1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/mtransport/transportflow.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,143 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this file,
1.8 + * You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +// Original author: ekr@rtfm.com
1.11 +
1.12 +#ifndef transportflow_h__
1.13 +#define transportflow_h__
1.14 +
1.15 +#include <deque>
1.16 +#include <queue>
1.17 +#include <string>
1.18 +
1.19 +#include "nscore.h"
1.20 +#include "nsISupportsImpl.h"
1.21 +#include "mozilla/Scoped.h"
1.22 +#include "transportlayer.h"
1.23 +#include "m_cpp_utils.h"
1.24 +#include "nsAutoPtr.h"
1.25 +
1.26 +// A stack of transport layers acts as a flow.
1.27 +// Generally, one reads and writes to the top layer.
1.28 +
1.29 +// This code has a confusing hybrid threading model which
1.30 +// probably needs some eventual refactoring.
1.31 +// TODO(ekr@rtfm.com): Bug 844891
1.32 +//
1.33 +// TransportFlows are not inherently bound to a thread *but*
1.34 +// TransportLayers can be. If any layer in a flow is bound
1.35 +// to a given thread, then all layers in the flow MUST be
1.36 +// bound to that thread and you can only manipulate the
1.37 +// flow (push layers, write, etc.) on that thread.
1.38 +//
1.39 +// The sole official exception to this is that you are
1.40 +// allowed to *destroy* a flow off the bound thread provided
1.41 +// that there are no listeners on its signals. This exception
1.42 +// is designed to allow idioms where you create the flow
1.43 +// and then something goes wrong and you destroy it and
1.44 +// you don't want to bother with a thread dispatch.
1.45 +//
1.46 +// Eventually we hope to relax the "no listeners"
1.47 +// restriction by thread-locking the signals, but previous
1.48 +// attempts have caused deadlocks.
1.49 +//
1.50 +// Most of these invariants are enforced by hard asserts
1.51 +// (i.e., those which fire even in production builds).
1.52 +
1.53 +namespace mozilla {
1.54 +
1.55 +class TransportFlow : public nsISupports,
1.56 + public sigslot::has_slots<> {
1.57 + public:
1.58 + TransportFlow()
1.59 + : id_("(anonymous)"),
1.60 + state_(TransportLayer::TS_NONE),
1.61 + layers_(new std::deque<TransportLayer *>) {}
1.62 + TransportFlow(const std::string id)
1.63 + : id_(id),
1.64 + state_(TransportLayer::TS_NONE),
1.65 + layers_(new std::deque<TransportLayer *>) {}
1.66 +
1.67 + ~TransportFlow();
1.68 +
1.69 + const std::string& id() const { return id_; }
1.70 +
1.71 + // Layer management. Note PushLayer() is not thread protected, so
1.72 + // either:
1.73 + // (a) Do it in the thread handling the I/O
1.74 + // (b) Do it before you activate the I/O system
1.75 + //
1.76 + // The flow takes ownership of the layers after a successful
1.77 + // push.
1.78 + nsresult PushLayer(TransportLayer *layer);
1.79 +
1.80 + // Convenience function to push multiple layers on. Layers
1.81 + // are pushed on in the order that they are in the queue.
1.82 + // Any failures cause the flow to become inoperable and
1.83 + // destroys all the layers including those already pushed.
1.84 + // TODO(ekr@rtfm.com): Change layers to be ref-counted.
1.85 + nsresult PushLayers(nsAutoPtr<std::queue<TransportLayer *> > layers);
1.86 +
1.87 + TransportLayer *top() const;
1.88 + TransportLayer *GetLayer(const std::string& id) const;
1.89 +
1.90 + // Wrappers for whatever TLayer happens to be the top layer
1.91 + // at the time. This way you don't need to do top()->Foo().
1.92 + TransportLayer::State state(); // Current state
1.93 + TransportResult SendPacket(const unsigned char *data, size_t len);
1.94 +
1.95 + // State has changed. Reflects the top flow.
1.96 + sigslot::signal2<TransportFlow *, TransportLayer::State>
1.97 + SignalStateChange;
1.98 +
1.99 + // Data received on the flow
1.100 + sigslot::signal3<TransportFlow*, const unsigned char *, size_t>
1.101 + SignalPacketReceived;
1.102 +
1.103 + bool Contains(TransportLayer *layer) const;
1.104 +
1.105 + NS_DECL_THREADSAFE_ISUPPORTS
1.106 +
1.107 + private:
1.108 + DISALLOW_COPY_ASSIGN(TransportFlow);
1.109 +
1.110 + // Check if we are on the right thread
1.111 + void CheckThread() const {
1.112 + if (!CheckThreadInt())
1.113 + MOZ_CRASH();
1.114 + }
1.115 +
1.116 + bool CheckThreadInt() const {
1.117 + bool on;
1.118 +
1.119 + if (!target_) // OK if no thread set.
1.120 + return true;
1.121 + if (NS_FAILED(target_->IsOnCurrentThread(&on)))
1.122 + return false;
1.123 +
1.124 + return on;
1.125 + }
1.126 +
1.127 + void EnsureSameThread(TransportLayer *layer);
1.128 +
1.129 + void StateChange(TransportLayer *layer, TransportLayer::State state);
1.130 + void StateChangeInt(TransportLayer::State state);
1.131 + void PacketReceived(TransportLayer* layer, const unsigned char *data,
1.132 + size_t len);
1.133 + static void DestroyFinal(nsAutoPtr<std::deque<TransportLayer *> > layers);
1.134 +
1.135 + // Overload needed because we use deque internally and queue externally.
1.136 + static void ClearLayers(std::deque<TransportLayer *>* layers);
1.137 + static void ClearLayers(std::queue<TransportLayer *>* layers);
1.138 +
1.139 + std::string id_;
1.140 + TransportLayer::State state_;
1.141 + ScopedDeletePtr<std::deque<TransportLayer *> > layers_;
1.142 + nsCOMPtr<nsIEventTarget> target_;
1.143 +};
1.144 +
1.145 +} // close namespace
1.146 +#endif
