        beginTest ("Atomic int32");
        AtomicTester <int32>::testInteger (*this);
        beginTest ("Atomic uint32");
        AtomicTester <uint32>::testInteger (*this);
        beginTest ("Atomic long");
        AtomicTester <long>::testInteger (*this);
        beginTest ("Atomic void*");
        AtomicTester <void*>::testInteger (*this);
        beginTest ("Atomic int*");
        AtomicTester <int*>::testInteger (*this);
        beginTest ("Atomic float");
        AtomicTester <float>::testFloat (*this);
      #if ! JUCE_64BIT_ATOMICS_UNAVAILABLE  // 64-bit intrinsics aren't available on some old platforms
        beginTest ("Atomic int64");
        AtomicTester <int64>::testInteger (*this);
        beginTest ("Atomic uint64");
        AtomicTester <uint64>::testInteger (*this);
        beginTest ("Atomic double");
        AtomicTester <double>::testFloat (*this);
      #endif
    }

    template <typename Type>
    class AtomicTester
    {
    public:
        AtomicTester() {}

        static void testInteger (UnitTest& test)
        {
            Atomic<Type> a, b;
            a.set ((Type) 10);
            test.expect (a.value == (Type) 10);
            test.expect (a.get() == (Type) 10);
            a += (Type) 15;
            test.expect (a.get() == (Type) 25);
            a.memoryBarrier();
            a -= (Type) 5;
            test.expect (a.get() == (Type) 20);
            test.expect (++a == (Type) 21);
            ++a;
            test.expect (--a == (Type) 21);
            test.expect (a.get() == (Type) 21);
            a.memoryBarrier();

            testFloat (test);
        }

        static void testFloat (UnitTest& test)
        {
            Atomic<Type> a, b;
            a = (Type) 21;
            a.memoryBarrier();

            /*  These are some simple test cases to check the atomics - let me know
                if any of these assertions fail on your system!
            */
            test.expect (a.get() == (Type) 21);
            test.expect (a.compareAndSetValue ((Type) 100, (Type) 50) == (Type) 21);
            test.expect (a.get() == (Type) 21);
            test.expect (a.compareAndSetValue ((Type) 101, a.get()) == (Type) 21);
            test.expect (a.get() == (Type) 101);
            test.expect (! a.compareAndSetBool ((Type) 300, (Type) 200));
            test.expect (a.get() == (Type) 101);
            test.expect (a.compareAndSetBool ((Type) 200, a.get()));
            test.expect (a.get() == (Type) 200);

            test.expect (a.exchange ((Type) 300) == (Type) 200);
            test.expect (a.get() == (Type) 300);

            b = a;
            test.expect (b.get() == a.get());
        }
    };
};

static AtomicTests atomicUnitTests;

#endif