1:10 a.m.
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(a)linux.microsoft.com>
>Co-authored-by: Vineeth Pillai <viremana(a)linux.microsoft.com>
>---
> 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