Speedups for reloading refs when there are lots of tags.

This change uses GCD to schedule certain git commands for
background execution. All background commands occur on the
queue returned by PBGetWorkQueue(), and the results are
executed on the main queue. This results in a dramatic
improvement in the performance of reloadRefs when there
are lots of tags.

More improvements are possible with this approach, this is
just something to get things rolling.

Author: darconeous

PBGitRepository.h

@@ -42,6 +42,8 @@ static NSString * PBStringFromBranchFilterType(PBGitXBranchFilterType type) {
 @class PBStashController;
 @class PBSubmoduleController;
 
+dispatch_queue_t PBGetWorkQueue();
+
 @interface PBGitRepository : NSDocument {
 	PBGitHistoryList* revisionList;
 	PBGitConfig *config;
@@ -58,6 +60,10 @@ static NSString * PBStringFromBranchFilterType(PBGitXBranchFilterType type) {
 	PBStashController *stashController;
 	PBSubmoduleController *submoduleController;
 	PBGitResetController *resetController;
+
+	BOOL didCheckBareRepository;
+	BOOL bareRepository;
+	NSString* workingDirectory;
 }
 @property (nonatomic, retain, readonly) PBStashController *stashController;
 @property (nonatomic, retain, readonly) PBSubmoduleController *submoduleController;

PBGitRepository.m

@@ -32,6 +32,18 @@
 @interface PBGitRepository()
 @end
 
+dispatch_queue_t PBGetWorkQueue() {
+#if 1
+	static dispatch_queue_t work_queue;
+	static dispatch_once_t onceToken;
+	dispatch_once(&onceToken, ^{
+		work_queue = dispatch_queue_create("PBWorkQueue", 0);
+	});
+	return work_queue;
+#else
+	return dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
+#endif
+}
 
 
 @implementation PBGitRepository
@@ -250,11 +262,13 @@ - (NSString*)gitIgnoreFilename
 
 - (BOOL)isBareRepository
 {
-	if([self workingDirectory]) {
-		return [PBGitRepository isBareRepository:[self workingDirectory]];
-	} else {
-		return true;
+	if(!didCheckBareRepository) {
+		if([self workingDirectory])
+			bareRepository = [PBGitRepository isBareRepository:[self workingDirectory]];
+		else
+			bareRepository = YES;
 	}
+	return bareRepository;
 }
 
 // Overridden to create our custom window controller
@@ -358,11 +372,16 @@ - (void) reloadRefs
 
 		PBGitRef *newRef = [PBGitRef refFromString:[components objectAtIndex:0]];
 		PBGitRevSpecifier *revSpec = [[PBGitRevSpecifier alloc] initWithRef:newRef];
-
-		[revSpec setHelpText:[self helpTextForRef:newRef]];
 		[self addBranch:revSpec];
 		[self addRef:newRef fromParameters:components];
 		[oldBranches removeObject:revSpec];
+
+		dispatch_async(PBGetWorkQueue(), ^{
+			NSString* helpText = [self helpTextForRef:newRef];
+			dispatch_async(dispatch_get_main_queue(), ^{
+				[revSpec setHelpText:helpText];
+			});
+		});
 	}
 
 	for (PBGitRevSpecifier *branch in oldBranches)
@@ -628,12 +647,14 @@ - (void) readCurrentBranch
 
 - (NSString *) workingDirectory
 {
-	if ([self.fileURL.path hasSuffix:@"/.git"])
-		return [self.fileURL.path substringToIndex:[self.fileURL.path length] - 5];
-	else if ([[self outputForCommand:@"rev-parse --is-inside-work-tree"] isEqualToString:@"true"])
-		return [PBGitBinary path];
+	if(!workingDirectory) {
+		if ([self.fileURL.path hasSuffix:@"/.git"])
+			workingDirectory = [[self.fileURL.path substringToIndex:[self.fileURL.path length] - 5] retain];
+		else if ([[self outputForCommand:@"rev-parse --is-inside-work-tree"] isEqualToString:@"true"])
+			workingDirectory = [PBGitBinary path];
+	}
 
-	return nil;
+	return workingDirectory;
 }
 
 #pragma mark Remotes

PBGitSidebarController.m

@@ -163,9 +163,15 @@ - (void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(
 		for(PBGitSVBranchItem* branch in [branches children]){
 			if([branch isKindOfClass:[PBGitSVBranchItem class]]){
 				NSString *bName=[branch title];
-				[branch setAhead:[self countCommintsOf:[NSString stringWithFormat:@"origin/%@..%@",bName,bName]]];
-				[branch setBehind:[self countCommintsOf:[NSString stringWithFormat:@"%@..origin/%@",bName,bName]]];
-				[branch setIsCheckedOut:[branch.revSpecifier isEqual:[repository headRef]]];
+				dispatch_async(PBGetWorkQueue(),^{
+					id ahead = [self countCommintsOf:[NSString stringWithFormat:@"origin/%@..%@",bName,bName]]; 
+					id behind = [self countCommintsOf:[NSString stringWithFormat:@"%@..origin/%@",bName,bName]];
+					dispatch_async(dispatch_get_main_queue(),^{
+						[branch setAhead:ahead];
+						[branch setBehind:behind];
+						[branch setIsCheckedOut:[branch.revSpecifier isEqual:[repository headRef]]];
+					});
+				});
 			}
 		}
 	}else{
@@ -178,8 +184,14 @@ - (void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(
 -(void)evaluateRemoteBadge:(PBGitSVRemoteItem *)remote
 {
 	DLog(@"remote.title=%@",[remote title]);
-    if([remote isKindOfClass:[PBGitSVRemoteItem class]])
-        [remote setAlert:[self remoteNeedFetch:[remote title]]];
+    if([remote isKindOfClass:[PBGitSVRemoteItem class]]) {
+		dispatch_async(PBGetWorkQueue(), ^{
+			bool needsFetch = [self remoteNeedFetch:[remote title]];
+			dispatch_async(dispatch_get_main_queue(), ^{
+				[remote setAlert:needsFetch];
+			});
+		});
+	}
 }
 
 -(NSNumber *)countCommintsOf:(NSString *)range