C# in a Nutshell, Second Edition

Name

Monitor

Synopsis

This class contains static methods for thread communication and synchronization. The Enter( ) and Exit( ) methods allow you to obtain and release a lock on an object, respectively. If an object lock has already been obtained by another thread, Enter( ) blocks and resumes executing when the lock is released.

Various languages have the ability to silently emit calls on this type as language built-in primitives. C#’s lock{ } syntax translates into these two methods: the beginning of the lock block is transformed into a call to Enter( ), and the close of the block calls Exit( ). (In the presence of exceptions and return calls, the C# compiler must ensure the release of the monitor regardless of how the code exits the lock block.)

TryEnter( ) attempts to obtain an object lock, but it continues executing and returns false if unsuccessful. Wait( ) releases an object lock and causes the current thread to wait until another thread calls Pulse( ) or PulseAll( ) on the same object. Wait( ) must be executed from a synchronized block of code.

public sealed class Monitor {
// Public Static Methods
   public static void Enter(object obj);
   public static void Exit(object obj);
   public static void Pulse(object obj);
   public static void PulseAll(object obj);
   public static bool TryEnter(object obj);
   public static bool TryEnter(object obj, int millisecondsTimeout);
   public static bool TryEnter(object obj, TimeSpan timeout);
   public static bool Wait(object obj);
   public static bool Wait