// Copyright (c) 2012 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 URL_LOADER_HANDLER_H_
#define URL_LOADER_HANDLER_H_
#include <string>
#include "ppapi/cpp/completion_callback.h"
#include "ppapi/cpp/instance.h"
#include "ppapi/cpp/url_loader.h"
#include "ppapi/cpp/url_request_info.h"
#include "ppapi/utility/completion_callback_factory.h"
#define READ_BUFFER_SIZE 32768
// URLLoaderHandler is used to download data from |url|. When download is
// finished or when an error occurs, it posts a message back to the browser
// with the results encoded in the message as a string and self-destroys.
//
// pp::URLLoader.GetDownloadProgress() is used to to allocate the memory
// required for url_response_body_ before the download starts. (This is not so
// much of a performance improvement, but it saves some memory since
// std::string.insert() typically grows the string's capacity by somewhere
// between 50% to 100% when it needs more memory, depending on the
// implementation.) Other performance improvements made as outlined in this
// bug: http://code.google.com/p/chromium/issues/detail?id=103947
//
// EXAMPLE USAGE:
// URLLoaderHandler* handler* = URLLoaderHandler::Create(instance,url);
// handler->Start();
//
class URLLoaderHandler {
public:
// Creates instance of URLLoaderHandler on the heap.
// URLLoaderHandler objects shall be created only on the heap (they
// self-destroy when all data is in).
static URLLoaderHandler* Create(pp::Instance* instance_,
const std::string& url);
// Initiates page (URL) download.
void Start();
private:
URLLoaderHandler(pp::Instance* instance_, const std::string& url);
~URLLoaderHandler();
// Callback for the pp::URLLoader::Open().
// Called by pp::URLLoader when response headers are received or when an
// error occurs (in response to the call of pp::URLLoader::Open()).
// Look at <ppapi/c/ppb_url_loader.h> and
// <ppapi/cpp/url_loader.h> for more information about pp::URLLoader.
void OnOpen(int32_t result);
// Callback for the pp::URLLoader::ReadResponseBody().
// |result| contains the number of bytes read or an error code.
// Appends data from this->buffer_ to this->url_response_body_.
void OnRead(int32_t result);
// Reads the response body (asynchronously) into this->buffer_.
// OnRead() will be called when bytes are received or when an error occurs.
void ReadBody();
// Append data bytes read from the URL onto the internal buffer. Does
// nothing if |num_bytes| is 0.
void AppendDataBytes(const char* buffer, int32_t num_bytes);
// Post a message back to the browser with the download results.
void ReportResult(const std::string& fname,
const std::string& text,
bool success);
// Post a message back to the browser with the download results and
// self-destroy. |this| is no longer valid when this method returns.
void ReportResultAndDie(const std::string& fname,
const std::string& text,
bool success);
pp::Instance* instance_; // Weak pointer.
std::string url_; // URL to be downloaded.
pp::URLRequestInfo url_request_;
pp::URLLoader url_loader_; // URLLoader provides an API to download URLs.
char* buffer_; // Temporary buffer for reads.
std::string url_response_body_; // Contains accumulated downloaded data.
pp::CompletionCallbackFactory<URLLoaderHandler> cc_factory_;
URLLoaderHandler(const URLLoaderHandler&);
void operator=(const URLLoaderHandler&);
};
#endif // URL_LOADER_HANDLER_H_