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ReaderWriterLockSlim.TryEnterUpgradeableReadLock Method (TimeSpan)

Tries to enter the lock in upgradeable mode, with an optional time-out.

Namespace:  System.Threading
Assembly:  System.Core (in System.Core.dll)

public bool TryEnterUpgradeableReadLock(
	TimeSpan timeout
)

Parameters

timeout
Type: System.TimeSpan

The interval to wait, or -1 milliseconds to wait indefinitely.

Return Value

Type: System.Boolean
true if the calling thread entered upgradeable mode, otherwise, false.

ExceptionCondition
LockRecursionException

The RecursionPolicy property is LockRecursionPolicy.NoRecursion and the current thread has already entered the lock.

-or-

The current thread initially entered the lock in read mode, and therefore trying to enter upgradeable mode would create the possibility of a deadlock.

-or-

The recursion number would exceed the capacity of the counter. The limit is so large that applications should never encounter it.

ArgumentOutOfRangeException

The value of timeout is negative, but it is not equal to -1 milliseconds, which is the only negative value allowed.

-or-

The value of timeout is greater than Int32.MaxValue milliseconds.

If timeout is 0 (zero), this method checks the lock state and returns false immediately if the desired state is unavailable.

Use upgradeable mode when a thread usually accesses the resource protected by the ReaderWriterLockSlim in read mode, but may need to enter write mode if certain conditions are met. A thread in upgradeable mode can upgrade to write mode or downgrade to read mode.

Only one thread can enter a lock in upgradeable mode at any given time. If a thread is in upgradeable mode, and there are no threads waiting to enter write mode, any number of other threads can enter read mode, even if there are threads waiting to enter upgradeable mode.

If one or more threads are waiting to enter write mode, a thread that calls the TryEnterUpgradeableReadLock method blocks until those threads have either timed out or entered write mode and then exited from it, or until the calling thread's own time-out interval expires.

NoteNote

If a lock allows recursion, a thread that has entered the lock in upgradeable mode can enter upgradeable mode recursively, even if other threads are waiting to enter write mode.

.NET Framework

Supported in: 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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