[Qemu-devel] [PATCH COLO-Frame v10 18/38] COLO failover: Introduce a new command to trigger a failover

[zhanghailiang]

We leave users to choose whatever heartbeat solution they want, if the heartbeat
is lost, or other errors they detect, they can use experimental command
'x_colo_lost_heartbeat' to tell COLO to do failover, COLO will do operations
accordingly.

For example, if the command is sent to the PVM, the Primary side will
exit COLO mode and take over operation. If sent to the Secondary, the
secondary will run failover work, then take over server operation to
become the new Primary.

Cc: Luiz Capitulino <address@hidden>
Cc: Eric Blake <address@hidden>
Cc: Markus Armbruster <address@hidden>
Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Li Zhijian <address@hidden>
---
v10: Rename command colo_lost_hearbeat to experimental 'x_colo_lost_heartbeat'
---
 hmp-commands.hx              | 15 +++++++++++++++
 hmp.c                        |  8 ++++++++
 hmp.h                        |  1 +
 include/migration/colo.h     |  4 ++++
 include/migration/failover.h | 20 ++++++++++++++++++++
 migration/Makefile.objs      |  2 +-
 migration/colo-comm.c        | 11 +++++++++++
 migration/colo-failover.c    | 41 +++++++++++++++++++++++++++++++++++++++++
 migration/colo.c             |  1 +
 qapi-schema.json             | 26 ++++++++++++++++++++++++++
 qmp-commands.hx              | 19 +++++++++++++++++++
 stubs/migration-colo.c       |  8 ++++++++
 12 files changed, 155 insertions(+), 1 deletion(-)
 create mode 100644 include/migration/failover.h
 create mode 100644 migration/colo-failover.c

diff --git a/hmp-commands.hx b/hmp-commands.hx
index a493101..9d12ba8 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1071,6 +1071,21 @@ Set the parameter @var{parameter} for migration.
 ETEXI
 
     {
+        .name       = "x_colo_lost_heartbeat",
+        .args_type  = "",
+        .params     = "",
+        .help       = "Tell COLO that heartbeat is lost,\n\t\t\t"
+                      "a failover or takeover is needed.",
+        .mhandler.cmd = hmp_x_colo_lost_heartbeat,
+    },
+
+STEXI
address@hidden x_colo_lost_heartbeat
address@hidden x_colo_lost_heartbeat
+Tell COLO that heartbeat is lost, a failover or takeover is needed.
+ETEXI
+
+    {
         .name       = "client_migrate_info",
         .args_type  = 
"protocol:s,hostname:s,port:i?,tls-port:i?,cert-subject:s?",
         .params     = "protocol hostname port tls-port cert-subject",
diff --git a/hmp.c b/hmp.c
index b46ccc2..5e416d0 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1294,6 +1294,14 @@ void hmp_client_migrate_info(Monitor *mon, const QDict 
*qdict)
     hmp_handle_error(mon, &err);
 }
 
+void hmp_x_colo_lost_heartbeat(Monitor *mon, const QDict *qdict)
+{
+    Error *err = NULL;
+
+    qmp_x_colo_lost_heartbeat(&err);
+    hmp_handle_error(mon, &err);
+}
+
 void hmp_set_password(Monitor *mon, const QDict *qdict)
 {
     const char *protocol  = qdict_get_str(qdict, "protocol");
diff --git a/hmp.h b/hmp.h
index 1783bdf..9996c3b 100644
--- a/hmp.h
+++ b/hmp.h
@@ -69,6 +69,7 @@ void hmp_migrate_set_capability(Monitor *mon, const QDict 
*qdict);
 void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict);
 void hmp_migrate_set_cache_size(Monitor *mon, const QDict *qdict);
 void hmp_client_migrate_info(Monitor *mon, const QDict *qdict);
+void hmp_x_colo_lost_heartbeat(Monitor *mon, const QDict *qdict);
 void hmp_set_password(Monitor *mon, const QDict *qdict);
 void hmp_expire_password(Monitor *mon, const QDict *qdict);
 void hmp_eject(Monitor *mon, const QDict *qdict);
diff --git a/include/migration/colo.h b/include/migration/colo.h
index be2890b..34e8127 100644
--- a/include/migration/colo.h
+++ b/include/migration/colo.h
@@ -17,6 +17,7 @@
 #include "migration/migration.h"
 #include "qemu/coroutine_int.h"
 #include "qemu/thread.h"
+#include "qemu/main-loop.h"
 
 bool colo_supported(void);
 void colo_info_mig_init(void);
@@ -29,6 +30,9 @@ bool migration_incoming_enable_colo(void);
 void migration_incoming_exit_colo(void);
 void *colo_process_incoming_thread(void *opaque);
 bool migration_incoming_in_colo_state(void);
+
+int get_colo_mode(void);
+
 /* ram cache */
 int colo_init_ram_cache(void);
 void colo_release_ram_cache(void);
diff --git a/include/migration/failover.h b/include/migration/failover.h
new file mode 100644
index 0000000..1785b52
--- /dev/null
+++ b/include/migration/failover.h
@@ -0,0 +1,20 @@
+/*
+ *  COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ *  (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO.,LTD.
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Copyright (c) 2015 Intel Corporation
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef QEMU_FAILOVER_H
+#define QEMU_FAILOVER_H
+
+#include "qemu-common.h"
+
+void failover_request_active(Error **errp);
+
+#endif
diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index cb7bd30..50d8392 100644
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -1,6 +1,6 @@
 common-obj-y += migration.o tcp.o
-common-obj-$(CONFIG_COLO) += colo.o
 common-obj-y += colo-comm.o
+common-obj-$(CONFIG_COLO) += colo.o colo-failover.o
 common-obj-y += vmstate.o
 common-obj-y += qemu-file.o qemu-file-buf.o qemu-file-unix.o qemu-file-stdio.o
 common-obj-y += xbzrle.o
diff --git a/migration/colo-comm.c b/migration/colo-comm.c
index 30df3d3..61a5fb3 100644
--- a/migration/colo-comm.c
+++ b/migration/colo-comm.c
@@ -20,6 +20,17 @@ typedef struct {
 
 static COLOInfo colo_info;
 
+int get_colo_mode(void)
+{
+    if (migration_in_colo_state()) {
+        return COLO_MODE_PRIMARY;
+    } else if (migration_incoming_in_colo_state()) {
+        return COLO_MODE_SECONDARY;
+    } else {
+        return COLO_MODE_UNKNOWN;
+    }
+}
+
 static void colo_info_pre_save(void *opaque)
 {
     COLOInfo *s = opaque;
diff --git a/migration/colo-failover.c b/migration/colo-failover.c
new file mode 100644
index 0000000..e3897c6
--- /dev/null
+++ b/migration/colo-failover.c
@@ -0,0 +1,41 @@
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO., LTD.
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Copyright (c) 2015 Intel Corporation
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#include "migration/colo.h"
+#include "migration/failover.h"
+#include "qmp-commands.h"
+#include "qapi/qmp/qerror.h"
+
+static QEMUBH *failover_bh;
+
+static void colo_failover_bh(void *opaque)
+{
+    qemu_bh_delete(failover_bh);
+    failover_bh = NULL;
+    /*TODO: Do failover work */
+}
+
+void failover_request_active(Error **errp)
+{
+    failover_bh = qemu_bh_new(colo_failover_bh, NULL);
+    qemu_bh_schedule(failover_bh);
+}
+
+void qmp_x_colo_lost_heartbeat(Error **errp)
+{
+    if (get_colo_mode() == COLO_MODE_UNKNOWN) {
+        error_setg(errp, QERR_FEATURE_DISABLED, "colo");
+        return;
+    }
+
+    failover_request_active(errp);
+}
diff --git a/migration/colo.c b/migration/colo.c
index a6791f4..64daee9 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -17,6 +17,7 @@
 #include "trace.h"
 #include "qemu/error-report.h"
 #include "qemu/sockets.h"
+#include "migration/failover.h"
 
 /*
  * checkpoint interval: unit ms
diff --git a/qapi-schema.json b/qapi-schema.json
index 49f2a90..ff0e941 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -734,6 +734,32 @@
             'checkpoint-reply', 'vmstate-send', 'vmstate-size',
             'vmstate-received', 'vmstate-loaded' ] }
 
+##
+# @COLOMode
+#
+# The colo mode
+#
+# @unknown: unknown mode
+#
+# @primary: master side
+#
+# @secondary: slave side
+#
+# Since: 2.5
+##
+{ 'enum': 'COLOMode',
+  'data': [ 'unknown', 'primary', 'secondary'] }
+
+##
+# @x-colo-lost-heartbeat
+#
+# Tell qemu that heartbeat is lost, request it to do takeover procedures.
+#
+# Since: 2.5
+##
+{ 'command': 'x-colo-lost-heartbeat' }
+
+##
 # @MouseInfo:
 #
 # Information about a mouse device.
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 2f885b3..eccdd17 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -786,6 +786,25 @@ Example:
 EQMP
 
     {
+        .name       = "x-colo-lost-heartbeat",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_x_colo_lost_heartbeat,
+    },
+
+SQMP
+x-colo-lost-heartbeat
+--------------------
+
+Tell COLO that heartbeat is lost, a failover or takeover is needed.
+
+Example:
+
+-> { "execute": "x-colo-lost-heartbeat" }
+<- { "return": {} }
+
+EQMP
+
+    {
         .name       = "client_migrate_info",
         .args_type  = 
"protocol:s,hostname:s,port:i?,tls-port:i?,cert-subject:s?",
         .params     = "protocol hostname port tls-port cert-subject",
diff --git a/stubs/migration-colo.c b/stubs/migration-colo.c
index c12516e..5028f63 100644
--- a/stubs/migration-colo.c
+++ b/stubs/migration-colo.c
@@ -11,6 +11,7 @@
  */
 
 #include "migration/colo.h"
+#include "qmp-commands.h"
 
 bool colo_supported(void)
 {
@@ -35,3 +36,10 @@ void *colo_process_incoming_thread(void *opaque)
 {
     return NULL;
 }
+
+void qmp_x_colo_lost_heartbeat(Error **errp)
+{
+    error_setg(errp, "COLO is not supported, please rerun configure"
+                     " with --enable-colo option in order to support"
+                     " COLO feature");
+}
-- 
1.8.3.1