1 files changed, 154 insertions, 0 deletions
diff --git a/mozglue/misc/TimeStamp.cpp b/mozglue/misc/TimeStamp.cpp
new file mode 100644
index 0000000000..0c02413e98
--- /dev/null
+++ b/mozglue/misc/TimeStamp.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/. */
+
+/*
+ * Implementation of the OS-independent methods of the TimeStamp class
+ */
+
+#include "mozilla/Atomics.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/Uptime.h"
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+namespace mozilla {
+
+/**
+ * Wrapper class used to initialize static data used by the TimeStamp class
+ */
+struct TimeStampInitialization {
+  /**
+   * First timestamp taken when the class static initializers are run. This
+   * timestamp is used to sanitize timestamps coming from different sources.
+   */
+  TimeStamp mFirstTimeStamp;
+
+  /**
+   * Timestamp representing the time when the process was created. This field
+   * is populated lazily the first time this information is required and is
+   * replaced every time the process is restarted.
+   */
+  TimeStamp mProcessCreation;
+
+  TimeStampInitialization() {
+    TimeStamp::Startup();
+    mFirstTimeStamp = TimeStamp::Now();
+    // On Windows < 10, initializing the uptime requires `mFirstTimeStamp` to be
+    // valid.
+    mozilla::InitializeUptime();
+  };
+
+  ~TimeStampInitialization() { TimeStamp::Shutdown(); };
+};
+
+static bool sFuzzyfoxEnabled;
+
+/* static */
+bool TimeStamp::GetFuzzyfoxEnabled() { return sFuzzyfoxEnabled; }
+
+/* static */
+void TimeStamp::SetFuzzyfoxEnabled(bool aValue) { sFuzzyfoxEnabled = aValue; }
+
+// These variables store the frozen time (as a TimeStamp) for FuzzyFox that
+// will be reported if FuzzyFox is enabled.
+// We overload the top bit of sCanonicalNow and sCanonicalGTC to
+// indicate if a Timestamp is a fuzzed timestamp (bit set) or not
+// (bit unset).
+#ifdef XP_WIN
+static Atomic<uint64_t> sCanonicalGTC;
+static Atomic<uint64_t> sCanonicalQPC;
+static Atomic<bool> sCanonicalHasQPC;
+#else
+static Atomic<uint64_t> sCanonicalNowTimeStamp;
+#endif
+static Atomic<int64_t> sCanonicalNowTime;
+// This variable stores the frozen time (as ms since the epoch) for FuzzyFox
+// to report if FuzzyFox is enabled.
+static TimeStampInitialization sInitOnce;
+
+MFBT_API TimeStamp TimeStamp::ProcessCreation(bool* aIsInconsistent) {
+  if (aIsInconsistent) {
+    *aIsInconsistent = false;
+  }
+
+  if (sInitOnce.mProcessCreation.IsNull()) {
+    char* mozAppRestart = getenv("MOZ_APP_RESTART");
+    TimeStamp ts;
+
+    /* When calling PR_SetEnv() with an empty value the existing variable may
+     * be unset or set to the empty string depending on the underlying platform
+     * thus we have to check if the variable is present and not empty. */
+    if (mozAppRestart && (strcmp(mozAppRestart, "") != 0)) {
+      /* Firefox was restarted, use the first time-stamp we've taken as the new
+       * process startup time. */
+      ts = sInitOnce.mFirstTimeStamp;
+    } else {
+      TimeStamp now = Now();
+      uint64_t uptime = ComputeProcessUptime();
+
+      ts = now - TimeDuration::FromMicroseconds(uptime);
+
+      if ((ts > sInitOnce.mFirstTimeStamp) || (uptime == 0)) {
+        /* If the process creation timestamp was inconsistent replace it with
+         * the first one instead and notify that a telemetry error was
+         * detected. */
+        if (aIsInconsistent) {
+          *aIsInconsistent = true;
+        }
+        ts = sInitOnce.mFirstTimeStamp;
+      }
+    }
+
+    sInitOnce.mProcessCreation = ts;
+  }
+
+  return sInitOnce.mProcessCreation;
+}
+
+void TimeStamp::RecordProcessRestart() {
+  sInitOnce.mProcessCreation = TimeStamp();
+}
+
+MFBT_API TimeStamp TimeStamp::NowFuzzy(TimeStampValue aValue) {
+#ifdef XP_WIN
+  TimeStampValue canonicalNow =
+      TimeStampValue(sCanonicalGTC, sCanonicalQPC, sCanonicalHasQPC, true);
+#else
+  TimeStampValue canonicalNow = TimeStampValue(sCanonicalNowTimeStamp);
+#endif
+
+  if (TimeStamp::GetFuzzyfoxEnabled()) {
+    if (MOZ_LIKELY(!canonicalNow.IsNull())) {
+      return TimeStamp(canonicalNow);
+    }
+  }
+  // When we disable Fuzzyfox, time may goes backwards, so we need to make sure
+  // we don't do that.
+  else if (MOZ_UNLIKELY(canonicalNow > aValue)) {
+    return TimeStamp(canonicalNow);
+  }
+
+  return TimeStamp(aValue);
+}
+
+MFBT_API void TimeStamp::UpdateFuzzyTimeStamp(TimeStamp aValue) {
+#ifdef XP_WIN
+  sCanonicalGTC = aValue.mValue.mGTC;
+  sCanonicalQPC = aValue.mValue.mQPC;
+  sCanonicalHasQPC = aValue.mValue.mHasQPC;
+#else
+  sCanonicalNowTimeStamp = aValue.mValue.mTimeStamp;
+#endif
+}
+
+MFBT_API int64_t TimeStamp::NowFuzzyTime() { return sCanonicalNowTime; }
+
+MFBT_API void TimeStamp::UpdateFuzzyTime(int64_t aValue) {
+  sCanonicalNowTime = aValue;
+}
+
+}  // namespace mozilla