Bug 1615921 - Suspend late write checks in Windows vprintf_stderr r=froydnj

Differential Revision: https://phabricator.services.mozilla.com/D63216

--HG--
extra : moz-landing-system : lando

xpcom/base/Logging.cpp

@@ -10,6 +10,7 @@
 
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/FileUtils.h"
+#include "mozilla/LateWriteChecks.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/StaticPtr.h"
 #include "mozilla/Printf.h"
@@ -390,6 +391,7 @@ class LogModuleManager {
 
   void Print(const char* aName, LogLevel aLevel, const TimeStamp* aStart,
              const char* aFmt, va_list aArgs) MOZ_FORMAT_PRINTF(5, 0) {
+    AutoSuspendLateWriteChecks suspendLateWriteChecks;
     long pid = static_cast<long>(base::GetCurrentProcId());
     const size_t kBuffSize = 1024;
     char buff[kBuffSize];

xpcom/base/nsCRTGlue.cpp

@@ -19,6 +19,7 @@
 #ifdef XP_WIN
 #  include <io.h>
 #  include <windows.h>
+#  include "mozilla/LateWriteChecks.h"
 #  include "mozilla/UniquePtr.h"
 #endif
 
@@ -259,6 +260,7 @@ void vprintf_stderr(const char* aFmt, va_list aArgs) {
 
   vfprintf(fp, aFmt, aArgs);
 
+  AutoSuspendLateWriteChecks suspend;
   fclose(fp);
 }
 

xpcom/build/LateWriteChecks.cpp

@@ -38,6 +38,15 @@
 
 /*************************** Auxiliary Declarations ***************************/
 
+static MOZ_THREAD_LOCAL(int) tlsSuspendLateWriteChecks;
+
+bool SuspendingLateWriteChecksForCurrentThread() {
+  if (!tlsSuspendLateWriteChecks.init()) {
+    return true;
+  }
+  return tlsSuspendLateWriteChecks.get() > 0;
+}
+
 // This a wrapper over a file descriptor that provides a Printf method and
 // computes the sha1 of the data that passes through it.
 class SHA1Stream {
@@ -103,6 +112,10 @@ class LateWriteObserver final : public mozilla::IOInterposeObserver {
 
 void LateWriteObserver::Observe(
     mozilla::IOInterposeObserver::Observation& aOb) {
+  if (SuspendingLateWriteChecksForCurrentThread()) {
+    return;
+  }
+
 #ifdef DEBUG
   MOZ_CRASH();
 #endif
@@ -233,4 +246,20 @@ void StopLateWriteChecks() {
   }
 }
 
+void PushSuspendLateWriteChecks() {
+  if (!tlsSuspendLateWriteChecks.init()) {
+    return;
+  }
+  tlsSuspendLateWriteChecks.set(tlsSuspendLateWriteChecks.get() + 1);
+}
+
+void PopSuspendLateWriteChecks() {
+  if (!tlsSuspendLateWriteChecks.init()) {
+    return;
+  }
+  int current = tlsSuspendLateWriteChecks.get();
+  MOZ_ASSERT(current > 0);
+  tlsSuspendLateWriteChecks.set(current - 1);
+}
+
 }  // namespace mozilla

xpcom/build/LateWriteChecks.h

@@ -54,6 +54,25 @@ void BeginLateWriteChecks();
  */
 void StopLateWriteChecks();
 
+/**
+ * Temporarily suspend late write checks for the current thread. This is useful
+ * if you're about to perform a write, but it would be fine if this write were
+ * interrupted or skipped during a fast shutdown.
+ */
+void PushSuspendLateWriteChecks();
+
+/**
+ * Resume late write checks for the current thread, assuming an ancestor in the
+ * call stack hasn't also pushed a suspension.
+ */
+void PopSuspendLateWriteChecks();
+
+class MOZ_RAII AutoSuspendLateWriteChecks {
+ public:
+  AutoSuspendLateWriteChecks() { PushSuspendLateWriteChecks(); }
+  ~AutoSuspendLateWriteChecks() { PopSuspendLateWriteChecks(); }
+};
+
 }  // namespace mozilla
 
 #endif  // mozilla_LateWriteChecks_h