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#include "chunks_download_strategy.hpp"
#include "../std/algorithm.hpp"
#define INVALID_CHUNK -1
namespace downloader
{
ChunksDownloadStrategy::RangeT const ChunksDownloadStrategy::INVALID_RANGE = RangeT(-1, -1);
ChunksDownloadStrategy::ChunksDownloadStrategy(vector<string> const & urls, int64_t fileSize,
int64_t chunkSize)
: m_chunkSize(chunkSize)
{
// init servers list
for (size_t i = 0; i < urls.size(); ++i)
m_servers.push_back(make_pair(urls[i], INVALID_RANGE));
// init chunks which should be downloaded
for (int64_t i = 0; i < fileSize; i += chunkSize)
m_chunksToDownload.insert(RangeT(i, min(i + chunkSize - 1, fileSize - 1)));
}
void ChunksDownloadStrategy::SetChunksToDownload(RangesContainerT & chunks)
{
m_chunksToDownload.swap(chunks);
}
void ChunksDownloadStrategy::ChunkFinished(bool successfully, int64_t begRange, int64_t endRange)
{
RangeT const chunk(begRange, endRange);
// find server which was downloading this chunk
for (ServersT::iterator it = m_servers.begin(); it != m_servers.end(); ++it)
{
if (it->second == chunk)
{
if (successfully)
it->second = INVALID_RANGE;
else
{
// remove failed server and mark chunk as not downloaded
m_servers.erase(it);
m_chunksToDownload.insert(chunk);
}
break;
}
}
}
ChunksDownloadStrategy::ResultT ChunksDownloadStrategy::NextChunk(string & outUrl,
int64_t & begRange,
int64_t & endRange)
{
if (m_servers.empty())
return EDownloadFailed;
if (m_chunksToDownload.empty())
{
// no more chunks to download
bool allChunksAreFinished = true;
for (size_t i = 0; i < m_servers.size(); ++i)
{
if (m_servers[i].second != INVALID_RANGE)
allChunksAreFinished = false;
}
if (allChunksAreFinished)
return EDownloadSucceeded;
else
return ENoFreeServers;
}
else
{
RangeT const nextChunk = *m_chunksToDownload.begin();
for (size_t i = 0; i < m_servers.size(); ++i)
{
if (m_servers[i].second == INVALID_RANGE)
{
// found not used server
m_servers[i].second = nextChunk;
outUrl = m_servers[i].first;
begRange = nextChunk.first;
endRange = nextChunk.second;
m_chunksToDownload.erase(m_chunksToDownload.begin());
return ENextChunk;
}
}
// if we're here, all servers are busy downloading
return ENoFreeServers;
}
}
} // namespace downloader
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