1 files changed, 109 insertions, 0 deletions
diff --git a/toolkit/components/glean/bindings/private/TimingDistribution.h b/toolkit/components/glean/bindings/private/TimingDistribution.h
new file mode 100644
index 0000000000..7c2e69d89e
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+++ b/toolkit/components/glean/bindings/private/TimingDistribution.h
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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/. */
+
+#ifndef mozilla_glean_GleanTimingDistribution_h
+#define mozilla_glean_GleanTimingDistribution_h
+
+#include "mozilla/glean/bindings/DistributionData.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/Result.h"
+#include "mozilla/TimeStamp.h"
+#include "nsIGleanMetrics.h"
+#include "nsTArray.h"
+
+namespace mozilla::glean {
+
+typedef uint64_t TimerId;
+
+namespace impl {
+class TimingDistributionMetric {
+ public:
+  constexpr explicit TimingDistributionMetric(uint32_t aId) : mId(aId) {}
+
+  /*
+   * Starts tracking time for the provided metric.
+   *
+   * @returns A unique TimerId for the new timer
+   */
+  TimerId Start() const;
+
+  /*
+   * Stops tracking time for the provided metric and associated timer id.
+   *
+   * Adds a count to the corresponding bucket in the timing distribution.
+   * This will record an error if no `Start` was called on this TimerId or
+   * if this TimerId was used to call `Cancel`.
+   *
+   * @param aId The TimerId to associate with this timing. This allows for
+   *            concurrent timing of events associated with different ids.
+   */
+  void StopAndAccumulate(const TimerId&& aId) const;
+
+  /*
+   * Adds a duration sample to a timing distribution metric.
+   *
+   * Adds a count to the corresponding bucket in the timing distribution.
+   * Prefer Start() and StopAndAccumulate() where possible.
+   * Users of this API are responsible for ensuring the timing source used
+   * to calculate the TimeDuration is monotonic and consistent accross
+   * platforms.
+   *
+   * NOTE: Negative durations are not handled and will saturate to INT64_MAX
+   *       nanoseconds.
+   *
+   * @param aDuration The duration of the sample to add to the distribution.
+   */
+  void AccumulateRawDuration(const TimeDuration& aDuration) const;
+
+  /*
+   * Aborts a previous `Start` call. No error is recorded if no `Start` was
+   * called.
+   *
+   * @param aId The TimerId whose `Start` you wish to abort.
+   */
+  void Cancel(const TimerId&& aId) const;
+
+  /**
+   * **Test-only API**
+   *
+   * Gets the currently stored value as a DistributionData.
+   *
+   * This function will attempt to await the last parent-process task (if any)
+   * writing to the the metric's storage engine before returning a value.
+   * This function will not wait for data from child processes.
+   *
+   * This doesn't clear the stored value.
+   * Parent process only. Panics in child processes.
+   *
+   * @param aPingName The (optional) name of the ping to retrieve the metric
+   *        for. Defaults to the first value in `send_in_pings`.
+   *
+   * @return value of the stored metric, or Nothing() if there is no value.
+   */
+  Result<Maybe<DistributionData>, nsCString> TestGetValue(
+      const nsACString& aPingName = nsCString()) const;
+
+ private:
+  const uint32_t mId;
+};
+}  // namespace impl
+
+class GleanTimingDistribution final : public nsIGleanTimingDistribution {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIGLEANTIMINGDISTRIBUTION
+
+  explicit GleanTimingDistribution(uint64_t aId) : mTimingDist(aId){};
+
+ private:
+  virtual ~GleanTimingDistribution() = default;
+
+  const impl::TimingDistributionMetric mTimingDist;
+};
+
+}  // namespace mozilla::glean
+
+#endif /* mozilla_glean_GleanTimingDistribution_h */