Re: [libvirt] [PATCH] json: add stream parser

On Thu, Mar 14, 2013 at 12:55:15PM +0400, Dmitry Guryanov wrote: > Add function virJSONValueFromStream, which reads data from > a stream and passes it to json parser. When end of the object > is reached, it returns this object. > To avoid reading from the stream by single bytes it reads to > a buffer (in a structure virJSONStreamParserState), which should > be passed to a consequent call of this function. So if the end > of one object and the beginning of the next object have been > read by a single system call - virJSONValueFromStream handle > it correctly. > > example of usage: > > virJSONValuePtr v; > virJSONStreamParserState state; > > memset(&state, 0, sizeof(state)); > > while (1) { > v = virJSONValueFromStream(mon->fd, &state); > if (v == (void *)-1) > /* error */ > break; > > if (v == NULL) > /* file descriptor has been closed */ > break; > > /* handle object 'v' */ > } > > I need such function for the parallels driver. It caches info > about domains and needs some mechanism to update this cache. > There is a "prlsrvctl monitor" command which waits for events > forever and prints info about events to stdout in json format. > So parallels driver could start separate thread which will > read from prlsrvctl's stdout and update cache accordingly. > > There is the same task in qemu_monitor_json, but each json object > is printed in a separate line there. It's not possible in my case, > because some fields could have line endings. Even QEMU could output multi-line JSON if you set the 'pretty' flag, so this would be useful for QEMU driver too at some point. > > Signed-off-by: Dmitry Guryanov <dguryanov(a)parallels.com&gt; > --- > src/util/virjson.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > src/util/virjson.h | 8 ++++ > 2 files changed, 118 insertions(+), 0 deletions(-) Since this is reasonably complex code can you also add some more test cases to the tests/jsontest.c file to cover this functionality.

Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|