net/colo-compare.c: Expose "compare_timeout" to users

The "compare_timeout" determines the maximum time to hold the primary net packet.
This patch expose the "compare_timeout", make user have ability to
adjest the value according to application scenarios.

QMP command demo:
    { "execute": "qom-get",
         "arguments": { "path": "/objects/comp0",
                        "property": "compare_timeout" } }

    { "execute": "qom-set",
         "arguments": { "path": "/objects/comp0",
                        "property": "compare_timeout",
                        "value": 5000} }

Signed-off-by: Zhang Chen <chen.zhang@intel.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

net/colo-compare.c

@@ -50,6 +50,7 @@ static NotifierList colo_compare_notifiers =
 
 /* TODO: Should be configurable */
 #define REGULAR_PACKET_CHECK_MS 3000
+#define DEFAULT_TIME_OUT_MS 3000
 
 static QemuMutex event_mtx;
 static QemuCond event_complete_cond;
@@ -92,6 +93,7 @@ typedef struct CompareState {
     SocketReadState sec_rs;
     SocketReadState notify_rs;
     bool vnet_hdr;
+    uint32_t compare_timeout;
 
     /*
      * Record the connection that through the NIC
@@ -607,10 +609,9 @@ static int colo_old_packet_check_one_conn(Connection *conn,
                                           CompareState *s)
 {
     GList *result = NULL;
-    int64_t check_time = REGULAR_PACKET_CHECK_MS;
 
     result = g_queue_find_custom(&conn->primary_list,
-                                 &check_time,
+                                 &s->compare_timeout,
                                  (GCompareFunc)colo_old_packet_check_one);
 
     if (result) {
@@ -984,6 +985,39 @@ static void compare_set_notify_dev(Object *obj, const char *value, Error **errp)
     s->notify_dev = g_strdup(value);
 }
 
+static void compare_get_timeout(Object *obj, Visitor *v,
+                                const char *name, void *opaque,
+                                Error **errp)
+{
+    CompareState *s = COLO_COMPARE(obj);
+    uint32_t value = s->compare_timeout;
+
+    visit_type_uint32(v, name, &value, errp);
+}
+
+static void compare_set_timeout(Object *obj, Visitor *v,
+                                const char *name, void *opaque,
+                                Error **errp)
+{
+    CompareState *s = COLO_COMPARE(obj);
+    Error *local_err = NULL;
+    uint32_t value;
+
+    visit_type_uint32(v, name, &value, &local_err);
+    if (local_err) {
+        goto out;
+    }
+    if (!value) {
+        error_setg(&local_err, "Property '%s.%s' requires a positive value",
+                   object_get_typename(obj), name);
+        goto out;
+    }
+    s->compare_timeout = value;
+
+out:
+    error_propagate(errp, local_err);
+}
+
 static void compare_pri_rs_finalize(SocketReadState *pri_rs)
 {
     CompareState *s = container_of(pri_rs, CompareState, pri_rs);
@@ -1090,6 +1124,11 @@ static void colo_compare_complete(UserCreatable *uc, Error **errp)
         return;
     }
 
+    if (!s->compare_timeout) {
+        /* Set default value to 3000 MS */
+        s->compare_timeout = DEFAULT_TIME_OUT_MS;
+    }
+
     if (find_and_check_chardev(&chr, s->pri_indev, errp) ||
         !qemu_chr_fe_init(&s->chr_pri_in, chr, errp)) {
         return;
@@ -1185,6 +1224,10 @@ static void colo_compare_init(Object *obj)
                             compare_get_notify_dev, compare_set_notify_dev,
                             NULL);
 
+    object_property_add(obj, "compare_timeout", "uint32",
+                        compare_get_timeout,
+                        compare_set_timeout, NULL, NULL, NULL);
+
     s->vnet_hdr = false;
     object_property_add_bool(obj, "vnet_hdr_support", compare_get_vnet_hdr,
                              compare_set_vnet_hdr, NULL);

qemu-options.hx

@@ -4615,7 +4615,7 @@ SRST
         stored. The file format is libpcap, so it can be analyzed with
         tools such as tcpdump or Wireshark.
 
-    ``-object colo-compare,id=id,primary_in=chardevid,secondary_in=chardevid,outdev=chardevid,iothread=id[,vnet_hdr_support][,notify_dev=id]``
+    ``-object colo-compare,id=id,primary_in=chardevid,secondary_in=chardevid,outdev=chardevid,iothread=id[,vnet_hdr_support][,notify_dev=id][,compare_timeout=@var{ms}]``
         Colo-compare gets packet from primary\_inchardevid and
         secondary\_inchardevid, than compare primary packet with
         secondary packet. If the packets are same, we will output
@@ -4624,8 +4624,10 @@ SRST
         outdevchardevid. In order to improve efficiency, we need to put
         the task of comparison in another thread. If it has the
         vnet\_hdr\_support flag, colo compare will send/recv packet with
-        vnet\_hdr\_len. If you want to use Xen COLO, will need the
+        vnet\_hdr\_len. Then compare\_timeout=@var{ms} determines the
-        notify\_dev to notify Xen colo-frame to do checkpoint.
+        maximum delay colo-compare wait for the packet.
+        If you want to use Xen COLO, will need the notify\_dev to
+        notify Xen colo-frame to do checkpoint.
 
         we must use it with the help of filter-mirror and
         filter-redirector.