LHEXMLStringProduct.cc

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#include <iostream>
#include <algorithm>
#include <lzma.h>

#include "FWCore/MessageLogger/interface/MessageLogger.h"

#include "SimDataFormats/GeneratorProducts/interface/LHEXMLStringProduct.h"

using namespace edm;
using namespace std;

LHEXMLStringProduct::LHEXMLStringProduct() {}

LHEXMLStringProduct::LHEXMLStringProduct(const string &onelheoutput) : content_() { content_.push_back(onelheoutput); }

LHEXMLStringProduct::~LHEXMLStringProduct() {}

void LHEXMLStringProduct::fillCompressedContent(std::istream &input, unsigned int initialSize) {
  //create blob with desired size
  compressedContent_.emplace_back(initialSize);
  std::vector<uint8_t> &output = compressedContent_.back();

  //read buffer
  constexpr unsigned int bufsize = 4096;
  char inbuf[bufsize];

  const unsigned int threshsize = 32 * 1024 * 1024;

  //initialize lzma
  uint32_t preset = 9;
  lzma_stream strm = LZMA_STREAM_INIT;
  lzma_ret ret = lzma_easy_encoder(&strm, preset, LZMA_CHECK_CRC64);

  lzma_action action = LZMA_RUN;

  strm.next_in = reinterpret_cast<uint8_t *>(&inbuf[0]);
  strm.avail_in = 0;
  strm.next_out = output.data();
  strm.avail_out = output.size();

  unsigned int compressedSize = 0;

  while (ret == LZMA_OK) {
    //read input to buffer if necessary
    if (strm.avail_in == 0 && !input.eof()) {
      input.read(inbuf, bufsize);
      strm.next_in = reinterpret_cast<uint8_t *>(&inbuf[0]);
      strm.avail_in = input.gcount();
      if (input.eof()) {
        //signal to lzma that there is no more input
        action = LZMA_FINISH;
      }
    }

    //actual compression
    ret = lzma_code(&strm, action);

    //update compressed size
    compressedSize = output.size() - strm.avail_out;

    //if output blob is full and compression is still going, allocate more memory
    if (strm.avail_out == 0 && ret == LZMA_OK) {
      unsigned int oldsize = output.size();
      if (oldsize < threshsize) {
        output.resize(2 * oldsize);
      } else {
        output.resize(oldsize + threshsize);
      }
      strm.next_out = &output[oldsize];
      strm.avail_out = output.size() - oldsize;
    }
  }

  lzma_end(&strm);

  if (ret != LZMA_STREAM_END) {
    throw cms::Exception("CompressionError") << "There was a failure in LZMA compression in LHEXMLStringProduct.";
  }

  //trim output blob
  output.resize(compressedSize);
}

void LHEXMLStringProduct::writeCompressedContent(std::ostream &output, unsigned int i) const {
  //initialize lzma
  lzma_stream strm = LZMA_STREAM_INIT;
  lzma_ret ret = lzma_stream_decoder(&strm, UINT64_MAX, LZMA_CONCATENATED);
  //all output available from the start, so start "close out" immediately
  lzma_action action = LZMA_FINISH;

  //write buffer
  constexpr unsigned int bufsize = 4096;
  char outbuf[bufsize];

  const std::vector<uint8_t> &input = compressedContent_[i];

  strm.next_in = input.data();
  strm.avail_in = input.size();
  strm.next_out = reinterpret_cast<uint8_t *>(&outbuf[0]);
  strm.avail_out = bufsize;

  while (ret == LZMA_OK) {
    ret = lzma_code(&strm, action);

    //write to stream
    output.write(outbuf, bufsize - strm.avail_out);

    //output buffer full, recycle
    if (strm.avail_out == 0 && ret == LZMA_OK) {
      strm.next_out = reinterpret_cast<uint8_t *>(&outbuf[0]);
      strm.avail_out = bufsize;
    }
  }

  lzma_end(&strm);

  if (ret != LZMA_STREAM_END) {
    throw cms::Exception("DecompressionError") << "There was a failure in LZMA decompression in LHEXMLStringProduct.";
  }
}

bool LHEXMLStringProduct::mergeProduct(LHEXMLStringProduct const &other) {
  content_.insert(content_.end(), other.getStrings().begin(), other.getStrings().end());
  compressedContent_.insert(compressedContent_.end(), other.getCompressed().begin(), other.getCompressed().end());
  return true;
}

void LHEXMLStringProduct::swap(LHEXMLStringProduct &other) {
  content_.swap(other.content_);
  compressedContent_.swap(other.compressedContent_);
}