Function ifstreamReadHelper

runtime/Perf.cc:172–196

* Reads a number of bytes from an ifstream repeatedly and times it * * \param readSize * Number of bytes to read at once * * \return total time taken to read the readSize in seconds */

 * \return total time taken to read the readSize in seconds
 */
double ifstreamReadHelper(int readSize) {
    int dataLen = 1000000;
    char *backing_buffer = static_cast<char*>(malloc(dataLen));

    std::ofstream oFile;
    oFile.open("/tmp/testLog.dat");
    oFile.write(backing_buffer, dataLen);
    oFile.close();

    // Read it back
    std::ifstream iFile;
    iFile.open("/tmp/testLog.dat");

    uint64_t start = Cycles::rdtsc();
    for (int i = 0; i < dataLen/readSize; ++i) {
        iFile.read(backing_buffer, readSize);
    }
    uint64_t stop = Cycles::rdtsc();

    discard(backing_buffer);
    std::remove("/tmp/testLog.dat");
    free(backing_buffer);

    return Cycles::toSeconds(stop - start)/(dataLen/readSize);
}

double ifstreamRead1() {
    return ifstreamReadHelper(1);