On 9/24/2024 8:22 AM, Purna Pavan Chandra Aekkaladevi wrote:
On Mon, Sep 23, 2024 at 04:29:35PM -0500, Praveen K Paladugu wrote:
On 9/19/2024 8:02 AM, Purna Pavan Chandra Aekkaladevi wrote:
Use a FIFO(named pipe) for --event-monitor option in CH. Introduce a new
thread, `virCHEventHandlerLoop`, to continuously monitor and handle
events from cloud-hypervisor.
Signed-off-by: Purna Pavan Chandra Aekkaladevi <paekkaladevi@xxxxxxxxxxxxxxxxxxx>
Co-authored-by: Vineeth Pillai <viremana@xxxxxxxxxxxxxxxxxxx>
---
po/POTFILES | 1 +
src/ch/ch_events.c | 96 +++++++++++++++++++++++++++++++++++++++++++++
src/ch/ch_events.h | 26 ++++++++++++
src/ch/ch_monitor.c | 28 +++++++++++++
src/ch/ch_monitor.h | 3 ++
src/ch/meson.build | 2 +
6 files changed, 156 insertions(+)
create mode 100644 src/ch/ch_events.c
create mode 100644 src/ch/ch_events.h
diff --git a/po/POTFILES b/po/POTFILES
index 1ed4086d2c..d53307cec4 100644
--- a/po/POTFILES
+++ b/po/POTFILES
@@ -21,6 +21,7 @@ src/bhyve/bhyve_process.c
src/ch/ch_conf.c
src/ch/ch_domain.c
src/ch/ch_driver.c
+src/ch/ch_events.c
src/ch/ch_interface.c
src/ch/ch_monitor.c
src/ch/ch_process.c
diff --git a/src/ch/ch_events.c b/src/ch/ch_events.c
new file mode 100644
index 0000000000..851fbc9f26
--- /dev/null
+++ b/src/ch/ch_events.c
@@ -0,0 +1,96 @@
+/*
+ * Copyright Microsoft Corp. 2024
+ *
+ * ch_events.h: Handle Cloud-Hypervisor events
please fix the filename here.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+
+#include <fcntl.h>
+
+#include "ch_events.h"
+#include "virfile.h"
+#include "virlog.h"
+
+VIR_LOG_INIT("ch.ch_events");
+
+static void virCHEventHandlerLoop(void *data)
+{
+ virCHMonitor *mon = data;
+ virDomainObj *vm = NULL;
+ int event_monitor_fd;
+
+ VIR_DEBUG("Event handler loop thread starting");
+
+ while ((event_monitor_fd = open(mon->eventmonitorpath, O_RDONLY)) < 0) {
+ if (errno == EINTR) {
+ g_usleep(100000); // 100 milli seconds
+ continue;
+ }
+ /*
+ * Any other error should be a BUG(kernel/libc/libvirtd)
+ * (ENOMEM can happen on exceeding per-user limits)
+ */
+ VIR_ERROR(_("Failed to open the event monitor FIFO(%1$s) read end!"),
+ mon->eventmonitorpath);
+ abort();
+ }
+ VIR_DEBUG("Opened the event monitor FIFO(%s)", mon->eventmonitorpath);
+
+ /*
+ * We would need to wait until VM is initialized.
+ */
Does this comment apply to next while loop where the events are
processed?
No, this applies to the immediate while loop where vm ref is obtained.
+ while (!(vm = virObjectRef(mon->vm)))
+ g_usleep(100000); // 100 milli seconds
In this while loop you are only getting a reference to vm object.
Yes. At this point, we are not sure if mon->vm is initialized. The
parent thread initializes mon->vm only after starting this event handler
thread. Hence, wait until we have a vm ref.
Why do you need to wait here? Is there a race condition here?
If yes, will just waiting for a reference for vm object enough?
+
+ while (g_atomic_int_get(&mon->event_handler_stop) == 0) {
+ VIR_DEBUG("Reading events from event monitor file...");
+ /* Read and process events here */
+ }
+
+ VIR_FORCE_CLOSE(event_monitor_fd);
+ virObjectUnref(vm);
+
+ VIR_DEBUG("Event handler loop thread exiting");
+ return;
+}
+
+int virCHStartEventHandler(virCHMonitor *mon)
+{
+ g_autofree char *name = NULL;
+ name = g_strdup_printf("event-handler-%d", mon->pid);
It would be better to name the thread something similar to
"event-handler_ch_${pid}_${vmname}". A similar format is
used for cgroup naming.
+
+ virObjectRef(mon);
+ if (virThreadCreateFull(&mon->event_handler_thread,
+ false,
+ virCHEventHandlerLoop,
+ name,
+ false,
+ mon) < 0) {
+ virObjectUnref(mon);
+ return -1;
+ }
+ virObjectUnref(mon);
+
+ g_atomic_int_set(&mon->event_handler_stop, 0);
+ return 0;
+}
+
+void virCHStopEventHandler(virCHMonitor *mon)
+{
+ g_atomic_int_set(&mon->event_handler_stop, 1);
+}
diff --git a/src/ch/ch_events.h b/src/ch/ch_events.h
new file mode 100644
index 0000000000..4c8a48231d
--- /dev/null
+++ b/src/ch/ch_events.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright Microsoft Corp. 2024
+ *
+ * ch_events.h: header file for handling Cloud-Hypervisor events
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "ch_monitor.h"
+
+int virCHStartEventHandler(virCHMonitor *mon);
+void virCHStopEventHandler(virCHMonitor *mon);
diff --git a/src/ch/ch_monitor.c b/src/ch/ch_monitor.c
index 8c99fe1019..5e43bf9ef8 100644
--- a/src/ch/ch_monitor.c
+++ b/src/ch/ch_monitor.c
@@ -26,6 +26,7 @@
#include "datatypes.h"
#include "ch_conf.h"
+#include "ch_events.h"
#include "ch_interface.h"
#include "ch_monitor.h"
#include "domain_interface.h"
@@ -572,6 +573,28 @@ virCHMonitorNew(virDomainObj *vm, virCHDriverConfig *cfg)
return NULL;
}
+ /* Event monitor file to listen for VM state changes */
+ mon->eventmonitorpath = g_strdup_printf("%s/%s-event-monitor-fifo",
+ cfg->stateDir, vm->def->name);
+ if (virFileExists(mon->eventmonitorpath) &&
+ !virFileIsNamedPipe(mon->eventmonitorpath)) {
+ VIR_WARN("Monitor file (%s) is not a FIFO, trying to delete!",
+ mon->eventmonitorpath);
+ if (virFileRemove(mon->eventmonitorpath, -1, -1) < 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Failed to remove the file: %1$s"),
+ mon->eventmonitorpath);
+ return NULL;
+ }
+ }
+
This does not cover the case when eventmonitorpath exists, and is a
named pipe, may be, not cleaned up from a previous run.
You are better off just deleting the file and open a new one with
mkfifo below.
+ if (mkfifo(mon->eventmonitorpath, S_IWUSR | S_IRUSR) < 0 &&
+ errno != EEXIST) {
+ virReportSystemError(errno, "%s",
+ _("Cannot create monitor FIFO"));
+ return NULL;
+ }
+
cmd = virCommandNew(vm->def->emulator);
virCommandSetUmask(cmd, 0x002);
socket_fd = chMonitorCreateSocket(mon->socketpath);
@@ -593,6 +616,9 @@ virCHMonitorNew(virDomainObj *vm, virCHDriverConfig *cfg)
if (virCommandRunAsync(cmd, &mon->pid) < 0)
return NULL;
+ if (virCHStartEventHandler(mon) < 0)
+ return NULL;
+
/* get a curl handle */
mon->handle = curl_easy_init();
@@ -641,6 +667,8 @@ void virCHMonitorClose(virCHMonitor *mon)
g_free(mon->eventmonitorpath);
}
+ virCHStopEventHandler(mon);
+
Please move virCHStopEventHandler above `if (mon->eventmonitorpath) {`
section. Doing so, will allow the event monitor thread to cleanly
exit, before you invoke `virFileRemove(mon->eventmonitorpath...`
Thanks for this catch. I will move it.
And will also apply other suggestions.
virObjectUnref(mon);
}
diff --git a/src/ch/ch_monitor.h b/src/ch/ch_monitor.h
index 2ef8706b99..878a185f29 100644
--- a/src/ch/ch_monitor.h
+++ b/src/ch/ch_monitor.h
@@ -97,6 +97,9 @@ struct _virCHMonitor {
char *eventmonitorpath;
+ virThread event_handler_thread;
+ int event_handler_stop;
+
pid_t pid;
virDomainObj *vm;
diff --git a/src/ch/meson.build b/src/ch/meson.build
index 633966aac7..684beac1f2 100644
--- a/src/ch/meson.build
+++ b/src/ch/meson.build
@@ -7,6 +7,8 @@ ch_driver_sources = [
'ch_domain.h',
'ch_driver.c',
'ch_driver.h',
+ 'ch_events.c',
+ 'ch_driver.h',
'ch_interface.c',
'ch_interface.h',
'ch_monitor.c',
--
Regards,
Praveen K Paladugu
Regards,
Purna Pavan Chandra
--
Regards,
Praveen K Paladugu
