1 files changed, 89 insertions, 0 deletions
diff --git a/xpcom/base/PHCManager.cpp b/xpcom/base/PHCManager.cpp
new file mode 100644
index 0000000000..f8124312f5
--- /dev/null
+++ b/xpcom/base/PHCManager.cpp
@@ -0,0 +1,89 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+
+#include "PHCManager.h"
+
+#include "PHC.h"
+#include "mozilla/Literals.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs_memory.h"
+#include "mozilla/Telemetry.h"
+#include "prsystem.h"
+
+namespace mozilla {
+
+using namespace phc;
+
+static const char kPHCEnabledPref[] = "memory.phc.enabled";
+static const char kPHCMinRamMBPref[] = "memory.phc.min_ram_mb";
+static const char kPHCAvgDelayFirst[] = "memory.phc.avg_delay.first";
+static const char kPHCAvgDelayNormal[] = "memory.phc.avg_delay.normal";
+static const char kPHCAvgDelayPageRuse[] = "memory.phc.avg_delay.page_reuse";
+
+// True if PHC has ever been enabled for this process.
+static bool sWasPHCEnabled = false;
+
+static void UpdatePHCState() {
+  size_t mem_size = PR_GetPhysicalMemorySize() / (1_MiB);
+  size_t min_mem_size = StaticPrefs::memory_phc_min_ram_mb();
+
+  // Only enable PHC if there are at least 8GB of ram.  Note that we use
+  // 1000 bytes per kilobyte rather than 1024.  Some 8GB machines will have
+  // slightly lower actual RAM available after some hardware devices
+  // reserve some.
+  if (StaticPrefs::memory_phc_enabled() && mem_size >= min_mem_size) {
+    // Set PHC probablities before enabling PHC so that the first allocation
+    // delay gets used.
+    SetPHCProbabilities(StaticPrefs::memory_phc_avg_delay_first(),
+                        StaticPrefs::memory_phc_avg_delay_normal(),
+                        StaticPrefs::memory_phc_avg_delay_page_reuse());
+
+    SetPHCState(Enabled);
+    sWasPHCEnabled = true;
+  } else {
+    SetPHCState(OnlyFree);
+  }
+}
+
+static void PrefChangeCallback(const char* aPrefName, void* aNull) {
+  MOZ_ASSERT((0 == strcmp(aPrefName, kPHCEnabledPref)) ||
+             (0 == strcmp(aPrefName, kPHCMinRamMBPref)) ||
+             (0 == strcmp(aPrefName, kPHCAvgDelayFirst)) ||
+             (0 == strcmp(aPrefName, kPHCAvgDelayNormal)) ||
+             (0 == strcmp(aPrefName, kPHCAvgDelayPageRuse)));
+
+  UpdatePHCState();
+}
+
+void InitPHCState() {
+  Preferences::RegisterCallback(PrefChangeCallback, kPHCEnabledPref);
+  Preferences::RegisterCallback(PrefChangeCallback, kPHCMinRamMBPref);
+  Preferences::RegisterCallback(PrefChangeCallback, kPHCAvgDelayFirst);
+  Preferences::RegisterCallback(PrefChangeCallback, kPHCAvgDelayNormal);
+  Preferences::RegisterCallback(PrefChangeCallback, kPHCAvgDelayPageRuse);
+  UpdatePHCState();
+}
+
+void ReportPHCTelemetry() {
+  if (!sWasPHCEnabled) {
+    return;
+  }
+
+  MemoryUsage usage;
+  PHCMemoryUsage(usage);
+
+  Accumulate(Telemetry::MEMORY_PHC_SLOP, usage.mFragmentationBytes);
+
+  PHCStats stats;
+  GetPHCStats(stats);
+
+  Accumulate(Telemetry::MEMORY_PHC_SLOTS_ALLOCATED, stats.mSlotsAllocated);
+  Accumulate(Telemetry::MEMORY_PHC_SLOTS_FREED, stats.mSlotsFreed);
+  // There are also slots that are unused (neither free nor allocated) they
+  // can be calculated by knowing the total number of slots.
+}
+
+};  // namespace mozilla