chromium/content/browser/renderer_host/spare_render_process_host_manager.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 CONTENT_BROWSER_RENDERER_HOST_SPARE_RENDER_PROCESS_HOST_MANAGER_H_
#define CONTENT_BROWSER_RENDERER_HOST_SPARE_RENDER_PROCESS_HOST_MANAGER_H_

#include <optional>

#include "base/callback_list.h"
#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "base/time/time.h"
#include "base/timer/elapsed_timer.h"
#include "base/timer/timer.h"
#include "content/common/content_export.h"
#include "content/public/browser/render_process_host_observer.h"

namespace content {

class BrowserContext;
class SiteInstanceImpl;
class RenderProcessHost;

// This class manages spare RenderProcessHosts.
//
// There is a singleton instance of this class which manages a single spare
// renderer (SpareRenderProcessHostManager::GetInstance(), below). This class
// encapsulates the implementation of
// RenderProcessHost::WarmupSpareRenderProcessHost()
//
// RenderProcessHostImpl should call
// SpareRenderProcessHostManager::MaybeTakeSpareRenderProcessHost when creating
// a new RPH. In this implementation, the spare renderer is bound to a
// BrowserContext and its default StoragePartition. If
// MaybeTakeSpareRenderProcessHost is called with a BrowserContext that does not
// match, the spare renderer is discarded. Only the default StoragePartition
// will be able to use a spare renderer. The spare renderer will also not be
// used as a guest renderer (flags_ contains kForGuestsOnly).
//
// It is safe to call WarmupSpareRenderProcessHost multiple times, although if
// called in a context where the spare renderer is not likely to be used
// performance may suffer due to the unnecessary RPH creation.
class CONTENT_EXPORT SpareRenderProcessHostManager
    : public RenderProcessHostObserver { … };

}  // namespace content

#endif  // CONTENT_BROWSER_RENDERER_HOST_SPARE_RENDER_PROCESS_HOST_MANAGER_H_