//

// ASTraceEvent.m

// AsyncDisplayKit

//

// Created by Adlai Holler on 9/13/16.

// Copyright © 2016 Facebook. All rights reserved.

//

#import "ASTraceEvent.h"

#import <QuartzCore/QuartzCore.h>

static NSString *const ASTraceEventThreadDescriptionKey = @"ASThreadTraceEventDescription";

@interface ASTraceEvent ()

@property (nonatomic, strong, readonly) NSString *objectDescription;

@property (nonatomic, strong, readonly) NSString *threadDescription;

@end

@implementation ASTraceEvent

- (instancetype)initWithBacktrace:(NSArray<NSString *> *)backtrace format:(NSString *)format arguments:(va_list)args

{

self = [super init];

if (self != nil) {

static NSTimeInterval refTime;

static dispatch_once_t onceToken;

dispatch_once(&onceToken, ^{

refTime = CACurrentMediaTime();

});

// Create the format string passed to us.

_message = [[NSString alloc] initWithFormat:format arguments:args];

NSThread *thread = [NSThread currentThread];

NSString *threadDescription = thread.name;

if (threadDescription.length == 0) {

if ([thread isMainThread]) {

threadDescription = @"Main";

} else {

// If the bg thread has no name, we cache a 4-character ptr string to identify it by

// inside the thread dictionary.

NSMutableDictionary *threadDict = thread.threadDictionary;

threadDescription = threadDict[ASTraceEventThreadDescriptionKey];

if (threadDescription == nil) {

// Want these to be 4-chars to line up with "Main". It's possible that a collision could happen

// here but it's so unbelievably likely to impact development, the risk is acceptable.

NSString *ptrString = [NSString stringWithFormat:@"%p", thread];

threadDescription = [ptrString substringFromIndex:MAX(0, ptrString.length - 4)];

threadDict[ASTraceEventThreadDescriptionKey] = threadDescription;

}

}

}

_threadDescription = threadDescription;

_backtrace = backtrace;

_timestamp = CACurrentMediaTime() - refTime;

}

return self;

}

- (NSString *)description

{

return [NSString stringWithFormat:@"<(%@) t=%7.3f: %@>", _threadDescription, _timestamp, _message];

}

@end