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Improved some misleading example code for ScopedLock.

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jules 2014-02-23 11:56:46 +00:00
parent cfead6205b
commit fe25f6ee3c
1 changed files with 51 additions and 40 deletions
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91
modules/juce_core/threads/juce_CriticalSection.h
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@ -38,6 +38,10 @@
one of these is by using RAII in the form of a local ScopedLock object - have a look
through the codebase for many examples of how to do this.
In almost all cases you'll want to declare your CriticalSection as a member variable.
Occasionally you may want to declare one as a static variable, but in that case the usual
C++ static object order-of-construction warnings should be heeded.
@see ScopedLock, ScopedTryLock, ScopedUnlock, SpinLock, ReadWriteLock, Thread, InterProcessLock
*/
class JUCE_API CriticalSection
@ -157,21 +161,27 @@ private:
/**
Automatically locks and unlocks a CriticalSection object.
Use one of these as a local variable to provide RAII-based locking of a CriticalSection.
You can use a ScopedLock as a local variable to provide RAII-based locking of a CriticalSection.
e.g. @code
CriticalSection myCriticalSection;
for (;;)
struct MyObject
{
const ScopedLock myScopedLock (myCriticalSection);
// myCriticalSection is now locked
CriticalSection objectLock;
...do some stuff...
// assuming that this example function will be called by multiple threads
void foo()
{
const ScopedLock myScopedLock (objectLock);
// myCriticalSection gets unlocked here.
}
// objectLock is now locked..
...do some thread-safe work here...
// ..and objectLock gets unlocked here, as myScopedLock goes out of
// scope at the end of the block
}
};
@endcode
@see CriticalSection, ScopedUnlock
@ -189,29 +199,29 @@ typedef CriticalSection::ScopedLockType ScopedLock;
e.g. @code
CriticalSection myCriticalSection;
for (;;)
struct MyObject
{
const ScopedLock myScopedLock (myCriticalSection);
// myCriticalSection is now locked
CriticalSection objectLock;
... do some stuff with it locked ..
while (xyz)
void foo()
{
... do some stuff with it locked ..
{
const ScopedLock myScopedLock (objectLock);
const ScopedUnlock unlocker (myCriticalSection);
// objectLock is now locked..
// myCriticalSection is now unlocked for the remainder of this block,
// and re-locked at the end.
{
ScopedUnlock myUnlocker (objectLock);
...do some stuff with it unlocked ...
// ..and now unlocked..
}
// ..and now locked again..
}
// ..and finally unlocked.
}
// myCriticalSection gets unlocked here.
}
};
@endcode
@see CriticalSection, ScopedLock
@ -225,26 +235,27 @@ typedef CriticalSection::ScopedUnlockType ScopedUnlock;
Use one of these as a local variable to control access to a CriticalSection.
e.g. @code
CriticalSection myCriticalSection;
for (;;)
struct MyObject
{
const ScopedTryLock myScopedTryLock (myCriticalSection);
CriticalSection objectLock;
// Unlike using a ScopedLock, this may fail to actually get the lock, so you
// should test this with the isLocked() method before doing your thread-unsafe
// action..
if (myScopedTryLock.isLocked())
void foo()
{
...do some stuff...
}
else
{
..our attempt at locking failed because another thread had already locked it..
}
const ScopedTryLock myScopedTryLock (objectLock);
// myCriticalSection gets unlocked here (if it was locked)
}
// Unlike using a ScopedLock, this may fail to actually get the lock, so you
// must call the isLocked() method before making any assumptions..
if (myScopedTryLock.isLocked())
{
...safely do some work...
}
else
{
// If we get here, then our attempt at locking failed because another thread had already locked it..
}
}
};
@endcode
@see CriticalSection::tryEnter, ScopedLock, ScopedUnlock, ScopedReadLock