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// Copyright (c) 2011 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 NET_DNS_ASYNC_HOST_RESOLVER_H_
#define NET_DNS_ASYNC_HOST_RESOLVER_H_
#pragma once
#include <list>
#include <map>
#include "base/observer_list.h"
#include "base/threading/non_thread_safe.h"
#include "net/base/address_family.h"
#include "net/base/host_cache.h"
#include "net/base/host_resolver.h"
#include "net/base/ip_endpoint.h"
#include "net/base/net_log.h"
#include "net/base/rand_callback.h"
#include "net/dns/dns_transaction.h"
namespace net {
class AddressesList;
class ClientSocketFactory;
class NET_EXPORT AsyncHostResolver
: public HostResolver,
public DnsTransaction::Delegate,
NON_EXPORTED_BASE(public base::NonThreadSafe) {
public:
AsyncHostResolver(const IPEndPoint& dns_server,
size_t max_transactions,
size_t max_pending_requests_,
const RandIntCallback& rand_int,
HostCache* cache,
ClientSocketFactory* factory,
NetLog* net_log);
virtual ~AsyncHostResolver();
// HostResolver interface
virtual int Resolve(const RequestInfo& info,
AddressList* addresses,
CompletionCallback* callback,
RequestHandle* out_req,
const BoundNetLog& source_net_log) OVERRIDE;
virtual int ResolveFromCache(const RequestInfo& info,
AddressList* addresses,
const BoundNetLog& source_net_log) OVERRIDE;
virtual void CancelRequest(RequestHandle req_handle) OVERRIDE;
virtual void AddObserver(HostResolver::Observer* observer) OVERRIDE;
virtual void RemoveObserver(HostResolver::Observer* observer) OVERRIDE;
virtual void SetDefaultAddressFamily(AddressFamily address_family) OVERRIDE;
virtual AddressFamily GetDefaultAddressFamily() const OVERRIDE;
virtual HostResolverImpl* GetAsHostResolverImpl() OVERRIDE;
// DnsTransaction::Delegate interface
virtual void OnTransactionComplete(
int result,
const DnsTransaction* transaction,
const IPAddressList& ip_addresses) OVERRIDE;
private:
FRIEND_TEST_ALL_PREFIXES(AsyncHostResolverTest, QueuedLookup);
FRIEND_TEST_ALL_PREFIXES(AsyncHostResolverTest, CancelPendingLookup);
FRIEND_TEST_ALL_PREFIXES(AsyncHostResolverTest,
ResolverDestructionCancelsLookups);
FRIEND_TEST_ALL_PREFIXES(AsyncHostResolverTest,
OverflowQueueWithLowPriorityLookup);
FRIEND_TEST_ALL_PREFIXES(AsyncHostResolverTest,
OverflowQueueWithHighPriorityLookup);
class Request;
typedef DnsTransaction::Key Key;
typedef std::list<Request*> RequestList;
typedef std::list<const DnsTransaction*> TransactionList;
typedef std::map<Key, RequestList> KeyRequestListMap;
// Create a new request for the incoming Resolve() call.
Request* CreateNewRequest(const RequestInfo& info,
CompletionCallback* callback,
AddressList* addresses,
const BoundNetLog& source_net_log);
// Called when a request has just been started.
void OnStart(Request* request);
// Called when a request has just completed (before its callback is run).
void OnFinish(Request* request, int result);
// Called when a request has been cancelled.
void OnCancel(Request* request);
// If there is an in-progress transaction for Request->key(), this will
// attach |request| to the respective list.
bool AttachToRequestList(Request* request);
// Will start a new transaction for |request|, will insert a new key in
// |requestlist_map_| and append |request| to the respective list.
int StartNewTransactionFor(Request* request);
// Will enqueue |request| in |pending_requests_|.
int Enqueue(Request* request);
// A helper used by Enqueue to insert |request| into |pending_requests_|.
Request* Insert(Request* request);
// Returns the number of pending requests.
size_t GetNumPending() const;
// Removes and returns a pointer to the lowest/highest priority request
// from |pending_requests_|.
Request* RemoveLowest();
Request* RemoveHighest();
// Once a transaction has completed, called to start a new transaction if
// there are pending requests.
void ProcessPending();
// Maximum number of concurrent transactions.
size_t max_transactions_;
// List of current transactions.
TransactionList transactions_;
// A map from Key to a list of requests waiting for the Key to resolve.
KeyRequestListMap requestlist_map_;
// Maximum number of pending requests.
size_t max_pending_requests_;
// Queues based on priority for putting pending requests.
RequestList pending_requests_[NUM_PRIORITIES];
// DNS server to which queries will be setn.
IPEndPoint dns_server_;
// Callback to be passed to DnsTransaction for generating DNS query ids.
RandIntCallback rand_int_cb_;
// Cache of host resolution results.
scoped_ptr<HostCache> cache_;
// Also passed to DnsTransaction; it's a dependency injection to aid
// testing, outside of unit tests, its value is always NULL.
ClientSocketFactory* factory_;
// The observers to notify when a request starts/ends.
ObserverList<HostResolver::Observer> observers_;
// Monotonically increasing ID number to assign to the next request.
// Observers are the only consumers of this ID number.
int next_request_id_;
NetLog* net_log_;
DISALLOW_COPY_AND_ASSIGN(AsyncHostResolver);
};
} // namespace net
#endif // NET_DNS_ASYNC_HOST_RESOLVER_H_