[Qemu-devel] [PATCH 02/15] colo-compare: implement the process of checkpoint

[zhanghailiang]

While do checkpoint, we need to flush all the unhandled packets,
By using the filter notifier mechanism, we can easily to notify
every compare object to do this process, which runs inside
of compare threads as a coroutine.

Cc: Jason Wang <address@hidden>
Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Zhang Chen <address@hidden>
---
 net/colo-compare.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 net/colo-compare.h | 20 +++++++++++++++
 2 files changed, 92 insertions(+)
 create mode 100644 net/colo-compare.h

diff --git a/net/colo-compare.c b/net/colo-compare.c
index a6fc2ff..61a8ee4 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -29,17 +29,24 @@
 #include "qemu/sockets.h"
 #include "qapi-visit.h"
 #include "net/colo.h"
+#include "net/colo-compare.h"
 
 #define TYPE_COLO_COMPARE "colo-compare"
 #define COLO_COMPARE(obj) \
     OBJECT_CHECK(CompareState, (obj), TYPE_COLO_COMPARE)
 
+static QTAILQ_HEAD(, CompareState) net_compares =
+       QTAILQ_HEAD_INITIALIZER(net_compares);
+
 #define COMPARE_READ_LEN_MAX NET_BUFSIZE
 #define MAX_QUEUE_SIZE 1024
 
 /* TODO: Should be configurable */
 #define REGULAR_PACKET_CHECK_MS 3000
 
+static QemuMutex event_mtx = { .lock = PTHREAD_MUTEX_INITIALIZER };
+static QemuCond event_complete_cond = { .cond = PTHREAD_COND_INITIALIZER };
+static int event_unhandled_count;
 /*
   + CompareState ++
   |               |
@@ -86,6 +93,10 @@ typedef struct CompareState {
 
     GMainContext *worker_context;
     GMainLoop *compare_loop;
+    /* Used for COLO to notify compare to do something */
+    FilterNotifier *notifier;
+
+    QTAILQ_ENTRY(CompareState) next;
 } CompareState;
 
 typedef struct CompareClass {
@@ -375,6 +386,11 @@ static void colo_compare_connection(void *opaque, void 
*user_data)
     while (!g_queue_is_empty(&conn->primary_list) &&
            !g_queue_is_empty(&conn->secondary_list)) {
         pkt = g_queue_pop_tail(&conn->primary_list);
+        if (!pkt) {
+            error_report("colo-compare pop pkt failed");
+            return;
+        }
+
         switch (conn->ip_proto) {
         case IPPROTO_TCP:
             result = g_queue_find_custom(&conn->secondary_list,
@@ -496,6 +512,52 @@ static gboolean check_old_packet_regular(void *opaque)
     return TRUE;
 }
 
+/* Public API, Used for COLO frame to notify compare event */
+void colo_notify_compares_event(void *opaque, int event, Error **errp)
+{
+    CompareState *s;
+    int ret;
+
+    qemu_mutex_lock(&event_mtx);
+    QTAILQ_FOREACH(s, &net_compares, next) {
+        ret = filter_notifier_set(s->notifier, event);
+        if (ret < 0) {
+            error_setg_errno(errp, -ret, "Failed to write value to eventfd");
+            goto fail;
+        }
+        event_unhandled_count++;
+    }
+    /* Wait all compare thread to finish handling this event */
+    while (event_unhandled_count) {
+        qemu_cond_wait(&event_complete_cond, &event_mtx);
+    }
+
+fail:
+    qemu_mutex_unlock(&event_mtx);
+}
+
+static void colo_flush_packets(void *opaque, void *user_data);
+
+static void colo_compare_handle_event(void *opaque, int event)
+{
+    FilterNotifier *notify = opaque;
+    CompareState *s = notify->opaque;
+
+    switch (event) {
+    case COLO_CHECKPOINT:
+        g_queue_foreach(&s->conn_list, colo_flush_packets, s);
+        break;
+    case COLO_FAILOVER:
+        break;
+    default:
+        break;
+    }
+    qemu_mutex_lock(&event_mtx);
+    event_unhandled_count--;
+    qemu_cond_broadcast(&event_complete_cond);
+    qemu_mutex_unlock(&event_mtx);
+}
+
 static void *colo_compare_thread(void *opaque)
 {
     CompareState *s = opaque;
@@ -516,8 +578,12 @@ static void *colo_compare_thread(void *opaque)
                           (GSourceFunc)check_old_packet_regular, s, NULL);
     g_source_attach(timeout_source, s->worker_context);
 
+    s->notifier = filter_noitifier_new(colo_compare_handle_event, s, NULL);
+    g_source_attach(&s->notifier->source, s->worker_context);
+
     g_main_loop_run(s->compare_loop);
 
+    g_source_unref(&s->notifier->source);
     g_source_unref(timeout_source);
     g_main_loop_unref(s->compare_loop);
     g_main_context_unref(s->worker_context);
@@ -660,6 +726,8 @@ static void colo_compare_complete(UserCreatable *uc, Error 
**errp)
     net_socket_rs_init(&s->pri_rs, compare_pri_rs_finalize);
     net_socket_rs_init(&s->sec_rs, compare_sec_rs_finalize);
 
+    QTAILQ_INSERT_TAIL(&net_compares, s, next);
+
     g_queue_init(&s->conn_list);
 
     s->connection_track_table = g_hash_table_new_full(connection_key_hash,
@@ -726,6 +794,10 @@ static void colo_compare_finalize(Object *obj)
     g_main_loop_quit(s->compare_loop);
     qemu_thread_join(&s->thread);
 
+    if (!QTAILQ_EMPTY(&net_compares)) {
+        QTAILQ_REMOVE(&net_compares, s, next);
+    }
+
     /* Release all unhandled packets after compare thead exited */
     g_queue_foreach(&s->conn_list, colo_flush_packets, s);
 
diff --git a/net/colo-compare.h b/net/colo-compare.h
new file mode 100644
index 0000000..ed823ed
--- /dev/null
+++ b/net/colo-compare.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) 2016 HUAWEI TECHNOLOGIES CO., LTD.
+ * Copyright (c) 2016 FUJITSU LIMITED
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Author: Zhang Chen <address@hidden>
+ *
+ * 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_COLO_COMPARE_H
+#define QEMU_COLO_COMPARE_H
+
+void colo_notify_compares_event(void *opaque, int event, Error **errp);
+
+#endif /* QEMU_COLO_COMPARE_H */
-- 
1.8.3.1