[Catfish_Man]

I'm writing a program in which it would be very useful to have a queue that could be added to and removed from simultaneously. I started writing my own, but got frustrated and decided to ask if there was one already out on the net that I could use. Googling turned up a lot of info that suggested this is a fairly common object to need, but no code. Does anyone know of a free thread safe queue?

[seppak]

This is one i made just using an array and not using nodes and such..

#import <Foundation/Foundation.h>

@interface SKQueue : NSObject <NSCoding>
{
NSMutableArray * data;
NSRecursiveLock * theLock;
}

#pragma mark —Initialization & Deallocation—
- (id)init;
- (id)initWithQueue:(SKQueue *)queue;
- (id)initWithCoder:(NSCoder *)coder;
- (void)dealloc;
- (void)encodeWithCoder:(NSCoder *)coder;

#pragma mark
#pragma mark —Accessor Methods—
- (int)size;
- (BOOL)isEmpty;
- (id)top;
- (NSArray *)data;

#pragma mark
#pragma mark —Modifier Methods—
- (void)enqueue:(id)object;
- (id)dequeue;
- (void)removeAll;

@end

#import "SKQueue.h"

@implementation SKQueue

#pragma mark —Initialization & Deallocation—
- (id)init
{
if (self = [super init]) {
data = [[NSMutableArray alloc] init];
theLock = [[NSRecursiveLock alloc] init];
}
return self;
}

- (id)initWithQueue:(SKQueue *)queue
{
if (self = [super init]) {
data = [[NSMutableArray alloc] initWithArray:[queue data]];
theLock = [[NSRecursiveLock alloc] init];
}
return self;
}

- (id)initWithCoder:(NSCoder *)coder
{
if (self = [super init]) {
data = [[NSMutableArray alloc] initWithArray:[coder decodeObject]];
theLock = [[NSRecursiveLock alloc] init];
}
return self;
}

- (void)dealloc
{
[data release];
[theLock release];
[super dealloc];
}

- (void)encodeWithCoder:(NSCoder *)coder;
{
[coder encodeObject:data];
}

#pragma mark
#pragma mark —Accessor Methods—
- (int)size
{
int size;
[theLock lock];
size = [data count];
[theLock unlock];
return size;
}

- (BOOL)isEmpty
{
BOOL empty;
[theLock lock];
empty = ([data count] == 0);
[theLock unlock];
return empty;
}

- (id)top
{
id object = nil;
[theLock lock];
if (![self isEmpty])
object = [data objectAtIndex:0];
[theLock unlock];
return object;
}

- (NSArray *)data
{
NSArray * array;
[theLock lock];
array = [NSArray arrayWithArray:data];
[theLock unlock];
return array;
}

#pragma mark
#pragma mark —Modifier Methods—
- (void)enqueue:(id)object
{
[theLock lock];
[data addObject:object];
[theLock unlock];
}

- (id)dequeue
{
id object = [self top];
if (object != nil) {
[theLock lock];
[object retain];
[data removeObjectAtIndex:0];
[theLock unlock];
}
return [object autorelease];
}

- (void)removeAll
{
[theLock lock];
while (![self isEmpty])
[data removeObjectAtIndex:0];
[theLock unlock];
}

@end

I'm sure it is not perfect, but it might help...

[Catfish_Man]

Thanks! I haven't tested it yet, but it looks good.