4:25 a.m.
Thanks for the review, Michal.
I will add your suggestion to not abort() and fix the possible memory
leak issue in V4.
On Mon, Nov 11, 2024 at 02:37:00PM +0100, Michal Prívozník wrote:
On 10/23/24 10:02, 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 | 136 +++++++++++++++++++++++++++++++++++++++++++-
> src/ch/ch_events.h | 2 +
> src/ch/ch_monitor.h | 6 ++
> 3 files changed, 143 insertions(+), 1 deletion(-)
>
> diff --git a/src/ch/ch_events.c b/src/ch/ch_events.c
> index bb27f340e2..d0ad5af0af 100644
> --- a/src/ch/ch_events.c
> +++ b/src/ch/ch_events.c
> @@ -28,6 +28,136 @@
>
> VIR_LOG_INIT("ch.ch_events");
>
> +/**
> + * virCHProcessEvents:
> + * @mon: the CH monitor object
> + *
> + * Parse the events from the event buffer and process them
> + * Example event:
> + * {
> + * "timestamp": {
> + * "secs": 0,
> + * "nanos": 29228206
> + * },
> + * "source": "vm",
> + * "event": "booted",
> + * "properties": null
> + * }
> + *
> + * Returns: 0 on success, -1 on failure
> + */
> +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;
> + }
> +
> + /* 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);
You mean saferead()?
Sure, will use saferead().
Also, I know you're opened this event_monitor_fd in blocking mode, so
this won't loop every second, so I'm not going to require use of event loop.
Yes, event_monitor_fd is in blocking mode and it might seem like this
loop is not required. But we could end up read()-ing a partial event
json; a loop here makes it possible to read the rest of the json ...
> + 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));
> + VIR_FORCE_CLOSE(event_monitor_fd);
> + abort();
Again, aborting is unacceptable.
> + }
> +
> + 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);
> +
... and the loop is run only when the read() event json is incomplete.
> + return;
> +}
> +
Michal
Regards,
Pavan