[mojo] Ports EDK

mojo/edk/system/node_controller.h

+// Copyright 2016 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 MOJO_EDK_SYSTEM_NODE_CONTROLLER_H_
+#define MOJO_EDK_SYSTEM_NODE_CONTROLLER_H_
+
+#include <queue>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/containers/hash_tables.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/task_runner.h"
+#include "mojo/edk/embedder/platform_handle_vector.h"
+#include "mojo/edk/embedder/platform_shared_buffer.h"
+#include "mojo/edk/embedder/scoped_platform_handle.h"
+#include "mojo/edk/system/node_channel.h"
+#include "mojo/edk/system/ports/hash_functions.h"
+#include "mojo/edk/system/ports/name.h"
+#include "mojo/edk/system/ports/node.h"
+#include "mojo/edk/system/ports/node_delegate.h"
+
+namespace mojo {
+namespace edk {
+
+class Core;
+class PortsMessage;
+
+// The owner of ports::Node which facilitates core EDK implementation. All
+// public interface methods are safe to call from any thread.
+class NodeController : public ports::NodeDelegate,
+                       public NodeChannel::Delegate {
+ public:
+  class PortObserver : public ports::UserData {
+   public:
+    virtual void OnPortStatusChanged() = 0;
+
+   protected:
+    ~PortObserver() override {}
+  };
+
+  // |core| owns and out-lives us.
+  explicit NodeController(Core* core);
+  ~NodeController() override;
+
+  const ports::NodeName& name() const { return name_; }
+  Core* core() const { return core_; }
+  ports::Node* node() const { return node_.get(); }
+  scoped_refptr<base::TaskRunner> io_task_runner() const {
+    return io_task_runner_;
+  }
+
+  // Called exactly once, shortly after construction, and before any other
+  // methods are called on this object.
+  void SetIOTaskRunner(scoped_refptr<base::TaskRunner> io_task_runner);
+
+  // Connects this node to a child node. This node will initiate a handshake.
+  void ConnectToChild(base::ProcessHandle process_handle,
+                      ScopedPlatformHandle platform_handle);
+
+  // Connects this node to a parent node. The parent node will initiate a
+  // handshake.
+  void ConnectToParent(ScopedPlatformHandle platform_handle);
+
+  // Sets a port's observer. If |observer| is null the port's current observer
+  // is removed.
+  void SetPortObserver(const ports::PortRef& port,
+                       const scoped_refptr<PortObserver>& observer);
+
+  // Closes a port. Use this in lieu of calling Node::ClosePort() directly, as
+  // it ensures the port's observer has also been removed.
+  void ClosePort(const ports::PortRef& port);
+
+  // Sends a message on a port to its peer. If message send fails, |message|
+  // is left intact. Otherwise ownership is transferred and it's reset.
+  int SendMessage(const ports::PortRef& port_ref,
+                  scoped_ptr<PortsMessage>* message);
+
+  using ReservePortCallback = base::Callback<void(const ports::PortRef& port)>;
+
+  // Reserves a port associated with |token|. A peer may associate one of their
+  // own ports with this one by sending us a RequestPortConnection message with
+  // the same token value.
+  //
+  // Note that the reservation is made synchronously. In order to avoid races,
+  // reservations should be acquired before |token| is communicated to any
+  // potential peer.
+  //
+  // |callback| must be runnable on any thread and will be run with a reference
+  // to the new local port once connected.
+  void ReservePort(const std::string& token,
+                   const ReservePortCallback& callback);
+
+  // Eventually initializes a local port with a parent port peer identified by
+  // |token|. The parent should also have |token| and should alrady have
+  // reserved a port for it. |callback| must be runnable on any thread and will
+  // be run if and when the local port is connected.
+  void ConnectToParentPort(const ports::PortRef& local_port,
+                           const std::string& token,
+                           const base::Closure& callback);
+
+  // Connects two reserved ports to each other. Useful when two independent
+  // systems in the same (parent) process need to establish a port pair without
+  // any direct knowledge of each other.
+  void ConnectReservedPorts(const std::string& token1,
+                            const std::string& token2);
+
+  // Creates a new shared buffer for use in the current process.
+  scoped_refptr<PlatformSharedBuffer> CreateSharedBuffer(size_t num_bytes);
+
+  // Request that the Node be shut down cleanly. This may take an arbitrarily
+  // long time to complete, at which point |callback| will be called.
+  //
+  // Note that while it is safe to continue using the NodeController's public
+  // interface after requesting shutdown, you do so at your own risk and there
+  // is NO guarantee that new messages will be sent or ports will complete
+  // transfer.
+  void RequestShutdown(const base::Closure& callback);
+
+ private:
+  friend Core;
+
+  using NodeMap = std::unordered_map<ports::NodeName,
+                                     scoped_refptr<NodeChannel>>;
+  using OutgoingMessageQueue = std::queue<ports::ScopedMessage>;
+
+  // Tracks a pending token-based connection to a parent port.
+  struct PendingPortRequest {
+    PendingPortRequest();
+    ~PendingPortRequest();
+
+    std::string token;
+    ports::PortRef local_port;
+    base::Closure callback;
+  };
+
+  // Tracks a reserved port.
+  struct ReservedPort {
+    ReservedPort();
+    ~ReservedPort();
+
+    ports::PortRef local_port;
+    ReservePortCallback callback;
+  };
+
+  void ConnectToChildOnIOThread(base::ProcessHandle process_handle,
+                                ScopedPlatformHandle platform_handle);
+  void ConnectToParentOnIOThread(ScopedPlatformHandle platform_handle);
+  void RequestParentPortConnectionOnIOThread(const ports::PortRef& local_port,
+                                             const std::string& token,
+                                             const base::Closure& callback);
+
+  scoped_refptr<NodeChannel> GetPeerChannel(const ports::NodeName& name);
+  scoped_refptr<NodeChannel> GetParentChannel();
+
+  void AddPeer(const ports::NodeName& name,
+               scoped_refptr<NodeChannel> channel,
+               bool start_channel);
+  void DropPeer(const ports::NodeName& name);
+  void SendPeerMessage(const ports::NodeName& name,
+                       ports::ScopedMessage message);
+  void AcceptIncomingMessages();
+  void DropAllPeers();
+
+  // ports::NodeDelegate:
+  void GenerateRandomPortName(ports::PortName* port_name) override;
+  void AllocMessage(size_t num_header_bytes,
+                    ports::ScopedMessage* message) override;
+  void ForwardMessage(const ports::NodeName& node,
+                      ports::ScopedMessage message) override;
+  void PortStatusChanged(const ports::PortRef& port) override;
+
+  // NodeChannel::Delegate:
+  void OnAcceptChild(const ports::NodeName& from_node,
+                     const ports::NodeName& parent_name,
+                     const ports::NodeName& token) override;
+  void OnAcceptParent(const ports::NodeName& from_node,
+                      const ports::NodeName& token,
+                      const ports::NodeName& child_name) override;
+  void OnPortsMessage(Channel::MessagePtr message) override;
+  void OnRequestPortConnection(const ports::NodeName& from_node,
+                               const ports::PortName& connector_port_name,
+                               const std::string& token) override;
+  void OnConnectToPort(const ports::NodeName& from_node,
+                       const ports::PortName& connector_port_name,
+                       const ports::PortName& connectee_port_name) override;
+  void OnRequestIntroduction(const ports::NodeName& from_node,
+                             const ports::NodeName& name) override;
+  void OnIntroduce(const ports::NodeName& from_node,
+                   const ports::NodeName& name,
+                   ScopedPlatformHandle channel_handle) override;
+#if defined(OS_WIN)
+  void OnRelayPortsMessage(const ports::NodeName& from_node,
+                           base::ProcessHandle from_process,
+                           const ports::NodeName& destination,
+                           Channel::MessagePtr message) override;
+#endif
+  void OnChannelError(const ports::NodeName& from_node) override;
+
+  // Marks this NodeController for destruction when the IO thread shuts down.
+  // This is used in case Core is torn down before the IO thread. Must only be
+  // called on the IO thread.
+  void DestroyOnIOThreadShutdown();
+
+  // If there is a registered shutdown callback (meaning shutdown has been
+  // requested, this checks the Node's status to see if clean shutdown is
+  // possible. If so, shutdown is performed and the shutdown callback is run.
+  void AttemptShutdownIfRequested();
+
+  // These are safe to access from any thread as long as the Node is alive.
+  Core* const core_;
+  const ports::NodeName name_;
+  const scoped_ptr<ports::Node> node_;
+  scoped_refptr<base::TaskRunner> io_task_runner_;
+
+  // Guards |peers_| and |pending_peer_messages_|.
+  base::Lock peers_lock_;
+
+  // Channels to known peers, including parent and children, if any.
+  NodeMap peers_;
+
+  // Outgoing message queues for peers we've heard of but can't yet talk to.
+  std::unordered_map<ports::NodeName, OutgoingMessageQueue>
+      pending_peer_messages_;
+
+  // Guards |reserved_ports_|.
+  base::Lock reserved_ports_lock_;
+
+  // Ports reserved by token.
+  base::hash_map<std::string, ReservedPort> reserved_ports_;
+
+  // Guards |parent_name_| and |bootstrap_parent_channel_|.
+  base::Lock parent_lock_;
+
+  // The name of our parent node, if any.
+  ports::NodeName parent_name_;
+
+  // A temporary reference to the parent channel before we know their name.
+  scoped_refptr<NodeChannel> bootstrap_parent_channel_;
+
+  // Guards |incoming_messages_|.
+  base::Lock messages_lock_;
+  std::queue<ports::ScopedMessage> incoming_messages_;
+
+  // Guards |shutdown_callback_|.
+  base::Lock shutdown_lock_;
+
+  // Set by RequestShutdown(). If this is non-null, the controller will
+  // begin polling the Node to see if clean shutdown is possible any time the
+  // Node's state is modified by the controller.
+  base::Closure shutdown_callback_;
+
+  // All other fields below must only be accessed on the I/O thread, i.e., the
+  // thread on which core_->io_task_runner() runs tasks.
+
+  // Channels to children during handshake.
+  NodeMap pending_children_;
+
+  // Port connection requests which have been deferred until we have a parent.
+  std::vector<PendingPortRequest> pending_port_requests_;
+
+  // Port connection requests awaiting a response from the parent.
+  std::unordered_map<ports::PortName, base::Closure> pending_port_connections_;
+
+  // Indicates whether this object should delete itself on IO thread shutdown.
+  // Must only be accessed from the IO thread.
+  bool destroy_on_io_thread_shutdown_ = false;
+
+  DISALLOW_COPY_AND_ASSIGN(NodeController);
+};
+
+}  // namespace edk
+}  // namespace mojo
+
+#endif  // MOJO_EDK_SYSTEM_NODE_CONTROLLER_H_