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CSyncObject Class

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A pure virtual class that provides functionality common to the synchronization objects in Win32.

Syntax

class CSyncObject : public CObject

Members

Public Constructors

Name Description
CSyncObject::CSyncObject Constructs a CSyncObject object.

Public Methods

Name Description
CSyncObject::Lock Gains access to the synchronization object.
CSyncObject::Unlock Gains access to the synchronization object.

Public Operators

Name Description
CSyncObject::operator HANDLE Provides access to the synchronization object.

Public Data Members

Name Description
CSyncObject::m_hObject The handle to the underlying synchronization object.

Remarks

The Microsoft Foundation Class Library provides several classes derived from CSyncObject. These are CEvent, CMutex, CCriticalSection, and CSemaphore.

For information on how to use the synchronization objects, see the article Multithreading: How to Use the Synchronization Classes.

Inheritance Hierarchy

CObject

CSyncObject

Requirements

Header: afxmt.h

CSyncObject::CSyncObject

Constructs a synchronization object with the supplied name.

explicit CSyncObject(LPCTSTR pstrName);
virtual ~CSyncObject();

Parameters

pstrName
The name of the object. If NULL, pstrName will be null.

CSyncObject::Lock

Call this function to gain access to the resource controlled by the synchronization object.

virtual BOOL Lock(DWORD dwTimeout = INFINITE);

Parameters

dwTimeout
Specifies the amount of time in milliseconds to wait for the synchronization object to be available (signaled). If INFINITE, Lock will wait until the object is signaled before returning.

Return Value

Nonzero if the function was successful; otherwise 0.

Remarks

If the synchronization object is signaled, Lock will return successfully and the thread now owns the object. If the synchronization object is nonsignaled (unavailable), Lock will wait for the synchronization object to become signaled up to the number of milliseconds specified in the dwTimeOut parameter. If the synchronization object did not become signaled in the specified amount of time, Lock returns failure.

CSyncObject::m_hObject

The handle to the underlying synchronization object.

HANDLE m_hObject;

CSyncObject::operator HANDLE

Use this operator to get the handle of the CSyncObject object.

operator HANDLE() const;

Return Value

If successful, the handle of the synchronization object; otherwise, NULL.

Remarks

You can use the handle to call Windows APIs directly.

CSyncObject::Unlock

The declaration of Unlock with no parameters is a pure virtual function, and must be overridden by all classes deriving from CSyncObject.

virtual BOOL Unlock() = 0; virtual BOOL Unlock(
    LONG lCount,
    LPLONG lpPrevCount = NULL);

Parameters

lCount
Not used by default implementation.

lpPrevCount
Not used by default implementation.

Return Value

Default implementation always returns TRUE.

Remarks

The default implementation of the declaration with two parameters always returns TRUE. This function is called to release access to the synchronization object owned by the calling thread. The second declaration is provided for synchronization objects such as semaphores that allow more than one access of a controlled resource.

See also

CObject Class
Hierarchy Chart