On Tue, Dec 10, 2024 at 10:28:41AM -0600, Praveen K Paladugu wrote:
>
>
> On 12/2/2024 3:46 AM, Purna Pavan Chandra Aekkaladevi wrote:
> >Implement `chReadProcessEvents` and `chProcessEvents` to read events from
> >event monitor FIFO file and parse them accordingly.
> >
> >Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi@xxxxxxxxxxxxxxxxxxx>
> >Co-authored-by: Vineeth Pillai <viremana@xxxxxxxxxxxxxxxxxxx>
> >---
> > src/ch/ch_events.c | 137 +++++++++++++++++++++++++++++++++++++++++++-
> > src/ch/ch_events.h | 2 +
> > src/ch/ch_monitor.h | 6 ++
> > 3 files changed, 144 insertions(+), 1 deletion(-)
> >
> >diff --git a/src/ch/ch_events.c b/src/ch/ch_events.c
> >index 247f99cef0..a4c2fc4130 100644
> >--- a/src/ch/ch_events.c
> >+++ b/src/ch/ch_events.c
> >@@ -45,6 +45,137 @@ static int virCHEventStopProcess(virDomainObj *vm,
> > return 0;
> > }
> >+static int virCHProcessEvents(virCHMonitor *mon)
> >+{
> >+ virDomainObj *vm = mon->vm;
> >+ char *buf = mon->event_buffer.buffer;
> >+ ssize_t sz = mon->event_buffer.buf_fill_sz;
> >+ virJSONValue *obj = NULL;
> >+ int blocks = 0;
> >+ size_t i = 0;
> >+ char *json_start;
> >+ ssize_t start_index = -1;
> >+ ssize_t end_index = -1;
> >+ char tmp;
> >+ int ret = 0;
> >+
> >+ while (i < sz) {
> >+ if (buf[i] == '{') {
> >+ blocks++;
> >+ if (blocks == 1)
> >+ start_index = i;
> >+ } else if (buf[i] == '}' && blocks > 0) {
> >+ blocks--;
> >+ if (blocks == 0) {
> >+ /* valid json document */
> >+ end_index = i;
> >+
> >+ /* temporarily null terminate the JSON doc */
> >+ tmp = buf[end_index + 1];
> >+ buf[end_index + 1] = '\0';
> >+ json_start = buf + start_index;
> >+
> >+ if ((obj = virJSONValueFromString(json_start))) {
> >+ /* Process the event string (obj) here */
> >+ virJSONValueFree(obj);
> >+ } else {
> >+ VIR_WARN("%s: Invalid JSON event doc: %s",
> >+ vm->def->name, json_start);
> >+ ret = -1;
> If you do encounter an invalid JSON, this implementation will continue
> processing rest of the events. You should return from this method with
> -1 here.
>
Returning -1 here does not halt the thread. So, even if we were to
return -1 here (after memmove-ing the rest of the json to the beginning
of buf, just as done in below 'else if' block), it essentially tries to
continue processing the rest of the events.
> >+ }
> >+
> >+ /* replace the original character */
> >+ buf[end_index + 1] = tmp;
> >+ start_index = -1;
> >+ }
> >+ }
> >+
> >+ i++;
> >+ }
> >+
> >+ if (start_index == -1) {
> >+ /* We have processed all the JSON docs in the buffer */
> >+ mon->event_buffer.buf_fill_sz = 0;
> >+ } else if (start_index > 0) {
> >+ /* We have an incomplete JSON doc at the end of the buffer
> >+ * Move it to the start of the buffer
> >+ */
> >+ mon->event_buffer.buf_fill_sz = sz - start_index;
> >+ memmove(buf, buf+start_index, mon->event_buffer.buf_fill_sz);
> >+ }
> >+
> >+ return ret;
> >+}
> >+
> >+static void virCHReadProcessEvents(virCHMonitor *mon,
> >+ int event_monitor_fd)
> >+{
> >+ /* Event json string must always terminate with null char.
> >+ * So, reserve one byte for '\0' at the end.
> >+ */
> >+ size_t max_sz = CH_EVENT_BUFFER_SZ - 1;
> >+ char *buf = mon->event_buffer.buffer;
> >+ virDomainObj *vm = mon->vm;
> >+ bool incomplete = false;
> >+ size_t sz = 0;
> >+
> >+ memset(buf, 0, max_sz);
> >+ do {
> >+ ssize_t ret;
> >+
> >+ ret = read(event_monitor_fd, buf + sz, max_sz - sz);
> >+ if (ret == 0 || (ret < 0 && errno == EINTR)) {
> >+ g_usleep(G_USEC_PER_SEC);
> >+ continue;
> >+ } else if (ret < 0) {
> >+ /* We should never reach here. read(2) says possible errors
> >+ * are EINTR, EAGAIN, EBADF, EFAULT, EINVAL, EIO, EISDIR
> >+ * We handle EINTR gracefully. There is some serious issue
> >+ * if we encounter any of the other errors(either in our code
> >+ * or in the system). Better to bail out.
> >+ */
> >+ VIR_ERROR(_("%1$s: Failed to read ch events!: %2$s"),
> >+ vm->def->name, g_strerror(errno));
> >+ virCHEventStopProcess(vm, VIR_DOMAIN_SHUTOFF_FAILED);
> >+ virCHStopEventHandler(mon);
> >+ return;
> >+ }
> >+
> >+ sz += ret;
> >+ mon->event_buffer.buf_fill_sz = sz;
> >+
> >+ if (virCHProcessEvents(mon) < 0)
> >+ VIR_WARN("%s: Failed to parse and process events", vm->def->name);
> >+
> >+ if (mon->event_buffer.buf_fill_sz != 0)
> >+ incomplete = true;
> >+ else
> >+ incomplete = false;
> >+ sz = mon->event_buffer.buf_fill_sz;
> >+
> >+ } while (virDomainObjIsActive(vm) && (sz < max_sz) && incomplete);
> >+
> >+ return;
> >+}
> >+
>
> --
> Regards,
> Praveen K Paladugu
Regards,
Purna Pavan Chandra
