326 lines
12 KiB
Objective-C
326 lines
12 KiB
Objective-C
/*
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* Copyright 2017 Google
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#import "FirebaseDatabase/Sources/Core/FSyncPoint.h"
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#import "FirebaseDatabase/Sources/Core/FQueryParams.h"
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#import "FirebaseDatabase/Sources/Core/FQuerySpec.h"
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#import "FirebaseDatabase/Sources/Core/FWriteTreeRef.h"
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#import "FirebaseDatabase/Sources/Core/Operation/FOperation.h"
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#import "FirebaseDatabase/Sources/Core/Operation/FOperationSource.h"
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#import "FirebaseDatabase/Sources/Core/Utilities/FPath.h"
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#import "FirebaseDatabase/Sources/Core/View/FCacheNode.h"
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#import "FirebaseDatabase/Sources/Core/View/FDataEvent.h"
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#import "FirebaseDatabase/Sources/Core/View/FEventRegistration.h"
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#import "FirebaseDatabase/Sources/Core/View/FView.h"
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#import "FirebaseDatabase/Sources/Core/View/FViewCache.h"
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#import "FirebaseDatabase/Sources/Persistence/FPersistenceManager.h"
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#import "FirebaseDatabase/Sources/Public/FirebaseDatabase/FIRDatabaseQuery.h"
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#import "FirebaseDatabase/Sources/Snapshot/FChildrenNode.h"
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#import "FirebaseDatabase/Sources/Snapshot/FEmptyNode.h"
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#import "FirebaseDatabase/Sources/Snapshot/FNode.h"
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#import "FirebaseDatabase/Sources/Utilities/Tuples/FTupleRemovedQueriesEvents.h"
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/**
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* SyncPoint represents a single location in a SyncTree with 1 or more event
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* registrations, meaning we need to maintain 1 or more Views at this location
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* to cache server data and raise appropriate events for server changes and user
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* writes (set, transaction, update).
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*
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* It's responsible for:
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* - Maintaining the set of 1 or more views necessary at this location (a
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* SyncPoint with 0 views should be removed).
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* - Proxying user / server operations to the views as appropriate (i.e.
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* applyServerOverwrite, applyUserOverwrite, etc.)
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*/
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@interface FSyncPoint ()
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/**
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* The Views being tracked at this location in the tree, stored as a map where
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* the key is a queryParams and the value is the View for that query.
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*
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* NOTE: This list will be quite small (usually 1, but perhaps 2 or 3; any more
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* is an odd use case).
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*
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* Maps NSString -> FView
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*/
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@property(nonatomic, strong) NSMutableDictionary *views;
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@property(nonatomic, strong) FPersistenceManager *persistenceManager;
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@end
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@implementation FSyncPoint
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- (id)initWithPersistenceManager:(FPersistenceManager *)persistence {
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self = [super init];
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if (self) {
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self.persistenceManager = persistence;
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self.views = [[NSMutableDictionary alloc] init];
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}
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return self;
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}
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- (BOOL)isEmpty {
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return [self.views count] == 0;
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}
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- (NSArray *)applyOperation:(id<FOperation>)operation
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toView:(FView *)view
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writesCache:(FWriteTreeRef *)writesCache
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serverCache:(id<FNode>)optCompleteServerCache {
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FViewOperationResult *result = [view applyOperation:operation
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writesCache:writesCache
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serverCache:optCompleteServerCache];
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if (!view.query.loadsAllData) {
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NSMutableSet *removed = [NSMutableSet set];
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NSMutableSet *added = [NSMutableSet set];
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[result.changes enumerateObjectsUsingBlock:^(
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FChange *change, NSUInteger idx, BOOL *stop) {
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if (change.type == FIRDataEventTypeChildAdded) {
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[added addObject:change.childKey];
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} else if (change.type == FIRDataEventTypeChildRemoved) {
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[removed addObject:change.childKey];
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}
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}];
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if ([removed count] > 0 || [added count] > 0) {
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[self.persistenceManager
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updateTrackedQueryKeysWithAddedKeys:added
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removedKeys:removed
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forQuery:view.query];
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}
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}
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return result.events;
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}
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- (NSArray *)applyOperation:(id<FOperation>)operation
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writesCache:(FWriteTreeRef *)writesCache
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serverCache:(id<FNode>)optCompleteServerCache {
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FQueryParams *queryParams = operation.source.queryParams;
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if (queryParams != nil) {
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FView *view = [self.views objectForKey:queryParams];
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NSAssert(view != nil, @"SyncTree gave us an op for an invalid query.");
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return [self applyOperation:operation
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toView:view
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writesCache:writesCache
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serverCache:optCompleteServerCache];
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} else {
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NSMutableArray *events = [[NSMutableArray alloc] init];
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[self.views enumerateKeysAndObjectsUsingBlock:^(
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FQueryParams *key, FView *view, BOOL *stop) {
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NSArray *eventsForView = [self applyOperation:operation
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toView:view
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writesCache:writesCache
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serverCache:optCompleteServerCache];
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[events addObjectsFromArray:eventsForView];
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}];
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return events;
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}
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}
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- (FView *)getView:(FQuerySpec *)query
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writesCache:(FWriteTreeRef *)writesCache
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serverCache:(FCacheNode *)serverCache {
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FView *view = self.views[query.params];
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if (view != nil) {
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return view;
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}
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id<FNode> eventCache = [writesCache
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calculateCompleteEventCacheWithCompleteServerCache:
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serverCache.isFullyInitialized ? serverCache.node : nil];
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BOOL eventCacheComplete;
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if (eventCache != nil) {
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eventCacheComplete = YES;
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} else {
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eventCache = [writesCache
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calculateCompleteEventChildrenWithCompleteServerChildren:
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serverCache.node != nil ? serverCache.node
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: [FEmptyNode emptyNode]];
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eventCacheComplete = NO;
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}
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FIndexedNode *indexed = [FIndexedNode indexedNodeWithNode:eventCache
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index:query.index];
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FCacheNode *eventCacheNode =
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[[FCacheNode alloc] initWithIndexedNode:indexed
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isFullyInitialized:eventCacheComplete
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isFiltered:NO];
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FViewCache *viewCache =
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[[FViewCache alloc] initWithEventCache:eventCacheNode
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serverCache:serverCache];
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return [[FView alloc] initWithQuery:query initialViewCache:viewCache];
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}
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/**
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* Add an event callback for the specified query
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* Returns an array of events to raise.
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*/
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- (NSArray *)addEventRegistration:(id<FEventRegistration>)eventRegistration
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forNonExistingViewForQuery:(FQuerySpec *)query
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writesCache:(FWriteTreeRef *)writesCache
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serverCache:(FCacheNode *)serverCache {
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NSAssert(self.views[query.params] == nil, @"Found view for query: %@",
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query.params);
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// TODO: make writesCache take flag for complete server node
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FView *view = [self getView:query
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writesCache:writesCache
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serverCache:serverCache];
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// If this is a non-default query we need to tell persistence our current
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// view of the data
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if (!query.loadsAllData) {
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NSMutableSet *allKeys = [NSMutableSet set];
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[view.eventCache enumerateChildrenUsingBlock:^(
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NSString *key, id<FNode> node, BOOL *stop) {
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[allKeys addObject:key];
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}];
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[self.persistenceManager setTrackedQueryKeys:allKeys forQuery:query];
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}
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self.views[query.params] = view;
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return [self addEventRegistration:eventRegistration
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forExistingViewForQuery:query];
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}
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- (NSArray *)addEventRegistration:(id<FEventRegistration>)eventRegistration
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forExistingViewForQuery:(FQuerySpec *)query {
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FView *view = self.views[query.params];
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NSAssert(view != nil, @"No view for query: %@", query);
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[view addEventRegistration:eventRegistration];
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return [view initialEvents:eventRegistration];
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}
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/**
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* Remove event callback(s). Return cancelEvents if a cancelError is specified.
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*
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* If query is the default query, we'll check all views for the specified
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* eventRegistration. If eventRegistration is nil, we'll remove all callbacks
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* for the specified view(s).
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*
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* @return FTupleRemovedQueriesEvents removed queries and any cancel events
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*/
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- (FTupleRemovedQueriesEvents *)removeEventRegistration:
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(id<FEventRegistration>)eventRegistration
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forQuery:(FQuerySpec *)query
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cancelError:(NSError *)cancelError {
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NSMutableArray *removedQueries = [[NSMutableArray alloc] init];
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__block NSMutableArray *cancelEvents = [[NSMutableArray alloc] init];
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BOOL hadCompleteView = [self hasCompleteView];
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if ([query isDefault]) {
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// When you do [ref removeObserverWithHandle:], we search all views for
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// the registration to remove.
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[self.views enumerateKeysAndObjectsUsingBlock:^(
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FQueryParams *viewQueryParams, FView *view,
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BOOL *stop) {
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[cancelEvents
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addObjectsFromArray:[view
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removeEventRegistration:eventRegistration
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cancelError:cancelError]];
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if ([view isEmpty]) {
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[self.views removeObjectForKey:viewQueryParams];
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// We'll deal with complete views later
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if (![view.query loadsAllData]) {
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[removedQueries addObject:view.query];
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}
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}
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}];
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} else {
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// remove the callback from the specific view
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FView *view = [self.views objectForKey:query.params];
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if (view != nil) {
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[cancelEvents addObjectsFromArray:
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[view removeEventRegistration:eventRegistration
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cancelError:cancelError]];
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if ([view isEmpty]) {
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[self.views removeObjectForKey:query.params];
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// We'll deal with complete views later
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if (![view.query loadsAllData]) {
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[removedQueries addObject:view.query];
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}
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}
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}
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}
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if (hadCompleteView && ![self hasCompleteView]) {
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// We removed our last complete view
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[removedQueries addObject:[FQuerySpec defaultQueryAtPath:query.path]];
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}
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return [[FTupleRemovedQueriesEvents alloc]
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initWithRemovedQueries:removedQueries
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cancelEvents:cancelEvents];
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}
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- (NSArray *)queryViews {
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__block NSMutableArray *filteredViews = [[NSMutableArray alloc] init];
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[self.views enumerateKeysAndObjectsUsingBlock:^(FQueryParams *key,
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FView *view, BOOL *stop) {
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if (![view.query loadsAllData]) {
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[filteredViews addObject:view];
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}
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}];
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return filteredViews;
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}
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- (id<FNode>)completeServerCacheAtPath:(FPath *)path {
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__block id<FNode> serverCache = nil;
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[self.views enumerateKeysAndObjectsUsingBlock:^(FQueryParams *key,
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FView *view, BOOL *stop) {
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serverCache = [view completeServerCacheFor:path];
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*stop = (serverCache != nil);
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}];
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return serverCache;
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}
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- (id<FNode>)completeEventCacheAtPath:(FPath *)path {
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__block id<FNode> eventCache = nil;
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[self.views enumerateKeysAndObjectsUsingBlock:^(FQueryParams *key,
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FView *view, BOOL *stop) {
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eventCache = [view completeEventCacheFor:path];
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*stop = (eventCache != nil);
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}];
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return eventCache;
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}
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- (FView *)viewForQuery:(FQuerySpec *)query {
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return [self.views objectForKey:query.params];
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}
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- (BOOL)viewExistsForQuery:(FQuerySpec *)query {
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return [self viewForQuery:query] != nil;
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}
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- (BOOL)hasCompleteView {
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return [self completeView] != nil;
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}
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- (FView *)completeView {
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__block FView *completeView = nil;
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[self.views enumerateKeysAndObjectsUsingBlock:^(FQueryParams *key,
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FView *view, BOOL *stop) {
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if ([view.query loadsAllData]) {
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completeView = view;
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*stop = YES;
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}
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}];
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return completeView;
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}
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@end
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