diff options
Diffstat (limited to 'gr-blocks/lib/file_source_impl.cc')
| -rw-r--r-- | gr-blocks/lib/file_source_impl.cc | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/gr-blocks/lib/file_source_impl.cc b/gr-blocks/lib/file_source_impl.cc index ee8e30f8a9..92f1d8220f 100644 --- a/gr-blocks/lib/file_source_impl.cc +++ b/gr-blocks/lib/file_source_impl.cc @@ -188,7 +188,34 @@ void file_source_impl::open(const char* filename, // Rewind to start offset if (d_seekable) { - if (GR_FSEEK(d_new_fp, start_offset_items * d_itemsize, SEEK_SET) == -1) { + auto start_offset = start_offset_items * d_itemsize; +#ifdef _POSIX_C_SOURCE +#if _POSIX_C_SOURCE >= 200112L + // If supported, tell the OS that we'll be accessing the file sequentially + // and that it would be a good idea to start prefetching it + auto fd = fileno(d_new_fp); + static const std::map<int, const std::string> fadv_errstrings = { + { EBADF, "bad file descriptor" }, + { EINVAL, "invalid advise" }, + { ESPIPE, "tried to act as if a pipe or similar was a file" } + }; + if (file_size && file_size != INT64_MAX) { + if (auto ret = posix_fadvise( + fd, start_offset, file_size - start_offset, POSIX_FADV_SEQUENTIAL)) { + GR_LOG_WARN(d_logger, + "failed to advise to read sequentially, " + + fadv_errstrings.at(ret)); + } + if (auto ret = posix_fadvise( + fd, start_offset, file_size - start_offset, POSIX_FADV_WILLNEED)) { + GR_LOG_WARN(d_logger, + "failed to advise we'll need file contents soon, " + + fadv_errstrings.at(ret)); + } + } +#endif +#endif + if (GR_FSEEK(d_new_fp, start_offset, SEEK_SET) == -1) { throw std::runtime_error("can't fseek()"); } } |