[COLO-Frame,v16,18/35] COLO failover: Introduce state to record failover process

Commit Message

Zhanghailiang April 8, 2016, 6:26 a.m. UTC

When handling failover, we do different things according to the different stage
of failover process, here we introduce a global atomic variable to record the
status of failover.

We add four failover status to indicate the different stage of failover process.
You should use the helpers to get and set the value.

Signed-off-by: zhanghailiang <[e-mail]>
Reviewed-by: Dr. David Alan Gilbert <[e-mail]>
---
v11:
- fix several typos found by Dave
- Add Reviewed-by tag
---
 include/migration/failover.h | 10 ++++++++++
 migration/colo-failover.c    | 37 +++++++++++++++++++++++++++++++++++++
 migration/colo.c             |  4 ++++
 trace-events                 |  1 +
 4 files changed, 52 insertions(+)

Patch

diff --git a/include/migration/failover.h b/include/migration/failover.h
index 3274735..fe71bb4 100644
--- a/include/migration/failover.h
+++ b/include/migration/failover.h
@@ -15,6 +15,16 @@ 
 
 #include "qemu-common.h"
 
+typedef enum COLOFailoverStatus {
+    FAILOVER_STATUS_NONE = 0,
+    FAILOVER_STATUS_REQUEST = 1, /* Request but not handled */
+    FAILOVER_STATUS_HANDLING = 2, /* In the process of handling failover */
+    FAILOVER_STATUS_COMPLETED = 3, /* Finish the failover process */
+} COLOFailoverStatus;
+
+void failover_init_state(void);
+int failover_set_state(int old_state, int new_state);
+int failover_get_state(void);
 void failover_request_active(Error **errp);
 
 #endif
diff --git a/migration/colo-failover.c b/migration/colo-failover.c
index 413675d..69aac55 100644
--- a/migration/colo-failover.c
+++ b/migration/colo-failover.c
@@ -15,22 +15,59 @@ 
 #include "migration/failover.h"
 #include "qmp-commands.h"
 #include "qapi/qmp/qerror.h"
+#include "qemu/error-report.h"
+#include "trace.h"
 
 static QEMUBH *failover_bh;
+static COLOFailoverStatus failover_state;
 
 static void colo_failover_bh(void *opaque)
 {
+    int old_state;
+
     qemu_bh_delete(failover_bh);
     failover_bh = NULL;
+    old_state = failover_set_state(FAILOVER_STATUS_REQUEST,
+                                   FAILOVER_STATUS_HANDLING);
+    if (old_state != FAILOVER_STATUS_REQUEST) {
+        error_report("Unkown error for failover, old_state=%d", old_state);
+        return;
+    }
     /*TODO: Do failover work */
 }
 
 void failover_request_active(Error **errp)
 {
+   if (failover_set_state(FAILOVER_STATUS_NONE, FAILOVER_STATUS_REQUEST)
+         != FAILOVER_STATUS_NONE) {
+        error_setg(errp, "COLO failover is already actived");
+        return;
+    }
     failover_bh = qemu_bh_new(colo_failover_bh, NULL);
     qemu_bh_schedule(failover_bh);
 }
 
+void failover_init_state(void)
+{
+    failover_state = FAILOVER_STATUS_NONE;
+}
+
+int failover_set_state(int old_state, int new_state)
+{
+    int old;
+
+    old = atomic_cmpxchg(&failover_state, old_state, new_state);
+    if (old == old_state) {
+        trace_colo_failover_set_state(new_state);
+    }
+    return old;
+}
+
+int failover_get_state(void)
+{
+    return atomic_read(&failover_state);
+}
+
 void qmp_x_colo_lost_heartbeat(Error **errp)
 {
     if (get_colo_mode() == COLO_MODE_UNKNOWN) {
diff --git a/migration/colo.c b/migration/colo.c
index 88bbab9..af1f8c2 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -237,6 +237,8 @@  static void colo_process_checkpoint(MigrationState *s)
     Error *local_err = NULL;
     int ret;
 
+    failover_init_state();
+
     s->rp_state.from_dst_file = qemu_file_get_return_path(s->to_dst_file);
     if (!s->rp_state.from_dst_file) {
         error_report("Open QEMUFile from_dst_file failed");
@@ -343,6 +345,8 @@  void *colo_process_incoming_thread(void *opaque)
     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
                       MIGRATION_STATUS_COLO);
 
+    failover_init_state();
+
     mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
     if (!mis->to_src_file) {
         error_report("colo incoming thread: Open QEMUFile to_src_file failed");
diff --git a/trace-events b/trace-events
index ebd93ee..ca7211b 100644
--- a/trace-events
+++ b/trace-events
@@ -1603,6 +1603,7 @@  postcopy_ram_incoming_cleanup_join(void) ""
 colo_vm_state_change(const char *old, const char *new) "Change '%s' => '%s'"
 colo_send_message(const char *msg) "Send '%s' message"
 colo_receive_message(const char *msg) "Receive '%s' message"
+colo_failover_set_state(int new_state) "new state %d"
 
 # kvm-all.c
 kvm_ioctl(int type, void *arg) "type 0x%x, arg %p"