Simplify code by using NSCache for the time zone cache dictionary ins…

…tead of a slower thread local variant. Also removes the requirement of registering for memory warnings as NSCache cleans up automatically.
boredzo · Mar 26, 2014 · 98bf9cb · 98bf9cb
1 parent fed060f
commit 98bf9cb
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Showing 2 changed files with 8 additions and 80 deletions.
diff --git a/ISO8601DateFormatter.m b/ISO8601DateFormatter.m
@@ -25,12 +25,6 @@
 #define ISO_TIMEZONE_OFFSET_FORMAT_NO_SEPARATOR @"%+.2d%.2d"
 #define ISO_TIMEZONE_OFFSET_FORMAT_WITH_SEPARATOR @"%+.2d%C%.2d"
 
-@interface ISO8601DateFormatter ()
-+ (void) createGlobalCachesThatDoNotAlreadyExist;
-//Used when a memory warning occurs (if at least one ISO 8601 Date Formatter exists at the time).
-+ (void) purgeGlobalCaches;
-@end
-
 @interface ISO8601DateFormatter(UnparsingPrivate)
 
 - (NSString *) replaceColonsInString:(NSString *)timeFormat withTimeSeparator:(unichar)timeSep;
@@ -40,40 +34,16 @@ - (NSString *) weekDateStringForDate:(NSDate *)date timeZone:(NSTimeZone *)timeZ
 
 @end
 
-@interface ISO8601TimeZoneCache: NSObject
-{}
-
-//The property being read-only means that the formatter cannot change the cache's dictionary, but the formatter is explicitly allowed to mutate the dictionary.
-@property(nonatomic, readonly, strong) NSMutableDictionary *timeZonesByOffset;
-
-@end
-
-static ISO8601TimeZoneCache *timeZoneCache;
-
-#if ISO8601_TESTING_PURPOSES_ONLY
-//This method only exists for use by the project's test cases. DO NOT use this in an application.
-extern bool ISO8601DateFormatter_GlobalCachesAreWarm(void);
-
-bool ISO8601DateFormatter_GlobalCachesAreWarm(void) {
-	return (timeZoneCache != nil) && (timeZoneCache.timeZonesByOffset.count > 0);
-}
-#endif
+static NSCache *timeZonesByOffset;
 
 @implementation ISO8601DateFormatter
-+ (void) initialize {
-	[self createGlobalCachesThatDoNotAlreadyExist];
-}
 
-+ (void) createGlobalCachesThatDoNotAlreadyExist {
-	if (!timeZoneCache) {
-		timeZoneCache = [[ISO8601TimeZoneCache alloc] init];
-	}
++ (void) initialize {
+    timeZonesByOffset = [[NSCache alloc] init];
 }
 
 + (void) purgeGlobalCaches {
-	ISO8601TimeZoneCache *oldCache = timeZoneCache;
-	timeZoneCache = nil;
-	[oldCache release];
+    [timeZonesByOffset removeAllObjects];
 }
 
 - (NSCalendar *) makeCalendarWithDesiredConfiguration {
@@ -92,22 +62,11 @@ - (id) init {
 		timeSeparator = ISO8601DefaultTimeSeparatorCharacter;
 		includeTime = NO;
 		parsesStrictly = NO;
-
-#if TARGET_OS_IPHONE
-		[[NSNotificationCenter defaultCenter] addObserver:self
-			selector:@selector(didReceiveMemoryWarning:)
-			name:UIApplicationDidReceiveMemoryWarningNotification
-			object:nil];
-#endif
 	}
 	return self;
 }
 
 - (void) dealloc {
-#if TARGET_OS_IPHONE
-	[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
-#endif
-
 	[defaultTimeZone release];
 
 	[unparsingFormatter release];
@@ -118,10 +77,6 @@ - (void) dealloc {
 	[super dealloc];
 }
 
-- (void) didReceiveMemoryWarning:(NSNotification *)notification {
-	[[self class] purgeGlobalCaches];
-}
-
 @synthesize defaultTimeZone;
 - (void) setDefaultTimeZone:(NSTimeZone *)tz {
 	if (defaultTimeZone != tz) {
@@ -607,15 +562,14 @@ - (NSDateComponents *) dateComponentsFromString:(NSString *)string timeZone:(out
 								if (negative) tz_minute = -tz_minute;
 							}
 
-							[[self class] createGlobalCachesThatDoNotAlreadyExist];
-
 							NSInteger timeZoneOffset = (tz_hour * 3600) + (tz_minute * 60);
 							NSNumber *offsetNum = [NSNumber numberWithInteger:timeZoneOffset];
-							timeZone = [timeZoneCache.timeZonesByOffset objectForKey:offsetNum];
+							timeZone = [timeZonesByOffset objectForKey:offsetNum];
 							if (!timeZone) {
 								timeZone = [NSTimeZone timeZoneForSecondsFromGMT:timeZoneOffset];
-								if (timeZone)
-									[timeZoneCache.timeZonesByOffset setObject:timeZone forKey:offsetNum];
+								if (timeZone) {
+                                    [timeZonesByOffset setObject:timeZone forKey:offsetNum];
+                                }
 							}
 						}
 				}
@@ -1002,19 +956,3 @@ static BOOL is_leap_year(NSUInteger year) {
 	&& (((year % 100U) != 0U)
 	||  ((year % 400U) == 0U));
 }
-
-static NSString *const ISO8601ThreadStorageTimeZoneCacheKey = @"org.boredzo.ISO8601ThreadStorageTimeZoneCacheKey";
-
-@implementation ISO8601TimeZoneCache: NSObject
-
-- (NSMutableDictionary *) timeZonesByOffset {
-	NSMutableDictionary *threadDict = [NSThread currentThread].threadDictionary;
-	NSMutableDictionary *currentCacheDict = [threadDict objectForKey:ISO8601ThreadStorageTimeZoneCacheKey];
-	if (currentCacheDict == nil) {
-		currentCacheDict = [NSMutableDictionary dictionaryWithCapacity:2UL];
-		[threadDict setObject:currentCacheDict forKey:ISO8601ThreadStorageTimeZoneCacheKey];
-	}
-	return currentCacheDict;
-}
-
-@end
diff --git a/ISO8601ForCocoa/ISO8601ForCocoaTouchTests/ISO8601MemoryWarningTests.m b/ISO8601ForCocoa/ISO8601ForCocoaTouchTests/ISO8601MemoryWarningTests.m
@@ -10,8 +10,6 @@
 
 #import "ISO8601DateFormatter.h"
 
-extern bool ISO8601DateFormatter_GlobalCachesAreWarm(void);
-
 @interface ISO8601DateFormatter (ISO8601MemoryWarningTesting)
 + (void) purgeGlobalCaches;
 @end
@@ -39,8 +37,6 @@ - (void) tearDown {
 }
 
 - (void) testMemoryWarning {
-	STAssertFalseNoThrow(ISO8601DateFormatter_GlobalCachesAreWarm(), @"Global caches are already warm before using an ISO 8601 date formatter!");
-
 	//Now parse a bunch of dates to try to warm the caches.
 	[_iso8601DateFormatter dateFromString:@"2013-09-18T07:34:21-1200"];
 	[_iso8601DateFormatter dateFromString:@"2013-09-18T07:34:21-0800"];
@@ -50,12 +46,6 @@ - (void) testMemoryWarning {
 	[_iso8601DateFormatter dateFromString:@"2013-09-18T07:34:21+0130"];
 	[_iso8601DateFormatter dateFromString:@"2013-09-18T07:34:21+0800"];
 	[_iso8601DateFormatter dateFromString:@"2013-09-18T07:34:21+1200"];
-
-	STAssertTrueNoThrow(ISO8601DateFormatter_GlobalCachesAreWarm(), @"Global caches were not warmed by using an ISO 8601 date formatter!");
-
-	[[NSNotificationCenter defaultCenter] postNotificationName:UIApplicationDidReceiveMemoryWarningNotification object:[UIApplication sharedApplication]];
-
-	STAssertFalseNoThrow(ISO8601DateFormatter_GlobalCachesAreWarm(), @"Global caches were not purged by a (simulated) memory warning!");
 }
 
 @end