ITextStoreACP::RequestLock method (textstor.h)

Article
10/13/2021

The ITextStoreACP::RequestLock method is called by the TSF manager to provide a document lock in order to modify the document. This method calls the ITextStoreACPSink::OnLockGranted method to create the document lock.

Syntax

HRESULT RequestLock(
  [in]  DWORD   dwLockFlags,
  [out] HRESULT *phrSession
);

Parameters

[in] dwLockFlags

Specifies the type of lock requested.

Value	Meaning
TS_LF_READ	The document has a read-only lock and cannot be modified.
TS_LF_READWRITE	The document has a read/write lock and can be modified.
TS_LF_SYNC	The document has a synchronous-lock if this flag is combined with other flags.

[out] phrSession

If the lock request is synchronous, receives an HRESULT value from the ITextStoreAnchorSink::OnLockGranted method that specifies the result of the lock request.

If the lock request is asynchronous and the result is TS_S_ASYNC, the document receives an asynchronous lock. If the lock request is asynchronous and the result is TS_E_SYNCHRONOUS, the document cannot be locked synchronously.

Return value

This method can return one of these values.

Value	Description
S_OK	The method was successful.
E_FAIL	An unspecified error occurred.

Remarks

This method uses the ITextStoreACPSink::OnLockGranted method to lock the document. Applications must never modify the document or send change notifications using the ITextStoreACPSink::OnTextChange method from within the ITextStoreACP::RequestLock method. If the application has pending changes to report, the application can only respond to the asynchronous lock request.

Applications should not attempt to queue multiple ITextStoreACP::RequestLock method calls, because the application requires only a single callback. If the caller makes several read requests and one or more write requests, however, the callback should be for write access.

Successful requests for synchronous locks supersede requests for asynchronous locks. Unsuccessful requests for synchronous locks do not supersede requests for asynchronous locks. The implementation must still serve the outstanding asynchronous request, if one exists.

If the lock is granted before the ITextStoreACP::RequestLock method returns, the phrSession parameter will receive the HRESULT returned by the ITextStoreACPSink::OnLockGranted method. If the call is successful, but the lock will be granted later, the phrSession parameter receives the TS_S_ASYNC flag. The phrSession parameter should be ignored if ITextStoreACP::RequestLock returns anything other than S_OK.

A caller should never call this method reentrantly, except in the case that the caller holds a read-only lock. In this case the method can be called reentrantly to ask for an asynchronous write lock. The write lock will be granted later, after the read-only lock ends.

For more information about document locks, see Document Locks.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	textstor.h
DLL	Msctf.dll
Redistributable	TSF 1.0 on Windows 2000 Professional