Adding OrtcFactory, and changing UdpTransport to match current plan.

webrtc/api/ortcfactoryinterface.h

+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_API_ORTCFACTORYINTERFACE_H_
+#define WEBRTC_API_ORTCFACTORYINTERFACE_H_
+
+#include <memory>
+
+#include "webrtc/api/udptransportinterface.h"
+#include "webrtc/base/network.h"
+#include "webrtc/base/thread.h"
+#include "webrtc/p2p/base/packetsocketfactory.h"
+
+namespace webrtc {
+
+// WARNING: This is experimental/under development, so use at your own risk; no
+// guarantee about API stability is guaranteed here yet.
+//
+// This class is the ORTC analog of PeerConnectionFactory. It acts as a factory
+// for ORTC objects that can be connected to each other.
+//
+// Some of these objects may not be represented by the ORTC specification, but
+// follow the same general principles.
+//
+// On object lifetimes: The factory must not be destroyed before destroying the
+// objects it created, and the objects passed into the factory must not be
+// destroyed before destroying the factory.
+class OrtcFactoryInterface {
+ public:
+  // |network_thread| is the thread on which packets are sent and received.
+  // If null, a new rtc::Thread with a default socket server is created.
+  //
+  // |worker_thread| is used for CPU-intensive operations.
+  // If null, a new rtc::Thread is created.

[pthatcher1, 2017/01/18 02:42:46]

So the problem here is that the worker_thread is *not* for CPU-intensive
operations.  It's a complete misnomer.  It's more like "the thread that media
operations use to configure stuff".  We can call it "worker_thread" for
consistency, but saying it's for CPU-intensive operations is not correct.  

[Taylor Brandstetter, 2017/01/18 22:19:04]

If the worker thread is just an artifact, and we want to remove it (or replace
it with a TaskQueue one day), I'll leave it out of the API for now.

+  //
+  // Note: In our current implementation, some API calls that deal with the
+  // media engine (such as RtpSender.SetParameters) will block on the worker
+  // thread.
+  // TODO(deadbeef): Fix this.
+  //
+  // |signaling_thread| is used for callbacks to the consumer of the API. If
+  // null, the current thread will be used, which assumes that the API consumer
+  // is running a message loop on this thread (either using an existing
+  // rtc::Thread, or by calling rtc::Thread::Current()->ProcessMessages).
+  //
+  // |network_manager| is used to determine which network interfaces are
+  // available. This is used for ICE, for example. If null, a default
+  // implementation will be used. Only accessed on |network_thread|.
+  //
+  // |socket_factory| is used (on the network thread) for creating sockets. If
+  // it's null, a default implementation will be used, which assumes
+  // |network_thread| is a normal rtc::Thread.
+  //
+  // Note that the OrtcFactoryInterface does not take ownership of any of the
+  // objects
+  // passed in, and as previously stated, these objects can't be destroyed
+  // before the factory is.
+  static std::unique_ptr<OrtcFactoryInterface> Create(
+      rtc::Thread* network_thread,
+      rtc::Thread* worker_thread,
+      rtc::Thread* signaling_thread,
+      rtc::NetworkManager* network_manager,
+      rtc::PacketSocketFactory* socket_factory);
+  // Constructor for convenience which uses default implementations of
+  // everything (though does still require that the current thread runs a
+  // message loop; see above).
+  static std::unique_ptr<OrtcFactoryInterface> Create() {
+    return Create(nullptr, nullptr, nullptr, nullptr, nullptr);
+  }
+
+  virtual ~OrtcFactoryInterface() {}
+
+  virtual std::unique_ptr<UdpTransportInterface>
+  CreateUdpTransport(int family, uint16_t min_port, uint16_t max_port) = 0;
+  // Method for convenience that has no port range restrictions.
+  std::unique_ptr<UdpTransportInterface> CreateUdpTransport(int family) {
+    return CreateUdpTransport(family, 0, 0);
+  }
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_API_ORTCFACTORYINTERFACE_H_