ReaderWriterLock.RestoreLock(LockCookie) 메서드
정의
중요
일부 정보는 릴리스되기 전에 상당 부분 수정될 수 있는 시험판 제품과 관련이 있습니다. Microsoft는 여기에 제공된 정보에 대해 어떠한 명시적이거나 묵시적인 보증도 하지 않습니다.
ReleaseLock()을 호출하기 전에 스레드의 이전 잠금 상태를 복구합니다.
public:
void RestoreLock(System::Threading::LockCookie % lockCookie);public void RestoreLock (ref System.Threading.LockCookie lockCookie);[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public void RestoreLock (ref System.Threading.LockCookie lockCookie);member this.RestoreLock : LockCookie -> unit[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
member this.RestoreLock : LockCookie -> unitPublic Sub RestoreLock (ByRef lockCookie As LockCookie)매개 변수
- lockCookie
- LockCookie
LockCookie에 의해 반환된 ReleaseLock()입니다.
- 특성
예외
lockCookie의 주소는 null 포인터입니다.
예제
다음 코드 예제에서는 스레드에서 잠금을 획득한 횟수 및 나중에 잠금 상태를 복원하는 방법에 관계없이 메서드를 사용하여 ReleaseLock 잠금을 해제하는 방법을 보여 줍니다.
이 코드는 클래스에 제공된 더 큰 예제의 ReaderWriterLock 일부입니다.
// The complete code is located in the ReaderWriterLock
// class topic.
using namespace System;
using namespace System::Threading;
public ref class Test
{
public:
// Declaring the ReaderWriterLock at the class level
// makes it visible to all threads.
static ReaderWriterLock^ rwl = gcnew ReaderWriterLock;
// For this example, the shared resource protected by the
// ReaderWriterLock is just an integer.
static int resource = 0;
// The complete code is located in the ReaderWriterLock class topic.
using System;
using System.Threading;
public class Example
{
static ReaderWriterLock rwl = new ReaderWriterLock();
// Define the shared resource protected by the ReaderWriterLock.
static int resource = 0;
' The complete code is located in the ReaderWriterLock class topic.
Imports System.Threading
Public Module Example
Private rwl As New ReaderWriterLock()
' Define the shared resource protected by the ReaderWriterLock.
Private resource As Integer = 0
// Shows how to release all locks and later restore
// the lock state. Shows how to use sequence numbers
// to determine whether another thread has obtained
// a writer lock since this thread last accessed the
// resource.
static void ReleaseRestore( Random^ rnd, int timeOut )
{
int lastWriter;
try
{
rwl->AcquireReaderLock( timeOut );
try
{
// It is safe for this thread to read from
// the shared resource. Cache the value. (You
// might do this if reading the resource is
// an expensive operation.)
int resourceValue = resource;
Display( String::Format( "reads resource value {0}", resourceValue ) );
Interlocked::Increment( reads );
// Save the current writer sequence number.
lastWriter = rwl->WriterSeqNum;
// Release the lock, and save a cookie so the
// lock can be restored later.
LockCookie lc = rwl->ReleaseLock();
// Wait for a random interval (up to a
// quarter of a second), and then restore
// the previous state of the lock. Note that
// there is no timeout on the Restore method.
Thread::Sleep( rnd->Next( 250 ) );
rwl->RestoreLock( lc );
// Check whether other threads obtained the
// writer lock in the interval. If not, then
// the cached value of the resource is still
// valid.
if ( rwl->AnyWritersSince( lastWriter ) )
{
resourceValue = resource;
Interlocked::Increment( reads );
Display( String::Format( "resource has changed {0}", resourceValue ) );
}
else
{
Display( String::Format( "resource has not changed {0}", resourceValue ) );
}
}
finally
{
// Ensure that the lock is released.
rwl->ReleaseReaderLock();
}
}
catch ( ApplicationException^ )
{
// The reader lock request timed out.
Interlocked::Increment( readerTimeouts );
}
}
// Release all locks and later restores the lock state.
// Uses sequence numbers to determine whether another thread has
// obtained a writer lock since this thread last accessed the resource.
static void ReleaseRestore(Random rnd, int timeOut)
{
int lastWriter;
try {
rwl.AcquireReaderLock(timeOut);
try {
// It's safe for this thread to read from the shared resource,
// so read and cache the resource value.
int resourceValue = resource; // Cache the resource value.
Display("reads resource value " + resourceValue);
Interlocked.Increment(ref reads);
// Save the current writer sequence number.
lastWriter = rwl.WriterSeqNum;
// Release the lock and save a cookie so the lock can be restored later.
LockCookie lc = rwl.ReleaseLock();
// Wait for a random interval and then restore the previous state of the lock.
Thread.Sleep(rnd.Next(250));
rwl.RestoreLock(ref lc);
// Check whether other threads obtained the writer lock in the interval.
// If not, then the cached value of the resource is still valid.
if (rwl.AnyWritersSince(lastWriter)) {
resourceValue = resource;
Interlocked.Increment(ref reads);
Display("resource has changed " + resourceValue);
}
else {
Display("resource has not changed " + resourceValue);
}
}
finally {
// Ensure that the lock is released.
rwl.ReleaseReaderLock();
}
}
catch (ApplicationException) {
// The reader lock request timed out.
Interlocked.Increment(ref readerTimeouts);
}
}
' Release all locks and later restores the lock state.
' Uses sequence numbers to determine whether another thread has
' obtained a writer lock since this thread last accessed the resource.
Sub ReleaseRestore(rnd As Random ,timeOut As Integer)
Dim lastWriter As Integer
Try
rwl.AcquireReaderLock(timeOut)
Try
' It's safe for this thread to read from the shared resource,
' so read and cache the resource value.
Dim resourceValue As Integer = resource
Display("reads resource value " & resourceValue)
Interlocked.Increment(reads)
' Save the current writer sequence number.
lastWriter = rwl.WriterSeqNum
' Release the lock and save a cookie so the lock can be restored later.
Dim lc As LockCookie = rwl.ReleaseLock()
' Wait for a random interval and then restore the previous state of the lock.
Thread.Sleep(rnd.Next(250))
rwl.RestoreLock(lc)
' Check whether other threads obtained the writer lock in the interval.
' If not, then the cached value of the resource is still valid.
If rwl.AnyWritersSince(lastWriter) Then
resourceValue = resource
Interlocked.Increment(reads)
Display("resource has changed " & resourceValue)
Else
Display("resource has not changed " & resourceValue)
End If
Finally
' Ensure that the lock is released.
rwl.ReleaseReaderLock()
End Try
Catch ex As ApplicationException
' The reader lock request timed out.
Interlocked.Increment(readerTimeouts)
End Try
End Sub
};
}
End Module
설명
복원된 RestoreLock 상태에는 재귀 잠금 수가 포함됩니다.
다른 스레드가 기록기 잠금을 획득한 후 판독기 잠금을 복원하려고 시도하거나 다른 스레드가 판독기 잠금 또는 기록기 잠금을 획득한 후 기록기 잠금을 복원하려는 경우 스레드가 차단됩니다. RestoreLock 제한 시간을 허용하지 않으므로 가능한 교착 상태를 방지하기 위해 주의해야 합니다.
주의
호출 RestoreLock하기 전에 호출 이후 획득한 모든 잠금을 해제했는지 확인합니다 ReleaseLock. 예를 들어 스레드는 판독기 잠금을 획득한 다음 이전 기록기 잠금을 복원하려고 하면 교착 상태가 됩니다. IsWriterLockHeld 이러한 추가 잠금을 사용하고 IsReaderLockHeld 검색합니다.
에서 UpgradeToWriterLock반환된 을 LockCookie 사용하지 마세요.