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Switch to using an NSRecursiveLock instead of @synchronized within RKEntityByAttributeCache. Avoid a potential deadlock when handling a NSManagedObjectContextObjectsDidChangeNotification notification

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Blake Watters
2013-02-01 18:59:26 -05:00
parent be5aea7286
commit 0bbb603b9e
1 changed files with 111 additions and 75 deletions
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186
Code/CoreData/RKEntityByAttributeCache.m
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@@ -83,6 +83,7 @@ static NSArray *RKCacheKeysForEntityFromAttributeValues(NSEntityDescription *ent
@interface RKEntityByAttributeCache ()
@property (nonatomic, strong) NSMutableDictionary *cacheKeysToObjectIDs;
@property (nonatomic, strong) NSRecursiveLock *lock;
@end
@implementation RKEntityByAttributeCache
@@ -99,6 +100,7 @@ static NSArray *RKCacheKeysForEntityFromAttributeValues(NSEntityDescription *ent
_attributes = attributeNames;
_managedObjectContext = context;
_monitorsContextForChanges = YES;
_lock = [NSRecursiveLock new];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(managedObjectContextDidChange:)
@@ -123,73 +125,87 @@ static NSArray *RKCacheKeysForEntityFromAttributeValues(NSEntityDescription *ent
- (NSUInteger)count
{
return [[[self.cacheKeysToObjectIDs allValues] valueForKeyPath:@"@sum.@count"] integerValue];
[self.lock lock];
NSUInteger count = [[[self.cacheKeysToObjectIDs allValues] valueForKeyPath:@"@sum.@count"] integerValue];
[self.lock unlock];
return count;
}
- (NSUInteger)countOfAttributeValues
{
return [self.cacheKeysToObjectIDs count];
[self.lock lock];
NSUInteger count = [self.cacheKeysToObjectIDs count];
[self.lock unlock];
return count;
}
- (NSUInteger)countWithAttributeValues:(NSDictionary *)attributeValues
{
return [[self objectsWithAttributeValues:attributeValues inContext:self.managedObjectContext] count];
[self.lock lock];
NSUInteger count = [[self objectsWithAttributeValues:attributeValues inContext:self.managedObjectContext] count];
[self.lock unlock];
return count;
}
- (void)load
{
[self.lock lock];
RKLogDebug(@"Loading entity cache for Entity '%@' by attributes '%@' in managed object context %@ (concurrencyType = %ld)",
self.entity.name, self.attributes, self.managedObjectContext, (unsigned long)self.managedObjectContext.concurrencyType);
@synchronized(self.cacheKeysToObjectIDs) {
self.cacheKeysToObjectIDs = [NSMutableDictionary dictionary];
self.cacheKeysToObjectIDs = [NSMutableDictionary dictionary];
NSExpressionDescription* objectIDExpression = [NSExpressionDescription new];
objectIDExpression.name = @"objectID";
objectIDExpression.expression = [NSExpression expressionForEvaluatedObject];
objectIDExpression.expressionResultType = NSObjectIDAttributeType;
NSExpressionDescription* objectIDExpression = [NSExpressionDescription new];
objectIDExpression.name = @"objectID";
objectIDExpression.expression = [NSExpression expressionForEvaluatedObject];
objectIDExpression.expressionResultType = NSObjectIDAttributeType;
// NOTE: `NSDictionaryResultType` does NOT support fetching pending changes. Pending objects must be manually added to the cache via `addObject:`.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
fetchRequest.entity = self.entity;
fetchRequest.resultType = NSDictionaryResultType;
fetchRequest.propertiesToFetch = [self.attributes arrayByAddingObject:objectIDExpression];
// NOTE: `NSDictionaryResultType` does NOT support fetching pending changes. Pending objects must be manually added to the cache via `addObject:`.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
fetchRequest.entity = self.entity;
fetchRequest.resultType = NSDictionaryResultType;
fetchRequest.propertiesToFetch = [self.attributes arrayByAddingObject:objectIDExpression];
[self.managedObjectContext performBlockAndWait:^{
NSError *error = nil;
NSArray *dictionaries = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
if (dictionaries) {
RKLogDebug(@"Retrieved %ld dictionaries for cachable `NSManagedObjectID` objects with fetch request: %@", (long) [dictionaries count], fetchRequest);
} else {
RKLogWarning(@"Failed to load entity cache. Failed to execute fetch request: %@", fetchRequest);
RKLogCoreDataError(error);
}
[self.managedObjectContext performBlockAndWait:^{
NSError *error = nil;
NSArray *dictionaries = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
if (dictionaries) {
RKLogDebug(@"Retrieved %ld dictionaries for cachable `NSManagedObjectID` objects with fetch request: %@", (long) [dictionaries count], fetchRequest);
} else {
RKLogWarning(@"Failed to load entity cache. Failed to execute fetch request: %@", fetchRequest);
RKLogCoreDataError(error);
}
for (NSDictionary *dictionary in dictionaries) {
NSManagedObjectID *objectID = [dictionary objectForKey:@"objectID"];
NSDictionary *attributeValues = [dictionary dictionaryWithValuesForKeys:self.attributes];
[self setObjectID:objectID forAttributeValues:attributeValues];
}
}];
}
for (NSDictionary *dictionary in dictionaries) {
NSManagedObjectID *objectID = [dictionary objectForKey:@"objectID"];
NSDictionary *attributeValues = [dictionary dictionaryWithValuesForKeys:self.attributes];
[self setObjectID:objectID forAttributeValues:attributeValues];
}
}];
[self.lock unlock];
}
- (void)flush
{
@synchronized(self.cacheKeysToObjectIDs) {
RKLogDebug(@"Flushing entity cache for Entity '%@' by attributes '%@'", self.entity.name, self.attributes);
self.cacheKeysToObjectIDs = nil;
}
[self.lock lock];
RKLogDebug(@"Flushing entity cache for Entity '%@' by attributes '%@'", self.entity.name, self.attributes);
self.cacheKeysToObjectIDs = nil;
[self.lock unlock];
}
- (void)reload
{
[self.lock lock];
[self flush];
[self load];
[self.lock unlock];
}
- (BOOL)isLoaded
{
return (self.cacheKeysToObjectIDs != nil);
[self.lock lock];
BOOL isLoaded = (self.cacheKeysToObjectIDs != nil);
[self.lock unlock];
return isLoaded;
}
- (NSManagedObject *)objectForObjectID:(NSManagedObjectID *)objectID inContext:(NSManagedObjectContext *)context
@@ -203,6 +219,7 @@ static NSArray *RKCacheKeysForEntityFromAttributeValues(NSEntityDescription *ent
*/
__block NSError *error = nil;
__block NSManagedObject *object;
[self.lock lock];
[context performBlockAndWait:^{
object = [context existingObjectWithID:objectID error:&error];
}];
@@ -211,21 +228,22 @@ static NSArray *RKCacheKeysForEntityFromAttributeValues(NSEntityDescription *ent
if (error && !([objectID isTemporaryID] && [error code] == NSManagedObjectReferentialIntegrityError)) {
RKLogError(@"Failed to retrieve managed object with ID %@. Error %@\n%@", objectID, [error localizedDescription], [error userInfo]);
}
return nil;
}
[self.lock unlock];
return object;
}
- (NSManagedObject *)objectWithAttributeValues:(NSDictionary *)attributeValues inContext:(NSManagedObjectContext *)context
{
[self.lock lock];
NSSet *objects = [self objectsWithAttributeValues:attributeValues inContext:context];
[self.lock unlock];
return ([objects count] > 0) ? [objects anyObject] : nil;
}
- (NSSet *)objectsWithAttributeValues:(NSDictionary *)attributeValues inContext:(NSManagedObjectContext *)context
{
[self.lock lock];
NSMutableSet *objects = [NSMutableSet set];
NSArray *cacheKeys = RKCacheKeysForEntityFromAttributeValues(self.entity, attributeValues);
for (NSString *cacheKey in cacheKeys) {
@@ -250,51 +268,52 @@ static NSArray *RKCacheKeysForEntityFromAttributeValues(NSEntityDescription *ent
}
}
}
[self.lock unlock];
return objects;
}
- (void)setObjectID:(NSManagedObjectID *)objectID forAttributeValues:(NSDictionary *)attributeValues
{
@synchronized(self.cacheKeysToObjectIDs) {
if (attributeValues && [attributeValues count]) {
NSString *cacheKey = RKCacheKeyForEntityWithAttributeValues(self.entity, attributeValues);
NSMutableArray *objectIDs = [self.cacheKeysToObjectIDs objectForKey:cacheKey];
if (objectIDs) {
if (! [objectIDs containsObject:objectID]) {
[objectIDs addObject:objectID];
}
} else {
objectIDs = [NSMutableArray arrayWithObject:objectID];
[self.lock lock];
if (attributeValues && [attributeValues count]) {
NSString *cacheKey = RKCacheKeyForEntityWithAttributeValues(self.entity, attributeValues);
NSMutableArray *objectIDs = [self.cacheKeysToObjectIDs objectForKey:cacheKey];
if (objectIDs) {
if (! [objectIDs containsObject:objectID]) {
[objectIDs addObject:objectID];
}
if (nil == self.cacheKeysToObjectIDs) self.cacheKeysToObjectIDs = [NSMutableDictionary dictionary];
[self.cacheKeysToObjectIDs setValue:objectIDs forKey:cacheKey];
} else {
RKLogWarning(@"Unable to add object for object ID %@: empty values dictionary for attributes '%@'", objectID, self.attributes);
objectIDs = [NSMutableArray arrayWithObject:objectID];
}
if (nil == self.cacheKeysToObjectIDs) self.cacheKeysToObjectIDs = [NSMutableDictionary dictionary];
[self.cacheKeysToObjectIDs setValue:objectIDs forKey:cacheKey];
} else {
RKLogWarning(@"Unable to add object for object ID %@: empty values dictionary for attributes '%@'", objectID, self.attributes);
}
[self.lock unlock];
}
- (void)removeObjectID:(NSManagedObjectID *)objectID forAttributeValues:(NSDictionary *)attributeValues
{
@synchronized(self.cacheKeysToObjectIDs) {
if (attributeValues && [attributeValues count]) {
NSArray *cacheKeys = RKCacheKeysForEntityFromAttributeValues(self.entity, attributeValues);
for (NSString *cacheKey in cacheKeys) {
NSMutableArray *objectIDs = [self.cacheKeysToObjectIDs objectForKey:cacheKey];
if (objectIDs && [objectIDs containsObject:objectID]) {
[objectIDs removeObject:objectID];
}
[self.lock lock];
if (attributeValues && [attributeValues count]) {
NSArray *cacheKeys = RKCacheKeysForEntityFromAttributeValues(self.entity, attributeValues);
for (NSString *cacheKey in cacheKeys) {
NSMutableArray *objectIDs = [self.cacheKeysToObjectIDs objectForKey:cacheKey];
if (objectIDs && [objectIDs containsObject:objectID]) {
[objectIDs removeObject:objectID];
}
} else {
RKLogWarning(@"Unable to remove object for object ID %@: empty values dictionary for attributes '%@'", objectID, self.attributes);
}
} else {
RKLogWarning(@"Unable to remove object for object ID %@: empty values dictionary for attributes '%@'", objectID, self.attributes);
}
[self.lock unlock];
}
- (void)addObject:(NSManagedObject *)object
{
[self.lock lock];
__block NSEntityDescription *entity;
__block NSDictionary *attributeValues;
__block NSManagedObjectID *objectID;
@@ -305,10 +324,12 @@ static NSArray *RKCacheKeysForEntityFromAttributeValues(NSEntityDescription *ent
}];
NSAssert([entity isKindOfEntity:self.entity], @"Cannot add object with entity '%@' to cache for entity of '%@'", [entity name], [self.entity name]);
[self setObjectID:objectID forAttributeValues:attributeValues];
[self.lock unlock];
}
- (void)removeObject:(NSManagedObject *)object
{
[self.lock lock];
__block NSEntityDescription *entity;
__block NSDictionary *attributeValues;
__block NSManagedObjectID *objectID;
@@ -319,41 +340,56 @@ static NSArray *RKCacheKeysForEntityFromAttributeValues(NSEntityDescription *ent
}];
NSAssert([entity isKindOfEntity:self.entity], @"Cannot remove object with entity '%@' from cache for entity of '%@'", [entity name], [self.entity name]);
[self removeObjectID:objectID forAttributeValues:attributeValues];
[self.lock unlock];
}
- (BOOL)containsObjectWithAttributeValues:(NSDictionary *)attributeValues
{
return [[self objectsWithAttributeValues:attributeValues inContext:self.managedObjectContext] count] > 0;
[self.lock lock];
BOOL containsObject = [[self objectsWithAttributeValues:attributeValues inContext:self.managedObjectContext] count] > 0;
[self.lock unlock];
return containsObject;
}
- (BOOL)containsObject:(NSManagedObject *)object
{
[self.lock lock];
NSArray *allObjectIDs = [[self.cacheKeysToObjectIDs allValues] valueForKeyPath:@"@distinctUnionOfArrays.self"];
[self.lock unlock];
return [allObjectIDs containsObject:object.objectID];
}
- (void)managedObjectContextDidChange:(NSNotification *)notification
{
if (self.monitorsContextForChanges == NO) return;
NSDictionary *userInfo = notification.userInfo;
NSSet *insertedObjects = [userInfo objectForKey:NSInsertedObjectsKey];
NSSet *updatedObjects = [userInfo objectForKey:NSUpdatedObjectsKey];
NSSet *deletedObjects = [userInfo objectForKey:NSDeletedObjectsKey];
RKLogTrace(@"insertedObjects=%@, updatedObjects=%@, deletedObjects=%@", insertedObjects, updatedObjects, deletedObjects);
NSMutableSet *objectsToAdd = [NSMutableSet setWithSet:insertedObjects];
[objectsToAdd unionSet:updatedObjects];
for (NSManagedObject *object in objectsToAdd) {
if ([object.entity isKindOfEntity:self.entity]) {
[self addObject:object];
/**
We dispatch async here to avoid a deadlock situation if the notification is delivered while another thread has acquired the lock. This is problematic for changes to `NSMainQueueConcurrencyType` MOC's in particular. We pre-calculate the attribute values from the object rather than invoking `addObject:` or `removeObject:` as the deleted objects will be unreadable once execution resumes following the notification's delivery.
*/
for (NSManagedObject *managedObject in objectsToAdd) {
if ([managedObject.entity isKindOfEntity:self.entity]) {
NSManagedObjectID *objectID = [managedObject objectID];
NSDictionary *attributeValues = [managedObject dictionaryWithValuesForKeys:self.attributes];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[self setObjectID:objectID forAttributeValues:attributeValues];
});
}
}
for (NSManagedObject *object in deletedObjects) {
if ([object.entity isKindOfEntity:self.entity]) {
[self removeObject:object];
for (NSManagedObject *managedObject in deletedObjects) {
if ([managedObject.entity isKindOfEntity:self.entity]) {
NSManagedObjectID *objectID = [managedObject objectID];
NSDictionary *attributeValues = [managedObject dictionaryWithValuesForKeys:self.attributes];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[self removeObjectID:objectID forAttributeValues:attributeValues];
});
}
}
}