Implement `chReadProcessEvents` and `chProcessEvents` to read events from
event monitor FIFO file and parse them accordingly.
Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi@linux.microsoft.com>
Co-authored-by: Vineeth Pillai <viremana@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);
+ 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();
+ }
+
+ 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;
+}
+
static void virCHEventHandlerLoop(void *data)
{
virCHMonitor *mon = data;
@@ -54,11 +184,15 @@ static void virCHEventHandlerLoop(void *data)
}
VIR_DEBUG("%s: Opened the event monitor FIFO(%s)", vm->def->name, mon->eventmonitorpath);
+ mon->event_buffer.buffer = g_malloc_n(sizeof(char), CH_EVENT_BUFFER_SZ);
+ mon->event_buffer.buf_fill_sz = 0;
+
while (g_atomic_int_get(&mon->event_handler_stop) == 0) {
VIR_DEBUG("%s: Reading events from event monitor file", vm->def->name);
- /* Read and process events here */
+ virCHReadProcessEvents(mon, event_monitor_fd);
}
+ g_free(mon->event_buffer.buffer);
VIR_FORCE_CLOSE(event_monitor_fd);
virObjectUnref(vm);
diff --git a/src/ch/ch_events.h b/src/ch/ch_events.h
index 4c8a48231d..2e9cdf03bb 100644
--- a/src/ch/ch_events.h
+++ b/src/ch/ch_events.h
@@ -22,5 +22,7 @@
#include "ch_monitor.h"
+#define CH_EVENT_BUFFER_SZ PIPE_BUF
+
int virCHStartEventHandler(virCHMonitor *mon);
void virCHStopEventHandler(virCHMonitor *mon);
diff --git a/src/ch/ch_monitor.h b/src/ch/ch_monitor.h
index 878a185f29..d31b924d0e 100644
--- a/src/ch/ch_monitor.h
+++ b/src/ch/ch_monitor.h
@@ -99,6 +99,12 @@ struct _virCHMonitor {
virThread event_handler_thread;
int event_handler_stop;
+ struct {
+ /* Buffer to hold the data read from pipe */
+ char *buffer;
+ /* Size of the data read from pipe into buffer */
+ size_t buf_fill_sz;
+ } event_buffer;
pid_t pid;
--
2.34.1On 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@linux.microsoft.com>
> Co-authored-by: Vineeth Pillai <viremana@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()?
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.
> + 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);
> +
> + return;
> +}
> +
Michal
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@linux.microsoft.com>
> > Co-authored-by: Vineeth Pillai <viremana@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
On Thu, Nov 14, 2024 at 02:25:09AM -0800, Purna Pavan Chandra Aekkaladevi wrote:
> 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.
> > >
> > > 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 @@
> > >
> > > +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().
>
Actually, saferead() is not apt here since it read()-s until count
bytes. But we are unsure of the byte count we want to read beforehand.
Simple read() fits in here.
> >
> > 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
Regards,
Pavan
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