On 130314 10:53:59, Daniel P. Berrange wrote:
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@parallels.com> --- 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.
Yes, I'll send test in a separate patch.
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 :|
-- Dmitry Guryanov