[Qemu-devel] [PATCH COLO-Frame v8 16/34] COLO failover: Introduce a new command to trigger a failover

[zhanghailiang]

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

For example,
If send the command to PVM, Primary will exit COLO mode, and takeover,
if to Secondary, Secondary will do failover work and at last takeover server.

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>
Signed-off-by: Yang Hongyang <address@hidden>
---
 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             | 25 +++++++++++++++++++++++++
 qmp-commands.hx              | 19 +++++++++++++++++++
 stubs/migration-colo.c       |  8 ++++++++
 12 files changed, 154 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 1d5b392..410637f 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1034,6 +1034,21 @@ Set the parameter @var{parameter} for migration.
 ETEXI
 
     {
+        .name       = "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_colo_lost_heartbeat,
+    },
+
+STEXI
address@hidden colo_lost_heartbeat
address@hidden 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 dcc66f1..7f3a8a9 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1272,6 +1272,14 @@ void hmp_client_migrate_info(Monitor *mon, const QDict 
*qdict)
     hmp_handle_error(mon, &err);
 }
 
+void hmp_colo_lost_heartbeat(Monitor *mon, const QDict *qdict)
+{
+    Error *err = NULL;
+
+    qmp_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 0cf4f2a..c36c99c 100644
--- a/hmp.h
+++ b/hmp.h
@@ -68,6 +68,7 @@ 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_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 79b5381..572af1c 100644
--- a/include/migration/colo.h
+++ b/include/migration/colo.h
@@ -17,6 +17,7 @@
 #include "migration/migration.h"
 #include "block/coroutine.h"
 #include "qemu/thread.h"
+#include "qemu/main-loop.h"
 
 bool colo_supported(void);
 void colo_info_mig_init(void);
@@ -30,6 +31,9 @@ bool migration_incoming_enable_colo(void);
 void migration_incoming_exit_colo(void);
 void *colo_process_incoming_checkpoints(void *opaque);
 bool migration_incoming_in_colo_state(void);
+
+int get_colo_mode(void);
+
 /* ram cache */
 int create_and_init_ram_cache(void);
 void colo_flush_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 0808d6c..1b6f690 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..af068d3
--- /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_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 bcbe748..1a08fec 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -15,6 +15,7 @@
 #include "trace.h"
 #include "qemu/error-report.h"
 #include "qemu/sockets.h"
+#include "migration/failover.h"
 
 /* Fix me: Convert to use QAPI */
 typedef enum COLOCommand {
diff --git a/qapi-schema.json b/qapi-schema.json
index 6f3e464..762a553 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -666,6 +666,31 @@
             '*tls-port': 'int', '*cert-subject': 'str' } }
 
 ##
+# @COLOMode
+#
+# The colo mode
+#
+# @unknown: unknown mode
+#
+# @primary: master side
+#
+# @secondary: slave side
+#
+# Since: 2.4
+##
+{ 'enum': 'COLOMode',
+  'data': [ 'unknown', 'primary', 'secondary'] }
+
+##
+# @colo-lost-heartbeat
+#
+# Tell qemu that heartbeat is lost, request it to do takeover working.
+#
+# Since: 2.4
+##
+{ 'command': 'colo-lost-heartbeat' }
+
+##
 # @MouseInfo:
 #
 # Information about a mouse device.
diff --git a/qmp-commands.hx b/qmp-commands.hx
index bb49a1a..28a7962 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -781,6 +781,25 @@ Example:
 EQMP
 
     {
+        .name       = "colo-lost-heartbeat",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_colo_lost_heartbeat,
+    },
+
+SQMP
+colo-lost-heartbeat
+--------------------
+
+Tell COLO that heartbeat is lost, a failover or takeover is needed.
+
+Example:
+
+-> { "execute": "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 a105049..fab1572 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_checkpoints(void *opaque)
 {
     return NULL;
 }
+
+void qmp_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