Add cachePolicy to ApolloClient#fetch

apollographql · Jan 21, 2017 · 76caa60 · 76caa60
1 parent cbc245b
commit 76caa60
Show file tree

Hide file tree

Showing 4 changed files with 400 additions and 24 deletions.
diff --git a/Apollo.xcodeproj/project.pbxproj b/Apollo.xcodeproj/project.pbxproj
@@ -84,6 +84,10 @@
 		9FC9A9D11E2FD3FE0023C4D5 /* Fragments.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FC9A9CF1E2FD3FE0023C4D5 /* Fragments.swift */; };
 		9FC9A9D31E2FD48B0023C4D5 /* GraphQLError.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FC9A9D21E2FD48B0023C4D5 /* GraphQLError.swift */; };
 		9FC9A9D41E2FD48B0023C4D5 /* GraphQLError.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FC9A9D21E2FD48B0023C4D5 /* GraphQLError.swift */; };
+		9FCDFD1F1E32EABB007519DC /* FetchQueryTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FCDFD1E1E32EABB007519DC /* FetchQueryTests.swift */; };
+		9FCDFD201E32EABB007519DC /* FetchQueryTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FCDFD1E1E32EABB007519DC /* FetchQueryTests.swift */; };
+		9FCDFD231E33A0D8007519DC /* AsynchronousOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FCDFD221E33A0D8007519DC /* AsynchronousOperation.swift */; };
+		9FCDFD241E33A0D8007519DC /* AsynchronousOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FCDFD221E33A0D8007519DC /* AsynchronousOperation.swift */; };
 		9FDC98481E2A369C005815DF /* HeroAndFriendsNames.graphql in Resources */ = {isa = PBXBuildFile; fileRef = 9FDC98471E2A369C005815DF /* HeroAndFriendsNames.graphql */; };
 		9FDC98491E2A369C005815DF /* HeroAndFriendsNames.graphql in Resources */ = {isa = PBXBuildFile; fileRef = 9FDC98471E2A369C005815DF /* HeroAndFriendsNames.graphql */; };
 		9FE3F3981DADBD870072078F /* check-and-run-apollo-codegen.sh in Resources */ = {isa = PBXBuildFile; fileRef = 9FE3F3971DADBD870072078F /* check-and-run-apollo-codegen.sh */; };
@@ -174,6 +178,8 @@
 		9FC9A9CB1E2FD0760023C4D5 /* Record.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Record.swift; sourceTree = "<group>"; };
 		9FC9A9CF1E2FD3FE0023C4D5 /* Fragments.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Fragments.swift; sourceTree = "<group>"; };
 		9FC9A9D21E2FD48B0023C4D5 /* GraphQLError.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = GraphQLError.swift; sourceTree = "<group>"; };
+		9FCDFD1E1E32EABB007519DC /* FetchQueryTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FetchQueryTests.swift; sourceTree = "<group>"; };
+		9FCDFD221E33A0D8007519DC /* AsynchronousOperation.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AsynchronousOperation.swift; sourceTree = "<group>"; };
 		9FDC98471E2A369C005815DF /* HeroAndFriendsNames.graphql */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = HeroAndFriendsNames.graphql; sourceTree = "<group>"; };
 		9FE3F3971DADBD870072078F /* check-and-run-apollo-codegen.sh */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.script.sh; name = "check-and-run-apollo-codegen.sh"; path = "scripts/check-and-run-apollo-codegen.sh"; sourceTree = SOURCE_ROOT; };
 		9FEB050C1DB5732300DA3B44 /* JSONSerializationFormat.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = JSONSerializationFormat.swift; sourceTree = "<group>"; };
@@ -326,7 +332,7 @@
 				9FC9A9CE1E2FD0CC0023C4D5 /* Network */,
 				9F27D4601D40363A00715680 /* Execution */,
 				9FC4B9231D2BE4F00046A641 /* JSON */,
-				9F578D8F1D8D2CB300C0EA36 /* Utilities.swift */,
+				9FCDFD211E33A09F007519DC /* Utilities */,
 				9FE3F3961DADBD0D0072078F /* Supporting Files */,
 			);
 			name = Apollo;
@@ -336,6 +342,7 @@
 		9FC750521D2A532D00458D91 /* ApolloTests */ = {
 			isa = PBXGroup;
 			children = (
+				9FCDFD1E1E32EABB007519DC /* FetchQueryTests.swift */,
 				9FF90A6C1DDDEB420034C3B6 /* ParseQueryResponseTests.swift */,
 				9F295E301E27534800A24949 /* NormalizeQueryResults.swift */,
 				9F55347D1DE1DB3500E54264 /* LoadQueryFromStoreTests.swift */,
@@ -379,6 +386,15 @@
 			name = Integration;
 			sourceTree = "<group>";
 		};
+		9FCDFD211E33A09F007519DC /* Utilities */ = {
+			isa = PBXGroup;
+			children = (
+				9F578D8F1D8D2CB300C0EA36 /* Utilities.swift */,
+				9FCDFD221E33A0D8007519DC /* AsynchronousOperation.swift */,
+			);
+			name = Utilities;
+			sourceTree = "<group>";
+		};
 		9FE3F3961DADBD0D0072078F /* Supporting Files */ = {
 			isa = PBXGroup;
 			children = (
@@ -777,6 +793,7 @@
 				9FC9A9CD1E2FD0760023C4D5 /* Record.swift in Sources */,
 				3C4DBD1A1DD231E1005B61D0 /* Utilities.swift in Sources */,
 				3C4DBD161DD231D9005B61D0 /* NetworkTransport.swift in Sources */,
+				9FCDFD241E33A0D8007519DC /* AsynchronousOperation.swift in Sources */,
 				9FC9A9C01E2C27FB0023C4D5 /* GraphQLResult.swift in Sources */,
 				3C4DBD231DD231F2005B61D0 /* JSON.swift in Sources */,
 				9FC9A9C31E2D3CAF0023C4D5 /* GraphQLTypes.swift in Sources */,
@@ -801,6 +818,7 @@
 				9FF90A701DDDEB420034C3B6 /* GraphQLInputValueEncodingTests.swift in Sources */,
 				9FF90A771DDDEB4C0034C3B6 /* Utilities.swift in Sources */,
 				9F55347F1DE1DB3500E54264 /* LoadQueryFromStoreTests.swift in Sources */,
+				9FCDFD201E32EABB007519DC /* FetchQueryTests.swift in Sources */,
 				9FF90A721DDDEB420034C3B6 /* GraphQLResultReaderTests.swift in Sources */,
 				9F295E331E27534800A24949 /* NormalizeQueryResults.swift in Sources */,
 				9F4FB2751DD853D800529F53 /* API.swift in Sources */,
@@ -819,6 +837,7 @@
 				9FC9A9D31E2FD48B0023C4D5 /* GraphQLError.swift in Sources */,
 				9FEB050D1DB5732300DA3B44 /* JSONSerializationFormat.swift in Sources */,
 				9FC9A9C51E2D6CE70023C4D5 /* Field.swift in Sources */,
+				9FCDFD231E33A0D8007519DC /* AsynchronousOperation.swift in Sources */,
 				9FC9A9CC1E2FD0760023C4D5 /* Record.swift in Sources */,
 				9FC4B9201D2A6F8D0046A641 /* JSON.swift in Sources */,
 				9F578D901D8D2CB300C0EA36 /* Utilities.swift in Sources */,
@@ -843,6 +862,7 @@
 				9FF90A6F1DDDEB420034C3B6 /* GraphQLInputValueEncodingTests.swift in Sources */,
 				9FF90A761DDDEB4C0034C3B6 /* Utilities.swift in Sources */,
 				9F55347E1DE1DB3500E54264 /* LoadQueryFromStoreTests.swift in Sources */,
+				9FCDFD1F1E32EABB007519DC /* FetchQueryTests.swift in Sources */,
 				9FF90A711DDDEB420034C3B6 /* GraphQLResultReaderTests.swift in Sources */,
 				9F295E311E27534800A24949 /* NormalizeQueryResults.swift in Sources */,
 				9F20CBC21DAF03F900A139BB /* API.swift in Sources */,

diff --git a/Sources/ApolloClient.swift b/Sources/ApolloClient.swift
@@ -4,54 +4,139 @@ public protocol Cancellable {
   func cancel()
 }
 
+public enum CachePolicy {
+  case returnCacheDataElseFetch
+  case fetchIgnoringCacheData
+  case returnCacheDataDontFetch
+}
+
+public typealias OperationCompletionHandler<Operation: GraphQLOperation> = (GraphQLResult<Operation.Data>?, Error?) -> Void
+
 public class ApolloClient {
+  private let operationQueue: OperationQueue
+
   let networkTransport: NetworkTransport
   let store: ApolloStore
 
-  var cacheKeyForObject: CacheKeyForObject?
+  public var cacheKeyForObject: CacheKeyForObject?
 
-  public init(networkTransport: NetworkTransport) {
+  public init(networkTransport: NetworkTransport, store: ApolloStore = ApolloStore()) {
+    operationQueue = OperationQueue()
     self.networkTransport = networkTransport
-    self.store = ApolloStore()
+    self.store = store
   }
 
   public convenience init(url: URL) {
     self.init(networkTransport: HTTPNetworkTransport(url: url))
   }
 
-  @discardableResult public func fetch<Query: GraphQLQuery>(query: Query, queue: DispatchQueue = DispatchQueue.main, completionHandler: @escaping (GraphQLResult<Query.Data>?, Error?) -> Void) -> Cancellable {
-    return perform(operation: query, completionHandler: completionHandler)
+  @discardableResult public func fetch<Query: GraphQLQuery>(query: Query, cachePolicy: CachePolicy = .returnCacheDataElseFetch, queue: DispatchQueue = DispatchQueue.main, completionHandler: @escaping OperationCompletionHandler<Query>) -> Cancellable {
+    if cachePolicy == .fetchIgnoringCacheData {
+      return send(operation: query) { (result, error) in
+        queue.async {
+          completionHandler(result, error)
+        }
+      }
+    } else {
+      let operation = FetchQueryOperation(client: self, query: query, cachePolicy: cachePolicy) { (result, error) in
+        queue.async {
+          completionHandler(result, error)
+        }
+      }
+
+      operationQueue.addOperation(operation)
+      return operation
+    }
   }
 
-  @discardableResult public func perform<Mutation: GraphQLMutation>(mutation: Mutation, queue: DispatchQueue = DispatchQueue.main, completionHandler: @escaping (GraphQLResult<Mutation.Data>?, Error?) -> Void) -> Cancellable {
-    return perform(operation: mutation, completionHandler: completionHandler)
+  public func watch<Query: GraphQLQuery>(query: Query, queue: DispatchQueue = DispatchQueue.main, handler: @escaping OperationCompletionHandler<Query>) -> Cancellable {
+    return fetch(query: query, queue: queue, completionHandler: handler)
+  }
+
+  @discardableResult public func perform<Mutation: GraphQLMutation>(mutation: Mutation, queue: DispatchQueue = DispatchQueue.main, completionHandler: @escaping OperationCompletionHandler<Mutation>) -> Cancellable {
+    return send(operation: mutation) { (result, error) in
+      queue.async {
+        completionHandler(result, error)
+      }
+    }
   }
 
-  private func perform<Operation: GraphQLOperation>(operation: Operation, queue: DispatchQueue = DispatchQueue.main, completionHandler: @escaping (GraphQLResult<Operation.Data>?, Error?) -> Void) -> Cancellable {
+  fileprivate func send<Operation: GraphQLOperation>(operation: Operation, completionHandler: @escaping OperationCompletionHandler<Operation>) -> Cancellable {
     return networkTransport.send(operation: operation) { (response, error) in
       guard let response = response else {
-        queue.async {
-          completionHandler(nil, error)
-        }
+        completionHandler(nil, error)
         return
       }
 
-      do {
-        let normalizer = GraphQLResultNormalizer()
-        normalizer.cacheKeyForObject = self.cacheKeyForObject
-
-        let result = try response.parseResult(delegate: normalizer)
-
-        queue.async {
+      DispatchQueue.global(qos: .default).async {
+        do {
+          let normalizer = GraphQLResultNormalizer()
+          normalizer.cacheKeyForObject = self.cacheKeyForObject
+
+          let result = try response.parseResult(delegate: normalizer)
+
+          self.store.publish(changedRecords: normalizer.records)
+
           completionHandler(result, nil)
-        }
-
-        self.store.publish(changedRecords: normalizer.records)
-      } catch {
-        queue.async {
+        } catch {
           completionHandler(nil, error)
         }
       }
     }
   }
 }
+
+private final class FetchQueryOperation<Query: GraphQLQuery>: AsynchronousOperation, Cancellable {
+  unowned let client: ApolloClient
+  let query: Query
+  let cachePolicy: CachePolicy
+  let completionHandler: OperationCompletionHandler<Query>
+
+  private var networkTask: Cancellable?
+
+  init(client: ApolloClient, query: Query, cachePolicy: CachePolicy, completionHandler: @escaping OperationCompletionHandler<Query>) {
+    self.client = client
+    self.query = query
+    self.cachePolicy = cachePolicy
+    self.completionHandler = completionHandler
+  }
+
+  override public func start() {
+    if isCancelled {
+      state = .finished
+      return
+    }
+
+    state = .executing
+
+    if cachePolicy != .fetchIgnoringCacheData {
+      if let data = try? client.store.load(query: query) {
+        completionHandler(GraphQLResult(data: data, errors: nil), nil)
+        state = .finished
+        return
+      }
+    }
+
+    if isCancelled {
+      state = .finished
+      return
+    }
+
+    if cachePolicy == .returnCacheDataDontFetch {
+      completionHandler(nil, nil)
+      state = .finished
+      return
+    }
+
+    networkTask = client.send(operation: query) { (result, error) in
+      self.completionHandler(result, error)
+      self.state = .finished
+      return
+    }
+  }
+
+  override public func cancel() {
+    super.cancel()
+    networkTask?.cancel()
+  }
+}
diff --git a/Sources/AsynchronousOperation.swift b/Sources/AsynchronousOperation.swift
@@ -0,0 +1,48 @@
+import Foundation
+
+class AsynchronousOperation: Operation {
+  class func keyPathsForValuesAffectingIsExecuting() -> Set<String> {
+    return ["state"]
+  }
+
+  class func keyPathsForValuesAffectingIsFinished() -> Set<String> {
+    return ["state"]
+  }
+
+  enum State {
+    case initialized
+    case ready
+    case executing
+    case finished
+  }
+
+  var state: State = .initialized {
+    willSet {
+      willChangeValue(forKey: "state")
+    }
+    didSet {
+      print(state)
+      didChangeValue(forKey: "state")
+    }
+  }
+
+  override var isAsynchronous: Bool {
+    return true
+  }
+
+  override var isReady: Bool {
+    let ready = super.isReady
+    if ready {
+      state = .ready
+    }
+    return ready
+  }
+
+  override var isExecuting: Bool {
+    return state == .executing
+  }
+
+  override var isFinished: Bool {
+    return state == .finished
+  }
+}