1 files changed, 152 insertions, 0 deletions
diff --git a/ipc/glue/IdleSchedulerChild.cpp b/ipc/glue/IdleSchedulerChild.cpp
new file mode 100644
index 0000000000..bd05f0958a
--- /dev/null
+++ b/ipc/glue/IdleSchedulerChild.cpp
@@ -0,0 +1,152 @@
+/* -*- 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/. */
+
+#include "mozilla/ipc/IdleSchedulerChild.h"
+#include "mozilla/ipc/IdleSchedulerParent.h"
+#include "mozilla/ipc/PBackgroundChild.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/IdlePeriodState.h"
+#include "mozilla/Telemetry.h"
+#include "BackgroundChild.h"
+
+namespace mozilla::ipc {
+
+static IdleSchedulerChild* sMainThreadIdleScheduler = nullptr;
+static bool sIdleSchedulerDestroyed = false;
+
+IdleSchedulerChild::~IdleSchedulerChild() {
+  if (sMainThreadIdleScheduler == this) {
+    sMainThreadIdleScheduler = nullptr;
+    sIdleSchedulerDestroyed = true;
+  }
+  MOZ_ASSERT(!mIdlePeriodState);
+}
+
+void IdleSchedulerChild::Init(IdlePeriodState* aIdlePeriodState) {
+  mIdlePeriodState = aIdlePeriodState;
+
+  RefPtr<IdleSchedulerChild> scheduler = this;
+  auto resolve =
+      [&](std::tuple<mozilla::Maybe<SharedMemoryHandle>, uint32_t>&& aResult) {
+        if (std::get<0>(aResult)) {
+          mActiveCounter.SetHandle(std::move(*std::get<0>(aResult)), false);
+          mActiveCounter.Map(sizeof(int32_t));
+          mChildId = std::get<1>(aResult);
+          if (mChildId && mIdlePeriodState && mIdlePeriodState->IsActive()) {
+            SetActive();
+          }
+        }
+      };
+
+  auto reject = [&](ResponseRejectReason) {};
+  SendInitForIdleUse(std::move(resolve), std::move(reject));
+}
+
+IPCResult IdleSchedulerChild::RecvIdleTime(uint64_t aId, TimeDuration aBudget) {
+  if (mIdlePeriodState) {
+    mIdlePeriodState->SetIdleToken(aId, aBudget);
+  }
+  return IPC_OK();
+}
+
+void IdleSchedulerChild::SetActive() {
+  if (mChildId && CanSend() && mActiveCounter.memory()) {
+    ++(static_cast<Atomic<int32_t>*>(
+        mActiveCounter.memory())[NS_IDLE_SCHEDULER_INDEX_OF_ACTIVITY_COUNTER]);
+    ++(static_cast<Atomic<int32_t>*>(mActiveCounter.memory())[mChildId]);
+  }
+}
+
+bool IdleSchedulerChild::SetPaused() {
+  if (mChildId && CanSend() && mActiveCounter.memory()) {
+    --(static_cast<Atomic<int32_t>*>(mActiveCounter.memory())[mChildId]);
+    // The following expression reduces the global activity count and checks if
+    // it drops below the cpu counter limit.
+    return (static_cast<Atomic<int32_t>*>(
+               mActiveCounter
+                   .memory())[NS_IDLE_SCHEDULER_INDEX_OF_ACTIVITY_COUNTER])-- ==
+           static_cast<Atomic<int32_t>*>(
+               mActiveCounter.memory())[NS_IDLE_SCHEDULER_INDEX_OF_CPU_COUNTER];
+  }
+
+  return false;
+}
+
+RefPtr<IdleSchedulerChild::MayGCPromise> IdleSchedulerChild::MayGCNow() {
+  if (mIsRequestingGC || mIsDoingGC) {
+    return MayGCPromise::CreateAndResolve(false, __func__);
+  }
+  TimeStamp wait_since = TimeStamp::Now();
+
+  mIsRequestingGC = true;
+  return SendRequestGC()->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [self = RefPtr(this), wait_since](bool aIgnored) {
+        // Only one of these may be true at a time.
+        MOZ_ASSERT(!(self->mIsRequestingGC && self->mIsDoingGC));
+
+        // The parent process always says yes, sometimes after a delay.
+        if (self->mIsRequestingGC) {
+          Telemetry::AccumulateTimeDelta(Telemetry::GC_WAIT_FOR_IDLE_MS,
+                                         wait_since);
+          self->mIsRequestingGC = false;
+          self->mIsDoingGC = true;
+          return MayGCPromise::CreateAndResolve(true, __func__);
+        }
+        return MayGCPromise::CreateAndResolve(false, __func__);
+      },
+      [self = RefPtr(this)](ResponseRejectReason reason) {
+        self->mIsRequestingGC = false;
+        return MayGCPromise::CreateAndReject(reason, __func__);
+      });
+}
+
+void IdleSchedulerChild::StartedGC() {
+  // Only one of these may be true at a time.
+  MOZ_ASSERT(!(mIsRequestingGC && mIsDoingGC));
+
+  // If mRequestingGC was true then when the outstanding GC request returns
+  // it'll see that the GC has already started.
+  mIsRequestingGC = false;
+
+  if (!mIsDoingGC) {
+    if (CanSend()) {
+      SendStartedGC();
+    }
+    mIsDoingGC = true;
+  }
+}
+
+void IdleSchedulerChild::DoneGC() {
+  if (mIsDoingGC) {
+    if (CanSend()) {
+      SendDoneGC();
+    }
+    mIsDoingGC = false;
+  }
+}
+
+IdleSchedulerChild* IdleSchedulerChild::GetMainThreadIdleScheduler() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (sMainThreadIdleScheduler) {
+    return sMainThreadIdleScheduler;
+  }
+
+  if (sIdleSchedulerDestroyed) {
+    return nullptr;
+  }
+
+  ipc::PBackgroundChild* background =
+      ipc::BackgroundChild::GetOrCreateForCurrentThread();
+  if (background) {
+    sMainThreadIdleScheduler = new ipc::IdleSchedulerChild();
+    background->SendPIdleSchedulerConstructor(sMainThreadIdleScheduler);
+  }
+  return sMainThreadIdleScheduler;
+}
+
+}  // namespace mozilla::ipc