chromium/components/performance_manager/public/resource_attribution/queries.h

// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_RESOURCE_ATTRIBUTION_QUERIES_H_
#define COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_RESOURCE_ATTRIBUTION_QUERIES_H_

#include <memory>

#include "base/functional/callback_forward.h"
#include "base/gtest_prod_util.h"
#include "base/memory/scoped_refptr.h"
#include "base/observer_list_threadsafe.h"
#include "base/scoped_observation.h"
#include "base/sequence_checker.h"
#include "base/task/sequenced_task_runner.h"
#include "base/time/time.h"
#include "base/types/pass_key.h"
#include "components/performance_manager/public/resource_attribution/query_results.h"
#include "components/performance_manager/public/resource_attribution/resource_contexts.h"
#include "components/performance_manager/public/resource_attribution/resource_types.h"
#include "components/performance_manager/public/resource_attribution/type_helpers.h"

namespace resource_attribution {

namespace internal {
class QueryParams;
class QueryScheduler;
}

class QueryBuilder;

// An observer that's notified by ScopedResourceUsageQuery whenever new results
// are available.
class QueryResultObserver { … };

// Repeatedly makes resource attribution queries on a schedule as long as it's
// in scope.
class ScopedResourceUsageQuery { … };

// Convenience alias for a ScopedObservation that observes a
// ScopedResourceUsageQuery.
ScopedQueryObservation;

// Creates a query to request resource usage measurements on a schedule.
//
// Use CreateScopedQuery() to return an object that makes repeated measurements
// as long as it's in scope, or QueryOnce() to take a single measurement. Before
// calling either of these, the query must specify:
//
//  * At least one resource type to measure, with AddResourceType().
//  * At least one resource context to attribute the measurements to, with
//    AddResourceContext() or AddAllContextsOfType().
//
// Example usage:
//
//   // To invoke `callback` with the CPU usage of all processes.
//   QueryBuilder()
//       .AddAllContextsOfType<ProcessContext>()
//       .AddResourceType(ResourceType::kCPUTime)
//       .QueryOnce(callback);
//
// QueryBuilder is move-only to prevent accidentally copying large state. Use
// Clone() to make an explicit copy.
class QueryBuilder { … };

}  // namespace resource_attribution

#endif  // COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_RESOURCE_ATTRIBUTION_QUERIES_H_