ServiceManager: Simplify Instance lifetime management

services/shell/service_manager.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SERVICES_SHELL_SERVICE_MANAGER_H_
 #define SERVICES_SHELL_SERVICE_MANAGER_H_
 
 #include <map>
 #include <memory>
 #include <vector>
@@ skipping 56 matching lines @@
   // by |params|, exchanging InterfaceProviders between them. If no existing
   // instance of the target application is running, one will be loaded.
   void Connect(std::unique_ptr<ConnectParams> params);
 
   // Creates a new Instance identified as |name|. This is intended for use by
   // the Service Manager's embedder to register itself. This must only be called
   // once.
   mojom::ServiceRequest StartEmbedderService(const std::string& name);
 
  private:
-  enum class InstanceErrorType {
-    // The Instance has lost it's Service pointer, but still has connections. It
-    // should not be immediately deleted.
-    LOST_SERVICE,
-
-    // The Instance should no longer be kept around.
-    DESTROY,
-  };
-
   class Instance;
 
   // Service:
   bool OnConnect(const Identity& remote_identity,
                  InterfaceRegistry* registry) override;
 
   void InitCatalog(mojom::ServicePtr catalog);
 
   // Returns the resolver to use for the specified identity.
   // NOTE: Resolvers are cached to ensure we service requests in order. If
   // we use a separate Resolver for each request ordering is not
   // guaranteed and can lead to random flake.
   mojom::Resolver* GetResolver(const Identity& identity);
 
   // Destroys all Service Manager-ends of connections established with Services.
   // Services connected by this Service Manager will observe pipe errors and
   // have a chance to shut down.
   void TerminateServiceManagerConnections();
 
-  // Called when |instance| encounters an error. If |error_type| is DESTROY
-  // the instance is deleted immediately, otherwise it is moved to
-  // |instances_without_service_|.
-  void OnInstanceError(Instance* instance, InstanceErrorType error_type);
+  // Called when |instance| encounters an error. Deletes |instance|.
+  void OnInstanceError(Instance* instance);
+
+  // Called when |instance| becomes unreachable to new connections because it
+  // no longer has any pipes to the ServiceManager.
+  void OnInstanceUnreachable(Instance* instance);
+
+  // Called by an Instance as it's being destroyed.
+  void OnInstanceStopped(const Identity& identity);
 
   // Completes a connection between a source and target application as defined
   // by |params|, exchanging InterfaceProviders between them. If no existing
   // instance of the target application is running, one will be loaded.
   //
   // If |service| is not null, there must not be an instance of the target
   // application already running. The Service Manager will create a new instance
   // and use |service| to control it.
   //
   // If |instance| is not null, the lifetime of the connection request is
@@ skipping 36 matching lines @@
   // new application instance. This may be null.
   // |result| contains the result of the resolve operation.
   void OnGotResolvedName(std::unique_ptr<ConnectParams> params,
                          mojom::ServicePtr service,
                          bool has_source_instance,
                          base::WeakPtr<Instance> source_instance,
                          mojom::ResolveResultPtr result);
 
   base::WeakPtr<ServiceManager> GetWeakPtr();
 
+  // Ownership of all root Instances. Non-root Instances are owned by their
+  // parent Instance.
+  using InstanceMap = std::map<Instance*, std::unique_ptr<Instance>>;
+  InstanceMap root_instances_;
+
+  // Maps service identities to reachable instances. Note that the Instance*
+  // values here are NOT owned by this map.
   std::map<Identity, Instance*> identity_to_instance_;
 
   // Tracks the names of instances that are allowed to field connection requests
   // from all users.
   std::set<std::string> singletons_;
 
-  // See OnInstanceError() for details.
-  std::set<Instance*> instances_without_service_;
-
   std::map<Identity, mojom::ServiceFactoryPtr> service_factories_;
   std::map<Identity, mojom::ResolverPtr> identity_to_resolver_;
   mojo::InterfacePtrSet<mojom::ServiceManagerListener> listeners_;
   base::Callback<void(const Identity&)> instance_quit_callback_;
   std::unique_ptr<NativeRunnerFactory> native_runner_factory_;
   std::unique_ptr<ServiceContext> service_context_;
   base::WeakPtrFactory<ServiceManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceManager);
 };
 
 mojom::Connector::ConnectCallback EmptyConnectCallback();
 
 }  // namespace shell
 
 #endif  // SERVICES_SHELL_SERVICE_MANAGER_H_