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// Copyright 2014 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.
// TODO(rdsmith): This class needs to delegate URLRequest::Delegate methods
// to the net/ embedder for correct implementation of authentication.
// Specifically, this class needs the embedder to provide functionality
// corresponding to
// URLRequest::Delegate::{OnAuthRequired,OnCertificateRequested}.
#ifndef NET_URL_REQUEST_SDCH_DICTIONARY_FETCHER_H_
#define NET_URL_REQUEST_SDCH_DICTIONARY_FETCHER_H_
#include <queue>
#include <set>
#include <string>
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/threading/non_thread_safe.h"
#include "net/base/sdch_manager.h"
#include "net/url_request/url_fetcher_delegate.h"
#include "net/url_request/url_request.h"
namespace net {
class URLRequest;
class URLRequestThrottlerEntryInterface;
// This class is used by embedder SDCH policy object to fetch
// dictionaries. It queues requests for dictionaries and dispatches
// them serially, implementing the URLRequest::Delegate interface to
// handle callbacks (but see above TODO). It tracks all requests, only
// attempting to fetch each dictionary once.
class NET_EXPORT SdchDictionaryFetcher : public URLRequest::Delegate,
public base::NonThreadSafe {
public:
typedef base::Callback<void(const std::string& dictionary_text,
const GURL& dictionary_url,
const BoundNetLog& net_log)>
OnDictionaryFetchedCallback;
// The consumer must guarantee that |*context| outlives this object.
// |callback| will be called on successful dictionary fetch
// requested through Schedule(). |callback| will not be called
// after object destruction.
SdchDictionaryFetcher(URLRequestContext* context,
const OnDictionaryFetchedCallback& callback);
~SdchDictionaryFetcher() override;
// Request a new dictionary fetch.
void Schedule(const GURL& dictionary_url);
// Cancel any in-progress requests.
void Cancel();
// Implementation of URLRequest::Delegate methods.
void OnResponseStarted(URLRequest* request) override;
void OnReadCompleted(URLRequest* request, int bytes_read) override;
private:
enum State {
STATE_NONE,
STATE_IDLE,
STATE_REQUEST_STARTED,
STATE_REQUEST_READING,
STATE_REQUEST_COMPLETE,
};
// State machine implementation.
int DoLoop(int rv);
int DoDispatchRequest(int rv);
int DoRequestStarted(int rv);
int DoRead(int rv);
int DoCompleteRequest(int rv);
State next_state_;
bool in_loop_;
// A queue of URLs that are being used to download dictionaries.
std::queue<GURL> fetch_queue_;
// The request and buffer used for getting the current dictionary
// Both are null when a fetch is not in progress.
scoped_ptr<URLRequest> current_request_;
scoped_refptr<IOBuffer> buffer_;
// The currently accumulating dictionary.
std::string dictionary_;
// Althought the SDCH spec does not preclude a server from using a single URL
// to load several distinct dictionaries (by telling a client to load a
// dictionary from an URL several times), current implementations seem to have
// that 1-1 relationship (i.e., each URL points at a single dictionary, and
// the dictionary content does not change over time, and hence is not worth
// trying to load more than once). In addition, some dictionaries prove
// unloadable only after downloading them (because they are too large? ...or
// malformed?). As a protective element, Chromium will *only* load a
// dictionary at most once from a given URL (so that it doesn't waste
// bandwidth trying repeatedly).
// The following set lists all the dictionary URLs that we've tried to load,
// so that we won't try to load from an URL more than once.
// TODO(jar): Try to augment the SDCH proposal to include this restiction.
std::set<GURL> attempted_load_;
// Store the URLRequestContext associated with the owning SdchManager for
// use while fetching.
URLRequestContext* const context_;
const OnDictionaryFetchedCallback dictionary_fetched_callback_;
base::WeakPtrFactory<SdchDictionaryFetcher> weak_factory_;
DISALLOW_COPY_AND_ASSIGN(SdchDictionaryFetcher);
};
} // namespace net
#endif // NET_URL_REQUEST_SDCH_DICTIONARY_FETCHER_H_