1 files changed, 16 insertions, 4 deletions
diff --git a/toolkit/components/glean/bindings/private/TimingDistribution.cpp b/toolkit/components/glean/bindings/private/TimingDistribution.cpp
index 036db5f9db..7273d3fd2f 100644
--- a/toolkit/components/glean/bindings/private/TimingDistribution.cpp
+++ b/toolkit/components/glean/bindings/private/TimingDistribution.cpp
@@ -106,7 +106,7 @@ extern "C" NS_EXPORT void GIFFT_TimingDistributionStart(
     uint32_t aMetricId, mozilla::glean::TimerId aTimerId) {
   auto mirrorId = mozilla::glean::HistogramIdForMetric(aMetricId);
   if (mirrorId) {
-    mozilla::glean::GetTimerIdToStartsLock().apply([&](auto& lock) {
+    mozilla::glean::GetTimerIdToStartsLock().apply([&](const auto& lock) {
       auto tuple = mozilla::glean::MetricTimerTuple{aMetricId, aTimerId};
       // It should be all but impossible for anyone to have already inserted
       // this timer for this metric given the monotonicity of timer ids.
@@ -121,7 +121,7 @@ extern "C" NS_EXPORT void GIFFT_TimingDistributionStopAndAccumulate(
     uint32_t aMetricId, mozilla::glean::TimerId aTimerId) {
   auto mirrorId = mozilla::glean::HistogramIdForMetric(aMetricId);
   if (mirrorId) {
-    mozilla::glean::GetTimerIdToStartsLock().apply([&](auto& lock) {
+    mozilla::glean::GetTimerIdToStartsLock().apply([&](const auto& lock) {
       auto tuple = mozilla::glean::MetricTimerTuple{aMetricId, aTimerId};
       auto optStart = lock.ref()->Extract(tuple);
       // The timer might not be in the map to be removed if it's already been
@@ -147,7 +147,7 @@ extern "C" NS_EXPORT void GIFFT_TimingDistributionCancel(
     uint32_t aMetricId, mozilla::glean::TimerId aTimerId) {
   auto mirrorId = mozilla::glean::HistogramIdForMetric(aMetricId);
   if (mirrorId) {
-    mozilla::glean::GetTimerIdToStartsLock().apply([&](auto& lock) {
+    mozilla::glean::GetTimerIdToStartsLock().apply([&](const auto& lock) {
       // The timer might not be in the map to be removed if it's already been
       // cancelled or stop_and_accumulate'd.
       auto tuple = mozilla::glean::MetricTimerTuple{aMetricId, aTimerId};
@@ -172,8 +172,20 @@ void TimingDistributionMetric::StopAndAccumulate(const TimerId&& aId) const {
 // type.
 void TimingDistributionMetric::AccumulateRawDuration(
     const TimeDuration& aDuration) const {
+  // `* 1000.0` is an acceptable overflow risk as durations are unlikely to be
+  // on the order of (-)10^282 years.
+  double durationNs = aDuration.ToMicroseconds() * 1000.0;
+  double roundedDurationNs = std::round(durationNs);
+  if (MOZ_UNLIKELY(
+          roundedDurationNs <
+              static_cast<double>(std::numeric_limits<uint64_t>::min()) ||
+          roundedDurationNs >
+              static_cast<double>(std::numeric_limits<uint64_t>::max()))) {
+    // TODO(bug 1691073): Instrument this error.
+    return;
+  }
   fog_timing_distribution_accumulate_raw_nanos(
-      mId, uint64_t(aDuration.ToMicroseconds() * 1000.00));
+      mId, static_cast<uint64_t>(roundedDurationNs));
 }
 
 void TimingDistributionMetric::Cancel(const TimerId&& aId) const {