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gecko-dev/ipc/glue/MessageChannel.cpp

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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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mozilla/ipc/MessageChannel.h"
#include <math.h>
#include <utility>
#include "CrashAnnotations.h"
#include "mozilla/Assertions.h"
#include "mozilla/CycleCollectedJSContext.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/Fuzzing.h"
#include "mozilla/IntentionalCrash.h"
#include "mozilla/Logging.h"
#include "mozilla/Monitor.h"
#include "mozilla/Mutex.h"
#include "mozilla/ProfilerMarkers.h"
#include "mozilla/ScopeExit.h"
#include "mozilla/Sprintf.h"
#include "mozilla/StaticMutex.h"
#include "mozilla/Telemetry.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/UniquePtrExtensions.h"
#include "mozilla/dom/ScriptSettings.h"
#include "mozilla/ipc/NodeController.h"
#include "mozilla/ipc/ProcessChild.h"
#include "mozilla/ipc/ProtocolUtils.h"
#include "nsAppRunner.h"
#include "nsContentUtils.h"
#include "nsTHashMap.h"
#include "nsDebug.h"
#include "nsExceptionHandler.h"
#include "nsIMemoryReporter.h"
#include "nsISupportsImpl.h"
#include "nsPrintfCString.h"
#include "nsThreadUtils.h"
#ifdef OS_WIN
# include "mozilla/gfx/Logging.h"
#endif
#ifdef FUZZING_SNAPSHOT
# include "mozilla/fuzzing/IPCFuzzController.h"
#endif
// Undo the damage done by mozzconf.h
#undef compress
static mozilla::LazyLogModule sLogModule("ipc");
#define IPC_LOG(...) MOZ_LOG(sLogModule, LogLevel::Debug, (__VA_ARGS__))
/*
* IPC design:
*
* There are two kinds of messages: async and sync. Sync messages are blocking.
*
* Terminology: To dispatch a message Foo is to run the RecvFoo code for
* it. This is also called "handling" the message.
*
* Sync and async messages can sometimes "nest" inside other sync messages
* (i.e., while waiting for the sync reply, we can dispatch the inner
* message). The three possible nesting levels are NOT_NESTED,
* NESTED_INSIDE_SYNC, and NESTED_INSIDE_CPOW. The intended uses are:
* NOT_NESTED - most messages.
* NESTED_INSIDE_SYNC - CPOW-related messages, which are always sync
* and can go in either direction.
* NESTED_INSIDE_CPOW - messages where we don't want to dispatch
* incoming CPOWs while waiting for the response.
* These nesting levels are ordered: NOT_NESTED, NESTED_INSIDE_SYNC,
* NESTED_INSIDE_CPOW. Async messages cannot be NESTED_INSIDE_SYNC but they can
* be NESTED_INSIDE_CPOW.
*
* To avoid jank, the parent process is not allowed to send NOT_NESTED sync
* messages. When a process is waiting for a response to a sync message M0, it
* will dispatch an incoming message M if:
* 1. M has a higher nesting level than M0, or
* 2. if M has the same nesting level as M0 and we're in the child, or
* 3. if M has the same nesting level as M0 and it was sent by the other side
* while dispatching M0.
* The idea is that messages with higher nesting should take precendence. The
* purpose of rule 2 is to handle a race where both processes send to each other
* simultaneously. In this case, we resolve the race in favor of the parent (so
* the child dispatches first).
*
* Messages satisfy the following properties:
* A. When waiting for a response to a sync message, we won't dispatch any
* messages of a lower nesting level.
* B. Messages of the same nesting level will be dispatched roughly in the
* order they were sent. The exception is when the parent and child send
* sync messages to each other simulataneously. In this case, the parent's
* message is dispatched first. While it is dispatched, the child may send
* further nested messages, and these messages may be dispatched before the
* child's original message. We can consider ordering to be preserved here
* because we pretend that the child's original message wasn't sent until
* after the parent's message is finished being dispatched.
*
* When waiting for a sync message reply, we dispatch an async message only if
* it is NESTED_INSIDE_CPOW. Normally NESTED_INSIDE_CPOW async
* messages are sent only from the child. However, the parent can send
* NESTED_INSIDE_CPOW async messages when it is creating a bridged protocol.
*/
using namespace mozilla;
using namespace mozilla::ipc;
using mozilla::MonitorAutoLock;
using mozilla::MonitorAutoUnlock;
using mozilla::dom::AutoNoJSAPI;
#define IPC_ASSERT(_cond, ...) \
do { \
AssertWorkerThread(); \
mMonitor->AssertCurrentThreadOwns(); \
if (!(_cond)) DebugAbort(__FILE__, __LINE__, #_cond, ##__VA_ARGS__); \
} while (0)
static MessageChannel* gParentProcessBlocker = nullptr;
namespace mozilla {
namespace ipc {
static const uint32_t kMinTelemetryMessageSize = 4096;
// Note: we round the time we spend waiting for a response to the nearest
// millisecond. So a min value of 1 ms actually captures from 500us and above.
// This is used for both the sending and receiving side telemetry for sync IPC,
// (IPC_SYNC_MAIN_LATENCY_MS and IPC_SYNC_RECEIVE_MS).
static const uint32_t kMinTelemetrySyncIPCLatencyMs = 1;
// static
bool MessageChannel::sIsPumpingMessages = false;
class AutoEnterTransaction {
public:
explicit AutoEnterTransaction(MessageChannel* aChan, int32_t aMsgSeqno,
int32_t aTransactionID, int aNestedLevel)
REQUIRES(*aChan->mMonitor)
: mChan(aChan),
mActive(true),
mOutgoing(true),
mNestedLevel(aNestedLevel),
mSeqno(aMsgSeqno),
mTransaction(aTransactionID),
mNext(mChan->mTransactionStack) {
mChan->mMonitor->AssertCurrentThreadOwns();
mChan->mTransactionStack = this;
}
explicit AutoEnterTransaction(MessageChannel* aChan,
const IPC::Message& aMessage)
REQUIRES(*aChan->mMonitor)
: mChan(aChan),
mActive(true),
mOutgoing(false),
mNestedLevel(aMessage.nested_level()),
mSeqno(aMessage.seqno()),
mTransaction(aMessage.transaction_id()),
mNext(mChan->mTransactionStack) {
mChan->mMonitor->AssertCurrentThreadOwns();
if (!aMessage.is_sync()) {
mActive = false;
return;
}
mChan->mTransactionStack = this;
}
~AutoEnterTransaction() {
mChan->mMonitor->AssertCurrentThreadOwns();
if (mActive) {
mChan->mTransactionStack = mNext;
}
}
void Cancel() {
mChan->mMonitor->AssertCurrentThreadOwns();
AutoEnterTransaction* cur = mChan->mTransactionStack;
MOZ_RELEASE_ASSERT(cur == this);
while (cur && cur->mNestedLevel != IPC::Message::NOT_NESTED) {
// Note that, in the following situation, we will cancel multiple
// transactions:
// 1. Parent sends NESTED_INSIDE_SYNC message P1 to child.
// 2. Child sends NESTED_INSIDE_SYNC message C1 to child.
// 3. Child dispatches P1, parent blocks.
// 4. Child cancels.
// In this case, both P1 and C1 are cancelled. The parent will
// remove C1 from its queue when it gets the cancellation message.
MOZ_RELEASE_ASSERT(cur->mActive);
cur->mActive = false;
cur = cur->mNext;
}
mChan->mTransactionStack = cur;
MOZ_RELEASE_ASSERT(IsComplete());
}
bool AwaitingSyncReply() const {
MOZ_RELEASE_ASSERT(mActive);
if (mOutgoing) {
return true;
}
return mNext ? mNext->AwaitingSyncReply() : false;
}
int AwaitingSyncReplyNestedLevel() const {
MOZ_RELEASE_ASSERT(mActive);
if (mOutgoing) {
return mNestedLevel;
}
return mNext ? mNext->AwaitingSyncReplyNestedLevel() : 0;
}
bool DispatchingSyncMessage() const {
MOZ_RELEASE_ASSERT(mActive);
if (!mOutgoing) {
return true;
}
return mNext ? mNext->DispatchingSyncMessage() : false;
}
int DispatchingSyncMessageNestedLevel() const {
MOZ_RELEASE_ASSERT(mActive);
if (!mOutgoing) {
return mNestedLevel;
}
return mNext ? mNext->DispatchingSyncMessageNestedLevel() : 0;
}
int NestedLevel() const {
MOZ_RELEASE_ASSERT(mActive);
return mNestedLevel;
}
int32_t SequenceNumber() const {
MOZ_RELEASE_ASSERT(mActive);
return mSeqno;
}
int32_t TransactionID() const {
MOZ_RELEASE_ASSERT(mActive);
return mTransaction;
}
void ReceivedReply(UniquePtr<IPC::Message> aMessage) {
MOZ_RELEASE_ASSERT(aMessage->seqno() == mSeqno);
MOZ_RELEASE_ASSERT(aMessage->transaction_id() == mTransaction);
MOZ_RELEASE_ASSERT(!mReply);
IPC_LOG("Reply received on worker thread: seqno=%d", mSeqno);
mReply = std::move(aMessage);
MOZ_RELEASE_ASSERT(IsComplete());
}
void HandleReply(UniquePtr<IPC::Message> aMessage) {
mChan->mMonitor->AssertCurrentThreadOwns();
AutoEnterTransaction* cur = mChan->mTransactionStack;
MOZ_RELEASE_ASSERT(cur == this);
while (cur) {
MOZ_RELEASE_ASSERT(cur->mActive);
if (aMessage->seqno() == cur->mSeqno) {
cur->ReceivedReply(std::move(aMessage));
break;
}
cur = cur->mNext;
MOZ_RELEASE_ASSERT(cur);
}
}
bool IsComplete() { return !mActive || mReply; }
bool IsOutgoing() { return mOutgoing; }
bool IsCanceled() { return !mActive; }
bool IsBottom() const { return !mNext; }
bool IsError() {
MOZ_RELEASE_ASSERT(mReply);
return mReply->is_reply_error();
}
UniquePtr<IPC::Message> GetReply() { return std::move(mReply); }
private:
MessageChannel* mChan;
// Active is true if this transaction is on the mChan->mTransactionStack
// stack. Generally we're not on the stack if the transaction was canceled
// or if it was for a message that doesn't require transactions (an async
// message).
bool mActive;
// Is this stack frame for an outgoing message?
bool mOutgoing;
// Properties of the message being sent/received.
int mNestedLevel;
int32_t mSeqno;
int32_t mTransaction;
// Next item in mChan->mTransactionStack.
AutoEnterTransaction* mNext;
// Pointer the a reply received for this message, if one was received.
UniquePtr<IPC::Message> mReply;
};
class PendingResponseReporter final : public nsIMemoryReporter {
~PendingResponseReporter() = default;
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_IMETHOD
CollectReports(nsIHandleReportCallback* aHandleReport, nsISupports* aData,
bool aAnonymize) override {
MOZ_COLLECT_REPORT(
"unresolved-ipc-responses", KIND_OTHER, UNITS_COUNT,
MessageChannel::gUnresolvedResponses,
"Outstanding IPC async message responses that are still not resolved.");
return NS_OK;
}
};
NS_IMPL_ISUPPORTS(PendingResponseReporter, nsIMemoryReporter)
class ChannelCountReporter final : public nsIMemoryReporter {
~ChannelCountReporter() = default;
struct ChannelCounts {
size_t mNow;
size_t mMax;
ChannelCounts() : mNow(0), mMax(0) {}
void Inc() {
++mNow;
if (mMax < mNow) {
mMax = mNow;
}
}
void Dec() {
MOZ_ASSERT(mNow > 0);
--mNow;
}
};
using CountTable = nsTHashMap<nsDepCharHashKey, ChannelCounts>;
static StaticMutex sChannelCountMutex;
static CountTable* sChannelCounts GUARDED_BY(sChannelCountMutex);
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_IMETHOD
CollectReports(nsIHandleReportCallback* aHandleReport, nsISupports* aData,
bool aAnonymize) override {
AutoTArray<std::pair<const char*, ChannelCounts>, 16> counts;
{
StaticMutexAutoLock countLock(sChannelCountMutex);
if (!sChannelCounts) {
return NS_OK;
}
counts.SetCapacity(sChannelCounts->Count());
for (const auto& entry : *sChannelCounts) {
counts.AppendElement(std::pair{entry.GetKey(), entry.GetData()});
}
}
for (const auto& entry : counts) {
nsPrintfCString pathNow("ipc-channels/%s", entry.first);
nsPrintfCString pathMax("ipc-channels-peak/%s", entry.first);
nsPrintfCString descNow(
"Number of IPC channels for"
" top-level actor type %s",
entry.first);
nsPrintfCString descMax(
"Peak number of IPC channels for"
" top-level actor type %s",
entry.first);
aHandleReport->Callback(""_ns, pathNow, KIND_OTHER, UNITS_COUNT,
entry.second.mNow, descNow, aData);
aHandleReport->Callback(""_ns, pathMax, KIND_OTHER, UNITS_COUNT,
entry.second.mMax, descMax, aData);
}
return NS_OK;
}
static void Increment(const char* aName) {
StaticMutexAutoLock countLock(sChannelCountMutex);
if (!sChannelCounts) {
sChannelCounts = new CountTable;
}
sChannelCounts->LookupOrInsert(aName).Inc();
}
static void Decrement(const char* aName) {
StaticMutexAutoLock countLock(sChannelCountMutex);
MOZ_ASSERT(sChannelCounts);
sChannelCounts->LookupOrInsert(aName).Dec();
}
};
StaticMutex ChannelCountReporter::sChannelCountMutex;
ChannelCountReporter::CountTable* ChannelCountReporter::sChannelCounts;
NS_IMPL_ISUPPORTS(ChannelCountReporter, nsIMemoryReporter)
// In child processes, the first MessageChannel is created before
// XPCOM is initialized enough to construct the memory reporter
// manager. This retries every time a MessageChannel is constructed,
// which is good enough in practice.
template <class Reporter>
static void TryRegisterStrongMemoryReporter() {
static Atomic<bool> registered;
if (registered.compareExchange(false, true)) {
RefPtr<Reporter> reporter = new Reporter();
if (NS_FAILED(RegisterStrongMemoryReporter(reporter))) {
registered = false;
}
}
}
Atomic<size_t> MessageChannel::gUnresolvedResponses;
MessageChannel::MessageChannel(const char* aName, IToplevelProtocol* aListener)
: mName(aName), mListener(aListener), mMonitor(new RefCountedMonitor()) {
MOZ_COUNT_CTOR(ipc::MessageChannel);
#ifdef OS_WIN
mEvent = CreateEventW(nullptr, TRUE, FALSE, nullptr);
MOZ_RELEASE_ASSERT(mEvent, "CreateEvent failed! Nothing is going to work!");
#endif
TryRegisterStrongMemoryReporter<PendingResponseReporter>();
TryRegisterStrongMemoryReporter<ChannelCountReporter>();
}
MessageChannel::~MessageChannel() {
MOZ_COUNT_DTOR(ipc::MessageChannel);
MonitorAutoLock lock(*mMonitor);
MOZ_RELEASE_ASSERT(!mOnCxxStack,
"MessageChannel destroyed while code on CxxStack");
#ifdef OS_WIN
if (mEvent) {
BOOL ok = CloseHandle(mEvent);
mEvent = nullptr;
if (!ok) {
gfxDevCrash(mozilla::gfx::LogReason::MessageChannelCloseFailure)
<< "MessageChannel failed to close. GetLastError: " << GetLastError();
}
MOZ_RELEASE_ASSERT(ok);
} else {
gfxDevCrash(mozilla::gfx::LogReason::MessageChannelCloseFailure)
<< "MessageChannel destructor ran without an mEvent Handle";
}
#endif
// Make sure that the MessageChannel was closed (and therefore cleared) before
// it was destroyed. We can't properly close the channel at this point, as it
// would be unsafe to invoke our listener's callbacks, and we may be being
// destroyed on a thread other than `mWorkerThread`.
if (!IsClosedLocked()) {
CrashReporter::AnnotateCrashReport(
CrashReporter::Annotation::IPCFatalErrorProtocol,
nsDependentCString(mName));
switch (mChannelState) {
case ChannelConnected:
MOZ_CRASH(
"MessageChannel destroyed without being closed "
"(mChannelState == ChannelConnected).");
break;
case ChannelTimeout:
MOZ_CRASH(
"MessageChannel destroyed without being closed "
"(mChannelState == ChannelTimeout).");
break;
case ChannelClosing:
MOZ_CRASH(
"MessageChannel destroyed without being closed "
"(mChannelState == ChannelClosing).");
break;
case ChannelError:
MOZ_CRASH(
"MessageChannel destroyed without being closed "
"(mChannelState == ChannelError).");
break;
default:
MOZ_CRASH("MessageChannel destroyed without being closed.");
}
}
// Double-check other properties for thoroughness.
MOZ_RELEASE_ASSERT(!mLink);
MOZ_RELEASE_ASSERT(mPendingResponses.empty());
MOZ_RELEASE_ASSERT(!mChannelErrorTask);
MOZ_RELEASE_ASSERT(mPending.isEmpty());
MOZ_RELEASE_ASSERT(!mShutdownTask);
}
#ifdef DEBUG
void MessageChannel::AssertMaybeDeferredCountCorrect() {
mMonitor->AssertCurrentThreadOwns();
size_t count = 0;
for (MessageTask* task : mPending) {
task->AssertMonitorHeld(*mMonitor);
if (!IsAlwaysDeferred(*task->Msg())) {
count++;
}
}
MOZ_ASSERT(count == mMaybeDeferredPendingCount);
}
#endif
// This function returns the current transaction ID. Since the notion of a
// "current transaction" can be hard to define when messages race with each
// other and one gets canceled and the other doesn't, we require that this
// function is only called when the current transaction is known to be for a
// NESTED_INSIDE_SYNC message. In that case, we know for sure what the caller is
// looking for.
int32_t MessageChannel::CurrentNestedInsideSyncTransaction() const {
mMonitor->AssertCurrentThreadOwns();
if (!mTransactionStack) {
return 0;
}
MOZ_RELEASE_ASSERT(mTransactionStack->NestedLevel() ==
IPC::Message::NESTED_INSIDE_SYNC);
return mTransactionStack->TransactionID();
}
bool MessageChannel::AwaitingSyncReply() const {
mMonitor->AssertCurrentThreadOwns();
return mTransactionStack ? mTransactionStack->AwaitingSyncReply() : false;
}
int MessageChannel::AwaitingSyncReplyNestedLevel() const {
mMonitor->AssertCurrentThreadOwns();
return mTransactionStack ? mTransactionStack->AwaitingSyncReplyNestedLevel()
: 0;
}
bool MessageChannel::DispatchingSyncMessage() const {
mMonitor->AssertCurrentThreadOwns();
return mTransactionStack ? mTransactionStack->DispatchingSyncMessage()
: false;
}
int MessageChannel::DispatchingSyncMessageNestedLevel() const {
mMonitor->AssertCurrentThreadOwns();
return mTransactionStack
? mTransactionStack->DispatchingSyncMessageNestedLevel()
: 0;
}
static const char* StringFromIPCSide(Side side) {
switch (side) {
case ChildSide:
return "Child";
case ParentSide:
return "Parent";
default:
return "Unknown";
}
}
static void PrintErrorMessage(Side side, const char* channelName,
const char* msg) {
printf_stderr("\n###!!! [%s][%s] Error: %s\n\n", StringFromIPCSide(side),
channelName, msg);
}
bool MessageChannel::Connected() const {
mMonitor->AssertCurrentThreadOwns();
return ChannelConnected == mChannelState;
}
bool MessageChannel::CanSend() const {
if (!mMonitor) {
return false;
}
MonitorAutoLock lock(*mMonitor);
return Connected();
}
void MessageChannel::Clear() {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
MOZ_DIAGNOSTIC_ASSERT(IsClosedLocked(), "MessageChannel cleared too early?");
// Don't clear mWorkerThread; we use it in AssertWorkerThread().
//
// Also don't clear mListener. If we clear it, then sending a message
// through this channel after it's Clear()'ed can cause this process to
// crash.
if (mShutdownTask) {
mShutdownTask->Clear();
mWorkerThread->UnregisterShutdownTask(mShutdownTask);
}
mShutdownTask = nullptr;
if (NS_IsMainThread() && gParentProcessBlocker == this) {
gParentProcessBlocker = nullptr;
}
gUnresolvedResponses -= mPendingResponses.size();
{
CallbackMap map = std::move(mPendingResponses);
MonitorAutoUnlock unlock(*mMonitor);
for (auto& pair : map) {
pair.second->Reject(ResponseRejectReason::ChannelClosed);
}
}
mPendingResponses.clear();
SetIsCrossProcess(false);
mLink = nullptr;
if (mChannelErrorTask) {
mChannelErrorTask->Cancel();
mChannelErrorTask = nullptr;
}
// Free up any memory used by pending messages.
mPending.clear();
mMaybeDeferredPendingCount = 0;
}
bool MessageChannel::Open(ScopedPort aPort, Side aSide,
nsISerialEventTarget* aEventTarget) {
nsCOMPtr<nsISerialEventTarget> eventTarget =
aEventTarget ? aEventTarget : GetCurrentSerialEventTarget();
MOZ_RELEASE_ASSERT(eventTarget,
"Must open MessageChannel on a nsISerialEventTarget");
MOZ_RELEASE_ASSERT(eventTarget->IsOnCurrentThread(),
"Must open MessageChannel from worker thread");
auto shutdownTask = MakeRefPtr<WorkerTargetShutdownTask>(eventTarget, this);
nsresult rv = eventTarget->RegisterShutdownTask(shutdownTask);
MOZ_ASSERT(rv != NS_ERROR_NOT_IMPLEMENTED,
"target for MessageChannel must support shutdown tasks");
if (rv == NS_ERROR_UNEXPECTED) {
// If shutdown tasks have already started running, dispatch our shutdown
// task manually.
NS_WARNING("Opening MessageChannel on EventTarget in shutdown");
rv = eventTarget->Dispatch(shutdownTask->AsRunnable());
}
MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv),
"error registering ShutdownTask for MessageChannel");
{
MonitorAutoLock lock(*mMonitor);
MOZ_RELEASE_ASSERT(!mLink, "Open() called > once");
MOZ_RELEASE_ASSERT(ChannelClosed == mChannelState, "Not currently closed");
MOZ_ASSERT(mSide == UnknownSide);
mWorkerThread = eventTarget;
mShutdownTask = shutdownTask;
mLink = MakeUnique<PortLink>(this, std::move(aPort));
mSide = aSide;
}
// Notify our listener that the underlying IPC channel has been established.
// IProtocol will use this callback to create the ActorLifecycleProxy, and
// perform an `AddRef` call to keep the actor alive until the channel is
// disconnected.
//
// We unlock our monitor before calling `OnIPCChannelOpened` to ensure that
// any calls back into `MessageChannel` do not deadlock. At this point, we may
// be receiving messages on the IO thread, however we cannot process them on
// the worker thread or have notified our listener until after this function
// returns.
mListener->OnIPCChannelOpened();
return true;
}
static Side GetOppSide(Side aSide) {
switch (aSide) {
case ChildSide:
return ParentSide;
case ParentSide:
return ChildSide;
default:
return UnknownSide;
}
}
bool MessageChannel::Open(MessageChannel* aTargetChan,
nsISerialEventTarget* aEventTarget, Side aSide) {
// Opens a connection to another thread in the same process.
MOZ_ASSERT(aTargetChan, "Need a target channel");
std::pair<ScopedPort, ScopedPort> ports =
NodeController::GetSingleton()->CreatePortPair();
// NOTE: This dispatch must be sync as it captures locals by non-owning
// reference, however we can't use `NS_DISPATCH_SYNC` as that will spin a
// nested event loop, and doesn't work with certain types of calling event
// targets.
base::WaitableEvent event(/* manual_reset */ true,
/* initially_signaled */ false);
MOZ_ALWAYS_SUCCEEDS(aEventTarget->Dispatch(NS_NewCancelableRunnableFunction(
"ipc::MessageChannel::OpenAsOtherThread", [&]() {
aTargetChan->Open(std::move(ports.second), GetOppSide(aSide),
aEventTarget);
event.Signal();
})));
bool ok = event.Wait();
MOZ_RELEASE_ASSERT(ok);
// Now that the other side has connected, open the port on our side.
return Open(std::move(ports.first), aSide);
}
bool MessageChannel::OpenOnSameThread(MessageChannel* aTargetChan,
mozilla::ipc::Side aSide) {
auto [porta, portb] = NodeController::GetSingleton()->CreatePortPair();
aTargetChan->mIsSameThreadChannel = true;
mIsSameThreadChannel = true;
auto* currentThread = GetCurrentSerialEventTarget();
return aTargetChan->Open(std::move(portb), GetOppSide(aSide),
currentThread) &&
Open(std::move(porta), aSide, currentThread);
}
bool MessageChannel::Send(UniquePtr<Message> aMsg) {
if (aMsg->size() >= kMinTelemetryMessageSize) {
Telemetry::Accumulate(Telemetry::IPC_MESSAGE_SIZE2, aMsg->size());
}
MOZ_RELEASE_ASSERT(!aMsg->is_sync());
MOZ_RELEASE_ASSERT(aMsg->nested_level() != IPC::Message::NESTED_INSIDE_SYNC);
AutoSetValue<bool> setOnCxxStack(mOnCxxStack, true);
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
if (MSG_ROUTING_NONE == aMsg->routing_id()) {
ReportMessageRouteError("MessageChannel::Send");
return false;
}
if (aMsg->seqno() == 0) {
aMsg->set_seqno(NextSeqno());
}
MonitorAutoLock lock(*mMonitor);
if (!Connected()) {
ReportConnectionError("Send", aMsg->type());
return false;
}
AddProfilerMarker(*aMsg, MessageDirection::eSending);
SendMessageToLink(std::move(aMsg));
return true;
}
void MessageChannel::SendMessageToLink(UniquePtr<Message> aMsg) {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
mLink->SendMessage(std::move(aMsg));
}
UniquePtr<MessageChannel::UntypedCallbackHolder> MessageChannel::PopCallback(
const Message& aMsg) {
auto iter = mPendingResponses.find(aMsg.seqno());
if (iter != mPendingResponses.end()) {
UniquePtr<MessageChannel::UntypedCallbackHolder> ret =
std::move(iter->second);
mPendingResponses.erase(iter);
gUnresolvedResponses--;
return ret;
}
return nullptr;
}
void MessageChannel::RejectPendingResponsesForActor(ActorIdType aActorId) {
auto itr = mPendingResponses.begin();
while (itr != mPendingResponses.end()) {
if (itr->second.get()->mActorId != aActorId) {
++itr;
continue;
}
itr->second.get()->Reject(ResponseRejectReason::ActorDestroyed);
// Take special care of advancing the iterator since we are
// removing it while iterating.
itr = mPendingResponses.erase(itr);
gUnresolvedResponses--;
}
}
class BuildIDsMatchMessage : public IPC::Message {
public:
BuildIDsMatchMessage()
: IPC::Message(MSG_ROUTING_NONE, BUILD_IDS_MATCH_MESSAGE_TYPE) {}
void Log(const std::string& aPrefix, FILE* aOutf) const {
fputs("(special `Build IDs match' message)", aOutf);
}
};
// Send the parent a special async message to confirm when the parent and child
// are of the same buildID. Skips sending the message and returns false if the
// buildIDs don't match. This is a minor variation on
// MessageChannel::Send(Message* aMsg).
bool MessageChannel::SendBuildIDsMatchMessage(const char* aParentBuildID) {
MOZ_ASSERT(!XRE_IsParentProcess());
nsCString parentBuildID(aParentBuildID);
nsCString childBuildID(mozilla::PlatformBuildID());
if (parentBuildID != childBuildID) {
// The build IDs didn't match, usually because an update occurred in the
// background.
return false;
}
auto msg = MakeUnique<BuildIDsMatchMessage>();
MOZ_RELEASE_ASSERT(!msg->is_sync());
MOZ_RELEASE_ASSERT(msg->nested_level() != IPC::Message::NESTED_INSIDE_SYNC);
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
// Don't check for MSG_ROUTING_NONE.
MonitorAutoLock lock(*mMonitor);
if (!Connected()) {
ReportConnectionError("SendBuildIDsMatchMessage", msg->type());
return false;
}
#if defined(MOZ_DEBUG) && defined(ENABLE_TESTS)
// Technically, the behavior is interesting for any kind of process
// but when exercising tests, we want to crash only a content process and
// avoid making noise with other kind of processes crashing
if (const char* dontSend = PR_GetEnv("MOZ_BUILDID_MATCH_DONTSEND")) {
if (dontSend[0] == '1') {
// Bug 1732999: We are going to crash, so we need to advise leak check
// tooling to avoid intermittent missing leakcheck
NoteIntentionalCrash(XRE_GetProcessTypeString());
if (XRE_IsContentProcess()) {
return false;
}
}
}
#endif
mLink->SendMessage(std::move(msg));
return true;
}
class CancelMessage : public IPC::Message {
public:
explicit CancelMessage(int transaction)
: IPC::Message(MSG_ROUTING_NONE, CANCEL_MESSAGE_TYPE) {
set_transaction_id(transaction);
}
static bool Read(const Message* msg) { return true; }
void Log(const std::string& aPrefix, FILE* aOutf) const {
fputs("(special `Cancel' message)", aOutf);
}
};
bool MessageChannel::MaybeInterceptSpecialIOMessage(const Message& aMsg) {
mMonitor->AssertCurrentThreadOwns();
if (MSG_ROUTING_NONE == aMsg.routing_id()) {
if (GOODBYE_MESSAGE_TYPE == aMsg.type()) {
// :TODO: Sort out Close() on this side racing with Close() on the
// other side
mChannelState = ChannelClosing;
if (LoggingEnabled()) {
printf(
"[%s %u] NOTE: %s actor received `Goodbye' message. Closing "
"channel.\n",
XRE_GeckoProcessTypeToString(XRE_GetProcessType()),
static_cast<uint32_t>(base::GetCurrentProcId()),
(mSide == ChildSide) ? "child" : "parent");
}
return true;
} else if (CANCEL_MESSAGE_TYPE == aMsg.type()) {
IPC_LOG("Cancel from message");
CancelTransaction(aMsg.transaction_id());
NotifyWorkerThread();
return true;
} else if (BUILD_IDS_MATCH_MESSAGE_TYPE == aMsg.type()) {
IPC_LOG("Build IDs match message");
mBuildIDsConfirmedMatch = true;
return true;
} else if (IMPENDING_SHUTDOWN_MESSAGE_TYPE == aMsg.type()) {
IPC_LOG("Impending Shutdown received");
ProcessChild::NotifiedImpendingShutdown();
return true;
}
}
return false;
}
/* static */
bool MessageChannel::IsAlwaysDeferred(const Message& aMsg) {
// If a message is not NESTED_INSIDE_CPOW and not sync, then we always defer
// it.
return aMsg.nested_level() != IPC::Message::NESTED_INSIDE_CPOW &&
!aMsg.is_sync();
}
bool MessageChannel::ShouldDeferMessage(const Message& aMsg) {
// Never defer messages that have the highest nested level, even async
// ones. This is safe because only the child can send these messages, so
// they can never nest.
if (aMsg.nested_level() == IPC::Message::NESTED_INSIDE_CPOW) {
MOZ_ASSERT(!IsAlwaysDeferred(aMsg));
return false;
}
// Unless they're NESTED_INSIDE_CPOW, we always defer async messages.
// Note that we never send an async NESTED_INSIDE_SYNC message.
if (!aMsg.is_sync()) {
MOZ_RELEASE_ASSERT(aMsg.nested_level() == IPC::Message::NOT_NESTED);
MOZ_ASSERT(IsAlwaysDeferred(aMsg));
return true;
}
MOZ_ASSERT(!IsAlwaysDeferred(aMsg));
int msgNestedLevel = aMsg.nested_level();
int waitingNestedLevel = AwaitingSyncReplyNestedLevel();
// Always defer if the nested level of the incoming message is less than the
// nested level of the message we're awaiting.
if (msgNestedLevel < waitingNestedLevel) return true;
// Never defer if the message has strictly greater nested level.
if (msgNestedLevel > waitingNestedLevel) return false;
// When both sides send sync messages of the same nested level, we resolve the
// race by dispatching in the child and deferring the incoming message in
// the parent. However, the parent still needs to dispatch nested sync
// messages.
//
// Deferring in the parent only sort of breaks message ordering. When the
// child's message comes in, we can pretend the child hasn't quite
// finished sending it yet. Since the message is sync, we know that the
// child hasn't moved on yet.
return mSide == ParentSide &&
aMsg.transaction_id() != CurrentNestedInsideSyncTransaction();
}
void MessageChannel::OnMessageReceivedFromLink(UniquePtr<Message> aMsg) {
mMonitor->AssertCurrentThreadOwns();
if (MaybeInterceptSpecialIOMessage(*aMsg)) {
return;
}
mListener->OnChannelReceivedMessage(*aMsg);
// If we're awaiting a sync reply, we know that it needs to be immediately
// handled to unblock us.
if (aMsg->is_sync() && aMsg->is_reply()) {
IPC_LOG("Received reply seqno=%d xid=%d", aMsg->seqno(),
aMsg->transaction_id());
if (aMsg->seqno() == mTimedOutMessageSeqno) {
// Drop the message, but allow future sync messages to be sent.
IPC_LOG("Received reply to timedout message; igoring; xid=%d",
mTimedOutMessageSeqno);
EndTimeout();
return;
}
MOZ_RELEASE_ASSERT(AwaitingSyncReply());
MOZ_RELEASE_ASSERT(!mTimedOutMessageSeqno);
mTransactionStack->HandleReply(std::move(aMsg));
NotifyWorkerThread();
return;
}
// Nested messages cannot be compressed.
MOZ_RELEASE_ASSERT(aMsg->compress_type() == IPC::Message::COMPRESSION_NONE ||
aMsg->nested_level() == IPC::Message::NOT_NESTED);
if (aMsg->compress_type() == IPC::Message::COMPRESSION_ENABLED &&
!mPending.isEmpty()) {
auto* last = mPending.getLast();
last->AssertMonitorHeld(*mMonitor);
bool compress = last->Msg()->type() == aMsg->type() &&
last->Msg()->routing_id() == aMsg->routing_id();
if (compress) {
// This message type has compression enabled, and the back of the
// queue was the same message type and routed to the same destination.
// Replace it with the newer message.
MOZ_RELEASE_ASSERT(last->Msg()->compress_type() ==
IPC::Message::COMPRESSION_ENABLED);
last->Msg() = std::move(aMsg);
return;
}
} else if (aMsg->compress_type() == IPC::Message::COMPRESSION_ALL &&
!mPending.isEmpty()) {
for (MessageTask* p = mPending.getLast(); p; p = p->getPrevious()) {
p->AssertMonitorHeld(*mMonitor);
if (p->Msg()->type() == aMsg->type() &&
p->Msg()->routing_id() == aMsg->routing_id()) {
// This message type has compression enabled, and the queue
// holds a message with the same message type and routed to the
// same destination. Erase it. Note that, since we always
// compress these redundancies, There Can Be Only One.
MOZ_RELEASE_ASSERT(p->Msg()->compress_type() ==
IPC::Message::COMPRESSION_ALL);
MOZ_RELEASE_ASSERT(IsAlwaysDeferred(*p->Msg()));
p->remove();
break;
}
}
}
bool alwaysDeferred = IsAlwaysDeferred(*aMsg);
bool shouldWakeUp = AwaitingSyncReply() && !ShouldDeferMessage(*aMsg);
IPC_LOG("Receive from link; seqno=%d, xid=%d, shouldWakeUp=%d", aMsg->seqno(),
aMsg->transaction_id(), shouldWakeUp);
// There are two cases we're concerned about, relating to the state of the
// worker thread:
//
// (1) We are waiting on a sync reply - worker thread is blocked on the
// IPC monitor.
// - If the message is NESTED_INSIDE_SYNC, we wake up the worker thread to
// deliver the message depending on ShouldDeferMessage. Otherwise, we
// leave it in the mPending queue, posting a task to the worker event
// loop, where it will be processed once the synchronous reply has been
// received.
//
// (2) We are not waiting on a reply.
// - We post a task to the worker event loop.
//
// Note that, we may notify the worker thread even though the monitor is not
// blocked. This is okay, since we always check for pending events before
// blocking again.
RefPtr<MessageTask> task = new MessageTask(this, std::move(aMsg));
mPending.insertBack(task);
if (!alwaysDeferred) {
mMaybeDeferredPendingCount++;
}
if (shouldWakeUp) {
NotifyWorkerThread();
}
// Although we usually don't need to post a message task if
// shouldWakeUp is true, it's easier to post anyway than to have to
// guarantee that every Send call processes everything it's supposed to
// before returning.
task->AssertMonitorHeld(*mMonitor);
task->Post();
}
void MessageChannel::PeekMessages(
const std::function<bool(const Message& aMsg)>& aInvoke) {
// FIXME: We shouldn't be holding the lock for aInvoke!
MonitorAutoLock lock(*mMonitor);
for (MessageTask* it : mPending) {
it->AssertMonitorHeld(*mMonitor);
const Message& msg = *it->Msg();
if (!aInvoke(msg)) {
break;
}
}
}
void MessageChannel::ProcessPendingRequests(
ActorLifecycleProxy* aProxy, AutoEnterTransaction& aTransaction) {
mMonitor->AssertCurrentThreadOwns();
AssertMaybeDeferredCountCorrect();
if (mMaybeDeferredPendingCount == 0) {
return;
}
IPC_LOG("ProcessPendingRequests for seqno=%d, xid=%d",
aTransaction.SequenceNumber(), aTransaction.TransactionID());
// Loop until there aren't any more nested messages to process.
for (;;) {
// If we canceled during ProcessPendingRequest, then we need to leave
// immediately because the results of ShouldDeferMessage will be
// operating with weird state (as if no Send is in progress). That could
// cause even NOT_NESTED sync messages to be processed (but not
// NOT_NESTED async messages), which would break message ordering.
if (aTransaction.IsCanceled()) {
return;
}
Vector<UniquePtr<Message>> toProcess;
for (MessageTask* p = mPending.getFirst(); p;) {
p->AssertMonitorHeld(*mMonitor);
UniquePtr<Message>& msg = p->Msg();
MOZ_RELEASE_ASSERT(!aTransaction.IsCanceled(),
"Calling ShouldDeferMessage when cancelled");
bool defer = ShouldDeferMessage(*msg);
// Only log the interesting messages.
if (msg->is_sync() ||
msg->nested_level() == IPC::Message::NESTED_INSIDE_CPOW) {
IPC_LOG("ShouldDeferMessage(seqno=%d) = %d", msg->seqno(), defer);
}
if (!defer) {
MOZ_ASSERT(!IsAlwaysDeferred(*msg));
if (!toProcess.append(std::move(msg))) MOZ_CRASH();
mMaybeDeferredPendingCount--;
p = p->removeAndGetNext();
continue;
}
p = p->getNext();
}
if (toProcess.empty()) {
break;
}
// Processing these messages could result in more messages, so we
// loop around to check for more afterwards.
for (auto& msg : toProcess) {
ProcessPendingRequest(aProxy, std::move(msg));
}
}
AssertMaybeDeferredCountCorrect();
}
bool MessageChannel::Send(UniquePtr<Message> aMsg, UniquePtr<Message>* aReply) {
mozilla::TimeStamp start = TimeStamp::Now();
if (aMsg->size() >= kMinTelemetryMessageSize) {
Telemetry::Accumulate(Telemetry::IPC_MESSAGE_SIZE2, aMsg->size());
}
// Sanity checks.
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
MOZ_RELEASE_ASSERT(!mIsSameThreadChannel,
"sync send over same-thread channel will deadlock!");
RefPtr<ActorLifecycleProxy> proxy = Listener()->GetLifecycleProxy();
#ifdef OS_WIN
SyncStackFrame frame(this);
NeuteredWindowRegion neuteredRgn(mFlags &
REQUIRE_DEFERRED_MESSAGE_PROTECTION);
#endif
AutoSetValue<bool> setOnCxxStack(mOnCxxStack, true);
MonitorAutoLock lock(*mMonitor);
if (mTimedOutMessageSeqno) {
// Don't bother sending another sync message if a previous one timed out
// and we haven't received a reply for it. Once the original timed-out
// message receives a reply, we'll be able to send more sync messages
// again.
IPC_LOG("Send() failed due to previous timeout");
mLastSendError = SyncSendError::PreviousTimeout;
return false;
}
if (DispatchingSyncMessageNestedLevel() == IPC::Message::NOT_NESTED &&
aMsg->nested_level() > IPC::Message::NOT_NESTED) {
// Don't allow sending CPOWs while we're dispatching a sync message.
IPC_LOG("Nested level forbids send");
mLastSendError = SyncSendError::SendingCPOWWhileDispatchingSync;
return false;
}
if (DispatchingSyncMessageNestedLevel() == IPC::Message::NESTED_INSIDE_CPOW ||
DispatchingAsyncMessageNestedLevel() ==
IPC::Message::NESTED_INSIDE_CPOW) {
// Generally only the parent dispatches urgent messages. And the only
// sync messages it can send are NESTED_INSIDE_SYNC. Mainly we want to
// ensure here that we don't return false for non-CPOW messages.
MOZ_RELEASE_ASSERT(aMsg->nested_level() ==
IPC::Message::NESTED_INSIDE_SYNC);
IPC_LOG("Sending while dispatching urgent message");
mLastSendError = SyncSendError::SendingCPOWWhileDispatchingUrgent;
return false;
}
if (aMsg->nested_level() < DispatchingSyncMessageNestedLevel() ||
aMsg->nested_level() < AwaitingSyncReplyNestedLevel()) {
MOZ_RELEASE_ASSERT(DispatchingSyncMessage() || DispatchingAsyncMessage());
IPC_LOG("Cancel from Send");
auto cancel =
MakeUnique<CancelMessage>(CurrentNestedInsideSyncTransaction());
CancelTransaction(CurrentNestedInsideSyncTransaction());
mLink->SendMessage(std::move(cancel));
}
IPC_ASSERT(aMsg->is_sync(), "can only Send() sync messages here");
IPC_ASSERT(aMsg->nested_level() >= DispatchingSyncMessageNestedLevel(),
"can't send sync message of a lesser nested level than what's "
"being dispatched");
IPC_ASSERT(AwaitingSyncReplyNestedLevel() <= aMsg->nested_level(),
"nested sync message sends must be of increasing nested level");
IPC_ASSERT(
DispatchingSyncMessageNestedLevel() != IPC::Message::NESTED_INSIDE_CPOW,
"not allowed to send messages while dispatching urgent messages");
IPC_ASSERT(
DispatchingAsyncMessageNestedLevel() != IPC::Message::NESTED_INSIDE_CPOW,
"not allowed to send messages while dispatching urgent messages");
if (!Connected()) {
ReportConnectionError("SendAndWait", aMsg->type());
mLastSendError = SyncSendError::NotConnectedBeforeSend;
return false;
}
aMsg->set_seqno(NextSeqno());
int32_t seqno = aMsg->seqno();
int nestedLevel = aMsg->nested_level();
msgid_t replyType = aMsg->type() + 1;
AutoEnterTransaction* stackTop = mTransactionStack;
// If the most recent message on the stack is NESTED_INSIDE_SYNC, then our
// message should nest inside that and we use the same transaction
// ID. Otherwise we need a new transaction ID (so we use the seqno of the
// message we're sending).
bool nest =
stackTop && stackTop->NestedLevel() == IPC::Message::NESTED_INSIDE_SYNC;
int32_t transaction = nest ? stackTop->TransactionID() : seqno;
aMsg->set_transaction_id(transaction);
bool handleWindowsMessages = mListener->HandleWindowsMessages(*aMsg.get());
AutoEnterTransaction transact(this, seqno, transaction, nestedLevel);
IPC_LOG("Send seqno=%d, xid=%d", seqno, transaction);
// aMsg will be destroyed soon, let's keep its type.
const char* msgName = aMsg->name();
const msgid_t msgType = aMsg->type();
AddProfilerMarker(*aMsg, MessageDirection::eSending);
SendMessageToLink(std::move(aMsg));
while (true) {
MOZ_RELEASE_ASSERT(!transact.IsCanceled());
ProcessPendingRequests(proxy, transact);
if (transact.IsComplete()) {
break;
}
if (!Connected()) {
ReportConnectionError("Send", msgType);
mLastSendError = SyncSendError::DisconnectedDuringSend;
return false;
}
MOZ_RELEASE_ASSERT(!mTimedOutMessageSeqno);
MOZ_RELEASE_ASSERT(!transact.IsComplete());
MOZ_RELEASE_ASSERT(mTransactionStack == &transact);
bool maybeTimedOut = !WaitForSyncNotify(handleWindowsMessages);
if (mListener->NeedArtificialSleep()) {
MonitorAutoUnlock unlock(*mMonitor);
mListener->ArtificialSleep();
}
if (!Connected()) {
ReportConnectionError("SendAndWait", msgType);
mLastSendError = SyncSendError::DisconnectedDuringSend;
return false;
}
if (transact.IsCanceled()) {
break;
}
MOZ_RELEASE_ASSERT(mTransactionStack == &transact);
// We only time out a message if it initiated a new transaction (i.e.,
// if neither side has any other message Sends on the stack).
bool canTimeOut = transact.IsBottom();
if (maybeTimedOut && canTimeOut && !ShouldContinueFromTimeout()) {
// Since ShouldContinueFromTimeout drops the lock, we need to
// re-check all our conditions here. We shouldn't time out if any of
// these things happen because there won't be a reply to the timed
// out message in these cases.
if (transact.IsComplete()) {
break;
}
IPC_LOG("Timing out Send: xid=%d", transaction);
mTimedOutMessageSeqno = seqno;
mTimedOutMessageNestedLevel = nestedLevel;
mLastSendError = SyncSendError::TimedOut;
return false;
}
if (transact.IsCanceled()) {
break;
}
}
if (transact.IsCanceled()) {
IPC_LOG("Other side canceled seqno=%d, xid=%d", seqno, transaction);
mLastSendError = SyncSendError::CancelledAfterSend;
return false;
}
if (transact.IsError()) {
IPC_LOG("Error: seqno=%d, xid=%d", seqno, transaction);
mLastSendError = SyncSendError::ReplyError;
return false;
}
uint32_t latencyMs = round((TimeStamp::Now() - start).ToMilliseconds());
IPC_LOG("Got reply: seqno=%d, xid=%d, msgName=%s, latency=%ums", seqno,
transaction, msgName, latencyMs);
UniquePtr<Message> reply = transact.GetReply();
MOZ_RELEASE_ASSERT(reply);
MOZ_RELEASE_ASSERT(reply->is_reply(), "expected reply");
MOZ_RELEASE_ASSERT(!reply->is_reply_error());
MOZ_RELEASE_ASSERT(reply->seqno() == seqno);
MOZ_RELEASE_ASSERT(reply->type() == replyType, "wrong reply type");
MOZ_RELEASE_ASSERT(reply->is_sync());
AddProfilerMarker(*reply, MessageDirection::eReceiving);
if (reply->size() >= kMinTelemetryMessageSize) {
Telemetry::Accumulate(Telemetry::IPC_REPLY_SIZE,
nsDependentCString(msgName), reply->size());
}
*aReply = std::move(reply);
// NOTE: Only collect IPC_SYNC_MAIN_LATENCY_MS on the main thread (bug
// 1343729)
if (NS_IsMainThread() && latencyMs >= kMinTelemetrySyncIPCLatencyMs) {
Telemetry::Accumulate(Telemetry::IPC_SYNC_MAIN_LATENCY_MS,
nsDependentCString(msgName), latencyMs);
}
return true;
}
bool MessageChannel::HasPendingEvents() {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
return Connected() && !mPending.isEmpty();
}
bool MessageChannel::ProcessPendingRequest(ActorLifecycleProxy* aProxy,
UniquePtr<Message> aUrgent) {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
IPC_LOG("Process pending: seqno=%d, xid=%d", aUrgent->seqno(),
aUrgent->transaction_id());
// keep the error relevant information
msgid_t msgType = aUrgent->type();
DispatchMessage(aProxy, std::move(aUrgent));
if (!Connected()) {
ReportConnectionError("ProcessPendingRequest", msgType);
return false;
}
return true;
}
bool MessageChannel::ShouldRunMessage(const Message& aMsg) {
if (!mTimedOutMessageSeqno) {
return true;
}
// If we've timed out a message and we're awaiting the reply to the timed
// out message, we have to be careful what messages we process. Here's what
// can go wrong:
// 1. child sends a NOT_NESTED sync message S
// 2. parent sends a NESTED_INSIDE_SYNC sync message H at the same time
// 3. parent times out H
// 4. child starts processing H and sends a NESTED_INSIDE_SYNC message H'
// nested within the same transaction
// 5. parent dispatches S and sends reply
// 6. child asserts because it instead expected a reply to H'.
//
// To solve this, we refuse to process S in the parent until we get a reply
// to H. More generally, let the timed out message be M. We don't process a
// message unless the child would need the response to that message in order
// to process M. Those messages are the ones that have a higher nested level
// than M or that are part of the same transaction as M.
if (aMsg.nested_level() < mTimedOutMessageNestedLevel ||
(aMsg.nested_level() == mTimedOutMessageNestedLevel &&
aMsg.transaction_id() != mTimedOutMessageSeqno)) {
return false;
}
return true;
}
void MessageChannel::RunMessage(ActorLifecycleProxy* aProxy,
MessageTask& aTask) {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
aTask.AssertMonitorHeld(*mMonitor);
UniquePtr<Message>& msg = aTask.Msg();
if (!Connected()) {
ReportConnectionError("RunMessage", msg->type());
return;
}
// Check that we're going to run the first message that's valid to run.
#if 0
# ifdef DEBUG
for (MessageTask* task : mPending) {
if (task == &aTask) {
break;
}
MOZ_ASSERT(!ShouldRunMessage(*task->Msg()) ||
aTask.Msg()->priority() != task->Msg()->priority());
}
# endif
#endif
if (!ShouldRunMessage(*msg)) {
return;
}
MOZ_RELEASE_ASSERT(aTask.isInList());
aTask.remove();
if (!IsAlwaysDeferred(*msg)) {
mMaybeDeferredPendingCount--;
}
DispatchMessage(aProxy, std::move(msg));
}
NS_IMPL_ISUPPORTS_INHERITED(MessageChannel::MessageTask, CancelableRunnable,
nsIRunnablePriority, nsIRunnableIPCMessageType)
static uint32_t ToRunnablePriority(IPC::Message::PriorityValue aPriority) {
switch (aPriority) {
case IPC::Message::NORMAL_PRIORITY:
return nsIRunnablePriority::PRIORITY_NORMAL;
case IPC::Message::INPUT_PRIORITY:
return nsIRunnablePriority::PRIORITY_INPUT_HIGH;
case IPC::Message::VSYNC_PRIORITY:
return nsIRunnablePriority::PRIORITY_VSYNC;
case IPC::Message::MEDIUMHIGH_PRIORITY:
return nsIRunnablePriority::PRIORITY_MEDIUMHIGH;
case IPC::Message::CONTROL_PRIORITY:
return nsIRunnablePriority::PRIORITY_CONTROL;
default:
MOZ_ASSERT_UNREACHABLE();
return nsIRunnablePriority::PRIORITY_NORMAL;
}
}
MessageChannel::MessageTask::MessageTask(MessageChannel* aChannel,
UniquePtr<Message> aMessage)
: CancelableRunnable(aMessage->name()),
mMonitor(aChannel->mMonitor),
mChannel(aChannel),
mMessage(std::move(aMessage)),
mPriority(ToRunnablePriority(mMessage->priority())),
mScheduled(false)
#ifdef FUZZING_SNAPSHOT
,
mIsFuzzMsg(mMessage->IsFuzzMsg()),
mFuzzStopped(false)
#endif
{
MOZ_DIAGNOSTIC_ASSERT(mMessage, "message may not be null");
#ifdef FUZZING_SNAPSHOT
if (mIsFuzzMsg) {
MOZ_FUZZING_IPC_MT_CTOR();
}
#endif
}
MessageChannel::MessageTask::~MessageTask() {
#ifdef FUZZING_SNAPSHOT
// We track fuzzing messages until their run is complete. To make sure
// that we don't miss messages that are for some reason destroyed without
// being run (e.g. canceled), we catch this condition in the destructor.
if (mIsFuzzMsg && !mFuzzStopped) {
MOZ_FUZZING_IPC_MT_STOP();
} else if (!mIsFuzzMsg && !fuzzing::Nyx::instance().started()) {
MOZ_FUZZING_IPC_PRE_FUZZ_MT_STOP();
}
#endif
}
nsresult MessageChannel::MessageTask::Run() {
mMonitor->AssertNotCurrentThreadOwns();
// Drop the toplevel actor's lifecycle proxy outside of our monitor if we take
// it, as destroying our ActorLifecycleProxy reference can acquire the
// monitor.
RefPtr<ActorLifecycleProxy> proxy;
MonitorAutoLock lock(*mMonitor);
// In case we choose not to run this message, we may need to be able to Post
// it again.
mScheduled = false;
if (!isInList()) {
return NS_OK;
}
#ifdef FUZZING_SNAPSHOT
if (!mIsFuzzMsg) {
if (fuzzing::Nyx::instance().started()) {
// Once we started fuzzing, prevent non-fuzzing tasks from being
// run and potentially blocking worker threads.
//
// TODO: This currently blocks all MessageTasks from running, not
// just those belonging to the target process pair. We currently
// do this for performance reasons, but it should be re-evaluated
// at a later stage when we found a better snapshot point.
return NS_OK;
}
// Record all running tasks prior to fuzzing, so we can wait for
// them to settle before snapshotting.
MOZ_FUZZING_IPC_PRE_FUZZ_MT_RUN();
}
#endif
Channel()->AssertWorkerThread();
mMonitor->AssertSameMonitor(*Channel()->mMonitor);
proxy = Channel()->Listener()->GetLifecycleProxy();
Channel()->RunMessage(proxy, *this);
#ifdef FUZZING_SNAPSHOT
if (mIsFuzzMsg && !mFuzzStopped) {
MOZ_FUZZING_IPC_MT_STOP();
mFuzzStopped = true;
}
#endif
return NS_OK;
}
// Warning: This method removes the receiver from whatever list it might be in.
nsresult MessageChannel::MessageTask::Cancel() {
mMonitor->AssertNotCurrentThreadOwns();
MonitorAutoLock lock(*mMonitor);
if (!isInList()) {
return NS_OK;
}
Channel()->AssertWorkerThread();
mMonitor->AssertSameMonitor(*Channel()->mMonitor);
if (!IsAlwaysDeferred(*Msg())) {
Channel()->mMaybeDeferredPendingCount--;
}
remove();
#ifdef FUZZING_SNAPSHOT
if (mIsFuzzMsg && !mFuzzStopped) {
MOZ_FUZZING_IPC_MT_STOP();
mFuzzStopped = true;
}
#endif
return NS_OK;
}
void MessageChannel::MessageTask::Post() {
mMonitor->AssertCurrentThreadOwns();
mMonitor->AssertSameMonitor(*Channel()->mMonitor);
MOZ_RELEASE_ASSERT(!mScheduled);
MOZ_RELEASE_ASSERT(isInList());
mScheduled = true;
Channel()->mWorkerThread->Dispatch(do_AddRef(this));
}
NS_IMETHODIMP
MessageChannel::MessageTask::GetPriority(uint32_t* aPriority) {
*aPriority = mPriority;
return NS_OK;
}
NS_IMETHODIMP
MessageChannel::MessageTask::GetType(uint32_t* aType) {
mMonitor->AssertNotCurrentThreadOwns();
MonitorAutoLock lock(*mMonitor);
if (!mMessage) {
// If mMessage has been moved already elsewhere, we can't know what the type
// has been.
return NS_ERROR_FAILURE;
}
*aType = mMessage->type();
return NS_OK;
}
void MessageChannel::DispatchMessage(ActorLifecycleProxy* aProxy,
UniquePtr<Message> aMsg) {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
Maybe<AutoNoJSAPI> nojsapi;
if (NS_IsMainThread() && CycleCollectedJSContext::Get()) {
nojsapi.emplace();
}
UniquePtr<Message> reply;
IPC_LOG("DispatchMessage: seqno=%d, xid=%d", aMsg->seqno(),
aMsg->transaction_id());
AddProfilerMarker(*aMsg, MessageDirection::eReceiving);
{
AutoEnterTransaction transaction(this, *aMsg);
int id = aMsg->transaction_id();
MOZ_RELEASE_ASSERT(!aMsg->is_sync() || id == transaction.TransactionID());
{
MonitorAutoUnlock unlock(*mMonitor);
AutoSetValue<bool> setOnCxxStack(mOnCxxStack, true);
mListener->ArtificialSleep();
if (aMsg->is_sync()) {
DispatchSyncMessage(aProxy, *aMsg, reply);
} else {
DispatchAsyncMessage(aProxy, *aMsg);
}
mListener->ArtificialSleep();
}
if (reply && transaction.IsCanceled()) {
// The transaction has been canceled. Don't send a reply.
IPC_LOG("Nulling out reply due to cancellation, seqno=%d, xid=%d",
aMsg->seqno(), id);
reply = nullptr;
}
}
if (reply && ChannelConnected == mChannelState) {
IPC_LOG("Sending reply seqno=%d, xid=%d", aMsg->seqno(),
aMsg->transaction_id());
AddProfilerMarker(*reply, MessageDirection::eSending);
mLink->SendMessage(std::move(reply));
}
}
void MessageChannel::DispatchSyncMessage(ActorLifecycleProxy* aProxy,
const Message& aMsg,
UniquePtr<Message>& aReply) {
AssertWorkerThread();
mozilla::TimeStamp start = TimeStamp::Now();
int nestedLevel = aMsg.nested_level();
MOZ_RELEASE_ASSERT(nestedLevel == IPC::Message::NOT_NESTED ||
NS_IsMainThread());
MessageChannel* dummy;
MessageChannel*& blockingVar =
mSide == ChildSide && NS_IsMainThread() ? gParentProcessBlocker : dummy;
Result rv;
{
AutoSetValue<MessageChannel*> blocked(blockingVar, this);
rv = aProxy->Get()->OnMessageReceived(aMsg, aReply);
}
uint32_t latencyMs = round((TimeStamp::Now() - start).ToMilliseconds());
if (latencyMs >= kMinTelemetrySyncIPCLatencyMs) {
Telemetry::Accumulate(Telemetry::IPC_SYNC_RECEIVE_MS,
nsDependentCString(aMsg.name()), latencyMs);
}
if (!MaybeHandleError(rv, aMsg, "DispatchSyncMessage")) {
aReply = Message::ForSyncDispatchError(aMsg.nested_level());
}
aReply->set_seqno(aMsg.seqno());
aReply->set_transaction_id(aMsg.transaction_id());
}
void MessageChannel::DispatchAsyncMessage(ActorLifecycleProxy* aProxy,
const Message& aMsg) {
AssertWorkerThread();
MOZ_RELEASE_ASSERT(!aMsg.is_sync());
if (aMsg.routing_id() == MSG_ROUTING_NONE) {
NS_WARNING("unhandled special message!");
MaybeHandleError(MsgNotKnown, aMsg, "DispatchAsyncMessage");
return;
}
Result rv;
{
int nestedLevel = aMsg.nested_level();
AutoSetValue<bool> async(mDispatchingAsyncMessage, true);
AutoSetValue<int> nestedLevelSet(mDispatchingAsyncMessageNestedLevel,
nestedLevel);
rv = aProxy->Get()->OnMessageReceived(aMsg);
}
MaybeHandleError(rv, aMsg, "DispatchAsyncMessage");
}
void MessageChannel::EnqueuePendingMessages() {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
// XXX performance tuning knob: could process all or k pending
// messages here, rather than enqueuing for later processing
RepostAllMessages();
}
bool MessageChannel::WaitResponse(bool aWaitTimedOut) {
AssertWorkerThread();
if (aWaitTimedOut) {
if (mInTimeoutSecondHalf) {
// We've really timed out this time.
return false;
}
// Try a second time.
mInTimeoutSecondHalf = true;
} else {
mInTimeoutSecondHalf = false;
}
return true;
}
#ifndef OS_WIN
bool MessageChannel::WaitForSyncNotify(bool /* aHandleWindowsMessages */) {
AssertWorkerThread();
# ifdef DEBUG
// WARNING: We don't release the lock here. We can't because the link
// could signal at this time and we would miss it. Instead we require
// ArtificialTimeout() to be extremely simple.
if (mListener->ArtificialTimeout()) {
return false;
}
# endif
MOZ_RELEASE_ASSERT(!mIsSameThreadChannel,
"Wait on same-thread channel will deadlock!");
TimeDuration timeout = (kNoTimeout == mTimeoutMs)
? TimeDuration::Forever()
: TimeDuration::FromMilliseconds(mTimeoutMs);
CVStatus status = mMonitor->Wait(timeout);
// If the timeout didn't expire, we know we received an event. The
// converse is not true.
return WaitResponse(status == CVStatus::Timeout);
}
void MessageChannel::NotifyWorkerThread() { mMonitor->Notify(); }
#endif
bool MessageChannel::ShouldContinueFromTimeout() {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
bool cont;
{
MonitorAutoUnlock unlock(*mMonitor);
cont = mListener->ShouldContinueFromReplyTimeout();
mListener->ArtificialSleep();
}
static enum {
UNKNOWN,
NOT_DEBUGGING,
DEBUGGING
} sDebuggingChildren = UNKNOWN;
if (sDebuggingChildren == UNKNOWN) {
sDebuggingChildren =
getenv("MOZ_DEBUG_CHILD_PROCESS") || getenv("MOZ_DEBUG_CHILD_PAUSE")
? DEBUGGING
: NOT_DEBUGGING;
}
if (sDebuggingChildren == DEBUGGING) {
return true;
}
return cont;
}
void MessageChannel::SetReplyTimeoutMs(int32_t aTimeoutMs) {
// Set channel timeout value. Since this is broken up into
// two period, the minimum timeout value is 2ms.
AssertWorkerThread();
mTimeoutMs =
(aTimeoutMs <= 0) ? kNoTimeout : (int32_t)ceil((double)aTimeoutMs / 2.0);
}
void MessageChannel::ReportConnectionError(const char* aFunctionName,
const uint32_t aMsgType) const {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
const char* errorMsg = nullptr;
switch (mChannelState) {
case ChannelClosed:
errorMsg = "Closed channel: cannot 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:
MOZ_CRASH("unreached");
}
// IPC connection errors are fairly common, especially "Channel closing: too
// late to send/recv, messages will be lost", so shouldn't be being reported
// on release builds, as that's misleading as to their severity.
NS_WARNING(nsPrintfCString("IPC Connection Error: [%s][%s] %s(msgname=%s) %s",
StringFromIPCSide(mSide), mName, aFunctionName,
IPC::StringFromIPCMessageType(aMsgType), errorMsg)
.get());
MonitorAutoUnlock unlock(*mMonitor);
mListener->ProcessingError(MsgDropped, errorMsg);
}
void MessageChannel::ReportMessageRouteError(const char* channelName) const {
PrintErrorMessage(mSide, channelName, "Need a route");
mListener->ProcessingError(MsgRouteError, "MsgRouteError");
}
bool MessageChannel::MaybeHandleError(Result code, const Message& aMsg,
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:
MOZ_CRASH("unknown Result code");
return false;
}
char reason[512];
const char* msgname = aMsg.name();
if (msgname[0] == '?') {
SprintfLiteral(reason, "(msgtype=0x%X) %s", aMsg.type(), errorMsg);
} else {
SprintfLiteral(reason, "%s %s", msgname, errorMsg);
}
PrintErrorMessage(mSide, channelName, reason);
// Error handled in mozilla::ipc::IPCResult.
if (code == MsgProcessingError) {
return false;
}
mListener->ProcessingError(code, reason);
return false;
}
void MessageChannel::OnChannelErrorFromLink() {
mMonitor->AssertCurrentThreadOwns();
IPC_LOG("OnChannelErrorFromLink");
if (AwaitingSyncReply()) {
NotifyWorkerThread();
}
if (ChannelClosing != mChannelState) {
if (mAbortOnError) {
// mAbortOnError is set by main actors (e.g., ContentChild) to ensure
// that the process terminates even if normal shutdown is prevented.
// A MOZ_CRASH() here is not helpful because crash reporting relies
// on the parent process which we know is dead or otherwise unusable.
//
// Additionally, the parent process can (and often is) killed on Android
// when apps are backgrounded. We don't need to report a crash for
// normal behavior in that case.
printf_stderr("Exiting due to channel error.\n");
ProcessChild::QuickExit();
}
mChannelState = ChannelError;
mMonitor->Notify();
}
PostErrorNotifyTask();
}
void MessageChannel::NotifyMaybeChannelError(ReleasableMonitorAutoLock& aLock) {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
aLock.AssertCurrentThreadOwns();
// 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(aLock);
return;
}
Clear();
// Oops, error! Let the listener know about it.
mChannelState = ChannelError;
// IPDL assumes these notifications do not fire twice, so we do not let
// that happen.
if (mNotifiedChannelDone) {
return;
}
mNotifiedChannelDone = true;
// Let our listener know that the channel errored. This may cause the
// channel to be deleted. Release our caller's `MonitorAutoLock` before
// invoking the listener, as this may call back into MessageChannel, and/or
// cause the channel to be destroyed.
aLock.Unlock();
mListener->OnChannelError();
}
void MessageChannel::OnNotifyMaybeChannelError() {
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
// This lock guard may be reset by `NotifyMaybeChannelError` before invoking
// listener callbacks which may destroy this `MessageChannel`.
//
// Acquiring the lock here also allows us to ensure that
// `OnChannelErrorFromLink` has finished running before this task is allowed
// to continue.
ReleasableMonitorAutoLock lock(*mMonitor);
mChannelErrorTask = nullptr;
if (IsOnCxxStack()) {
// This used to post a 10ms delayed task; however not all
// nsISerialEventTarget implementations support delayed dispatch.
// The delay being completely arbitrary, we may not as well have any.
PostErrorNotifyTask();
return;
}
// This call may destroy `this`.
NotifyMaybeChannelError(lock);
}
void MessageChannel::PostErrorNotifyTask() {
mMonitor->AssertCurrentThreadOwns();
if (mChannelErrorTask) {
return;
}
// This must be the last code that runs on this thread!
mChannelErrorTask = NewNonOwningCancelableRunnableMethod(
"ipc::MessageChannel::OnNotifyMaybeChannelError", this,
&MessageChannel::OnNotifyMaybeChannelError);
mWorkerThread->Dispatch(do_AddRef(mChannelErrorTask));
}
// Special async message.
class GoodbyeMessage : public IPC::Message {
public:
GoodbyeMessage() : IPC::Message(MSG_ROUTING_NONE, GOODBYE_MESSAGE_TYPE) {}
static bool Read(const Message* msg) { return true; }
void Log(const std::string& aPrefix, FILE* aOutf) const {
fputs("(special `Goodbye' message)", aOutf);
}
};
void MessageChannel::SynchronouslyClose() {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
mLink->SendClose();
MOZ_RELEASE_ASSERT(!mIsSameThreadChannel || ChannelClosed == mChannelState,
"same-thread channel failed to synchronously close?");
while (ChannelClosed != mChannelState) mMonitor->Wait();
}
void MessageChannel::CloseWithError() {
AssertWorkerThread();
MonitorAutoLock lock(*mMonitor);
if (ChannelConnected != mChannelState) {
return;
}
SynchronouslyClose();
mChannelState = ChannelError;
PostErrorNotifyTask();
}
void MessageChannel::CloseWithTimeout() {
AssertWorkerThread();
MonitorAutoLock lock(*mMonitor);
if (ChannelConnected != mChannelState) {
return;
}
SynchronouslyClose();
mChannelState = ChannelTimeout;
}
void MessageChannel::NotifyImpendingShutdown() {
UniquePtr<Message> msg =
MakeUnique<Message>(MSG_ROUTING_NONE, IMPENDING_SHUTDOWN_MESSAGE_TYPE);
MonitorAutoLock lock(*mMonitor);
if (Connected()) {
mLink->SendMessage(std::move(msg));
}
}
void MessageChannel::Close() {
AssertWorkerThread();
mMonitor->AssertNotCurrentThreadOwns();
// This lock guard may be reset by `Notify{ChannelClosed,MaybeChannelError}`
// before invoking listener callbacks which may destroy this `MessageChannel`.
ReleasableMonitorAutoLock lock(*mMonitor);
switch (mChannelState) {
case ChannelError:
case ChannelTimeout:
// 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.
NotifyMaybeChannelError(lock);
return;
case ChannelClosed:
// Slightly unexpected but harmless; ignore. See bug 1554244.
return;
default:
// Notify the other side that we're about to close our socket. If we've
// already received a Goodbye from the other side (and our state is
// ChannelClosing), there's no reason to send one.
if (ChannelConnected == mChannelState) {
mLink->SendMessage(MakeUnique<GoodbyeMessage>());
}
SynchronouslyClose();
NotifyChannelClosed(lock);
return;
}
}
void MessageChannel::NotifyChannelClosed(ReleasableMonitorAutoLock& aLock) {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
aLock.AssertCurrentThreadOwns();
if (ChannelClosed != mChannelState) {
MOZ_CRASH("channel should have been closed!");
}
Clear();
// IPDL assumes these notifications do not fire twice, so we do not let
// that happen.
if (mNotifiedChannelDone) {
return;
}
mNotifiedChannelDone = true;
// Let our listener know that the channel was closed. This may cause the
// channel to be deleted. Release our caller's `MonitorAutoLock` before
// invoking the listener, as this may call back into MessageChannel, and/or
// cause the channel to be destroyed.
aLock.Unlock();
mListener->OnChannelClose();
}
void MessageChannel::DebugAbort(const char* file, int line, const char* cond,
const char* why, bool reply) {
AssertWorkerThread();
mMonitor->AssertCurrentThreadOwns();
printf_stderr(
"###!!! [MessageChannel][%s][%s:%d] "
"Assertion (%s) failed. %s %s\n",
mSide == ChildSide ? "Child" : "Parent", file, line, cond, why,
reply ? "(reply)" : "");
MessageQueue pending = std::move(mPending);
while (!pending.isEmpty()) {
pending.getFirst()->AssertMonitorHeld(*mMonitor);
printf_stderr(" [ %s%s ]\n",
pending.getFirst()->Msg()->is_sync() ? "sync" : "async",
pending.getFirst()->Msg()->is_reply() ? "reply" : "");
pending.popFirst();
}
MOZ_CRASH_UNSAFE(why);
}
void MessageChannel::AddProfilerMarker(const IPC::Message& aMessage,
MessageDirection aDirection) {
mMonitor->AssertCurrentThreadOwns();
if (profiler_feature_active(ProfilerFeature::IPCMessages)) {
base::ProcessId pid = mListener->OtherPidMaybeInvalid();
// Only record markers for IPCs with a valid pid.
// And if one of the profiler mutexes is locked on this thread, don't record
// markers, because we don't want to expose profiler IPCs due to the
// profiler itself, and also to avoid possible re-entrancy issues.
if (pid != base::kInvalidProcessId &&
!profiler_is_locked_on_current_thread()) {
// The current timestamp must be given to the `IPCMarker` payload.
[[maybe_unused]] const TimeStamp now = TimeStamp::Now();
bool isThreadBeingProfiled =
profiler_thread_is_being_profiled_for_markers();
PROFILER_MARKER(
"IPC", IPC,
mozilla::MarkerOptions(
mozilla::MarkerTiming::InstantAt(now),
// If the thread is being profiled, add the marker to
// the current thread. If the thread is not being
// profiled, add the marker to the main thread. It
// will appear in the main thread's IPC track. Profiler analysis
// UI correlates all the IPC markers from different threads and
// generates processed markers.
isThreadBeingProfiled ? mozilla::MarkerThreadId::CurrentThread()
: mozilla::MarkerThreadId::MainThread()),
IPCMarker, now, now, pid, aMessage.seqno(), aMessage.type(), mSide,
aDirection, MessagePhase::Endpoint, aMessage.is_sync(),
// aOriginThreadId: If the thread is being profiled, do not include a
// thread ID, as it's the same as the markers. Only include this field
// when the marker is being sent from another thread.
isThreadBeingProfiled ? mozilla::MarkerThreadId{}
: mozilla::MarkerThreadId::CurrentThread());
}
}
}
void MessageChannel::EndTimeout() {
mMonitor->AssertCurrentThreadOwns();
IPC_LOG("Ending timeout of seqno=%d", mTimedOutMessageSeqno);
mTimedOutMessageSeqno = 0;
mTimedOutMessageNestedLevel = 0;
RepostAllMessages();
}
void MessageChannel::RepostAllMessages() {
mMonitor->AssertCurrentThreadOwns();
bool needRepost = false;
for (MessageTask* task : mPending) {
task->AssertMonitorHeld(*mMonitor);
if (!task->IsScheduled()) {
needRepost = true;
break;
}
}
if (!needRepost) {
// If everything is already scheduled to run, do nothing.
return;
}
// In some cases we may have deferred dispatch of some messages in the
// queue. Now we want to run them again. However, we can't just re-post
// those messages since the messages after them in mPending would then be
// before them in the event queue. So instead we cancel everything and
// re-post all messages in the correct order.
MessageQueue queue = std::move(mPending);
while (RefPtr<MessageTask> task = queue.popFirst()) {
task->AssertMonitorHeld(*mMonitor);
RefPtr<MessageTask> newTask = new MessageTask(this, std::move(task->Msg()));
newTask->AssertMonitorHeld(*mMonitor);
mPending.insertBack(newTask);
newTask->Post();
}
AssertMaybeDeferredCountCorrect();
}
void MessageChannel::CancelTransaction(int transaction) {
mMonitor->AssertCurrentThreadOwns();
// When we cancel a transaction, we need to behave as if there's no longer
// any IPC on the stack. Anything we were dispatching or sending will get
// canceled. Consequently, we have to update the state variables below.
//
// We also need to ensure that when any IPC functions on the stack return,
// they don't reset these values using an RAII class like AutoSetValue. To
// avoid that, these RAII classes check if the variable they set has been
// tampered with (by us). If so, they don't reset the variable to the old
// value.
IPC_LOG("CancelTransaction: xid=%d", transaction);
// An unusual case: We timed out a transaction which the other side then
// cancelled. In this case we just leave the timedout state and try to
// forget this ever happened.
if (transaction == mTimedOutMessageSeqno) {
IPC_LOG("Cancelled timed out message %d", mTimedOutMessageSeqno);
EndTimeout();
// Normally mCurrentTransaction == 0 here. But it can be non-zero if:
// 1. Parent sends NESTED_INSIDE_SYNC message H.
// 2. Parent times out H.
// 3. Child dispatches H and sends nested message H' (same transaction).
// 4. Parent dispatches H' and cancels.
MOZ_RELEASE_ASSERT(!mTransactionStack ||
mTransactionStack->TransactionID() == transaction);
if (mTransactionStack) {
mTransactionStack->Cancel();
}
} else {
MOZ_RELEASE_ASSERT(mTransactionStack->TransactionID() == transaction);
mTransactionStack->Cancel();
}
bool foundSync = false;
for (MessageTask* p = mPending.getFirst(); p;) {
p->AssertMonitorHeld(*mMonitor);
UniquePtr<Message>& msg = p->Msg();
// If there was a race between the parent and the child, then we may
// have a queued sync message. We want to drop this message from the
// queue since if will get cancelled along with the transaction being
// cancelled. This happens if the message in the queue is
// NESTED_INSIDE_SYNC.
if (msg->is_sync() && msg->nested_level() != IPC::Message::NOT_NESTED) {
MOZ_RELEASE_ASSERT(!foundSync);
MOZ_RELEASE_ASSERT(msg->transaction_id() != transaction);
IPC_LOG("Removing msg from queue seqno=%d xid=%d", msg->seqno(),
msg->transaction_id());
foundSync = true;
if (!IsAlwaysDeferred(*msg)) {
mMaybeDeferredPendingCount--;
}
p = p->removeAndGetNext();
continue;
}
p = p->getNext();
}
AssertMaybeDeferredCountCorrect();
}
void MessageChannel::CancelCurrentTransaction() {
MonitorAutoLock lock(*mMonitor);
if (DispatchingSyncMessageNestedLevel() >= IPC::Message::NESTED_INSIDE_SYNC) {
if (DispatchingSyncMessageNestedLevel() ==
IPC::Message::NESTED_INSIDE_CPOW ||
DispatchingAsyncMessageNestedLevel() ==
IPC::Message::NESTED_INSIDE_CPOW) {
mListener->IntentionalCrash();
}
IPC_LOG("Cancel requested: current xid=%d",
CurrentNestedInsideSyncTransaction());
MOZ_RELEASE_ASSERT(DispatchingSyncMessage());
auto cancel =
MakeUnique<CancelMessage>(CurrentNestedInsideSyncTransaction());
CancelTransaction(CurrentNestedInsideSyncTransaction());
mLink->SendMessage(std::move(cancel));
}
}
void CancelCPOWs() {
MOZ_ASSERT(NS_IsMainThread());
if (gParentProcessBlocker) {
mozilla::Telemetry::Accumulate(mozilla::Telemetry::IPC_TRANSACTION_CANCEL,
true);
gParentProcessBlocker->CancelCurrentTransaction();
}
}
bool MessageChannel::IsCrossProcess() const {
mMonitor->AssertCurrentThreadOwns();
return mIsCrossProcess;
}
void MessageChannel::SetIsCrossProcess(bool aIsCrossProcess) {
mMonitor->AssertCurrentThreadOwns();
if (aIsCrossProcess == mIsCrossProcess) {
return;
}
mIsCrossProcess = aIsCrossProcess;
if (mIsCrossProcess) {
ChannelCountReporter::Increment(mName);
} else {
ChannelCountReporter::Decrement(mName);
}
}
NS_IMPL_ISUPPORTS(MessageChannel::WorkerTargetShutdownTask,
nsITargetShutdownTask)
MessageChannel::WorkerTargetShutdownTask::WorkerTargetShutdownTask(
nsISerialEventTarget* aTarget, MessageChannel* aChannel)
: mTarget(aTarget), mChannel(aChannel) {}
void MessageChannel::WorkerTargetShutdownTask::TargetShutdown() {
MOZ_RELEASE_ASSERT(mTarget->IsOnCurrentThread());
IPC_LOG("Closing channel due to event target shutdown");
if (MessageChannel* channel = std::exchange(mChannel, nullptr)) {
channel->Close();
}
}
void MessageChannel::WorkerTargetShutdownTask::Clear() {
MOZ_RELEASE_ASSERT(mTarget->IsOnCurrentThread());
mChannel = nullptr;
}
} // namespace ipc
} // namespace mozilla
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