NSLock class reference

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.

Instance Variables for NSCondition Class

_condition

@protected gs_cond_public_t _condition;

Availability: OpenStep

Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.

_mutex

@protected gs_mutex_public_t _mutex;

Availability: OpenStep

_name

@protected NSString* _name;

Availability: OpenStep

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.

Instance Variables

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.

isLockedByCurrentThread

- (BOOL) isLockedByCurrentThread;

Availability: OpenStep

Report whether this lock is held by the current thread.
Raises an exception if this is not supported by the system lock mechanism.

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.

Instance Variables for NSConditionLock Class

_condition

@protected NSCondition* _condition;

Availability: OpenStep

_condition_value

@protected int _condition_value;

Availability: OpenStep

_name

@protected NSString* _name;

Availability: OpenStep

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.

Instance Variables

Method summary

isLockedByCurrentThread

- (BOOL) isLockedByCurrentThread;

Availability: OpenStep

Report whether this lock is held by the current thread.
Raises an exception if this is not supported by the system lock mechanism.

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.

Instance Variables for NSLock Class

_mutex

@protected gs_mutex_public_t _mutex;

Availability: OpenStep

_name

@protected NSString* _name;

Availability: OpenStep

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.

Instance Variables

Method summary

isLockedByCurrentThread

- (BOOL) isLockedByCurrentThread;

Availability: OpenStep

Report whether this lock is held by the current thread.
Raises an exception if this is not supported by the system lock mechanism.

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.

Instance Variables for NSRecursiveLock Class

_mutex

@protected gs_mutex_public_t _mutex;

Availability: OpenStep

_name

@protected NSString* _name;

Availability: OpenStep

Software documentation for the NSObject(GSTraceLocks) informal protocol

NSObject(GSTraceLocks)

Declared in:

Foundation/NSLock.h

Availability: OpenStep

Controls tracing of locks for deadlocking.

Method summary

shouldCreateTraceableLocks:

+ (BOOL) shouldCreateTraceableLocks: (BOOL)shouldTrace;

Availability: OpenStep

Sets whether newly created lock objects (NSCondition, NSConditionLock, NSLock, NSRecursiveLock but NOT NSDistributedLock) should be created so that their use by threads is traced and deadlocks can be detected.
Returns the old value of the setting.