昨天抽空用Swift寫了個LRU算法，最后執(zhí)行1百萬數(shù)據(jù)效率一點都不好，一直都找不到效率慢的原因！早上剛到公司抽空用Objecttive-C和Swift寫了個差不多思想的代碼(線程安全字典)，對比了下兩種語言的效率，你猜怎么著？看結果吧?。?！

測試環(huán)境：iPhone 5S、16G
測試方法：執(zhí)行1000000(1百萬)次set
測試結果：柱子越矮越好

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測試代碼：

Swift版本：

// 被測試類
class ThreadSafeDictionary {
    
    var spinLock:OSSpinLock = OS_SPINLOCK_INIT
    var buffer:Dictionary<String,AnyObject> = Dictionary()
    
    static let sharedInstance = ThreadSafeDictionary()
    
    private init(){
    }
    
    internal func safeSetObject(object:AnyObject?,forKey:String?) {
        if (nil == forKey || nil == object) {
            return
        }
        OSSpinLockLock(&spinLock)
        buffer[forKey!] = object
        OSSpinLockUnlock(&spinLock)
    }
    
    internal func safeGetObject(forKey:String?) -> AnyObject? {
        if (nil == forKey) {
            return nil
        }
        var value:AnyObject?
        OSSpinLockLock(&spinLock)
        value = buffer[forKey!]
        OSSpinLockUnlock(&spinLock)
        return value
    }
    
}

    // 測試代碼
    let ITERATOR = 1000000 // 1百萬
    let keys:NSMutableArray = NSMutableArray()
    let values:NSMutableArray = NSMutableArray()
    for (var i = 0; i < ITERATOR; i++) {
        keys.addObject("\(i)")
        values.addObject("simple value"+"\(i)")
    }
    let then = CFAbsoluteTimeGetCurrent()
    for (var i = 0; i < ITERATOR; i++) {
        ThreadSafeDictionary.sharedInstance.safeSetObject(values[i], forKey: keys[i] as? String)
    }
    let now = CFAbsoluteTimeGetCurrent();
    print("\(now-then)秒")

Objective-C版本：

// 被測試類
#import <Foundation/Foundation.h>

@interface ThreadSafeDictionary : NSObject

+ (instancetype)sharedInstance;

- (void)safeSetObject:(id)object forKey:(NSString*)key;

- (id)safeGetForKey:(NSString*)key;

@end



#import "ThreadSafeDictionary.h"
#import <libkern/OSAtomic.h>

@implementation ThreadSafeDictionary
{
    OSSpinLock spinLock;
    NSMutableDictionary *buffer;
}

+ (instancetype)sharedInstance {
    static dispatch_once_t onceToken;
    static ThreadSafeDictionary *instance;
    dispatch_once(&onceToken, ^{
        instance = [[ThreadSafeDictionary alloc] init];
    });
    return instance;
}

- (instancetype)init {
    if ((self = [super init])) {
        spinLock = OS_SPINLOCK_INIT;
        buffer = [NSMutableDictionary dictionaryWithCapacity:50];
    }
    return self;
}

- (void)safeSetObject:(id)object forKey:(NSString*)key {
    if (!object || !key) {
        return;
    }
    OSSpinLockLock(&spinLock);
    buffer[key] = object;
    OSSpinLockUnlock(&spinLock);
}

- (id)safeGetForKey:(NSString*)key {
    if (!key) {
        return nil;
    }
    id value = nil;
    OSSpinLockLock(&spinLock);
    value = buffer[key];
    OSSpinLockUnlock(&spinLock);
    return value;
}
@end



// 測試代碼
#define ITERATOR 1000000 // 1百萬
NSMutableArray *keys = [NSMutableArray array];
NSMutableArray *values = [NSMutableArray array];
for (NSInteger i = 0; i < ITERATOR; i++) {
    [keys addObject:[NSString stringWithFormat:@"%ld",i]];
    [values addObject:[NSString stringWithFormat:@"simple value%ld",i]];
}
CFAbsoluteTime then = CFAbsoluteTimeGetCurrent();
@autoreleasepool {
    for (NSInteger i = 0; i < ITERATOR; ++i) {
        [[ThreadSafeDictionary sharedInstance] safeSetObject:values[i] forKey:keys[i]];
    }
}
CFAbsoluteTime now = CFAbsoluteTimeGetCurrent();
printf("%f秒\n",now-then);