Verified Commit c8400c9a authored by Tommaso Tocci's avatar Tommaso Tocci
Browse files

bugfix: implement segmented read 

According to the read manpage a read could return less bytes then
requested due to an interrupt or an error.

We now try to repeat the read operation until all the existent data have
been read correctly.
parent 71f1363b

ifs/src/daemon/backend/data/chunk_storage.cpp

+30 −9
Original line number Diff line number Diff line
@@ -95,15 +95,36 @@ void ChunkStorage::read_chunk(const std::string& file_path, unsigned int chunk_i 
        log->error("Failed to open chunk file for read. File: {}, Error: {}", chunk_path, std::strerror(errno));

        throw std::system_error(errno, std::system_category(), "Failed to open chunk file for read");

    }

    size_t tot_read = 0;

    ssize_t read = 0;



    do {

        read = pread64(fd,

                       buff + tot_read,

                       size - tot_read,

                       offset + tot_read);

        if(read == 0) {

            break;

        }



    auto read = pread64(fd, buff, size, offset);

        if (read < 0) {

            log->error("Failed to read chunk file. File: {}, size: {}, offset: {}, Error: {}",

                    chunk_path, size, offset, std::strerror(errno));

            throw std::system_error(errno, std::system_category(), "Failed to read chunk file");

        }



    ABT_eventual_set(eventual, &read, sizeof(size_t));

#ifndef NDEBUG

        if(tot_read + read < size) {

            log->warn("Read less bytes than requested: {}/{}. Total read was {}", read, size - tot_read, size);

        }

#endif

        assert(read > 0);

        tot_read += read;





    } while (tot_read != size);



    ABT_eventual_set(eventual, &tot_read, sizeof(size_t));



    auto err = close(fd);

    if (err < 0) {