|
[Contents] [Previous] [Next] [Last]
This chapter describes the NSPR API for creation and manipulation of a mutex of type PRLock.
Lock Type
Lock Functions
In NSPR, a mutex of type PRLock controls locking, and associated condition variables communicate changes in state among threads. When a programmer associates a mutex with an arbitrary collection of data, the mutex provides a protective monitor around the data.
In general, a monitor is a conceptual entity composed of a mutex, one or more condition variables, and the monitored data. Monitors in this generic sense should not be confused with monitors used in Java programming. In addition to PRLock, NSPR provides another mutex type, PRMonitor, which is reentrant and can have only one associated condition variable. PRMonitor is intended for use with Java and reflects the Java approach to thread synchronization.
For an introduction to NSPR thread synchronization, including locks and condition variables, see Chapter 1, "Introduction to NSPR."
For reference information on NSPR condition variables, see Chapter 6, "Condition Variables."
Lock Type
PRLock
A mutual exclusion lock.
Syntax
#include <prlock.h>
typedef struct PRLock PRLock;
Description
NSPR represents a lock as an opaque entity to clients of the functions described in this
chapter. Functions that operate on locks do not have timeouts and are not interruptible.
Lock Functions
PR_NewLock
Creates a new lock.
Syntax
#include <prlock.h>
PRLock* PR_NewLock(void);
Returns
The function returns one of the following values:
Description
PR_NewLock creates a new opaque lock
PR_DestroyLock
Destroys a specified lock object.
Syntax
#include <prlock.h>
void PR_DestroyLock(PRLock *lock);
Parameter
PR_DestroyLock has one parameter:
Caution
The caller must ensure that no thread is currently in a lock-specific function. Locks do not provide self-referential protection against deletion.
PR_Lock
Locks a specified lock object.
Syntax
#include <prlock.h>
void PR_Lock(PRLock *lock);
Parameter
PR_Lock has one parameter:
Description
When PR_Lock returns, the calling thread is "in the monitor," also called "holding the monitor's lock." Any thread that attempts to acquire the same lock blocks until the holder of the lock exits the monitor. Acquiring the lock is not an interruptible operation, nor is there any timeout mechanism.
PR_Unlock
Releases a specified lock object. Releasing an unlocked lock results in an error.
Syntax
#include <prlock.h>
PRStatus PR_UnLock(PRLock *lock);
Parameter
PR_UnLock has one parameter:
Returns
The function returns one of the following values:
[Contents] [Previous] [Next] [Last]
Last Updated: Mon Jul 13 17:32:18 PDT 1998
Copyright © 1998
Netscape Communications Corporation
|
