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// This is a simple high-level driver to write items into streams
// in a compressed form. Useful if, due to some reason, we do not
// want to write directly into a compressed archive.
//
// Note that this code is rather slow, and is not recommended for
// saving a lot of small objects (use a compressed archive instead).
#ifndef GENERS_COMPRESSEDIO_HH_
#define GENERS_COMPRESSEDIO_HH_
#include "Alignment/Geners/interface/CStringStream.hh"
#include "Alignment/Geners/interface/GenericIO.hh"
namespace gs {
// The following function returns "true" on success, "false" on failure
template <class Item>
bool write_compressed_item(std::ostream &os,
const Item &item,
CStringStream::CompressionMode m = CStringStream::ZLIB,
int compressionLevel = -1,
unsigned minSizeToCompress = 1024U,
unsigned bufSize = 1048576U);
template <class Item>
void restore_compressed_item(std::istream &in, Item *item);
template <class Item>
std::unique_ptr<Item> read_compressed_item(std::istream &in);
} // namespace gs
namespace gs {
template <class Item>
inline bool write_compressed_item(std::ostream &os,
const Item &item,
const CStringStream::CompressionMode m,
const int compressionLevel,
const unsigned minSizeToCompress,
const unsigned bufSize) {
CStringStream cs(m, compressionLevel, minSizeToCompress, bufSize);
unsigned compressionCode = 0;
long long len = 0;
const std::streampos base = os.tellp();
write_pod(os, len);
write_pod(os, compressionCode);
if (os.fail() || os.bad())
return false;
const std::streampos start = os.tellp();
cs.setSink(os);
if (!write_item(cs, item))
return false;
cs.flush();
compressionCode = static_cast<unsigned>(cs.writeCompressed());
const std::streampos now = os.tellp();
const std::streamoff off = now - start;
len = off;
os.seekp(base);
write_pod(os, len);
write_pod(os, compressionCode);
os.seekp(now);
return !(cs.fail() || cs.bad() || os.fail() || os.bad());
}
template <class Item>
inline void restore_compressed_item(std::istream &is, Item *item) {
long long len;
read_pod(is, &len);
unsigned compressionCode;
read_pod(is, &compressionCode);
CStringStream::CompressionMode m = static_cast<CStringStream::CompressionMode>(compressionCode);
CStringStream cs(m, -1, 1024U, 1048576U);
cs.readCompressed(is, compressionCode, len);
if (!is.good())
throw IOReadFailure(
"In restore_compressed_item: "
"input stream failure");
restore_item(cs, item);
}
template <class Item>
inline std::unique_ptr<Item> read_compressed_item(std::istream &is) {
long long len;
read_pod(is, &len);
unsigned compressionCode;
read_pod(is, &compressionCode);
CStringStream::CompressionMode m = static_cast<CStringStream::CompressionMode>(compressionCode);
CStringStream cs(m, -1, 1024U, 1048576U);
cs.readCompressed(is, compressionCode, len);
if (!is.good())
throw IOReadFailure(
"In read_compressed_item: "
"input stream failure");
return read_item<Item, std::istream>(cs);
}
} // namespace gs
#endif // GENERS_COMPRESSEDIO_HH_
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