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Bug 1408086 - Append log of the latest 2 sets of composition events when ContentCacheInParent::OnEventNeedingAckHandled() meets unexpected state and crash itself r=m_kato

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We have a lot of crash reports in OnEventNeedingAckHandled() due to unexpected
state (hit MOZ_RELEASE_ASSERT). However, it's unclear what occurs and we're not
sure there are how many cases to crash because the stack trace is too short
because the method is called when TabParent receives event handled message from
the remote process. I.e., it doesn't show what happens immediately before the
crash.

This patch puts 2 sets of composition events to app notes of crash report when
it needs to crash.  This *might* make damage to the performance.  If so, after
fixing the crashes, we should back this out.  Fortunately, we have a lot of
reports from either Nightly or Beta.

MozReview-Commit-ID: 9tDrEIf72MG

--HG--
extra : rebase_source : 523c183466740e08d6c8cc3836b6b52310c1e53a
This commit is contained in:
Masayuki Nakano 2017-10-13 02:50:47 +09:00
parent 7d84c84a7a
commit 929e66153e
2 changed files with 117 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

100
widget/ContentCache.cpp
View File

@ -15,6 +15,9 @@
#include "mozilla/TextComposition.h"
#include "mozilla/TextEvents.h"
#include "mozilla/dom/TabParent.h"
#ifdef MOZ_CRASHREPORTER
#include "nsExceptionHandler.h"
#endif // #ifdef MOZ_CRASHREPORTER
#include "nsIWidget.h"
namespace mozilla {
@ -1110,6 +1113,10 @@ ContentCacheInParent::OnCompositionEvent(const WidgetCompositionEvent& aEvent)
GetBoolName(mWidgetHasComposition), mPendingCompositionCount,
mCommitStringByRequest));
#ifdef MOZ_CRASHREPORTER
mDispatchedEventMessages.AppendElement(aEvent.mMessage);
#endif // #ifdef MOZ_CRASHREPORTER
// We must be able to simulate the selection because
// we might not receive selection updates in time
if (!mWidgetHasComposition) {
@ -1186,6 +1193,10 @@ ContentCacheInParent::OnSelectionEvent(
GetBoolName(aSelectionEvent.mUseNativeLineBreak), mPendingEventsNeedingAck,
GetBoolName(mWidgetHasComposition), mPendingCompositionCount));
#ifdef MOZ_CRASHREPORTER
mDispatchedEventMessages.AppendElement(aSelectionEvent.mMessage);
#endif // #ifdef MOZ_CRASHREPORTER
mPendingEventsNeedingAck++;
}
@ -1201,9 +1212,30 @@ ContentCacheInParent::OnEventNeedingAckHandled(nsIWidget* aWidget,
"aMessage=%s), mPendingEventsNeedingAck=%u, mPendingCompositionCount=%" PRIu8,
this, aWidget, ToChar(aMessage), mPendingEventsNeedingAck, mPendingCompositionCount));
#ifdef MOZ_CRASHREPORTER
mReceivedEventMessages.AppendElement(aMessage);
#endif // #ifdef MOZ_CRASHREPORTER
if (WidgetCompositionEvent::IsFollowedByCompositionEnd(aMessage) ||
aMessage == eCompositionCommitRequestHandled) {
MOZ_RELEASE_ASSERT(mPendingCompositionCount > 0);
#ifdef MOZ_CRASHREPORTER
if (mPendingCompositionCount == 1) {
RemoveUnnecessaryEventMessageLog();
}
#endif // #ifdef MOZ_CRASHREPORTER
if (NS_WARN_IF(!mPendingCompositionCount)) {
#ifdef MOZ_CRASHREPORTER
nsPrintfCString info("There is no pending composition but received %s "
"message from the remote child\n\n",
ToChar(aMessage));
AppendEventMessageLog(info);
CrashReporter::AppendAppNotesToCrashReport(info);
#endif // #ifdef MOZ_CRASHREPORTER
MOZ_CRASH("No pending composition but received unexpected commit event");
}
mPendingCompositionCount--;
// Forget composition string only when the latest composition string is
// handled in the remote process because if there is 2 or more pending
@ -1219,7 +1251,16 @@ ContentCacheInParent::OnEventNeedingAckHandled(nsIWidget* aWidget,
mPendingCommitLength = 0;
}
MOZ_RELEASE_ASSERT(mPendingEventsNeedingAck > 0);
if (NS_WARN_IF(!mPendingEventsNeedingAck)) {
#ifdef MOZ_CRASHREPORTER
nsPrintfCString info("There is no pending events but received %s "
"message from the remote child\n\n",
ToChar(aMessage));
AppendEventMessageLog(info);
CrashReporter::AppendAppNotesToCrashReport(info);
#endif // #ifdef MOZ_CRASHREPORTER
MOZ_CRASH("No pending event message but received unexpected event");
}
if (--mPendingEventsNeedingAck) {
return;
}
@ -1409,6 +1450,61 @@ ContentCacheInParent::FlushPendingNotifications(nsIWidget* aWidget)
}
}
#ifdef MOZ_CRASHREPORTER
void
ContentCacheInParent::RemoveUnnecessaryEventMessageLog()
{
bool foundLastCompositionStart = false;
for (size_t i = mDispatchedEventMessages.Length(); i > 1; i--) {
if (mDispatchedEventMessages[i - 1] != eCompositionStart) {
continue;
}
if (!foundLastCompositionStart) {
// Find previous eCompositionStart of the latest eCompositionStart.
foundLastCompositionStart = true;
continue;
}
// Remove the messages before the last 2 sets of composition events.
mDispatchedEventMessages.RemoveElementsAt(0, i - 1);
break;
}
foundLastCompositionStart = false;
for (size_t i = mReceivedEventMessages.Length(); i > 1; i--) {
if (mReceivedEventMessages[i - 1] != eCompositionStart) {
continue;
}
if (!foundLastCompositionStart) {
// Find previous eCompositionStart of the latest eCompositionStart.
foundLastCompositionStart = true;
continue;
}
// Remove the messages before the last 2 sets of composition events.
mReceivedEventMessages.RemoveElementsAt(0, i - 1);
break;
}
}
void
ContentCacheInParent::AppendEventMessageLog(nsACString& aLog) const
{
aLog.AppendLiteral("Dispatched Event Message Log:\n");
for (EventMessage message : mDispatchedEventMessages) {
aLog.AppendLiteral(" ");
aLog.Append(ToChar(message));
aLog.AppendLiteral("\n");
}
aLog.AppendLiteral("\nReceived Event Message Log:\n");
for (EventMessage message : mReceivedEventMessages) {
aLog.AppendLiteral(" ");
aLog.Append(ToChar(message));
aLog.AppendLiteral("\n");
}
aLog.AppendLiteral("\n");
}
#endif // #ifdef MOZ_CRASHREPORTER
/*****************************************************************************
* mozilla::ContentCache::TextRectArray
*****************************************************************************/

19
widget/ContentCache.h
View File

@ -410,6 +410,12 @@ private:
IMENotification mPendingLayoutChange;
IMENotification mPendingCompositionUpdate;
#ifdef MOZ_CRASHREPORTER
// Log of event messages to be output to crash report.
nsTArray<EventMessage> mDispatchedEventMessages;
nsTArray<EventMessage> mReceivedEventMessages;
#endif // #ifdef MOZ_CRASHREPORTER
// mTabParent is owner of the instance.
dom::TabParent& MOZ_NON_OWNING_REF mTabParent;
// mCompositionString is composition string which were sent to the remote
@ -464,6 +470,19 @@ private:
LayoutDeviceIntRect& aUnionTextRect) const;
void FlushPendingNotifications(nsIWidget* aWidget);
#ifdef MOZ_CRASHREPORTER
/**
* Remove unnecessary messages from mDispatchedEventMessages and
* mReceivedEventMessages.
*/
void RemoveUnnecessaryEventMessageLog();
/**
* Append event message log to aLog.
*/
void AppendEventMessageLog(nsACString& aLog) const;
#endif // #ifdef MOZ_CRASHREPORTER
};
} // namespace mozilla