juce::ReadWriteLock Class Reference

A critical section that allows multiple simultaneous readers. More...

#include <juce_ReadWriteLock.h>

Collaboration diagram for juce::ReadWriteLock:

Classes
struct	ThreadRecursionCount

Public Member Functions
	ReadWriteLock () noexcept
	Creates a ReadWriteLock object. More...
	~ReadWriteLock () noexcept
	Destructor. More...
void	enterRead () const noexcept
	Locks this object for reading. More...
void	enterWrite () const noexcept
	Locks this object for writing. More...
void	exitRead () const noexcept
	Releases the read-lock. More...
void	exitWrite () const noexcept
	Releases the write-lock. More...
bool	tryEnterRead () const noexcept
	Tries to lock this object for reading. More...
bool	tryEnterWrite () const noexcept
	Tries to lock this object for writing. More...

Private Member Functions
bool	tryEnterWriteInternal (Thread::ThreadID) const noexcept

Private Attributes
SpinLock	accessLock
int	numWaitingWriters = 0
int	numWriters = 0
Array< ThreadRecursionCount >	readerThreads
WaitableEvent	readWaitEvent
Thread::ThreadID	writerThreadId = {}
WaitableEvent	writeWaitEvent

Detailed Description

A critical section that allows multiple simultaneous readers.

Features of this type of lock are:

• Multiple readers can hold the lock at the same time, but only one writer can hold it at once.
• Writers trying to gain the lock will be blocked until all readers and writers have released it
• Readers trying to gain the lock while a writer is waiting to acquire it will be blocked until the writer has obtained and released it
• If a thread already has a read lock and tries to obtain a write lock, it will succeed if there are no other readers
• If a thread already has the write lock and tries to obtain a read lock, this will succeed.
• Recursive locking is supported.

See also

ScopedReadLock, ScopedWriteLock, CriticalSection

@tags{Core}

Constructor & Destructor Documentation

ReadWriteLock()

juce::ReadWriteLock::ReadWriteLock ( )

noexcept

Creates a ReadWriteLock object.

~ReadWriteLock()

juce::ReadWriteLock::~ReadWriteLock ( )

noexcept

Destructor.

If the object is deleted whilst locked, any subsequent behaviour is undefined.

Member Function Documentation

enterRead()

void juce::ReadWriteLock::enterRead ( ) const

noexcept

Locks this object for reading.

Multiple threads can simultaneously lock the object for reading, but if another thread has it locked for writing, then this will block until it releases the lock.

See also

exitRead, ScopedReadLock

enterWrite()

void juce::ReadWriteLock::enterWrite ( ) const

noexcept

Locks this object for writing.

This will block until any other threads that have it locked for reading or writing have released their lock.

See also

exitWrite, ScopedWriteLock

exitRead()

void juce::ReadWriteLock::exitRead ( ) const

noexcept

Releases the read-lock.

If the caller thread hasn't got the lock, this can have unpredictable results.

If the enterRead() method has been called multiple times by the thread, each call must be matched by a call to exitRead() before other threads will be allowed to take over the lock.

See also

enterRead, ScopedReadLock

exitWrite()

void juce::ReadWriteLock::exitWrite ( ) const

noexcept

Releases the write-lock.

If the caller thread hasn't got the lock, this can have unpredictable results.

If the enterWrite() method has been called multiple times by the thread, each call must be matched by a call to exit() before other threads will be allowed to take over the lock.

See also

enterWrite, ScopedWriteLock

tryEnterRead()

bool juce::ReadWriteLock::tryEnterRead ( ) const

noexcept

Tries to lock this object for reading.

Multiple threads can simultaneously lock the object for reading, but if another thread has it locked for writing, then this will fail and return false.

Returns

true if the lock is successfully gained.

See also

exitRead, ScopedReadLock

tryEnterWrite()

bool juce::ReadWriteLock::tryEnterWrite ( ) const

noexcept

Tries to lock this object for writing.

This is like enterWrite(), but doesn't block - it returns true if it manages to obtain the lock.

Returns

true if the lock is successfully gained.

See also

enterWrite

tryEnterWriteInternal()

bool juce::ReadWriteLock::tryEnterWriteInternal ( Thread::ThreadID  ) const

privatenoexcept

Member Data Documentation

accessLock

SpinLock juce::ReadWriteLock::accessLock

private

numWaitingWriters

int juce::ReadWriteLock::numWaitingWriters = 0

mutableprivate

numWriters

int juce::ReadWriteLock::numWriters = 0

private

readerThreads

Array<ThreadRecursionCount> juce::ReadWriteLock::readerThreads

mutableprivate

readWaitEvent

WaitableEvent juce::ReadWriteLock::readWaitEvent

private

writerThreadId

Thread::ThreadID juce::ReadWriteLock::writerThreadId = {}

mutableprivate

writeWaitEvent

WaitableEvent juce::ReadWriteLock::writeWaitEvent

private

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The documentation for this class was generated from the following file:

• juce_ReadWriteLock.h