/
FindOperation.swift
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/
FindOperation.swift
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//
// FindOperation.swift
// Kinvey
//
// Created by Victor Barros on 2016-02-15.
// Copyright © 2016 Kinvey. All rights reserved.
//
import Foundation
import PromiseKit
private let MaxIdsPerQuery = 200
internal class FindOperation<T: Persistable>: ReadOperation<T, AnyRandomAccessCollection<T>, Swift.Error>, ReadOperationType where T: NSObject {
let query: Query
let deltaSet: Bool
let deltaSetCompletionHandler: ((AnyRandomAccessCollection<T>) -> Void)?
lazy var isEmptyQuery: Bool = {
return (self.query.predicate == nil || self.query.predicate == NSPredicate()) && self.query.skip == nil && self.query.limit == nil
}()
var mustRemoveCachedRecords: Bool {
return isEmptyQuery
}
typealias ResultsHandler = ([JsonDictionary]) -> Void
let resultsHandler: ResultsHandler?
init(
query: Query,
deltaSet: Bool,
deltaSetCompletionHandler: ((AnyRandomAccessCollection<T>) -> Void)? = nil,
readPolicy: ReadPolicy,
cache: AnyCache<T>?,
options: Options?,
resultsHandler: ResultsHandler? = nil
) {
self.query = query
self.deltaSet = deltaSet
self.deltaSetCompletionHandler = deltaSetCompletionHandler
self.resultsHandler = resultsHandler
super.init(
readPolicy: readPolicy,
cache: cache,
options: options
)
}
@discardableResult
func executeLocal(_ completionHandler: CompletionHandler? = nil) -> Request {
let request = LocalRequest()
request.execute { () -> Void in
if let cache = self.cache {
let json = cache.find(byQuery: self.query)
completionHandler?(.success(json))
} else {
completionHandler?(.success(AnyRandomAccessCollection<T>([])))
}
}
return request
}
typealias ArrayCompletionHandler = ([Any]?, Error?) -> Void
@discardableResult
func executeNetwork(_ completionHandler: CompletionHandler? = nil) -> Request {
let multiRequest = MultiRequest()
let deltaSet = self.deltaSet && (cache != nil ? !cache!.isEmpty() : false)
let fields: Set<String>? = deltaSet ? [Entity.Key.entityId, "\(Entity.Key.metadata).\(Metadata.Key.lastModifiedTime)"] : nil
let request = client.networkRequestFactory.buildAppDataFindByQuery(
collectionName: T.collectionName(),
query: fields != nil ? Query(query) { $0.fields = fields } : query,
options: options
)
request.execute() { data, response, error in
if let response = response, response.isOK,
let jsonArray = self.client.responseParser.parseArray(data)
{
self.resultsHandler?(jsonArray)
if let cache = self.cache, deltaSet {
let refObjs = self.reduceToIdsLmts(jsonArray)
guard jsonArray.count == refObjs.count else {
let operation = FindOperation(
query: self.query,
deltaSet: false,
readPolicy: self.readPolicy,
cache: cache,
options: self.options
)
let request = operation.executeNetwork(completionHandler)
multiRequest += request
return
}
let deltaSet = self.computeDeltaSet(self.query, refObjs: refObjs)
var allIds = Set<String>(minimumCapacity: deltaSet.created.count + deltaSet.updated.count + deltaSet.deleted.count)
allIds.formUnion(deltaSet.created)
allIds.formUnion(deltaSet.updated)
allIds.formUnion(deltaSet.deleted)
if allIds.count > MaxIdsPerQuery {
let allIds = Array<String>(allIds)
var promises = [Promise<AnyRandomAccessCollection<T>>]()
var newRefObjs = [String : String]()
for offset in stride(from: 0, to: allIds.count, by: MaxIdsPerQuery) {
let limit = min(offset + MaxIdsPerQuery, allIds.count - 1)
let allIds = Set<String>(allIds[offset...limit])
let promise = Promise<AnyRandomAccessCollection<T>> { fulfill, reject in
let query = Query(format: "\(Entity.Key.entityId) IN %@", allIds)
let operation = FindOperation<T>(
query: query,
deltaSet: false,
readPolicy: .forceNetwork,
cache: cache,
options: self.options
) { jsonArray in
for (key, value) in self.reduceToIdsLmts(jsonArray) {
newRefObjs[key] = value
}
}
operation.execute { (result) -> Void in
switch result {
case .success(let results):
fulfill(results)
case .failure(let error):
reject(error)
}
}
}
promises.append(promise)
}
when(fulfilled: promises).then { results -> Void in
if self.mustRemoveCachedRecords {
self.removeCachedRecords(
cache,
keys: refObjs.keys,
deleted: deltaSet.deleted
)
}
if let deltaSetCompletionHandler = self.deltaSetCompletionHandler {
deltaSetCompletionHandler(AnyRandomAccessCollection(results.flatMap { $0 }))
}
self.executeLocal(completionHandler)
}.catch { error in
completionHandler?(.failure(error))
}
} else if allIds.count > 0 {
let query = Query(format: "\(Entity.Key.entityId) IN %@", allIds)
var newRefObjs: [String : String]? = nil
let operation = FindOperation<T>(
query: query,
deltaSet: false,
readPolicy: .forceNetwork,
cache: cache,
options: self.options
) { jsonArray in
newRefObjs = self.reduceToIdsLmts(jsonArray)
}
operation.execute { (result) -> Void in
switch result {
case .success:
if self.mustRemoveCachedRecords,
let refObjs = newRefObjs
{
self.removeCachedRecords(
cache,
keys: refObjs.keys,
deleted: deltaSet.deleted
)
}
self.executeLocal(completionHandler)
case .failure(let error):
completionHandler?(.failure(buildError(data, response, error, self.client)))
}
}
} else {
self.executeLocal(completionHandler)
}
} else {
func convert(_ jsonArray: [JsonDictionary]) -> AnyRandomAccessCollection<T> {
let startTime = CFAbsoluteTimeGetCurrent()
let entities = AnyRandomAccessCollection(jsonArray.lazy.filter {
($0[Entity.Key.entityId] as? String) != nil
}.map {
T(JSON: $0)!
})
log.debug("Time elapsed: \(CFAbsoluteTimeGetCurrent() - startTime) s")
return entities
}
let entities = convert(jsonArray)
if let cache = self.cache {
if self.mustRemoveCachedRecords {
let refObjs = self.reduceToIdsLmts(jsonArray)
let deltaSet = self.computeDeltaSet(
self.query,
refObjs: refObjs
)
self.removeCachedRecords(
cache,
keys: refObjs.keys,
deleted: deltaSet.deleted
)
}
if let cache = cache.dynamic {
cache.save(entities: AnyRandomAccessCollection(jsonArray))
} else {
cache.save(entities: entities)
}
}
completionHandler?(.success(entities))
}
} else {
completionHandler?(.failure(buildError(data, response, error, self.client)))
}
}
multiRequest += request
return multiRequest
}
fileprivate func removeCachedRecords<S : Sequence>(_ cache: AnyCache<T>, keys: S, deleted: Set<String>) where S.Iterator.Element == String {
let refKeys = Set<String>(keys)
let deleted = deleted.subtracting(refKeys)
if deleted.count > 0 {
let query = Query(format: "\(T.entityIdProperty()) IN %@", deleted as AnyObject)
cache.remove(byQuery: query)
}
}
}