Framelet Prototype 2016 using Mojo IPC

components/framelet/browser/resource_usage_reporter.h

+// Copyright 2015 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.
+
+#ifndef COMPONENTS_FRAMELET_BROWSER_RESOURCE_USAGE_REPORTER_H_
+#define COMPONENTS_FRAMELET_BROWSER_RESOURCE_USAGE_REPORTER_H_
+
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/framelet/browser/resource_usage_range.h"
+
+namespace framelet {
+
+template <class T>
+class ResourceUsageReporterClient;
+
+enum class ResourceUsageLevel : int {
+  LOW = 0,
+  MEDIUM,
+  HIGH,
+  CRITICAL,
+  MAX_VALUE
+};
+
+template <class T>
+class ResourceUsageReporter {
+ public:
+  explicit ResourceUsageReporter(ResourceUsageReporterClient<T>* client)
+      : client_(client), last_reported_usage_level_(ResourceUsageLevel::LOW) {
+    for (int usage_level = static_cast<int>(ResourceUsageLevel::LOW);
+         usage_level < static_cast<int>(ResourceUsageLevel::MAX_VALUE);
+         ++usage_level) {
+      usage_levels_[usage_level] = std::move(client_->GetRangeForUsageLevel(
+          static_cast<ResourceUsageLevel>(usage_level)));
+    }
+  }
+
+  ~ResourceUsageReporter() {}
+
+  void ReportUsage(T usage) {
+    int usage_level = static_cast<int>(last_reported_usage_level_);
+    // TODO(fsamuel): This could be an infinite loop if the ranges are not
+    // monotonically increasing in high value and low value.
+    while (!usage_levels_[usage_level]->Contains(usage)) {
+      if (usage_levels_[usage_level]->IsLowerThan(usage)) {
+        ++usage_level;
+      } else {
+        --usage_level;
+      }
+    }
+    if (static_cast<int>(last_reported_usage_level_) != usage_level) {
+      last_reported_usage_level_ = static_cast<ResourceUsageLevel>(usage_level);
+      client_->OnResourceUsageLevelChanged(last_reported_usage_level_);
+    }
+  }
+
+ private:
+  ResourceUsageReporterClient<T>* const client_;
+  scoped_ptr<ResourceUsageRange<T>>
+      usage_levels_[static_cast<int>(ResourceUsageLevel::MAX_VALUE)];
+  ResourceUsageLevel last_reported_usage_level_;
+
+  DISALLOW_COPY_AND_ASSIGN(ResourceUsageReporter);
+};
+
+}  // namespace framelet
+
+#endif  // COMPONENTS_FRAMELET_BROWSER_RESOURCE_USAGE_REPORTER_H_