Concurrency::critical_section Class Reference

A non-reentrant mutex which is explicitly aware of the Concurrency Runtime. More...

#include <concrt.h>

Classes
class	scoped_lock
	An exception safe RAII wrapper for a critical_section object. More...

Public Types
typedef critical_section &	native_handle_type
	A reference to a critical_section object. More...

Public Member Functions
_CONCRTIMP	critical_section ()
	Constructs a new critical section. More...
_CONCRTIMP	~critical_section ()
	Destroys a critical section. More...
_CONCRTIMP void	lock ()
	Acquires this critical section. More...
_CONCRTIMP bool	try_lock ()
	Tries to acquire the lock without blocking. More...
_CONCRTIMP bool	try_lock_for (unsigned int _Timeout)
	Tries to acquire the lock without blocking for a specific number of milliseconds. More...
_CONCRTIMP void	unlock ()
	Unlocks the critical section. More...
_CONCRTIMP native_handle_type	native_handle ()
	Returns a platform specific native handle, if one exists. More...
void	_Flush_current_owner ()
	Guarantees that if any context holds the lock at the time the method is called, that context has released the lock before this method returns. More...
bool	_Acquire_lock (void *_PLockingNode, bool _FHasExternalNode)
	Acquires this critical section given a specific node to lock. More...

Private Member Functions
void	_Switch_to_active (void *_PLockingNode)
	The node allocated on the stack never really owns the lock because it would go out of scope and the insides would not be visible in unlock() where it could potentially need to unblock the next in the queue. Instead, its state is transferred to the internal node which is used as a scratch node. More...
	critical_section (const critical_section &)
	Hide copy constructor for a critical section More...
critical_section &	operator= (const critical_section &)
	Hide assignment operator for a critical section More...

Private Attributes
_CONCRT_BUFFER	_M_activeNode [(4 *sizeof(void *)+2 *sizeof(unsigned int)+sizeof(_CONCRT_BUFFER)-1)/sizeof(_CONCRT_BUFFER)]
void *volatile	_M_pHead
void *volatile	_M_pTail

Detailed Description

A non-reentrant mutex which is explicitly aware of the Concurrency Runtime.

For more information, see Synchronization Data Structures.

See also

reader_writer_lock Class

Member Typedef Documentation

typedef critical_section& Concurrency::critical_section::native_handle_type

A reference to a critical_section object.

Constructor & Destructor Documentation

_CONCRTIMP Concurrency::critical_section::critical_section

(

)

Constructs a new critical section.

_CONCRTIMP Concurrency::critical_section::~critical_section

(

)

Destroys a critical section.

It is expected that the lock is no longer held when the destructor runs. Allowing the critical section to destruct with the lock still held results in undefined behavior.

Concurrency::critical_section::critical_section ( const critical_section &  )

private

Hide copy constructor for a critical section

Member Function Documentation

bool Concurrency::critical_section::_Acquire_lock	(	void *	_PLockingNode,
		bool	_FHasExternalNode
	)

Acquires this critical section given a specific node to lock.

Parameters

_PLockingNode	The node that needs to own the lock.
_FHasExternalNode	An indication if the node being locked is external to the critical_section.

If the lock is already held by the calling context, an .improper_lock exception will be thrown.

void Concurrency::critical_section::_Flush_current_owner

(

)

Guarantees that if any context holds the lock at the time the method is called, that context has released the lock before this method returns.

If no context holds the lock at the instant this method is called, it returns instantly.

void Concurrency::critical_section::_Switch_to_active ( void *  _PLockingNode )

private

The node allocated on the stack never really owns the lock because it would go out of scope and the insides would not be visible in unlock() where it could potentially need to unblock the next in the queue. Instead, its state is transferred to the internal node which is used as a scratch node.

Parameters

_PLockingNode

The node that needs to own the lock.

_CONCRTIMP void Concurrency::critical_section::lock

(

)

Acquires this critical section.

It is often safer to utilize the scoped_lock construct to acquire and release a critical_section object in an exception safe way.

If the lock is already held by the calling context, an improper_lock exception will be thrown.

See also

critical_section::unlock Method, critical_section::scoped_lock Class

_CONCRTIMP native_handle_type Concurrency::critical_section::native_handle

(

)

Returns a platform specific native handle, if one exists.

Returns

A reference to the critical section.

A critical_section object is not associated with a platform specific native handle for the Windows operating system. The method simply returns a reference to the object itself.

critical_section& Concurrency::critical_section::operator= ( const critical_section &  )

private

Hide assignment operator for a critical section

_CONCRTIMP bool Concurrency::critical_section::try_lock

(

)

Tries to acquire the lock without blocking.

Returns

If the lock was acquired, the value true; otherwise, the value false.

See also

critical_section::unlock Method

_CONCRTIMP bool Concurrency::critical_section::try_lock_for

(

unsigned int

_Timeout

)

Tries to acquire the lock without blocking for a specific number of milliseconds.

Parameters

_Timeout

The number of milliseconds to wait before timing out.

Returns

If the lock was acquired, the value true; otherwise, the value false.

See also

critical_section::unlock Method

_CONCRTIMP void Concurrency::critical_section::unlock

(

)

Unlocks the critical section.

See also

critical_section::lock Method, critical_section::try_lock Method

Member Data Documentation

_CONCRT_BUFFER Concurrency::critical_section::_M_activeNode[(4 *sizeof(void *)+2 *sizeof(unsigned int)+sizeof(_CONCRT_BUFFER)-1)/sizeof(_CONCRT_BUFFER)]

private

void* volatile Concurrency::critical_section::_M_pHead

private

void* volatile Concurrency::critical_section::_M_pTail

private

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

• VS2017/inc/concrt.h