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/*
* Copyright 2017 Google
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#import "FView.h"
#import "FNode.h"
#import "FWriteTreeRef.h"
#import "FOperation.h"
#import "FIRDatabaseQuery.h"
#import "FIRDatabaseQuery_Private.h"
#import "FEventRegistration.h"
#import "FQueryParams.h"
#import "FQuerySpec.h"
#import "FViewCache.h"
#import "FPath.h"
#import "FEventGenerator.h"
#import "FOperationSource.h"
#import "FCancelEvent.h"
#import "FIndexedFilter.h"
#import "FCacheNode.h"
#import "FEmptyNode.h"
#import "FViewProcessor.h"
#import "FViewProcessorResult.h"
#import "FIndexedNode.h"
@interface FViewOperationResult ()
@property (nonatomic, strong, readwrite) NSArray *changes;
@property (nonatomic, strong, readwrite) NSArray *events;
@end
@implementation FViewOperationResult
- (id)initWithChanges:(NSArray *)changes events:(NSArray *)events {
self = [super init];
if (self != nil) {
self->_changes = changes;
self->_events = events;
}
return self;
}
@end
/**
* A view represents a specific location and query that has 1 or more event registrations.
*
* It does several things:
* - Maintains the list of event registration for this location/query.
* - Maintains a cache of the data visible for this location/query.
* - Applies new operations (via applyOperation), updates the cache, and based on the event
* registrations returns the set of events to be raised.
*/
@interface FView ()
@property (nonatomic, strong, readwrite) FQuerySpec *query;
@property (nonatomic, strong) FViewProcessor *processor;
@property (nonatomic, strong) FViewCache *viewCache;
@property (nonatomic, strong) NSMutableArray *eventRegistrations;
@property (nonatomic, strong) FEventGenerator *eventGenerator;
@end
@implementation FView
- (id) initWithQuery:(FQuerySpec *)query initialViewCache:(FViewCache *)initialViewCache {
self = [super init];
if (self) {
self.query = query;
FIndexedFilter *indexFilter = [[FIndexedFilter alloc] initWithIndex:query.index];
id<FNodeFilter> filter = query.params.nodeFilter;
self.processor = [[FViewProcessor alloc] initWithFilter:filter];
FCacheNode *initialServerCache = initialViewCache.cachedServerSnap;
FCacheNode *initialEventCache = initialViewCache.cachedEventSnap;
// Don't filter server node with other filter than index, wait for tagged listen
FIndexedNode *emptyIndexedNode = [FIndexedNode indexedNodeWithNode:[FEmptyNode emptyNode] index:query.index];
FIndexedNode *serverSnap = [indexFilter updateFullNode:emptyIndexedNode
withNewNode:initialServerCache.indexedNode
accumulator:nil];
FIndexedNode *eventSnap = [filter updateFullNode:emptyIndexedNode
withNewNode:initialEventCache.indexedNode
accumulator:nil];
FCacheNode *newServerCache = [[FCacheNode alloc] initWithIndexedNode:serverSnap
isFullyInitialized:initialServerCache.isFullyInitialized
isFiltered:indexFilter.filtersNodes];
FCacheNode *newEventCache = [[FCacheNode alloc] initWithIndexedNode:eventSnap
isFullyInitialized:initialEventCache.isFullyInitialized
isFiltered:filter.filtersNodes];
self.viewCache = [[FViewCache alloc] initWithEventCache:newEventCache serverCache:newServerCache];
self.eventRegistrations = [[NSMutableArray alloc] init];
self.eventGenerator = [[FEventGenerator alloc] initWithQuery:query];
}
return self;
}
- (id <FNode>) serverCache {
return self.viewCache.cachedServerSnap.node;
}
- (id <FNode>) eventCache {
return self.viewCache.cachedEventSnap.node;
}
- (id <FNode>) completeServerCacheFor:(FPath*)path {
id<FNode> cache = self.viewCache.completeServerSnap;
if (cache) {
// If this isn't a "loadsAllData" view, then cache isn't actually a complete cache and
// we need to see if it contains the child we're interested in.
if ([self.query loadsAllData] ||
(!path.isEmpty && ![cache getImmediateChild:path.getFront].isEmpty)) {
return [cache getChild:path];
}
}
return nil;
}
- (BOOL) isEmpty {
return self.eventRegistrations.count == 0;
}
- (void) addEventRegistration:(id <FEventRegistration>)eventRegistration {
[self.eventRegistrations addObject:eventRegistration];
}
/**
* @param eventRegistration If null, remove all callbacks.
* @param cancelError If a cancelError is provided, appropriate cancel events will be returned.
* @return Cancel events, if cancelError was provided.
*/
- (NSArray *) removeEventRegistration:(id <FEventRegistration>)eventRegistration cancelError:(NSError *)cancelError {
NSMutableArray *cancelEvents = [[NSMutableArray alloc] init];
if (cancelError != nil) {
NSAssert(eventRegistration == nil, @"A cancel should cancel all event registrations.");
FPath *path = self.query.path;
for (id <FEventRegistration> registration in self.eventRegistrations) {
FCancelEvent *maybeEvent = [registration createCancelEventFromError:cancelError path:path];
if (maybeEvent) {
[cancelEvents addObject:maybeEvent];
}
}
}
if (eventRegistration) {
NSUInteger i = 0;
while (i < self.eventRegistrations.count) {
id<FEventRegistration> existing = self.eventRegistrations[i];
if ([existing matches:eventRegistration]) {
[self.eventRegistrations removeObjectAtIndex:i];
} else {
i++;
}
}
} else {
[self.eventRegistrations removeAllObjects];
}
return cancelEvents;
}
/**
* Applies the given Operation, updates our cache, and returns the appropriate events and changes
*/
- (FViewOperationResult *) applyOperation:(id <FOperation>)operation writesCache:(FWriteTreeRef *)writesCache serverCache:(id <FNode>)optCompleteServerCache {
if (operation.type == FOperationTypeMerge && operation.source.queryParams != nil) {
NSAssert(self.viewCache.completeServerSnap != nil, @"We should always have a full cache before handling merges");
NSAssert(self.viewCache.completeEventSnap != nil, @"Missing event cache, even though we have a server cache");
}
FViewCache *oldViewCache = self.viewCache;
FViewProcessorResult *result = [self.processor applyOperationOn:oldViewCache operation:operation writesCache:writesCache completeCache:optCompleteServerCache];
NSAssert(result.viewCache.cachedServerSnap.isFullyInitialized || !oldViewCache.cachedServerSnap.isFullyInitialized, @"Once a server snap is complete, it should never go back.");
self.viewCache = result.viewCache;
NSArray *events = [self generateEventsForChanges:result.changes eventCache:result.viewCache.cachedEventSnap.indexedNode registration:nil];
return [[FViewOperationResult alloc] initWithChanges:result.changes events:events];
}
- (NSArray *) initialEvents:(id<FEventRegistration>)registration {
FCacheNode *eventSnap = self.viewCache.cachedEventSnap;
NSMutableArray *initialChanges = [[NSMutableArray alloc] init];
[eventSnap.indexedNode.node enumerateChildrenUsingBlock:^(NSString *key, id<FNode> node, BOOL *stop) {
FIndexedNode *indexed = [FIndexedNode indexedNodeWithNode:node];
FChange *change = [[FChange alloc] initWithType:FIRDataEventTypeChildAdded indexedNode:indexed childKey:key];
[initialChanges addObject:change];
}];
if (eventSnap.isFullyInitialized) {
FChange *change = [[FChange alloc] initWithType:FIRDataEventTypeValue indexedNode:eventSnap.indexedNode];
[initialChanges addObject:change];
}
return [self generateEventsForChanges:initialChanges eventCache:eventSnap.indexedNode registration:registration];
}
- (NSArray *) generateEventsForChanges:(NSArray *)changes eventCache:(FIndexedNode *)eventCache registration:(id<FEventRegistration>)registration {
NSArray *registrations;
if (registration == nil) {
registrations = [[NSArray alloc] initWithArray:self.eventRegistrations];
} else {
registrations = [[NSArray alloc] initWithObjects:registration, nil];
}
return [self.eventGenerator generateEventsForChanges:changes eventCache:eventCache eventRegistrations:registrations];
}
- (NSString *) description {
return [NSString stringWithFormat:@"FView (%@)", self.query];
}
@end
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