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NSLock class reference

Authors

David Chisnall (csdavec@swan.ac.uk)

Copyright: (C) 1996-2010 Free Software Foundation, Inc.


Contents -

  1. Software documentation for the NSCondition class
  2. Software documentation for the NSConditionLock class
  3. Software documentation for the NSLock class
  4. Software documentation for the NSRecursiveLock class
  5. Software documentation for the NSLocking protocol

Software documentation for the NSCondition class

NSCondition : NSObject

Declared in:
Foundation/NSLock.h
Conforms to:
NSLocking
Availability: OpenStep

NSCondition provides an interface to POSIX condition variables.
Method summary

broadcast 

- (void) broadcast;
Availability: OpenStep

Wakes all threads that are waiting on this condition.

name 

- (NSString*) name;
Availability: OpenStep

Returns the name used for debugging messages.

setName: 

- (void) setName: (NSString*)newName;
Availability: OpenStep

Sets the name used for debugging messages.

signal 

- (void) signal;
Availability: OpenStep

Wakes wany one of the threads that are waiting on this condition.

wait 

- (void) wait;
Availability: OpenStep

Blocks and atomically unlocks the receiver. This method should only be called when the receiver is locked. The caller will then block until the receiver is sent either a -signal or -broadcast message from another thread. At which point, the calling thread will reacquire the lock.

waitUntilDate: 

- (BOOL) waitUntilDate: (NSDate*)limit;
Availability: OpenStep

Blocks the calling thread and acquires the lock, in the same way as -wait . Returns YES if the condition is signaled, or NO if the timeout is reached.

Software documentation for the NSConditionLock class

NSConditionLock : NSObject

Declared in:
Foundation/NSLock.h
Conforms to:
NSLocking
Availability: OpenStep

Lock that allows user to request it only when an internal integer condition is equal to a particular value. The condition is set on initialization and whenever the lock is relinquished.
Method summary

condition 

- (NSInteger) condition;
Availability: OpenStep

Return the current condition of the lock.

initWithCondition: 

- (id) initWithCondition: (NSInteger)value;
Availability: OpenStep

Initialize lock with given condition.

lock 

- (void) lock;
Availability: OpenStep

Block until acquiring lock.

lockBeforeDate: 

- (BOOL) lockBeforeDate: (NSDate*)limit;
Availability: OpenStep

Try to acquire lock and return before limit, YES if succeeded, NO if not.

lockWhenCondition: 

- (void) lockWhenCondition: (NSInteger)value;
Availability: OpenStep

Acquire lock when it is available and the internal condition is equal to value. Blocks until this occurs.

lockWhenCondition: beforeDate: 

- (BOOL) lockWhenCondition: (NSInteger)condition_to_meet beforeDate: (NSDate*)limitDate;
Availability: OpenStep

Try to acquire lock, when internal condition is equal to condition_to_meet, and return before limit, YES if succeeded, NO if not.

name 

- (NSString*) name;
Availability: MacOS-X 10.5.0

Return the name of the receiver or nil of none has been set.

setName: 

- (void) setName: (NSString*)name;
Availability: MacOS-X 10.5.0

Sets the name of the receiver (for use in debugging).

tryLock 

- (BOOL) tryLock;
Availability: OpenStep

Try to acquire lock regardless of condition and return immediately, YES if succeeded, NO if not.

tryLockWhenCondition: 

- (BOOL) tryLockWhenCondition: (NSInteger)value;
Availability: OpenStep

Try to acquire lock if condition is equal to value and return immediately in any case, YES if succeeded, NO if not.

unlock 

- (void) unlock;
Availability: OpenStep

Relinquish lock.

unlockWithCondition: 

- (void) unlockWithCondition: (NSInteger)value;
Availability: OpenStep

Relinquish the lock, setting internal condition to value.

Software documentation for the NSLock class

NSLock : NSObject

Declared in:
Foundation/NSLock.h
Conforms to:
NSLocking
Availability: OpenStep

Simplest lock for protecting critical sections of code.

An NSLock is used in multi-threaded applications to protect critical pieces of code. While one thread holds a lock within a piece of code, another thread cannot execute that code until the first thread has given up its hold on the lock. The limitation of NSLock is that you can only lock an NSLock once and it must be unlocked before it can be acquired again.
Other lock classes, notably NSRecursiveLock , have different restrictions.

Method summary

lock 

- (void) lock;
Availability: OpenStep

Block until acquiring lock.

lockBeforeDate: 

- (BOOL) lockBeforeDate: (NSDate*)limit;
Availability: OpenStep

Try to acquire lock and return before limit, YES if succeeded, NO if not.

name 

- (NSString*) name;
Availability: MacOS-X 10.5.0

Return the name of the receiver or nil of none has been set.

setName: 

- (void) setName: (NSString*)name;
Availability: MacOS-X 10.5.0

Sets the name of the receiver (for use in debugging).

tryLock 

- (BOOL) tryLock;
Availability: OpenStep

Try to acquire lock and return immediately, YES if succeeded, NO if not.

unlock 

- (void) unlock;
Availability: OpenStep

Relinquish lock.

Software documentation for the NSRecursiveLock class

NSRecursiveLock : NSObject

Declared in:
Foundation/NSLock.h
Conforms to:
NSLocking
Availability: OpenStep

Allows the lock to be recursively acquired by the same thread. If the same thread locks the mutex (n) times then that same thread must also unlock it (n) times before another thread can acquire the lock.
Method summary

lock 

- (void) lock;
Availability: OpenStep

Block until acquiring lock.

lockBeforeDate: 

- (BOOL) lockBeforeDate: (NSDate*)limit;
Availability: OpenStep

Try to acquire lock and return before limit, YES if succeeded, NO if not.

name 

- (NSString*) name;
Availability: MacOS-X 10.5.0

Return the name of the receiver or nil of none has been set.

setName: 

- (void) setName: (NSString*)name;
Availability: MacOS-X 10.5.0

Sets the name of the receiver (for use in debugging).

tryLock 

- (BOOL) tryLock;
Availability: OpenStep

Try to acquire lock regardless of condition and return immediately, YES if succeeded, NO if not.

unlock 

- (void) unlock;
Availability: OpenStep

Relinquish lock.

Software documentation for the NSLocking protocol

NSLocking

Declared in:
Foundation/NSLock.h
Availability: OpenStep

Protocol defining lock and unlock operations.
Method summary

lock 

- (void) lock;
Availability: OpenStep

Block until acquiring lock.

unlock 

- (void) unlock;
Availability: OpenStep

Relinquish lock.


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