Add multi-threading safe initialization of singleton objects. Off by …

…default, enabled with the C Preprocessor flag DT_USE_THREAD_SAFE_INITIALIZATION.
AlohaSilver · Jun 27, 2011 · e5e1568 · e5e1568
1 parent 41650c9
commit e5e1568
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Showing 6 changed files with 518 additions and 3 deletions.
diff --git a/Classes/DTCoreTextFontCollection.m b/Classes/DTCoreTextFontCollection.m
@@ -27,10 +27,17 @@ @implementation DTCoreTextFontCollection
 
 + (DTCoreTextFontCollection *)availableFontsCollection
 {
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	static dispatch_once_t predicate;
+	dispatch_once(&predicate, ^{
+		_availableFontsCollection = [[DTCoreTextFontCollection alloc] initWithAvailableFonts];
+	});
+#else
 	if (!_availableFontsCollection)
 	{
 		_availableFontsCollection = [[DTCoreTextFontCollection alloc] initWithAvailableFonts];
 	}
+#endif
 
 	return _availableFontsCollection;
 }

diff --git a/Classes/DTCoreTextFontDescriptor.m b/Classes/DTCoreTextFontDescriptor.m
@@ -11,23 +11,47 @@
 static NSCache *_fontCache = nil;
 static NSMutableDictionary *_fontOverrides = nil;
 
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+static NSRecursiveLock *_fontOverridesLock = nil;
 
-@implementation DTCoreTextFontDescriptor
+static void dt_loadTimeInitialization(void) __attribute__ ((constructor, used));
+static void dt_loadTimeInitialization(void) {
+	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; // Though technically not required, the run time environment at load time initialization may be less than ideal.
+
+	_fontOverridesLock = [[NSRecursiveLock alloc] init];
+	[_fontOverridesLock setName:@"DTCoreTextFontDescriptor fontOverrides lock"];
 
+	[pool drain]; pool = NULL;
+}
+#endif // DT_USE_THREAD_SAFE_INITIALIZATION
 
 
+@implementation DTCoreTextFontDescriptor
+
 + (NSCache *)fontCache
 {
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	static dispatch_once_t predicate;
+	dispatch_once(&predicate, ^{
+		_fontCache = [[NSCache alloc] init];
+	});
+#else
 	if (!_fontCache)
 	{
 		_fontCache = [[NSCache alloc] init];
 	}
+#endif
 
 	return _fontCache;
 }
 
 + (NSMutableDictionary *)fontOverrides
 {
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	NSParameterAssert(_fontOverridesLock != nil);
+	[_fontOverridesLock lock];
+#endif
+
 	if (!_fontOverrides)
 	{
 		_fontOverrides = [[NSMutableDictionary alloc] init];
@@ -56,36 +80,72 @@ + (NSMutableDictionary *)fontOverrides
 			}
 		}
 	}
-
+
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	[_fontOverridesLock unlock];
+#endif
+
 	return _fontOverrides;
 }
 
 + (void)setSmallCapsFontName:(NSString *)fontName forFontFamily:(NSString *)fontFamily bold:(BOOL)bold italic:(BOOL)italic
 {
 	NSString *key = [NSString stringWithFormat:@"%@-%d-%d-smallcaps", fontFamily, bold, italic];
 
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	NSParameterAssert(_fontOverridesLock != nil);
+	[_fontOverridesLock lock];
+#endif
 	[[DTCoreTextFontDescriptor fontOverrides] setObject:fontName forKey:key];
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	[_fontOverridesLock unlock];
+#endif
 }
 
 + (NSString *)smallCapsFontNameforFontFamily:(NSString *)fontFamily bold:(BOOL)bold italic:(BOOL)italic
 {
 	NSString *key = [NSString stringWithFormat:@"%@-%d-%d-smallcaps", fontFamily, bold, italic];
-
+
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	NSParameterAssert(_fontOverridesLock != nil);
+	[_fontOverridesLock lock];
+	NSString *returnString = [[[DTCoreTextFontDescriptor fontOverrides] objectForKey:key] retain];
+	[_fontOverridesLock unlock];
+
+	return [returnString autorelease];
+#else
 	return [[DTCoreTextFontDescriptor fontOverrides] objectForKey:key];
+#endif
 }
 
 + (void)setOverrideFontName:(NSString *)fontName forFontFamily:(NSString *)fontFamily bold:(BOOL)bold italic:(BOOL)italic
 {
 	NSString *key = [NSString stringWithFormat:@"%@-%d-%d-override", fontFamily, bold, italic];
 
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	NSParameterAssert(_fontOverridesLock != nil);
+	[_fontOverridesLock lock];
+#endif
 	[[DTCoreTextFontDescriptor fontOverrides] setObject:fontName forKey:key];
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	[_fontOverridesLock unlock];
+#endif
 }
 
 + (NSString *)overrideFontNameforFontFamily:(NSString *)fontFamily bold:(BOOL)bold italic:(BOOL)italic
 {
 	NSString *key = [NSString stringWithFormat:@"%@-%d-%d-override", fontFamily, bold, italic];
 
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	NSParameterAssert(_fontOverridesLock != nil);
+	[_fontOverridesLock lock];
+	NSString *returnString = [[[DTCoreTextFontDescriptor fontOverrides] objectForKey:key] retain];
+	[_fontOverridesLock unlock];
+
+	return [returnString autorelease];
+#else
 	return [[DTCoreTextFontDescriptor fontOverrides] objectForKey:key];
+#endif
 }
 
 + (DTCoreTextFontDescriptor *)fontDescriptorWithFontAttributes:(NSDictionary *)attributes

diff --git a/Classes/DTLazyImageView.m b/Classes/DTLazyImageView.m
@@ -163,10 +163,17 @@ - (void)completeDownloadWithData:(NSData *)data
 
 	[self notify];
 
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	static dispatch_once_t predicate;
+	dispatch_once(&predicate, ^{
+		_imageCache = [[NSCache alloc] init];
+	});
+#else
 	if (!_imageCache)
 	{
 		_imageCache = [[NSCache alloc] init];
 	}
+#endif
 
 	if (_url)
 	{

diff --git a/Classes/NSCharacterSet+HTML.m b/Classes/NSCharacterSet+HTML.m
@@ -17,43 +17,73 @@ @implementation NSCharacterSet (HTML)
 
 + (NSCharacterSet *)tagNameCharacterSet
 {
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	static dispatch_once_t predicate;
+	dispatch_once(&predicate, ^{
+		_tagNameCharacterSet = [[NSCharacterSet characterSetWithCharactersInString:@"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"] retain];
+	});
+#else
 	if (!_tagNameCharacterSet)
 	{
 		_tagNameCharacterSet = [[NSCharacterSet characterSetWithCharactersInString:@"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"] retain];
 	}
+#endif
 
 	return _tagNameCharacterSet;
 }
 
 + (NSCharacterSet *)tagAttributeNameCharacterSet
 {
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	static dispatch_once_t predicate;
+	dispatch_once(&predicate, ^{
+	});
+#else
 	if (!_tagAttributeNameCharacterSet)
 	{
 		_tagAttributeNameCharacterSet = [[NSCharacterSet characterSetWithCharactersInString:@"-_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"] retain];
 	}
+#endif
 
 	return _tagAttributeNameCharacterSet;
 }
 
 + (NSCharacterSet *)quoteCharacterSet
 {
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	static dispatch_once_t predicate;
+	dispatch_once(&predicate, ^{
+		_quoteCharacterSet = [[NSCharacterSet characterSetWithCharactersInString:@"'\""] retain];
+	});
+#else
 	if (!_quoteCharacterSet)
 	{
 		_quoteCharacterSet = [[NSCharacterSet characterSetWithCharactersInString:@"'\""] retain];
 	}
+#endif
 
 	return _quoteCharacterSet;
 }
 
 + (NSCharacterSet *)nonQuotedAttributeEndCharacterSet
 {
+#ifdef DT_USE_THREAD_SAFE_INITIALIZATION
+	static dispatch_once_t predicate;
+	dispatch_once(&predicate, ^{
+		NSMutableCharacterSet *tmpCharacterSet = [NSMutableCharacterSet characterSetWithCharactersInString:@"/>"];
+		[tmpCharacterSet formUnionWithCharacterSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
+
+		_nonQuotedAttributeEndCharacterSet = [tmpCharacterSet copy];
+	});
+#else
 	if (!_nonQuotedAttributeEndCharacterSet)
 	{
 		NSMutableCharacterSet *tmpCharacterSet = [NSMutableCharacterSet characterSetWithCharactersInString:@"/>"];
 		[tmpCharacterSet formUnionWithCharacterSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
 
 		_nonQuotedAttributeEndCharacterSet = [tmpCharacterSet copy];
 	}
+#endif
 
 	return _nonQuotedAttributeEndCharacterSet;
 }