michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim: set ts=2 et sw=2 tw=80: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: // Original author: ekr@rtfm.com
michael@0: 
michael@0: #ifndef transportflow_h__
michael@0: #define transportflow_h__
michael@0: 
michael@0: #include <deque>
michael@0: #include <queue>
michael@0: #include <string>
michael@0: 
michael@0: #include "nscore.h"
michael@0: #include "nsISupportsImpl.h"
michael@0: #include "mozilla/Scoped.h"
michael@0: #include "transportlayer.h"
michael@0: #include "m_cpp_utils.h"
michael@0: #include "nsAutoPtr.h"
michael@0: 
michael@0: // A stack of transport layers acts as a flow.
michael@0: // Generally, one reads and writes to the top layer.
michael@0: 
michael@0: // This code has a confusing hybrid threading model which
michael@0: // probably needs some eventual refactoring.
michael@0: // TODO(ekr@rtfm.com): Bug 844891
michael@0: //
michael@0: // TransportFlows are not inherently bound to a thread *but*
michael@0: // TransportLayers can be. If any layer in a flow is bound
michael@0: // to a given thread, then all layers in the flow MUST be
michael@0: // bound to that thread and you can only manipulate the
michael@0: // flow (push layers, write, etc.) on that thread.
michael@0: //
michael@0: // The sole official exception to this is that you are
michael@0: // allowed to *destroy* a flow off the bound thread provided
michael@0: // that there are no listeners on its signals. This exception
michael@0: // is designed to allow idioms where you create the flow
michael@0: // and then something goes wrong and you destroy it and
michael@0: // you don't want to bother with a thread dispatch.
michael@0: //
michael@0: // Eventually we hope to relax the "no listeners"
michael@0: // restriction by thread-locking the signals, but previous
michael@0: // attempts have caused deadlocks.
michael@0: //
michael@0: // Most of these invariants are enforced by hard asserts
michael@0: // (i.e., those which fire even in production builds).
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: class TransportFlow : public nsISupports,
michael@0:                       public sigslot::has_slots<> {
michael@0:  public:
michael@0:   TransportFlow()
michael@0:     : id_("(anonymous)"),
michael@0:       state_(TransportLayer::TS_NONE),
michael@0:       layers_(new std::deque<TransportLayer *>) {}
michael@0:   TransportFlow(const std::string id)
michael@0:     : id_(id),
michael@0:       state_(TransportLayer::TS_NONE),
michael@0:       layers_(new std::deque<TransportLayer *>) {}
michael@0: 
michael@0:   ~TransportFlow();
michael@0: 
michael@0:   const std::string& id() const { return id_; }
michael@0: 
michael@0:   // Layer management. Note PushLayer() is not thread protected, so
michael@0:   // either:
michael@0:   // (a) Do it in the thread handling the I/O
michael@0:   // (b) Do it before you activate the I/O system
michael@0:   //
michael@0:   // The flow takes ownership of the layers after a successful
michael@0:   // push.
michael@0:   nsresult PushLayer(TransportLayer *layer);
michael@0: 
michael@0:   // Convenience function to push multiple layers on. Layers
michael@0:   // are pushed on in the order that they are in the queue.
michael@0:   // Any failures cause the flow to become inoperable and
michael@0:   // destroys all the layers including those already pushed.
michael@0:   // TODO(ekr@rtfm.com): Change layers to be ref-counted.
michael@0:   nsresult PushLayers(nsAutoPtr<std::queue<TransportLayer *> > layers);
michael@0: 
michael@0:   TransportLayer *top() const;
michael@0:   TransportLayer *GetLayer(const std::string& id) const;
michael@0: 
michael@0:   // Wrappers for whatever TLayer happens to be the top layer
michael@0:   // at the time. This way you don't need to do top()->Foo().
michael@0:   TransportLayer::State state(); // Current state
michael@0:   TransportResult SendPacket(const unsigned char *data, size_t len);
michael@0: 
michael@0:   // State has changed. Reflects the top flow.
michael@0:   sigslot::signal2<TransportFlow *, TransportLayer::State>
michael@0:     SignalStateChange;
michael@0: 
michael@0:   // Data received on the flow
michael@0:   sigslot::signal3<TransportFlow*, const unsigned char *, size_t>
michael@0:     SignalPacketReceived;
michael@0: 
michael@0:   bool Contains(TransportLayer *layer) const;
michael@0: 
michael@0:   NS_DECL_THREADSAFE_ISUPPORTS
michael@0: 
michael@0:  private:
michael@0:   DISALLOW_COPY_ASSIGN(TransportFlow);
michael@0: 
michael@0:   // Check if we are on the right thread
michael@0:   void CheckThread() const {
michael@0:     if (!CheckThreadInt())
michael@0:       MOZ_CRASH();
michael@0:   }
michael@0: 
michael@0:   bool CheckThreadInt() const {
michael@0:     bool on;
michael@0: 
michael@0:     if (!target_)  // OK if no thread set.
michael@0:       return true;
michael@0:     if (NS_FAILED(target_->IsOnCurrentThread(&on)))
michael@0:       return false;
michael@0: 
michael@0:     return on;
michael@0:   }
michael@0: 
michael@0:   void EnsureSameThread(TransportLayer *layer);
michael@0: 
michael@0:   void StateChange(TransportLayer *layer, TransportLayer::State state);
michael@0:   void StateChangeInt(TransportLayer::State state);
michael@0:   void PacketReceived(TransportLayer* layer, const unsigned char *data,
michael@0:       size_t len);
michael@0:   static void DestroyFinal(nsAutoPtr<std::deque<TransportLayer *> > layers);
michael@0: 
michael@0:   // Overload needed because we use deque internally and queue externally.
michael@0:   static void ClearLayers(std::deque<TransportLayer *>* layers);
michael@0:   static void ClearLayers(std::queue<TransportLayer *>* layers);
michael@0: 
michael@0:   std::string id_;
michael@0:   TransportLayer::State state_;
michael@0:   ScopedDeletePtr<std::deque<TransportLayer *> > layers_;
michael@0:   nsCOMPtr<nsIEventTarget> target_;
michael@0: };
michael@0: 
michael@0: }  // close namespace
michael@0: #endif