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MiddlemanCall.cpp
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MiddlemanCall.cpp
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "MiddlemanCall.h"
#include <unordered_map>
namespace mozilla {
namespace recordreplay {
// In a replaying or middleman process, all middleman calls that have been
// encountered, indexed by their ID.
static StaticInfallibleVector<MiddlemanCall*> gMiddlemanCalls;
// In a replaying or middleman process, association between values produced by
// a middleman call and the call itself.
typedef std::unordered_map<const void*, MiddlemanCall*> MiddlemanCallMap;
static MiddlemanCallMap* gMiddlemanCallMap;
// In a middleman process, any buffers allocated for performed calls.
static StaticInfallibleVector<void*> gAllocatedBuffers;
// Lock protecting middleman call state.
static Monitor* gMonitor;
void InitializeMiddlemanCalls() {
MOZ_RELEASE_ASSERT(IsRecordingOrReplaying() || IsMiddleman());
gMiddlemanCallMap = new MiddlemanCallMap();
gMonitor = new Monitor();
}
// Apply the ReplayInput phase to aCall and any calls it depends on that have
// not been sent to the middleman yet, filling aOutgoingCalls with the set of
// such calls.
static bool GatherDependentCalls(
InfallibleVector<MiddlemanCall*>& aOutgoingCalls, MiddlemanCall* aCall) {
MOZ_RELEASE_ASSERT(!aCall->mSent);
aCall->mSent = true;
const Redirection& redirection = GetRedirection(aCall->mCallId);
CallArguments arguments;
aCall->mArguments.CopyTo(&arguments);
InfallibleVector<MiddlemanCall*> dependentCalls;
MiddlemanCallContext cx(aCall, &arguments, MiddlemanCallPhase::ReplayInput);
cx.mDependentCalls = &dependentCalls;
redirection.mMiddlemanCall(cx);
if (cx.mFailed) {
if (child::CurrentRepaintCannotFail()) {
child::ReportFatalError(Nothing(), "Middleman call input failed: %s\n",
redirection.mName);
}
return false;
}
for (MiddlemanCall* dependent : dependentCalls) {
if (!dependent->mSent && !GatherDependentCalls(aOutgoingCalls, dependent)) {
return false;
}
}
aOutgoingCalls.append(aCall);
return true;
}
bool SendCallToMiddleman(size_t aCallId, CallArguments* aArguments,
bool aDiverged) {
MOZ_RELEASE_ASSERT(IsReplaying());
const Redirection& redirection = GetRedirection(aCallId);
MOZ_RELEASE_ASSERT(redirection.mMiddlemanCall);
MonitorAutoLock lock(*gMonitor);
// Allocate and fill in a new MiddlemanCall.
size_t id = gMiddlemanCalls.length();
MiddlemanCall* newCall = new MiddlemanCall();
gMiddlemanCalls.emplaceBack(newCall);
newCall->mId = id;
newCall->mCallId = aCallId;
newCall->mArguments.CopyFrom(aArguments);
// Perform the ReplayPreface phase on the new call.
{
MiddlemanCallContext cx(newCall, aArguments,
MiddlemanCallPhase::ReplayPreface);
redirection.mMiddlemanCall(cx);
if (cx.mFailed) {
delete newCall;
gMiddlemanCalls.popBack();
if (child::CurrentRepaintCannotFail()) {
child::ReportFatalError(Nothing(),
"Middleman call preface failed: %s\n",
redirection.mName);
}
return false;
}
}
// Other phases will not run if we have not diverged from the recording.
// Any outputs for the call have been handled by the SaveOutput hook.
if (!aDiverged) {
return true;
}
// Perform the ReplayInput phase on the new call and any others it depends on.
InfallibleVector<MiddlemanCall*> outgoingCalls;
if (!GatherDependentCalls(outgoingCalls, newCall)) {
for (MiddlemanCall* call : outgoingCalls) {
call->mSent = false;
}
return false;
}
// Encode all calls we are sending to the middleman.
InfallibleVector<char> inputData;
BufferStream inputStream(&inputData);
for (MiddlemanCall* call : outgoingCalls) {
call->EncodeInput(inputStream);
}
// Perform the calls synchronously in the middleman.
InfallibleVector<char> outputData;
child::SendMiddlemanCallRequest(inputData.begin(), inputData.length(),
&outputData);
// Decode outputs for the calls just sent, and perform the ReplayOutput phase
// on any older dependent calls we sent.
BufferStream outputStream(outputData.begin(), outputData.length());
for (MiddlemanCall* call : outgoingCalls) {
call->DecodeOutput(outputStream);
if (call != newCall) {
CallArguments oldArguments;
call->mArguments.CopyTo(&oldArguments);
MiddlemanCallContext cx(call, &oldArguments,
MiddlemanCallPhase::ReplayOutput);
cx.mReplayOutputIsOld = true;
GetRedirection(call->mCallId).mMiddlemanCall(cx);
}
}
// Perform the ReplayOutput phase to fill in outputs for the current call.
newCall->mArguments.CopyTo(aArguments);
MiddlemanCallContext cx(newCall, aArguments,
MiddlemanCallPhase::ReplayOutput);
redirection.mMiddlemanCall(cx);
return true;
}
void ProcessMiddlemanCall(const char* aInputData, size_t aInputSize,
InfallibleVector<char>* aOutputData) {
MOZ_RELEASE_ASSERT(IsMiddleman());
BufferStream inputStream(aInputData, aInputSize);
BufferStream outputStream(aOutputData);
while (!inputStream.IsEmpty()) {
MiddlemanCall* call = new MiddlemanCall();
call->DecodeInput(inputStream);
const Redirection& redirection = GetRedirection(call->mCallId);
MOZ_RELEASE_ASSERT(redirection.mMiddlemanCall);
CallArguments arguments;
call->mArguments.CopyTo(&arguments);
bool skipCall;
{
MiddlemanCallContext cx(call, &arguments,
MiddlemanCallPhase::MiddlemanInput);
redirection.mMiddlemanCall(cx);
skipCall = cx.mSkipCallInMiddleman;
}
if (!skipCall) {
RecordReplayInvokeCall(redirection.mBaseFunction, &arguments);
}
{
MiddlemanCallContext cx(call, &arguments,
MiddlemanCallPhase::MiddlemanOutput);
redirection.mMiddlemanCall(cx);
}
call->mArguments.CopyFrom(&arguments);
call->EncodeOutput(outputStream);
while (call->mId >= gMiddlemanCalls.length()) {
gMiddlemanCalls.emplaceBack(nullptr);
}
MOZ_RELEASE_ASSERT(!gMiddlemanCalls[call->mId]);
gMiddlemanCalls[call->mId] = call;
}
}
void* MiddlemanCallContext::AllocateBytes(size_t aSize) {
void* rv = malloc(aSize);
// In a middleman process, any buffers we allocate live until the calls are
// reset. In a replaying process, the buffers will either live forever
// (if they are allocated in the ReplayPreface phase, to match the lifetime
// of the MiddlemanCall itself) or will be recovered when we rewind after we
// are done with our divergence from the recording (any other phase).
if (IsMiddleman()) {
gAllocatedBuffers.append(rv);
}
return rv;
}
void ResetMiddlemanCalls() {
MOZ_RELEASE_ASSERT(IsMiddleman());
for (MiddlemanCall* call : gMiddlemanCalls) {
if (call) {
CallArguments arguments;
call->mArguments.CopyTo(&arguments);
MiddlemanCallContext cx(call, &arguments,
MiddlemanCallPhase::MiddlemanRelease);
GetRedirection(call->mCallId).mMiddlemanCall(cx);
}
}
// Delete the calls in a second pass. The MiddlemanRelease phase depends on
// previous middleman calls still existing.
for (MiddlemanCall* call : gMiddlemanCalls) {
delete call;
}
gMiddlemanCalls.clear();
for (auto buffer : gAllocatedBuffers) {
free(buffer);
}
gAllocatedBuffers.clear();
gMiddlemanCallMap->clear();
}
///////////////////////////////////////////////////////////////////////////////
// System Values
///////////////////////////////////////////////////////////////////////////////
static void AddMiddlemanCallValue(const void* aThing, MiddlemanCall* aCall) {
gMiddlemanCallMap->erase(aThing);
gMiddlemanCallMap->insert(MiddlemanCallMap::value_type(aThing, aCall));
}
static MiddlemanCall* LookupMiddlemanCall(const void* aThing) {
MiddlemanCallMap::const_iterator iter = gMiddlemanCallMap->find(aThing);
if (iter != gMiddlemanCallMap->end()) {
return iter->second;
}
return nullptr;
}
static const void* GetMiddlemanCallValue(size_t aId) {
MOZ_RELEASE_ASSERT(IsMiddleman());
MOZ_RELEASE_ASSERT(aId < gMiddlemanCalls.length() && gMiddlemanCalls[aId] &&
gMiddlemanCalls[aId]->mMiddlemanValue.isSome());
return gMiddlemanCalls[aId]->mMiddlemanValue.ref();
}
bool MM_SystemInput(MiddlemanCallContext& aCx, const void** aThingPtr) {
MOZ_RELEASE_ASSERT(aCx.AccessPreface());
if (!*aThingPtr) {
// Null values are handled by the normal argument copying logic.
return true;
}
Maybe<size_t> callId;
if (aCx.mPhase == MiddlemanCallPhase::ReplayPreface) {
// Determine any middleman call this object came from, before the pointer
// has a chance to be clobbered by another call between this and the
// ReplayInput phase.
MiddlemanCall* call = LookupMiddlemanCall(*aThingPtr);
if (call) {
callId.emplace(call->mId);
}
}
aCx.ReadOrWritePrefaceBytes(&callId, sizeof(callId));
switch (aCx.mPhase) {
case MiddlemanCallPhase::ReplayPreface:
return true;
case MiddlemanCallPhase::ReplayInput:
if (callId.isSome()) {
aCx.WriteInputScalar(callId.ref());
aCx.mDependentCalls->append(gMiddlemanCalls[callId.ref()]);
return true;
}
return false;
case MiddlemanCallPhase::MiddlemanInput:
if (callId.isSome()) {
size_t callIndex = aCx.ReadInputScalar();
*aThingPtr = GetMiddlemanCallValue(callIndex);
return true;
}
return false;
default:
MOZ_CRASH("Bad phase");
}
}
// Pointer system values are preserved during the replay so that null tests
// and equality tests work as expected. We additionally mangle the
// pointers here by setting one of the two highest bits, depending on whether
// the pointer came from the recording or from the middleman. This avoids
// accidentally conflating pointers that happen to have the same value but
// which originate from different processes.
static const void* MangleSystemValue(const void* aValue, bool aFromRecording) {
return (const void*)((size_t)aValue | (1ULL << (aFromRecording ? 63 : 62)));
}
void MM_SystemOutput(MiddlemanCallContext& aCx, const void** aOutput,
bool aUpdating) {
if (!*aOutput) {
if (aCx.mPhase == MiddlemanCallPhase::MiddlemanOutput) {
aCx.mCall->SetMiddlemanValue(*aOutput);
}
return;
}
switch (aCx.mPhase) {
case MiddlemanCallPhase::ReplayPreface:
if (!HasDivergedFromRecording()) {
// If we haven't diverged from the recording, use the output value saved
// in the recording.
if (!aUpdating) {
*aOutput = MangleSystemValue(*aOutput, true);
}
aCx.mCall->SetRecordingValue(*aOutput);
AddMiddlemanCallValue(*aOutput, aCx.mCall);
}
break;
case MiddlemanCallPhase::MiddlemanOutput:
aCx.mCall->SetMiddlemanValue(*aOutput);
AddMiddlemanCallValue(*aOutput, aCx.mCall);
break;
case MiddlemanCallPhase::ReplayOutput: {
if (!aUpdating) {
*aOutput = MangleSystemValue(*aOutput, false);
}
aCx.mCall->SetMiddlemanValue(*aOutput);
// Associate the value produced by the middleman with this call. If the
// call previously went through the ReplayPreface phase when we did not
// diverge from the recording, we will associate values from both the
// recording and middleman processes with this call. If a call made after
// diverging produced the same value as a call made before diverging, use
// the value saved in the recording for the first call, so that equality
// tests on the value work as expected.
MiddlemanCall* previousCall = LookupMiddlemanCall(*aOutput);
if (previousCall) {
if (previousCall->mRecordingValue.isSome()) {
*aOutput = previousCall->mRecordingValue.ref();
}
} else {
AddMiddlemanCallValue(*aOutput, aCx.mCall);
}
break;
}
default:
return;
}
}
///////////////////////////////////////////////////////////////////////////////
// MiddlemanCall
///////////////////////////////////////////////////////////////////////////////
void MiddlemanCall::EncodeInput(BufferStream& aStream) const {
aStream.WriteScalar(mId);
aStream.WriteScalar(mCallId);
aStream.WriteBytes(&mArguments, sizeof(CallRegisterArguments));
aStream.WriteScalar(mPreface.length());
aStream.WriteBytes(mPreface.begin(), mPreface.length());
aStream.WriteScalar(mInput.length());
aStream.WriteBytes(mInput.begin(), mInput.length());
}
void MiddlemanCall::DecodeInput(BufferStream& aStream) {
mId = aStream.ReadScalar();
mCallId = aStream.ReadScalar();
aStream.ReadBytes(&mArguments, sizeof(CallRegisterArguments));
size_t prefaceLength = aStream.ReadScalar();
mPreface.appendN(0, prefaceLength);
aStream.ReadBytes(mPreface.begin(), prefaceLength);
size_t inputLength = aStream.ReadScalar();
mInput.appendN(0, inputLength);
aStream.ReadBytes(mInput.begin(), inputLength);
}
void MiddlemanCall::EncodeOutput(BufferStream& aStream) const {
aStream.WriteBytes(&mArguments, sizeof(CallRegisterArguments));
aStream.WriteScalar(mOutput.length());
aStream.WriteBytes(mOutput.begin(), mOutput.length());
}
void MiddlemanCall::DecodeOutput(BufferStream& aStream) {
// Only update the return value when decoding arguments, so that we don't
// clobber the call's arguments with any changes made in the middleman.
CallRegisterArguments newArguments;
aStream.ReadBytes(&newArguments, sizeof(CallRegisterArguments));
mArguments.CopyRvalFrom(&newArguments);
size_t outputLength = aStream.ReadScalar();
mOutput.appendN(0, outputLength);
aStream.ReadBytes(mOutput.begin(), outputLength);
}
} // namespace recordreplay
} // namespace mozilla