134 lines
5.2 KiB
Objective-C
134 lines
5.2 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 "FWriteTreeRef.h"
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#import "FPath.h"
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#import "FNode.h"
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#import "FWriteTree.h"
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#import "FChildrenNode.h"
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#import "FNamedNode.h"
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#import "FWriteRecord.h"
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#import "FIndex.h"
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#import "FCacheNode.h"
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@interface FWriteTreeRef ()
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/**
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* The path to this particular FWriteTreeRef. Used for calling methods on writeTree while exposing a simpler interface
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* to callers.
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*/
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@property (nonatomic, strong) FPath *path;
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/**
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* A reference to the actual tree of the write data. All methods are pass-through to the tree, but with the appropriate
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* path prefixed.
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*
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* This lets us make cheap references to points in the tree for sync points without having to copy and maintain all of
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* the data.
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*/
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@property (nonatomic, strong) FWriteTree *writeTree;
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@end
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/**
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* A FWriteTreeRef wraps a FWriteTree and a FPath, for convenient access to a particular subtree. All the methods just
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* proxy to the underlying FWriteTree.
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*/
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@implementation FWriteTreeRef
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- (id) initWithPath:(FPath *)aPath writeTree:(FWriteTree *)tree {
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self = [super init];
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if (self) {
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self.path = aPath;
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self.writeTree = tree;
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}
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return self;
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}
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/**
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* @return If possible, returns a complete event cache, using the underlying server data if possible. In addition, can
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* be used to get a cache that includes hidden writes, and excludes arbitrary writes. Note that customizing the returned
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* node can lead to a more expensive calculation.
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*/
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- (id <FNode>) calculateCompleteEventCacheWithCompleteServerCache:(id<FNode>)completeServerCache {
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return [self.writeTree calculateCompleteEventCacheAtPath:self.path completeServerCache:completeServerCache excludeWriteIds:nil includeHiddenWrites:NO];
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}
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/**
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* @return If possible, returns a children node containing all of the complete children we have data for. The returned
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* data is a mix of the given server data and write data.
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*/
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- (FChildrenNode *) calculateCompleteEventChildrenWithCompleteServerChildren:(id<FNode>)completeServerChildren {
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return [self.writeTree calculateCompleteEventChildrenAtPath:self.path completeServerChildren:completeServerChildren];
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}
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/**
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* Given that either the underlying server data has updated or the outstanding writes have been updating, determine what,
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* if anything, needs to be applied to the event cache.
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*
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* Possibilities:
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*
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* 1. No writes are shadowing. Events should be raised, the snap to be applied comes from the server data.
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*
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* 2. Some writes are completly shadowing. No events to be raised.
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*
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* 3. Is partially shadowed. Events should be raised.
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*
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* Either existingEventSnap or existingServerSnap must exist, this is validated via an assert.
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*/
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- (id<FNode>) calculateEventCacheAfterServerOverwriteWithChildPath:(FPath *)childPath existingEventSnap:(id <FNode>)existingEventSnap existingServerSnap:(id <FNode>)existingServerSnap {
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return [self.writeTree calculateEventCacheAfterServerOverwriteAtPath:self.path childPath:childPath existingEventSnap:existingEventSnap existingServerSnap:existingServerSnap];
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}
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/**
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* Returns a node if there is a complete overwrite for this path. More specifically, if there is a write at a higher
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* path, this will return the child of that write relative to the write and this path.
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* Returns nil if there is no write at this path.
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*/
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- (id<FNode>) shadowingWriteAtPath:(FPath *)path {
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return [self.writeTree shadowingWriteAtPath:[self.path child:path]];
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}
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/**
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* This method is used when processing child remove events on a query. If we can, we pull in children that are outside
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* the window, but may now be in the window.
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*/
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- (FNamedNode *)calculateNextNodeAfterPost:(FNamedNode *)post
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completeServerData:(id<FNode>)completeServerData
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reverse:(BOOL)reverse
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index:(id<FIndex>)index
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{
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return [self.writeTree calculateNextNodeAfterPost:post
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atPath:self.path
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completeServerData:completeServerData
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reverse:reverse
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index:index];
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}
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/**
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* Returns a complete child for a given server snap after applying all user writes or nil if there is no complete child
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* for this child key.
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*/
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- (id<FNode>) calculateCompleteChild:(NSString *)childKey cache:(FCacheNode *)existingServerCache {
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return [self.writeTree calculateCompleteChildAtPath:self.path childKey:childKey cache:existingServerCache];
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}
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/**
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* @return a WriteTreeref for a child.
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*/
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- (FWriteTreeRef *) childWriteTreeRef:(NSString *)childKey {
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return [[FWriteTreeRef alloc] initWithPath:[self.path childFromString:childKey] writeTree:self.writeTree];
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}
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@end
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