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// Copyright (c) 2009 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_HTTP_PARTIAL_DATA_H_
#define NET_HTTP_PARTIAL_DATA_H_
#include <string>
#include "base/basictypes.h"
#include "net/base/completion_callback.h"
#include "net/http/http_byte_range.h"
namespace disk_cache {
class Entry;
}
namespace net {
class HttpResponseHeaders;
class IOBuffer;
// This class provides support for dealing with range requests and the
// subsequent partial-content responses. We use sparse cache entries to store
// these requests. This class is tightly integrated with HttpCache::Transaction
// and it is intended to allow a cleaner implementation of that class.
//
// In order to fulfill range requests, we may have to perform a sequence of
// reads from the cache, interleaved with reads from the network / writes to the
// cache. This class basically keeps track of the data required to perform each
// of those individual network / cache requests.
class PartialData {
public:
PartialData()
: range_present_(false), final_range_(false), sparse_entry_(true),
truncated_(false) {}
~PartialData() {}
// Performs initialization of the object by parsing the request |headers|
// and verifying that we can process the requested range. Returns true if
// we can process the requested range, and false otherwise.
bool Init(const std::string& headers);
// Sets the headers that we should use to make byte range requests. This is a
// subset of the request extra headers, with byte-range related headers
// removed.
void SetHeaders(const std::string& headers);
// Restores the byte-range headers, by appending the byte range to the headers
// provided to SetHeaders().
void RestoreHeaders(std::string* headers) const;
// Builds the required |headers| to perform the proper cache validation for
// the next range to be fetched. Returns 0 when there is no need to perform
// more operations because we reached the end of the request (so 0 bytes
// should be actually returned to the user), a positive number to indicate
// that |headers| should be used to validate the cache, or an appropriate
// error code.
int PrepareCacheValidation(disk_cache::Entry* entry, std::string* headers);
// Returns true if the current range is stored in the cache.
bool IsCurrentRangeCached() const;
// Returns true if the current range is the last one needed to fulfill the
// user's request.
bool IsLastRange() const;
// Extracts info from headers already stored in the cache. Returns false if
// there is any problem with the headers. |truncated| should be true if we
// have an incomplete 200 entry.
bool UpdateFromStoredHeaders(const HttpResponseHeaders* headers,
disk_cache::Entry* entry, bool truncated);
// Returns true if the requested range is valid given the stored data.
bool IsRequestedRangeOK();
// Returns true if the response headers match what we expect, false otherwise.
bool ResponseHeadersOK(const HttpResponseHeaders* headers);
// Fixes the response headers to include the right content length and range.
void FixResponseHeaders(HttpResponseHeaders* headers);
// Fixes the content length that we want to store in the cache.
void FixContentLength(HttpResponseHeaders* headers);
// Reads up to |data_len| bytes from the cache and stores them in the provided
// buffer (|data|). Basically, this is just a wrapper around the API of the
// cache that provides the right arguments for the current range. When the IO
// operation completes, OnCacheReadCompleted() must be called with the result
// of the operation.
int CacheRead(disk_cache::Entry* entry, IOBuffer* data, int data_len,
CompletionCallback* callback);
// Writes |data_len| bytes to cache. This is basically a wrapper around the
// API of the cache that provides the right arguments for the current range.
int CacheWrite(disk_cache::Entry* entry, IOBuffer* data, int data_len,
CompletionCallback* callback);
// This method should be called when CacheRead() finishes the read, to update
// the internal state about the current range.
void OnCacheReadCompleted(int result);
// This method should be called after receiving data from the network, to
// update the internal state about the current range.
void OnNetworkReadCompleted(int result);
private:
static void AddRangeHeader(int64 start, int64 end, std::string* headers);
int64 current_range_start_;
int64 cached_start_;
int64 resource_size_;
int cached_min_len_;
HttpByteRange byte_range_; // The range requested by the user.
std::string extra_headers_; // The clean set of extra headers (no ranges).
bool range_present_; // True if next range entry is already stored.
bool final_range_;
bool sparse_entry_;
bool truncated_; // We have an incomplete 200 stored.
DISALLOW_COPY_AND_ASSIGN(PartialData);
};
} // namespace net
#endif // NET_HTTP_PARTIAL_DATA_H_
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