Upgrading to version 1.6 of CocoaLumberjack

Vendor/CocoaLumberjack/DDLog.h

@@ -427,9 +427,22 @@ NSString *DDExtractFileNameWithoutExtension(const char *filePath, BOOL copy);
  * The formatter may also optionally filter the log message by returning nil,
  * in which case the logger will not log the message.
 **/
-
 - (NSString *)formatLogMessage:(DDLogMessage *)logMessage;
 
+@optional
+
+/**
+ * A single formatter instance can be added to multiple loggers.
+ * These methods provides hooks to notify the formatter of when it's added/removed.
+ *
+ * This is primarily for thread-safety.
+ * If a formatter is explicitly not thread-safe, it may wish to throw an exception if added to multiple loggers.
+ * Or if a formatter has potentially thread-unsafe code (e.g. NSDateFormatter),
+ * it could possibly use these hooks to switch to thread-safe versions of the code.
+**/
+- (void)didAddToLogger:(id <DDLogger>)logger;
+- (void)willRemoveFromLogger:(id <DDLogger>)logger;
+
 @end
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

Vendor/CocoaLumberjack/DDLog.m

@@ -1022,11 +1022,21 @@ - (void)setLogFormatter:(id <DDLogFormatter>)logFormatter
 {
 	// The design of this method is documented extensively in the logFormatter message (above in code).
 
-	dispatch_block_t block = ^{
-		if (formatter != logFormatter) {
+	dispatch_block_t block = ^{ @autoreleasepool {
+
+		if (formatter != logFormatter)
+		{
+			if ([formatter respondsToSelector:@selector(willRemoveFromLogger:)]) {
+				[formatter willRemoveFromLogger:self];
+			}
+
 			formatter = logFormatter;
+
+			if ([formatter respondsToSelector:@selector(didAddToLogger:)]) {
+				[formatter didAddToLogger:self];
+			}
 		}
-	};
+	}};
 
 	dispatch_queue_t currentQueue = dispatch_get_current_queue();
 	if (currentQueue == loggerQueue)

Vendor/CocoaLumberjack/Extensions/DispatchQueueLogFormatter.h

@@ -53,10 +53,13 @@
 {
 	@protected
 
-	NSDateFormatter *dateFormatter;
+	NSString *dateFormatString;
 
 	@private
 
+	int32_t atomicLoggerCount;
+	NSDateFormatter *threadUnsafeDateFormatter; // Use [self stringFromDate]
+
 	OSSpinLock lock;
 
 	NSUInteger _minQueueLength;           // _prefix == Only access via atomic property

Vendor/CocoaLumberjack/Extensions/DispatchQueueLogFormatter.m

@@ -1,4 +1,5 @@
 #import "DispatchQueueLogFormatter.h"
+#import <libkern/OSAtomic.h>
 
 /**
  * Welcome to Cocoa Lumberjack!
@@ -21,9 +22,10 @@ - (id)init
 {
 	if ((self = [super init]))
 	{
-		dateFormatter = [[NSDateFormatter alloc] init];
-		[dateFormatter setFormatterBehavior:NSDateFormatterBehavior10_4];
-		[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss:SSS"];
+		dateFormatString = @"yyyy-MM-dd HH:mm:ss:SSS";
+
+		atomicLoggerCount = 0;
+		threadUnsafeDateFormatter = nil;
 
 		_minQueueLength = 0;
 		_maxQueueLength = 0;
@@ -73,6 +75,46 @@ - (void)setReplacementString:(NSString *)shortLabel forQueueLabel:(NSString *)lo
 #pragma mark DDLogFormatter
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
+- (NSString *)stringFromDate:(NSDate *)date
+{
+	int32_t loggerCount = OSAtomicAdd32(0, &atomicLoggerCount);
+
+	if (loggerCount <= 1)
+	{
+		// Single-threaded mode.
+
+		if (threadUnsafeDateFormatter == nil)
+		{
+			threadUnsafeDateFormatter = [[NSDateFormatter alloc] init];
+			[threadUnsafeDateFormatter setFormatterBehavior:NSDateFormatterBehavior10_4];
+			[threadUnsafeDateFormatter setDateFormat:dateFormatString];
+		}
+
+		return [threadUnsafeDateFormatter stringFromDate:date];
+	}
+	else
+	{
+		// Multi-threaded mode.
+		// NSDateFormatter is NOT thread-safe.
+
+		NSString *key = @"DispatchQueueLogFormatter_NSDateFormatter";
+
+		NSMutableDictionary *threadDictionary = [[NSThread currentThread] threadDictionary];
+		NSDateFormatter *dateFormatter = [threadDictionary objectForKey:key];
+
+		if (dateFormatter == nil)
+		{
+			dateFormatter = [[NSDateFormatter alloc] init];
+			[dateFormatter setFormatterBehavior:NSDateFormatterBehavior10_4];
+			[dateFormatter setDateFormat:dateFormatString];
+
+			[threadDictionary setObject:dateFormatter forKey:key];
+		}
+
+		return [dateFormatter stringFromDate:date];
+	}
+}
+
 - (NSString *)queueThreadLabelForLogMessage:(DDLogMessage *)logMessage
 {
 	// As per the DDLogFormatter contract, this method is always invoked on the same thread/dispatch_queue
@@ -180,10 +222,20 @@ - (NSString *)queueThreadLabelForLogMessage:(DDLogMessage *)logMessage
 
 - (NSString *)formatLogMessage:(DDLogMessage *)logMessage
 {
-	NSString *timestamp = [dateFormatter stringFromDate:(logMessage->timestamp)];
+	NSString *timestamp = [self stringFromDate:(logMessage->timestamp)];
 	NSString *queueThreadLabel = [self queueThreadLabelForLogMessage:logMessage];
 
 	return [NSString stringWithFormat:@"%@ [%@] %@", timestamp, queueThreadLabel, logMessage->logMsg];
 }
 
+- (void)didAddToLogger:(id <DDLogger>)logger
+{
+	OSAtomicIncrement32(&atomicLoggerCount);
+}
+
+- (void)willRemoveFromLogger:(id <DDLogger>)logger
+{
+	OSAtomicDecrement32(&atomicLoggerCount);
+}
+
 @end