gecko/ipc/glue/AsyncChannel.cpp

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: sw=4 ts=4 et :
*/
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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mozilla/ipc/AsyncChannel.h"
#include "mozilla/ipc/BrowserProcessSubThread.h"
#include "mozilla/ipc/ProtocolUtils.h"
#include "nsDebug.h"
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#include "nsTraceRefcnt.h"
#include "nsXULAppAPI.h"
using namespace mozilla;
using namespace std;
template<>
struct RunnableMethodTraits<mozilla::ipc::AsyncChannel>
{
static void RetainCallee(mozilla::ipc::AsyncChannel* obj) { }
static void ReleaseCallee(mozilla::ipc::AsyncChannel* obj) { }
};
template<>
struct RunnableMethodTraits<mozilla::ipc::AsyncChannel::ProcessLink>
{
static void RetainCallee(mozilla::ipc::AsyncChannel::ProcessLink* obj) { }
static void ReleaseCallee(mozilla::ipc::AsyncChannel::ProcessLink* obj) { }
};
// We rely on invariants about the lifetime of the transport:
//
// - outlives this AsyncChannel
// - deleted on the IO thread
//
// These invariants allow us to send messages directly through the
// transport without having to worry about orphaned Send() tasks on
// the IO thread touching AsyncChannel memory after it's been deleted
// on the worker thread. We also don't need to refcount the
// Transport, because whatever task triggers its deletion only runs on
// the IO thread, and only runs after this AsyncChannel is done with
// the Transport.
template<>
struct RunnableMethodTraits<mozilla::ipc::AsyncChannel::Transport>
{
static void RetainCallee(mozilla::ipc::AsyncChannel::Transport* obj) { }
static void ReleaseCallee(mozilla::ipc::AsyncChannel::Transport* obj) { }
};
namespace {
// This is an async message
class GoodbyeMessage : public IPC::Message
{
public:
enum { ID = GOODBYE_MESSAGE_TYPE };
GoodbyeMessage() :
IPC::Message(MSG_ROUTING_NONE, ID, PRIORITY_NORMAL)
{
}
// XXX not much point in implementing this; maybe could help with
// debugging?
static bool Read(const Message* msg)
{
return true;
}
void Log(const std::string& aPrefix,
FILE* aOutf) const
{
fputs("(special `Goodbye' message)", aOutf);
}
};
} // namespace <anon>
namespace mozilla {
namespace ipc {
AsyncChannel::Link::Link(AsyncChannel *aChan)
: mChan(aChan)
{
}
AsyncChannel::Link::~Link()
{
mChan = 0;
}
AsyncChannel::ProcessLink::ProcessLink(AsyncChannel *aChan)
: Link(aChan)
, mExistingListener(NULL)
{
}
AsyncChannel::ProcessLink::~ProcessLink()
{
mIOLoop = 0;
if (mTransport) {
mTransport->set_listener(0);
// we only hold a weak ref to the transport, which is "owned"
// by GeckoChildProcess/GeckoThread
mTransport = 0;
}
}
void
AsyncChannel::ProcessLink::Open(mozilla::ipc::Transport* aTransport,
MessageLoop *aIOLoop,
Side aSide)
{
NS_PRECONDITION(aTransport, "need transport layer");
// FIXME need to check for valid channel
mTransport = aTransport;
// FIXME figure out whether we're in parent or child, grab IO loop
// appropriately
bool needOpen = true;
if(aIOLoop) {
// We're a child or using the new arguments. Either way, we
// need an open.
needOpen = true;
mChan->mChild = (aSide == AsyncChannel::Unknown) || (aSide == AsyncChannel::Child);
} else {
NS_PRECONDITION(aSide == Unknown, "expected default side arg");
// parent
mChan->mChild = false;
needOpen = false;
aIOLoop = XRE_GetIOMessageLoop();
}
mIOLoop = aIOLoop;
NS_ASSERTION(mIOLoop, "need an IO loop");
NS_ASSERTION(mChan->mWorkerLoop, "need a worker loop");
{
MonitorAutoLock lock(*mChan->mMonitor);
if (needOpen) {
// Transport::Connect() has not been called. Call it so
// we start polling our pipe and processing outgoing
// messages.
mIOLoop->PostTask(
FROM_HERE,
NewRunnableMethod(this, &ProcessLink::OnChannelOpened));
} else {
// Transport::Connect() has already been called. Take
// over the channel from the previous listener and process
// any queued messages.
mIOLoop->PostTask(
FROM_HERE,
NewRunnableMethod(this, &ProcessLink::OnTakeConnectedChannel));
}
// FIXME/cjones: handle errors
while (!mChan->Connected()) {
mChan->mMonitor->Wait();
}
}
}
void
AsyncChannel::ProcessLink::EchoMessage(Message *msg)
{
mChan->AssertWorkerThread();
mChan->mMonitor->AssertCurrentThreadOwns();
// NB: Go through this OnMessageReceived indirection so that
// echoing this message does the right thing for SyncChannel
// and RPCChannel too
mIOLoop->PostTask(
FROM_HERE,
NewRunnableMethod(this, &ProcessLink::OnEchoMessage, msg));
// OnEchoMessage takes ownership of |msg|
}
void
AsyncChannel::ProcessLink::SendMessage(Message *msg)
{
mChan->AssertWorkerThread();
mChan->mMonitor->AssertCurrentThreadOwns();
mIOLoop->PostTask(
FROM_HERE,
NewRunnableMethod(mTransport, &Transport::Send, msg));
}
void
AsyncChannel::ProcessLink::SendClose()
{
mChan->AssertWorkerThread();
mChan->mMonitor->AssertCurrentThreadOwns();
mIOLoop->PostTask(
FROM_HERE, NewRunnableMethod(this, &ProcessLink::OnCloseChannel));
}
AsyncChannel::ThreadLink::ThreadLink(AsyncChannel *aChan,
AsyncChannel *aTargetChan)
: Link(aChan),
mTargetChan(aTargetChan)
{
}
AsyncChannel::ThreadLink::~ThreadLink()
{
MonitorAutoLock lock(*mChan->mMonitor);
// Bug 848949: We need to prevent the other side
// from sending us any more messages to avoid Use-After-Free.
// The setup here is as shown:
//
// (Us) (Them)
// AsyncChannel AsyncChannel
// | ^ \ / ^ |
// | | X | |
// v | / \ | v
// ThreadLink ThreadLink
//
// We want to null out the diagonal link from their ThreadLink
// to our AsyncChannel. Note that we must hold the monitor so
// that we do this atomically with respect to them trying to send
// us a message.
if (mTargetChan) {
static_cast<ThreadLink*>(mTargetChan->mLink)->mTargetChan = 0;
}
mTargetChan = 0;
}
void
AsyncChannel::ThreadLink::EchoMessage(Message *msg)
{
mChan->AssertWorkerThread();
mChan->mMonitor->AssertCurrentThreadOwns();
mChan->OnMessageReceivedFromLink(*msg);
delete msg;
}
void
AsyncChannel::ThreadLink::SendMessage(Message *msg)
{
mChan->AssertWorkerThread();
mChan->mMonitor->AssertCurrentThreadOwns();
if (mTargetChan)
mTargetChan->OnMessageReceivedFromLink(*msg);
delete msg;
}
void
AsyncChannel::ThreadLink::SendClose()
{
mChan->AssertWorkerThread();
mChan->mMonitor->AssertCurrentThreadOwns();
mChan->mChannelState = ChannelClosed;
// In a ProcessLink, we would close our half the channel. This
// would show up on the other side as an error on the I/O thread.
// The I/O thread would then invoke OnChannelErrorFromLink().
// As usual, we skip that process and just invoke the
// OnChannelErrorFromLink() method directly.
if (mTargetChan)
mTargetChan->OnChannelErrorFromLink();
}
AsyncChannel::AsyncChannel(AsyncListener* aListener)
: mListener(aListener),
mChannelState(ChannelClosed),
mWorkerLoop(),
mChild(false),
mChannelErrorTask(NULL),
mLink(NULL)
{
MOZ_COUNT_CTOR(AsyncChannel);
}
AsyncChannel::~AsyncChannel()
{
MOZ_COUNT_DTOR(AsyncChannel);
Clear();
}
bool
AsyncChannel::Open(Transport* aTransport,
MessageLoop* aIOLoop,
AsyncChannel::Side aSide)
{
ProcessLink *link;
NS_PRECONDITION(!mLink, "Open() called > once");
mMonitor = new RefCountedMonitor();
mWorkerLoop = MessageLoop::current();
mLink = link = new ProcessLink(this);
link->Open(aTransport, aIOLoop, aSide); // n.b.: sets mChild
return true;
}
/* Opens a connection to another thread in the same process.
This handshake proceeds as follows:
- Let A be the thread initiating the process (either child or parent)
and B be the other thread.
- A spawns thread for B, obtaining B's message loop
- A creates ProtocolChild and ProtocolParent instances.
Let PA be the one appropriate to A and PB the side for B.
- A invokes PA->Open(PB, ...):
- set state to mChannelOpening
- this will place a work item in B's worker loop (see next bullet)
and then spins until PB->mChannelState becomes mChannelConnected
- meanwhile, on PB's worker loop, the work item is removed and:
- invokes PB->SlaveOpen(PA, ...):
- sets its state and that of PA to Connected
*/
bool
AsyncChannel::Open(AsyncChannel *aTargetChan,
MessageLoop *aTargetLoop,
AsyncChannel::Side aSide)
{
NS_PRECONDITION(aTargetChan, "Need a target channel");
NS_PRECONDITION(ChannelClosed == mChannelState, "Not currently closed");
CommonThreadOpenInit(aTargetChan, aSide);
Side oppSide = Unknown;
switch(aSide) {
case Child: oppSide = Parent; break;
case Parent: oppSide = Child; break;
case Unknown: break;
}
mMonitor = new RefCountedMonitor();
MonitorAutoLock lock(*mMonitor);
mChannelState = ChannelOpening;
aTargetLoop->PostTask(
FROM_HERE,
NewRunnableMethod(aTargetChan, &AsyncChannel::OnOpenAsSlave,
this, oppSide));
while (ChannelOpening == mChannelState)
mMonitor->Wait();
NS_ASSERTION(ChannelConnected == mChannelState, "not connected when awoken");
return (ChannelConnected == mChannelState);
}
void
AsyncChannel::CommonThreadOpenInit(AsyncChannel *aTargetChan, Side aSide)
{
mWorkerLoop = MessageLoop::current();
mLink = new ThreadLink(this, aTargetChan);
mChild = (aSide == Child);
}
// Invoked when the other side has begun the open.
void
AsyncChannel::OnOpenAsSlave(AsyncChannel *aTargetChan, Side aSide)
{
NS_PRECONDITION(ChannelClosed == mChannelState,
"Not currently closed");
NS_PRECONDITION(ChannelOpening == aTargetChan->mChannelState,
"Target channel not in the process of opening");
CommonThreadOpenInit(aTargetChan, aSide);
mMonitor = aTargetChan->mMonitor;
MonitorAutoLock lock(*mMonitor);
NS_ASSERTION(ChannelOpening == aTargetChan->mChannelState,
"Target channel not in the process of opening");
mChannelState = ChannelConnected;
aTargetChan->mChannelState = ChannelConnected;
aTargetChan->mMonitor->Notify();
}
void
AsyncChannel::Close()
{
AssertWorkerThread();
{
// n.b.: We increase the ref count of monitor temporarily
// for the duration of this block. Otherwise, the
// function NotifyMaybeChannelError() will call
// ::Clear() which can free the monitor.
nsRefPtr<RefCountedMonitor> monitor(mMonitor);
MonitorAutoLock lock(*monitor);
if (ChannelError == mChannelState ||
ChannelTimeout == mChannelState) {
// See bug 538586: if the listener gets deleted while the
// IO thread's NotifyChannelError event is still enqueued
// and subsequently deletes us, then the error event will
// also be deleted and the listener will never be notified
// of the channel error.
if (mListener) {
MonitorAutoUnlock unlock(*monitor);
NotifyMaybeChannelError();
}
return;
}
if (ChannelConnected != mChannelState)
// XXX be strict about this until there's a compelling reason
// to relax
NS_RUNTIMEABORT("Close() called on closed channel!");
AssertWorkerThread();
// notify the other side that we're about to close our socket
SendSpecialMessage(new GoodbyeMessage());
SynchronouslyClose();
}
NotifyChannelClosed();
}
void
AsyncChannel::SynchronouslyClose()
{
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
mLink->SendClose();
while (ChannelClosed != mChannelState)
mMonitor->Wait();
}
bool
AsyncChannel::Send(Message* _msg)
{
nsAutoPtr<Message> msg(_msg);
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
NS_ABORT_IF_FALSE(MSG_ROUTING_NONE != msg->routing_id(), "need a route");
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{
MonitorAutoLock lock(*mMonitor);
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if (!Connected()) {
ReportConnectionError("AsyncChannel");
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return false;
}
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mLink->SendMessage(msg.forget());
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}
return true;
}
bool
AsyncChannel::Echo(Message* _msg)
{
nsAutoPtr<Message> msg(_msg);
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
NS_ABORT_IF_FALSE(MSG_ROUTING_NONE != msg->routing_id(), "need a route");
{
MonitorAutoLock lock(*mMonitor);
if (!Connected()) {
ReportConnectionError("AsyncChannel");
return false;
}
mLink->EchoMessage(msg.forget());
}
return true;
}
void
AsyncChannel::OnDispatchMessage(const Message& msg)
{
AssertWorkerThread();
NS_ASSERTION(!msg.is_reply(), "can't process replies here");
NS_ASSERTION(!(msg.is_sync() || msg.is_rpc()), "async dispatch only");
if (MSG_ROUTING_NONE == msg.routing_id()) {
if (!OnSpecialMessage(msg.type(), msg))
// XXX real error handling
NS_RUNTIMEABORT("unhandled special message!");
return;
}
// it's OK to dispatch messages if the channel is closed/error'd,
// since we don't have a reply to send back
(void)MaybeHandleError(mListener->OnMessageReceived(msg), "AsyncChannel");
}
bool
AsyncChannel::OnSpecialMessage(uint16_t id, const Message& msg)
{
return false;
}
void
AsyncChannel::SendSpecialMessage(Message* msg) const
{
AssertWorkerThread();
mLink->SendMessage(msg);
}
void
AsyncChannel::OnNotifyMaybeChannelError()
{
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
mChannelErrorTask = NULL;
// OnChannelError holds mMonitor when it posts this task and this
// task cannot be allowed to run until OnChannelError has
// exited. We enforce that order by grabbing the mutex here which
// should only continue once OnChannelError has completed.
{
MonitorAutoLock lock(*mMonitor);
// nothing to do here
}
if (ShouldDeferNotifyMaybeError()) {
mChannelErrorTask =
NewRunnableMethod(this, &AsyncChannel::OnNotifyMaybeChannelError);
// 10 ms delay is completely arbitrary
mWorkerLoop->PostDelayedTask(FROM_HERE, mChannelErrorTask, 10);
return;
}
NotifyMaybeChannelError();
}
void
AsyncChannel::NotifyChannelClosed()
{
mMonitor->AssertNotCurrentThreadOwns();
if (ChannelClosed != mChannelState)
NS_RUNTIMEABORT("channel should have been closed!");
// OK, the IO thread just closed the channel normally. Let the
// listener know about it.
mListener->OnChannelClose();
Clear();
}
void
AsyncChannel::NotifyMaybeChannelError()
{
mMonitor->AssertNotCurrentThreadOwns();
// TODO sort out Close() on this side racing with Close() on the
// other side
if (ChannelClosing == mChannelState) {
// the channel closed, but we received a "Goodbye" message
// warning us about it. no worries
mChannelState = ChannelClosed;
NotifyChannelClosed();
return;
}
// Oops, error! Let the listener know about it.
mChannelState = ChannelError;
mListener->OnChannelError();
Clear();
}
void
AsyncChannel::Clear()
{
mListener = 0;
mWorkerLoop = 0;
delete mLink;
mLink = 0;
mMonitor = 0;
if (mChannelErrorTask) {
mChannelErrorTask->Cancel();
mChannelErrorTask = NULL;
}
}
static void
PrintErrorMessage(bool isChild, const char* channelName, const char* msg)
{
printf_stderr("\n###!!! [%s][%s] Error: %s\n\n",
isChild ? "Child" : "Parent", channelName, msg);
}
bool
AsyncChannel::MaybeHandleError(Result code, const char* channelName)
{
if (MsgProcessed == code)
return true;
const char* errorMsg = nullptr;
switch (code) {
case MsgNotKnown:
errorMsg = "Unknown message: not processed";
break;
case MsgNotAllowed:
errorMsg = "Message not allowed: cannot be sent/recvd in this state";
break;
case MsgPayloadError:
errorMsg = "Payload error: message could not be deserialized";
break;
case MsgProcessingError:
errorMsg = "Processing error: message was deserialized, but the handler returned false (indicating failure)";
break;
case MsgRouteError:
errorMsg = "Route error: message sent to unknown actor ID";
break;
case MsgValueError:
errorMsg = "Value error: message was deserialized, but contained an illegal value";
break;
default:
NS_RUNTIMEABORT("unknown Result code");
return false;
}
PrintErrorMessage(mChild, channelName, errorMsg);
mListener->OnProcessingError(code);
return false;
}
void
AsyncChannel::ReportConnectionError(const char* channelName) const
{
const char* errorMsg = nullptr;
switch (mChannelState) {
case ChannelClosed:
errorMsg = "Closed channel: cannot send/recv";
break;
case ChannelOpening:
errorMsg = "Opening channel: not yet ready for send/recv";
break;
case ChannelTimeout:
errorMsg = "Channel timeout: cannot send/recv";
break;
case ChannelClosing:
errorMsg = "Channel closing: too late to send/recv, messages will be lost";
break;
case ChannelError:
errorMsg = "Channel error: cannot send/recv";
break;
default:
NS_RUNTIMEABORT("unreached");
}
PrintErrorMessage(mChild, channelName, errorMsg);
mListener->OnProcessingError(MsgDropped);
}
void
AsyncChannel::DispatchOnChannelConnected(int32_t peer_pid)
{
AssertWorkerThread();
if (mListener)
mListener->OnChannelConnected(peer_pid);
}
//
// The methods below run in the context of the IO thread
//
void
AsyncChannel::ProcessLink::OnMessageReceived(const Message& msg)
{
AssertIOThread();
NS_ASSERTION(mChan->mChannelState != ChannelError, "Shouldn't get here!");
MonitorAutoLock lock(*mChan->mMonitor);
mChan->OnMessageReceivedFromLink(msg);
}
void
AsyncChannel::ProcessLink::OnEchoMessage(Message* msg)
{
AssertIOThread();
OnMessageReceived(*msg);
delete msg;
}
void
AsyncChannel::ProcessLink::OnChannelOpened()
{
mChan->AssertLinkThread();
{
MonitorAutoLock lock(*mChan->mMonitor);
mExistingListener = mTransport->set_listener(this);
#ifdef DEBUG
if (mExistingListener) {
queue<Message> pending;
mExistingListener->GetQueuedMessages(pending);
MOZ_ASSERT(pending.empty());
}
#endif // DEBUG
mChan->mChannelState = ChannelOpening;
lock.Notify();
}
/*assert*/mTransport->Connect();
}
void
AsyncChannel::ProcessLink::OnTakeConnectedChannel()
{
AssertIOThread();
queue<Message> pending;
{
MonitorAutoLock lock(*mChan->mMonitor);
mChan->mChannelState = ChannelConnected;
mExistingListener = mTransport->set_listener(this);
if (mExistingListener) {
mExistingListener->GetQueuedMessages(pending);
}
lock.Notify();
}
// Dispatch whatever messages the previous listener had queued up.
while (!pending.empty()) {
OnMessageReceived(pending.front());
pending.pop();
}
}
void
AsyncChannel::ProcessLink::OnChannelConnected(int32_t peer_pid)
{
AssertIOThread();
{
MonitorAutoLock lock(*mChan->mMonitor);
mChan->mChannelState = ChannelConnected;
mChan->mMonitor->Notify();
}
if(mExistingListener)
mExistingListener->OnChannelConnected(peer_pid);
mChan->mWorkerLoop->PostTask(
FROM_HERE,
NewRunnableMethod(mChan,
&AsyncChannel::DispatchOnChannelConnected,
peer_pid));
}
void
AsyncChannel::ProcessLink::OnChannelError()
{
AssertIOThread();
MonitorAutoLock lock(*mChan->mMonitor);
mChan->OnChannelErrorFromLink();
}
void
AsyncChannel::ProcessLink::OnCloseChannel()
{
AssertIOThread();
mTransport->Close();
MonitorAutoLock lock(*mChan->mMonitor);
mChan->mChannelState = ChannelClosed;
mChan->mMonitor->Notify();
}
//
// The methods below run in the context of the link thread
//
void
AsyncChannel::OnMessageReceivedFromLink(const Message& msg)
{
AssertLinkThread();
mMonitor->AssertCurrentThreadOwns();
if (!MaybeInterceptSpecialIOMessage(msg))
// wake up the worker, there's work to do
mWorkerLoop->PostTask(
FROM_HERE,
NewRunnableMethod(this, &AsyncChannel::OnDispatchMessage, msg));
}
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void
AsyncChannel::OnChannelErrorFromLink()
{
AssertLinkThread();
mMonitor->AssertCurrentThreadOwns();
if (ChannelClosing != mChannelState)
mChannelState = ChannelError;
PostErrorNotifyTask();
}
void
AsyncChannel::CloseWithError()
{
AssertWorkerThread();
MonitorAutoLock lock(*mMonitor);
if (ChannelConnected != mChannelState) {
return;
}
SynchronouslyClose();
mChannelState = ChannelError;
PostErrorNotifyTask();
}
void
AsyncChannel::PostErrorNotifyTask()
{
mMonitor->AssertCurrentThreadOwns();
if (mChannelErrorTask)
return;
// This must be the last code that runs on this thread!
mChannelErrorTask =
NewRunnableMethod(this, &AsyncChannel::OnNotifyMaybeChannelError);
mWorkerLoop->PostTask(FROM_HERE, mChannelErrorTask);
}
bool
AsyncChannel::MaybeInterceptSpecialIOMessage(const Message& msg)
{
AssertLinkThread();
mMonitor->AssertCurrentThreadOwns();
if (MSG_ROUTING_NONE == msg.routing_id()
&& GOODBYE_MESSAGE_TYPE == msg.type()) {
ProcessGoodbyeMessage();
return true;
}
return false;
}
void
AsyncChannel::ProcessGoodbyeMessage()
{
AssertLinkThread();
mMonitor->AssertCurrentThreadOwns();
// TODO sort out Close() on this side racing with Close() on the
// other side
mChannelState = ChannelClosing;
printf("NOTE: %s process received `Goodbye', closing down\n",
mChild ? "child" : "parent");
}
} // namespace ipc
} // namespace mozilla