Clear shader disk cache after glProgramBinary failure.

gpu/ipc/common/activity_flags.cc

+// Copyright (c) 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "gpu/ipc/common/activity_flags.h"
+
+#include "base/memory/singleton.h"
+
+namespace gpu {
+
+ActivityFlagsBase::ActivityFlagsBase() = default;
+
+ActivityFlagsBase::~ActivityFlagsBase() = default;
+
+void ActivityFlagsBase::Initialize(mojo::ScopedSharedBufferHandle handle) {
+  handle_ = std::move(handle);
+  mapping_ = handle_->Map(sizeof(Flag));
+}
+
+volatile base::subtle::Atomic32* ActivityFlagsBase::AsAtomic() {
+  return reinterpret_cast<volatile base::subtle::Atomic32*>(mapping_.get());
+}
+
+GpuProcessActivityFlags* GpuProcessActivityFlags::GetInstance() {
+  return base::Singleton<GpuProcessActivityFlags>::get();
+}
+
+void GpuProcessActivityFlags::InitializeInstance(
+    mojo::ScopedSharedBufferHandle handle) {
+  // In cases where we are running without a GpuProcessHost, we may not
+  // have a valid handle. In this case, just return.
+  if (!handle.is_valid())
+    return;
+
+  GetInstance()->Initialize(std::move(handle));
+}
+
+void GpuProcessActivityFlags::SetFlag(Flag flag) {
+  // In cases where we are running without a GpuProcessHost, we may not
+  // initialize the GpuProcessActivityFlags. In this case, just return.
+  if (!is_initialized())
+    return;
+
+  base::subtle::Atomic32 old_value = base::subtle::NoBarrier_Load(AsAtomic());
+  base::subtle::Atomic32 new_value = old_value | flag;
+
+  // These flags are *only* written by a single process, and should only be
+  // written from the main GPU thread. We should never double-set them.
+  DCHECK_NE(old_value, new_value);
+  base::subtle::Acquire_Store(AsAtomic(), new_value);
+}
+
+void GpuProcessActivityFlags::UnsetFlag(Flag flag) {
+  // In cases where we are running without a GpuProcessHost, we may not
+  // initialize the GpuProcessActivityFlags. In this case, just return.
+  if (!is_initialized())
+    return;
+
+  // These flags are *only* written by a single process, and should only be
+  // written from the main GPU thread. No need to check for failure.
+  base::subtle::Atomic32 old_value = base::subtle::NoBarrier_Load(AsAtomic());
+  base::subtle::Atomic32 new_value = old_value ^ flag;
+
+  // These flags are *only* written by a single process, and should only be
+  // written from the main GPU thread. We should never double-unset them.
+  DCHECK_NE(old_value, new_value);

[vmiura, 2017/03/13 20:18:36]

This doesn't really check anything since x ^ flag always toggles the flag.

If you want to check for double-unset, check the old_value has 'flag' set.

[ericrk, 2017/03/13 20:30:45]

Yup, good point.

+  base::subtle::Release_Store(AsAtomic(), new_value);
+}
+
+GpuProcessHostActivityFlags::GpuProcessHostActivityFlags() {
+  Initialize(mojo::SharedBufferHandle::Create(sizeof(Flag)));
+}
+
+bool GpuProcessHostActivityFlags::IsFlagSet(Flag flag) {
+  DCHECK(is_initialized());
+  return !!(base::subtle::Acquire_Load(AsAtomic()) & flag);
+}
+
+}  // namespace gpu