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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: sw=2 ts=4 et :
*/
/* 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
#ifndef ipc_glue_MessageChannel_h
#define ipc_glue_MessageChannel_h
#include "ipc/EnumSerializer.h"
#include "mozilla/Atomics.h"
#include "mozilla/BaseProfilerMarkers.h"
#include "mozilla/LinkedList.h"
#include "mozilla/Monitor.h"
#include "mozilla/Vector.h"
#if defined(XP_WIN)
# include "mozilla/ipc/Neutering.h"
#endif // defined(XP_WIN)
#include <functional>
#include <map>
#include <stack>
#include <vector>
#include "MessageLink.h" // for HasResultCodes
#include "mozilla/ipc/ScopedPort.h"
#include "nsITargetShutdownTask.h"
#ifdef FUZZING_SNAPSHOT
# include "mozilla/fuzzing/IPCFuzzController.h"
#endif
class MessageLoop;
namespace IPC {
template <typename T>
struct ParamTraits;
}
namespace mozilla {
namespace ipc {
class IToplevelProtocol;
class ActorLifecycleProxy;
class RefCountedMonitor : public Monitor {
public:
RefCountedMonitor() : Monitor("mozilla.ipc.MessageChannel.mMonitor") {}
void AssertSameMonitor(const RefCountedMonitor& aOther) const
MOZ_REQUIRES(*this) MOZ_ASSERT_CAPABILITY(aOther) {
MOZ_ASSERT(this == &aOther);
}
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(RefCountedMonitor)
private:
~RefCountedMonitor() = default;
};
enum class MessageDirection {
eSending,
eReceiving,
};
enum class MessagePhase {
Endpoint,
TransferStart,
TransferEnd,
};
enum class SyncSendError {
SendSuccess,
PreviousTimeout,
SendingCPOWWhileDispatchingSync,
SendingCPOWWhileDispatchingUrgent,
NotConnectedBeforeSend,
DisconnectedDuringSend,
CancelledBeforeSend,
CancelledAfterSend,
TimedOut,
ReplyError,
};
enum class ResponseRejectReason {
SendError,
ChannelClosed,
HandlerRejected,
ActorDestroyed,
ResolverDestroyed,
EndGuard_,
};
template <typename T>
using ResolveCallback = std::function<void(T&&)>;
using RejectCallback = std::function<void(ResponseRejectReason)>;
enum ChannelState {
ChannelClosed,
ChannelConnected,
ChannelClosing,
ChannelError
};
class AutoEnterTransaction;
class MessageChannel : HasResultCodes {
friend class PortLink;
typedef mozilla::Monitor Monitor;
public:
using Message = IPC::Message;
struct UntypedCallbackHolder {
UntypedCallbackHolder(int32_t aActorId, Message::msgid_t aReplyMsgId,
RejectCallback&& aReject)
: mActorId(aActorId),
mReplyMsgId(aReplyMsgId),
mReject(std::move(aReject)) {}
virtual ~UntypedCallbackHolder() = default;
void Reject(ResponseRejectReason&& aReason) { mReject(std::move(aReason)); }
int32_t mActorId;
Message::msgid_t mReplyMsgId;
RejectCallback mReject;
};
template <typename Value>
struct CallbackHolder : public UntypedCallbackHolder {
CallbackHolder(int32_t aActorId, Message::msgid_t aReplyMsgId,
ResolveCallback<Value>&& aResolve, RejectCallback&& aReject)
: UntypedCallbackHolder(aActorId, aReplyMsgId, std::move(aReject)),
mResolve(std::move(aResolve)) {}
void Resolve(Value&& aReason) { mResolve(std::move(aReason)); }
ResolveCallback<Value> mResolve;
};
private:
static Atomic<size_t> gUnresolvedResponses;
friend class PendingResponseReporter;
public:
static constexpr int32_t kNoTimeout = INT32_MIN;
using ScopedPort = mozilla::ipc::ScopedPort;
explicit MessageChannel(const char* aName, IToplevelProtocol* aListener);
~MessageChannel();
IToplevelProtocol* Listener() const { return mListener; }
// Returns the event target which the worker lives on and must be used for
// operations on the current thread. Only safe to access after the
// MessageChannel has been opened.
nsISerialEventTarget* GetWorkerEventTarget() const { return mWorkerThread; }
// "Open" a connection using an existing ScopedPort. The ScopedPort must be
// valid and connected to a remote.
//
// The `aEventTarget` parameter must be on the current thread.
bool Open(ScopedPort aPort, Side aSide, const nsID& aMessageChannelId,
nsISerialEventTarget* aEventTarget = nullptr);
// "Open" a connection to another thread in the same process.
//
// Returns true if the transport layer was successfully connected,
// i.e., mChannelState == ChannelConnected.
//
// For more details on the process of opening a channel between
// threads, see the extended comment on this function
// in MessageChannel.cpp.
bool Open(MessageChannel* aTargetChan, nsISerialEventTarget* aEventTarget,
Side aSide);
// "Open" a connection to an actor on the current thread.
//
// Returns true if the transport layer was successfully connected,
// i.e., mChannelState == ChannelConnected.
//
// Same-thread channels may not perform synchronous or blocking message
// sends, to avoid deadlocks.
bool OpenOnSameThread(MessageChannel* aTargetChan, Side aSide);
/**
* This sends a special message that is processed on the IO thread, so that
* other actors can know that the process will soon shutdown.
*/
void NotifyImpendingShutdown() MOZ_EXCLUDES(*mMonitor);
// Close the underlying transport channel.
void Close() MOZ_EXCLUDES(*mMonitor);
// Induce an error in this MessageChannel's connection.
//
// After this method is called, no more message notifications will be
// delivered to the listener, and the channel will be unable to send or
// receive future messages, as if the peer dropped the connection
// unexpectedly.
//
// The OnChannelError notification will be delivered either asynchronously or
// during an explicit call to Close(), whichever happens first.
//
// NOTE: If SetAbortOnError(true) has been called on this MessageChannel,
// calling this function will immediately exit the current process.
void InduceConnectionError() MOZ_EXCLUDES(*mMonitor);
void SetAbortOnError(bool abort) MOZ_EXCLUDES(*mMonitor) {
MonitorAutoLock lock(*mMonitor);
mAbortOnError = abort;
}
// Call aInvoke for each pending message until it returns false.
// XXX: You must get permission from an IPC peer to use this function
// since it requires custom deserialization and re-orders events.
void PeekMessages(const std::function<bool(const Message& aMsg)>& aInvoke)
MOZ_EXCLUDES(*mMonitor);
// Misc. behavioral traits consumers can request for this channel
enum ChannelFlags {
REQUIRE_DEFAULT = 0,
// Windows: if this channel operates on the UI thread, indicates
// WindowsMessageLoop code should enable deferred native message
// handling to prevent deadlocks. Should only be used for protocols
// that manage child processes which might create native UI, like
// plugins.
REQUIRE_DEFERRED_MESSAGE_PROTECTION = 1 << 0,
};
void SetChannelFlags(ChannelFlags aFlags) { mFlags = aFlags; }
ChannelFlags GetChannelFlags() { return mFlags; }
// Asynchronously send a message to the other side of the channel
bool Send(UniquePtr<Message> aMsg) MOZ_EXCLUDES(*mMonitor);
// Asynchronously send a message to the other side of the channel
// and wait for asynchronous reply.
template <typename Value>
void Send(UniquePtr<Message> aMsg, int32_t aActorId,
Message::msgid_t aReplyMsgId, ResolveCallback<Value>&& aResolve,
RejectCallback&& aReject) MOZ_EXCLUDES(*mMonitor) {
int32_t seqno = NextSeqno();
aMsg->set_seqno(seqno);
if (!Send(std::move(aMsg))) {
aReject(ResponseRejectReason::SendError);
return;
}
UniquePtr<UntypedCallbackHolder> callback =
MakeUnique<CallbackHolder<Value>>(
aActorId, aReplyMsgId, std::move(aResolve), std::move(aReject));
mPendingResponses.insert(std::make_pair(seqno, std::move(callback)));
gUnresolvedResponses++;
}
bool SendBuildIDsMatchMessage(const char* aParentBuildID)
MOZ_EXCLUDES(*mMonitor);
bool DoBuildIDsMatch() MOZ_EXCLUDES(*mMonitor) {
MonitorAutoLock lock(*mMonitor);
return mBuildIDsConfirmedMatch;
}
// Synchronously send |aMsg| (i.e., wait for |aReply|)
bool Send(UniquePtr<Message> aMsg, UniquePtr<Message>* aReply)
MOZ_EXCLUDES(*mMonitor);
bool CanSend() const MOZ_EXCLUDES(*mMonitor);
// Remove and return a callback that needs reply
UniquePtr<UntypedCallbackHolder> PopCallback(const Message& aMsg,
int32_t aActorId);
// Used to reject and remove pending responses owned by the given
// actor when it's about to be destroyed.
void RejectPendingResponsesForActor(int32_t aActorId);
// If sending a sync message returns an error, this function gives a more
// descriptive error message.
SyncSendError LastSendError() const {
AssertWorkerThread();
return mLastSendError;
}
void SetReplyTimeoutMs(int32_t aTimeoutMs);
bool IsOnCxxStack() const { return mOnCxxStack; }
void CancelCurrentTransaction() MOZ_EXCLUDES(*mMonitor);
// Return whether the current transaction is complete.
//
// This is intended only for tests.
bool TestOnlyIsTransactionComplete() const MOZ_EXCLUDES(*mMonitor);
// IsClosed and NumQueuedMessages are safe to call from any thread, but
// may provide an out-of-date value.
bool IsClosed() MOZ_EXCLUDES(*mMonitor) {
MonitorAutoLock lock(*mMonitor);
return IsClosedLocked();
}
bool IsClosedLocked() const MOZ_REQUIRES(*mMonitor) {
mMonitor->AssertCurrentThreadOwns();
return mLink ? mLink->IsClosed() : true;
}
static bool IsPumpingMessages() { return sIsPumpingMessages; }
static void SetIsPumpingMessages(bool aIsPumping) {
sIsPumpingMessages = aIsPumping;
}
/**
* Does this MessageChannel currently cross process boundaries?
*/
bool IsCrossProcess() const MOZ_REQUIRES(*mMonitor);
void SetIsCrossProcess(bool aIsCrossProcess) MOZ_REQUIRES(*mMonitor);
nsID GetMessageChannelId() const {
MonitorAutoLock lock(*mMonitor);
return mMessageChannelId;
}
#ifdef FUZZING_SNAPSHOT
Maybe<mojo::core::ports::PortName> GetPortName() {
MonitorAutoLock lock(*mMonitor);
return mLink ? mLink->GetPortName() : Nothing();
}
#endif
#ifdef XP_WIN
struct MOZ_STACK_CLASS SyncStackFrame {
explicit SyncStackFrame(MessageChannel* channel);
~SyncStackFrame();
bool mSpinNestedEvents;
bool mListenerNotified;
MessageChannel* mChannel;
// The previous stack frame for this channel.
SyncStackFrame* mPrev;
// The previous stack frame on any channel.
SyncStackFrame* mStaticPrev;
};
friend struct MessageChannel::SyncStackFrame;
static bool IsSpinLoopActive() {
for (SyncStackFrame* frame = sStaticTopFrame; frame; frame = frame->mPrev) {
if (frame->mSpinNestedEvents) return true;
}
return false;
}
protected:
// The deepest sync stack frame for this channel.
SyncStackFrame* mTopFrame = nullptr;
bool mIsSyncWaitingOnNonMainThread = false;
// The deepest sync stack frame on any channel.
static SyncStackFrame* sStaticTopFrame;
public:
void ProcessNativeEventsInInterruptCall();
static void NotifyGeckoEventDispatch();
private:
void SpinInternalEventLoop();
#endif // defined(XP_WIN)
private:
void PostErrorNotifyTask() MOZ_REQUIRES(*mMonitor);
void OnNotifyMaybeChannelError() MOZ_EXCLUDES(*mMonitor);
void ReportConnectionError(const char* aFunctionName,
const uint32_t aMsgTyp) const
MOZ_REQUIRES(*mMonitor);
void ReportMessageRouteError(const char* channelName) const
MOZ_EXCLUDES(*mMonitor);
bool MaybeHandleError(Result code, const Message& aMsg,
const char* channelName) MOZ_EXCLUDES(*mMonitor);
void Clear() MOZ_REQUIRES(*mMonitor);
bool HasPendingEvents() MOZ_REQUIRES(*mMonitor);
void ProcessPendingRequests(ActorLifecycleProxy* aProxy,
AutoEnterTransaction& aTransaction)
MOZ_REQUIRES(*mMonitor);
bool ProcessPendingRequest(ActorLifecycleProxy* aProxy,
UniquePtr<Message> aUrgent)
MOZ_REQUIRES(*mMonitor);
void EnqueuePendingMessages() MOZ_REQUIRES(*mMonitor);
// Dispatches an incoming message to its appropriate handler.
void DispatchMessage(ActorLifecycleProxy* aProxy, UniquePtr<Message> aMsg)
MOZ_REQUIRES(*mMonitor);
// DispatchMessage will route to one of these functions depending on the
// protocol type of the message.
void DispatchSyncMessage(ActorLifecycleProxy* aProxy, const Message& aMsg,
UniquePtr<Message>& aReply) MOZ_EXCLUDES(*mMonitor);
void DispatchAsyncMessage(ActorLifecycleProxy* aProxy, const Message& aMsg)
MOZ_EXCLUDES(*mMonitor);
// Return true if the wait ended because a notification was received.
//
// Return false if the time elapsed from when we started the process of
// waiting until afterwards exceeded the currently allotted timeout.
// That *DOES NOT* mean false => "no event" (== timeout); there are many
// circumstances that could cause the measured elapsed time to exceed the
// timeout EVEN WHEN we were notified.
//
// So in sum: true is a meaningful return value; false isn't,
// necessarily.
bool WaitForSyncNotify() MOZ_REQUIRES(*mMonitor);
bool WaitResponse(bool aWaitTimedOut);
bool ShouldContinueFromTimeout() MOZ_REQUIRES(*mMonitor);
void EndTimeout() MOZ_REQUIRES(*mMonitor);
void CancelTransaction(int transaction) MOZ_REQUIRES(*mMonitor);
void RepostAllMessages() MOZ_REQUIRES(*mMonitor);
int32_t NextSeqno() {
AssertWorkerThread();
return (mSide == ChildSide) ? --mNextSeqno : ++mNextSeqno;
}
void DebugAbort(const char* file, int line, const char* cond, const char* why,
bool reply = false) MOZ_REQUIRES(*mMonitor);
void AddProfilerMarker(const IPC::Message& aMessage,
MessageDirection aDirection) MOZ_REQUIRES(*mMonitor);
private:
// Returns true if we're dispatching an async message's callback.
bool DispatchingAsyncMessage() const {
AssertWorkerThread();
return mDispatchingAsyncMessage;
}
int DispatchingAsyncMessageNestedLevel() const {
AssertWorkerThread();
return mDispatchingAsyncMessageNestedLevel;
}
// Check if there is still a live connection to our peer. This may change to
// `false` at any time due to the connection to our peer being closed or
// dropped (e.g. due to a crash).
bool Connected() const MOZ_REQUIRES(*mMonitor);
// Check if there is either still a live connection to our peer, or we have
// received a `Goodbye` from our peer, and are actively shutting down our
// connection with our peer.
bool ConnectedOrClosing() const MOZ_REQUIRES(*mMonitor);
private:
// Executed on the IO thread.
void NotifyWorkerThread() MOZ_REQUIRES(*mMonitor);
// Return true if |aMsg| is a special message targeted at the IO
// thread, in which case it shouldn't be delivered to the worker.
bool MaybeInterceptSpecialIOMessage(const Message& aMsg)
MOZ_REQUIRES(*mMonitor);
// Returns true if ShouldDeferMessage(aMsg) is guaranteed to return true.
// Otherwise, the result of ShouldDeferMessage(aMsg) may be true or false,
// depending on context.
static bool IsAlwaysDeferred(const Message& aMsg);
// Helper for sending a message via the link. If the message is [LazySend], it
// will be queued, and if the message is not-[LazySend], it will flush any
// pending [LazySend] messages.
void SendMessageToLink(UniquePtr<Message> aMsg) MOZ_REQUIRES(*mMonitor);
// Called to flush [LazySend] messages to the link.
void FlushLazySendMessages() MOZ_REQUIRES(*mMonitor);
bool WasTransactionCanceled(int transaction);
bool ShouldDeferMessage(const Message& aMsg) MOZ_REQUIRES(*mMonitor);
void OnMessageReceivedFromLink(UniquePtr<Message> aMsg)
MOZ_REQUIRES(*mMonitor);
void OnChannelErrorFromLink() MOZ_REQUIRES(*mMonitor);
private:
// Clear this channel, and notify the listener that the channel has either
// closed or errored.
//
// These methods must be called on the worker thread, passing in a
// `ReleasableMonitorAutoLock`. This lock guard will be reset before the
// listener is called, allowing for the monitor to be unlocked before the
// MessageChannel is potentially destroyed.
void NotifyChannelClosed(ReleasableMonitorAutoLock& aLock)
MOZ_REQUIRES(*mMonitor);
void NotifyMaybeChannelError(ReleasableMonitorAutoLock& aLock)
MOZ_REQUIRES(*mMonitor);
private:
void AssertWorkerThread() const {
MOZ_ASSERT(mWorkerThread, "Channel hasn't been opened yet");
MOZ_RELEASE_ASSERT(mWorkerThread && mWorkerThread->IsOnCurrentThread(),
"not on worker thread!");
}
private:
class MessageTask : public CancelableRunnable,
public LinkedListElement<RefPtr<MessageTask>>,
public nsIRunnablePriority,
public nsIRunnableIPCMessageType {
public:
explicit MessageTask(MessageChannel* aChannel, UniquePtr<Message> aMessage);
MessageTask() = delete;
MessageTask(const MessageTask&) = delete;
NS_DECL_ISUPPORTS_INHERITED
NS_IMETHOD Run() override;
nsresult Cancel() override;
NS_IMETHOD GetPriority(uint32_t* aPriority) override;
NS_DECL_NSIRUNNABLEIPCMESSAGETYPE
void Post() MOZ_REQUIRES(*mMonitor);
bool IsScheduled() const MOZ_REQUIRES(*mMonitor) {
mMonitor->AssertCurrentThreadOwns();
return mScheduled;
}
UniquePtr<Message>& Msg() MOZ_REQUIRES(*mMonitor) {
MOZ_DIAGNOSTIC_ASSERT(mMessage, "message was moved");
return mMessage;
}
const UniquePtr<Message>& Msg() const MOZ_REQUIRES(*mMonitor) {
MOZ_DIAGNOSTIC_ASSERT(mMessage, "message was moved");
return mMessage;
}
void AssertMonitorHeld(const RefCountedMonitor& aMonitor)
MOZ_REQUIRES(aMonitor) MOZ_ASSERT_CAPABILITY(*mMonitor) {
aMonitor.AssertSameMonitor(*mMonitor);
}
private:
~MessageTask();
MessageChannel* Channel() MOZ_REQUIRES(*mMonitor) {
mMonitor->AssertCurrentThreadOwns();
MOZ_RELEASE_ASSERT(isInList());
return mChannel;
}
// The connected MessageChannel's monitor. Guards `mChannel` and
// `mScheduled`.
RefPtr<RefCountedMonitor> const mMonitor;
// The channel which this MessageTask is associated with. Only valid while
// `mMonitor` is held, and this MessageTask `isInList()`.
MessageChannel* const mChannel;
UniquePtr<Message> mMessage MOZ_GUARDED_BY(*mMonitor);
uint32_t const mPriority;
bool mScheduled : 1 MOZ_GUARDED_BY(*mMonitor);
#ifdef FUZZING_SNAPSHOT
const bool mIsFuzzMsg;
bool mFuzzStopped MOZ_GUARDED_BY(*mMonitor);
#endif
};
bool ShouldRunMessage(const Message& aMsg) MOZ_REQUIRES(*mMonitor);
void RunMessage(ActorLifecycleProxy* aProxy, MessageTask& aTask)
MOZ_REQUIRES(*mMonitor);
class WorkerTargetShutdownTask final : public nsITargetShutdownTask {
public:
NS_DECL_THREADSAFE_ISUPPORTS
WorkerTargetShutdownTask(nsISerialEventTarget* aTarget,
MessageChannel* aChannel);
void TargetShutdown() override;
void Clear();
private:
~WorkerTargetShutdownTask() = default;
const nsCOMPtr<nsISerialEventTarget> mTarget;
// Cleared by MessageChannel before it is destroyed.
MessageChannel* MOZ_NON_OWNING_REF mChannel;
};
class FlushLazySendMessagesRunnable final : public CancelableRunnable {
public:
explicit FlushLazySendMessagesRunnable(MessageChannel* aChannel);
NS_DECL_ISUPPORTS_INHERITED
NS_IMETHOD Run() override;
nsresult Cancel() override;
void PushMessage(UniquePtr<Message> aMsg);
nsTArray<UniquePtr<Message>> TakeMessages();
private:
~FlushLazySendMessagesRunnable() = default;
// Cleared by MessageChannel before it is destroyed.
MessageChannel* MOZ_NON_OWNING_REF mChannel;
// LazySend messages which haven't been sent yet, but will be sent as soon
// as a non-LazySend message is sent, or this runnable is executed.
nsTArray<UniquePtr<Message>> mQueue;
};
typedef LinkedList<RefPtr<MessageTask>> MessageQueue;
typedef std::map<size_t, UniquePtr<UntypedCallbackHolder>> CallbackMap;
typedef IPC::Message::msgid_t msgid_t;
private:
// This will be a string literal, so lifetime is not an issue.
const char* const mName;
// ID for each MessageChannel. Set when it is opened, and never cleared
// afterwards.
//
// This ID is only intended for diagnostics, debugging, and reporting
// purposes, and shouldn't be used for message routing or permissions checks.
nsID mMessageChannelId MOZ_GUARDED_BY(*mMonitor) = {};
// Based on presumption the listener owns and overlives the channel,
// this is never nullified.
IToplevelProtocol* const mListener;
// This monitor guards all state in this MessageChannel, except where
// otherwise noted. It is refcounted so a reference to it can be shared with
// IPC listener objects which need to access weak references to this
// `MessageChannel`.
RefPtr<RefCountedMonitor> const mMonitor;
ChannelState mChannelState MOZ_GUARDED_BY(*mMonitor) = ChannelClosed;
Side mSide = UnknownSide;
bool mIsCrossProcess MOZ_GUARDED_BY(*mMonitor) = false;
UniquePtr<MessageLink> mLink MOZ_GUARDED_BY(*mMonitor);
// NotifyMaybeChannelError runnable
RefPtr<CancelableRunnable> mChannelErrorTask MOZ_GUARDED_BY(*mMonitor);
// Thread we are allowed to send and receive on. Set in Open(); never
// changed, and we can only call Open() once. We shouldn't be accessing
// from multiple threads before Open().
nsCOMPtr<nsISerialEventTarget> mWorkerThread;
// Shutdown task to close the channel before mWorkerThread goes away.
RefPtr<WorkerTargetShutdownTask> mShutdownTask MOZ_GUARDED_BY(*mMonitor);
// Task to force sending lazy messages when mQueuedLazyMessages is non-empty.
RefPtr<FlushLazySendMessagesRunnable> mFlushLazySendTask
MOZ_GUARDED_BY(*mMonitor);
// Timeout periods are broken up in two to prevent system suspension from
// triggering an abort. This method (called by WaitForEvent with a 'did
// timeout' flag) decides if we should wait again for half of mTimeoutMs
// or give up.
// only accessed on WorkerThread
int32_t mTimeoutMs = kNoTimeout;
bool mInTimeoutSecondHalf = false;
// Worker-thread only; sequence numbers for messages that require
// replies.
int32_t mNextSeqno = 0;
static bool sIsPumpingMessages;
// If ::Send returns false, this gives a more descriptive error.
SyncSendError mLastSendError = SyncSendError::SendSuccess;
template <class T>
class AutoSetValue {
public:
explicit AutoSetValue(T& var, const T& newValue)
: mVar(var), mPrev(var), mNew(newValue) {
mVar = newValue;
}
~AutoSetValue() {
// The value may have been zeroed if the transaction was
// canceled. In that case we shouldn't return it to its previous
// value.
if (mVar == mNew) {
mVar = mPrev;
}
}
private:
T& mVar;
T mPrev;
T mNew;
};
bool mDispatchingAsyncMessage = false;
int mDispatchingAsyncMessageNestedLevel = 0;
// When we send an urgent request from the parent process, we could race
// with an RPC message that was issued by the child beforehand. In this
// case, if the parent were to wake up while waiting for the urgent reply,
// and process the RPC, it could send an additional urgent message. The
// child would wake up to process the urgent message (as it always will),
// then send a reply, which could be received by the parent out-of-order
// with respect to the first urgent reply.
//
// To address this problem, urgent or RPC requests are associated with a
// "transaction". Whenever one side of the channel wishes to start a
// chain of RPC/urgent messages, it allocates a new transaction ID. Any
// messages the parent receives, not apart of this transaction, are
// deferred. When issuing RPC/urgent requests on top of a started
// transaction, the initiating transaction ID is used.
//
// To ensure IDs are unique, we use sequence numbers for transaction IDs,
// which grow in opposite directions from child to parent.
friend class AutoEnterTransaction;
AutoEnterTransaction* mTransactionStack MOZ_GUARDED_BY(*mMonitor) = nullptr;
int32_t CurrentNestedInsideSyncTransaction() const MOZ_REQUIRES(*mMonitor);
bool AwaitingSyncReply() const MOZ_REQUIRES(*mMonitor);
int AwaitingSyncReplyNestedLevel() const MOZ_REQUIRES(*mMonitor);
bool DispatchingSyncMessage() const MOZ_REQUIRES(*mMonitor);
int DispatchingSyncMessageNestedLevel() const MOZ_REQUIRES(*mMonitor);
#ifdef DEBUG
void AssertMaybeDeferredCountCorrect() MOZ_REQUIRES(*mMonitor);
#else
void AssertMaybeDeferredCountCorrect() MOZ_REQUIRES(*mMonitor) {}
#endif
// If a sync message times out, we store its sequence number here. Any
// future sync messages will fail immediately. Once the reply for original
// sync message is received, we allow sync messages again.
//
// When a message times out, nothing is done to inform the other side. The
// other side will eventually dispatch the message and send a reply. Our
// side is responsible for replying to all sync messages sent by the other
// side when it dispatches the timed out message. The response is always an
// error.
//
// A message is only timed out if it initiated a transaction. This avoids
// hitting a lot of corner cases with message nesting that we don't really
// care about.
int32_t mTimedOutMessageSeqno MOZ_GUARDED_BY(*mMonitor) = 0;
int mTimedOutMessageNestedLevel MOZ_GUARDED_BY(*mMonitor) = 0;
// Queue of all incoming messages.
//
// If both this side and the other side are functioning correctly, the other
// side can send as many async messages as it wants before sending us a
// blocking message. After sending a blocking message, the other side must be
// blocked, and thus can't send us any more messages until we process the sync
// in-msg.
//
MessageQueue mPending MOZ_GUARDED_BY(*mMonitor);
// The number of messages in mPending for which IsAlwaysDeferred is false
// (i.e., the number of messages that might not be deferred, depending on
// context).
size_t mMaybeDeferredPendingCount MOZ_GUARDED_BY(*mMonitor) = 0;
// Is there currently MessageChannel logic for this channel on the C++ stack?
// This member is only accessed on the worker thread, and so is not protected
// by mMonitor.
bool mOnCxxStack = false;
// Map of async Callbacks that are still waiting replies.
CallbackMap mPendingResponses;
#ifdef XP_WIN
HANDLE mEvent;
#endif
// Should the channel abort the process from the I/O thread when
// a channel error occurs?
bool mAbortOnError MOZ_GUARDED_BY(*mMonitor) = false;
// True if the listener has already been notified of a channel close or
// error.
bool mNotifiedChannelDone MOZ_GUARDED_BY(*mMonitor) = false;
// See SetChannelFlags
ChannelFlags mFlags = REQUIRE_DEFAULT;
bool mBuildIDsConfirmedMatch MOZ_GUARDED_BY(*mMonitor) = false;
// If this is true, both ends of this message channel have event targets
// on the same thread.
bool mIsSameThreadChannel = false;
};
void CancelCPOWs();
} // namespace ipc
} // namespace mozilla
namespace IPC {
template <>
struct ParamTraits<mozilla::ipc::ResponseRejectReason>
: public ContiguousEnumSerializer<
mozilla::ipc::ResponseRejectReason,
mozilla::ipc::ResponseRejectReason::SendError,
mozilla::ipc::ResponseRejectReason::EndGuard_> {};
} // namespace IPC
namespace geckoprofiler::markers {
struct IPCMarker {
static constexpr mozilla::Span<const char> MarkerTypeName() {
return mozilla::MakeStringSpan("IPC");
}
static void StreamJSONMarkerData(
mozilla::baseprofiler::SpliceableJSONWriter& aWriter,
mozilla::TimeStamp aStart, mozilla::TimeStamp aEnd, int32_t aOtherPid,
int32_t aMessageSeqno, IPC::Message::msgid_t aMessageType,
mozilla::ipc::Side aSide, mozilla::ipc::MessageDirection aDirection,
mozilla::ipc::MessagePhase aPhase, bool aSync,
mozilla::MarkerThreadId aOriginThreadId) {
using namespace mozilla::ipc;
// This payload still streams a startTime and endTime property because it
// made the migration to MarkerTiming on the front-end easier.
aWriter.TimeProperty("startTime", aStart);
aWriter.TimeProperty("endTime", aEnd);
aWriter.IntProperty("otherPid", aOtherPid);
aWriter.IntProperty("messageSeqno", aMessageSeqno);
aWriter.StringProperty(
"messageType",
mozilla::MakeStringSpan(IPC::StringFromIPCMessageType(aMessageType)));
aWriter.StringProperty("side", IPCSideToString(aSide));
aWriter.StringProperty("direction",
aDirection == MessageDirection::eSending
? mozilla::MakeStringSpan("sending")
: mozilla::MakeStringSpan("receiving"));
aWriter.StringProperty("phase", IPCPhaseToString(aPhase));
aWriter.BoolProperty("sync", aSync);
if (!aOriginThreadId.IsUnspecified()) {
// Tech note: If `ToNumber()` returns a uint64_t, the conversion to
// int64_t is "implementation-defined" before C++20. This is acceptable
// here, because this is a one-way conversion to a unique identifier
// that's used to visually separate data by thread on the front-end.
aWriter.IntProperty(
"threadId",
static_cast<int64_t>(aOriginThreadId.ThreadId().ToNumber()));
}
}
static mozilla::MarkerSchema MarkerTypeDisplay() {
return mozilla::MarkerSchema::SpecialFrontendLocation{};
}
private:
static mozilla::Span<const char> IPCSideToString(mozilla::ipc::Side aSide) {
switch (aSide) {
case mozilla::ipc::ParentSide:
return mozilla::MakeStringSpan("parent");
case mozilla::ipc::ChildSide:
return mozilla::MakeStringSpan("child");
case mozilla::ipc::UnknownSide:
return mozilla::MakeStringSpan("unknown");
default:
MOZ_ASSERT_UNREACHABLE("Invalid IPC side");
return mozilla::MakeStringSpan("<invalid IPC side>");
}
}
static mozilla::Span<const char> IPCPhaseToString(
mozilla::ipc::MessagePhase aPhase) {
switch (aPhase) {
case mozilla::ipc::MessagePhase::Endpoint:
return mozilla::MakeStringSpan("endpoint");
case mozilla::ipc::MessagePhase::TransferStart:
return mozilla::MakeStringSpan("transferStart");
case mozilla::ipc::MessagePhase::TransferEnd:
return mozilla::MakeStringSpan("transferEnd");
default:
MOZ_ASSERT_UNREACHABLE("Invalid IPC phase");
return mozilla::MakeStringSpan("<invalid IPC phase>");
}
}
};
} // namespace geckoprofiler::markers
#endif // ifndef ipc_glue_MessageChannel_h