blob: 6b71a646b46e7815a29424da7fba6d1c4156d4d5 [file] [log] [blame]
// Copyright 2016 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 <map>
#include "base/macros.h"
#include "base/observer_list.h"
#include "base/threading/thread_checker.h"
#include "net/base/net_export.h"
#include "net/nqe/cached_network_quality.h"
#include "net/nqe/effective_connection_type.h"
#include "net/nqe/network_id.h"
namespace net {
namespace nqe {
namespace internal {
// NetworkQualityStore holds the network qualities of different networks in
// memory. Entries are stored in LRU order, and older entries may be evicted.
class NET_EXPORT_PRIVATE NetworkQualityStore {
// Observes changes in the cached network qualities.
class NET_EXPORT NetworkQualitiesCacheObserver {
// Notifies the observer of a change in the cached network quality. The
// observer must register and unregister itself on the IO thread. All the
// observers would be notified on the IO thread. |network_id| is the ID of
// the network whose cached quality is being reported.
virtual void OnChangeInCachedNetworkQuality(
const nqe::internal::NetworkID& network_id,
const nqe::internal::CachedNetworkQuality& cached_network_quality) = 0;
NetworkQualitiesCacheObserver() {}
virtual ~NetworkQualitiesCacheObserver() {}
// Stores the network quality |cached_network_quality| of network with ID
// |network_id|.
void Add(const nqe::internal::NetworkID& network_id,
const nqe::internal::CachedNetworkQuality& cached_network_quality);
// Returns true if the network quality estimate was successfully read
// for a network with ID |network_id|, and sets |cached_network_quality| to
// the estimate read.
bool GetById(const nqe::internal::NetworkID& network_id,
nqe::internal::CachedNetworkQuality* cached_network_quality);
// Adds and removes |observer| from the list of cache observers. The
// observers are notified on the same thread on which it was added. Addition
// and removal of the observer must happen on the same thread.
void AddNetworkQualitiesCacheObserver(
NetworkQualitiesCacheObserver* observer);
void RemoveNetworkQualitiesCacheObserver(
NetworkQualitiesCacheObserver* observer);
// Maximum size of the store that holds network quality estimates.
// A smaller size may reduce the cache hit rate due to frequent evictions.
// A larger size may affect performance.
static const size_t kMaximumNetworkQualityCacheSize = 10;
// This does not use an unordered_map or hash_map for code simplicity (the key
// just implements operator<, rather than hash and equality) and because the
// map is tiny.
typedef std::map<nqe::internal::NetworkID,
// Data structure that stores the qualities of networks.
CachedNetworkQualities cached_network_qualities_;
// Observer list for changes in the cached network quality.
base::ThreadChecker thread_checker_;
} // namespace internal
} // namespace nqe
} // namespace net