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Use ::read instead of pread in AudioSource::read_peaks for portability

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This destroys the atomicity of pread() and thus suggests that we should do something else to ensure
that multithread access to peakfiles (if it does in fact exist) is safe. OTOH, there may be no
such thing, since they are designed for the GUI, which is single threaded (for now)
This commit is contained in:
Paul Davis 2013-07-15 07:52:37 -04:00
parent 0aac62e013
commit 13a0f14db7
1 changed files with 22 additions and 10 deletions
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32
libs/ardour/audiosource.cc
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@ -370,8 +370,9 @@ AudioSource::read_peaks_with_fpp (PeakData *peaks, framecnt_t npeaks, framepos_t
if (scale == 1.0) {
off_t offset = 0;
off_t first_peak_byte = (start / samples_per_file_peak) * sizeof (PeakData);
ssize_t bytes_to_read = sizeof (PeakData)* npeaks;
/* open, read, close */
if ((peakfile_fd = peakfile_descriptor->allocate ()) < 0) {
@ -381,11 +382,16 @@ AudioSource::read_peaks_with_fpp (PeakData *peaks, framecnt_t npeaks, framepos_t
DEBUG_TRACE (DEBUG::Peaks, "DIRECT PEAKS\n");
#ifndef WIN32
nread = ::pread (peakfile_fd, peaks, sizeof (PeakData)* npeaks, first_peak_byte);
#endif
offset = lseek (peakfile_fd, first_peak_byte, SEEK_SET);
if (nread != sizeof (PeakData) * npeaks) {
if (offset != first_peak_byte) {
error << string_compose(_("AudioSource: could not seek to correct location in peak file \"%1\" (%2)"), peakpath, strerror (errno)) << endmsg;
return -1;
}
nread = ::read (peakfile_fd, peaks, bytes_to_read);
if (nread != bytes_to_read) {
DEBUG_TRACE (DEBUG::Peaks, string_compose ("[%1]: Cannot read peaks from peakfile! (read only %2 not %3 at sample %4 = byte %5 )\n"
, _name, nread, npeaks, start, first_peak_byte));
return -1;
@ -448,13 +454,20 @@ AudioSource::read_peaks_with_fpp (PeakData *peaks, framecnt_t npeaks, framepos_t
uint32_t start_byte = current_stored_peak * sizeof(PeakData);
tnp = min ((framecnt_t)(_length/samples_per_file_peak - current_stored_peak), (framecnt_t) expected_peaks);
to_read = min (chunksize, tnp);
ssize_t bytes_to_read = sizeof (PeakData) * to_read;
DEBUG_TRACE (DEBUG::Peaks, string_compose ("reading %1 bytes from peakfile @ %2\n"
, sizeof (PeakData) * to_read, start_byte));
, bytes_to_read, start_byte));
#ifndef WIN32
if ((nread = ::pread (peakfile_fd, staging.get(), sizeof (PeakData) * to_read, start_byte))
!= sizeof (PeakData) * to_read) {
off_t offset = lseek (peakfile_fd, start_byte, SEEK_SET);
if (offset != start_byte) {
error << string_compose(_("AudioSource: could not seek to correct location in peak file \"%1\" (%2)"), peakpath, strerror (errno)) << endmsg;
return -1;
}
if ((nread = ::read (peakfile_fd, staging.get(), bytes_to_read)) != bytes_to_read) {
off_t fend = lseek (peakfile_fd, 0, SEEK_END);
@ -462,7 +475,6 @@ AudioSource::read_peaks_with_fpp (PeakData *peaks, framecnt_t npeaks, framepos_t
, _name, (nread / sizeof(PeakData)), to_read, g_strerror (errno), start_byte, _length, fend, ((_length - current_frame)/samples_per_file_peak), npeaks));
return -1;
}
#endif
i = 0;
stored_peaks_read = nread / sizeof(PeakData);
}