BUG/MINOR: peers: empty chunks after a resync.

After pushing the last update related to a resync process, the teacher resets
the re-connection's origin to the saved one (pointer position when he receive
the resync request). But the last acknowledgement overwrites this pointer to
an inconsistent value. In peersv2, it results with empty table chunks
regularly pushed.

The fix consist to move the confirm code to assure that the confirm message is
always sent after the last acknowledgement related to the resync. And to reset
the re-connection's origin to the saved one when a confirm message is received.

This bug affects versions 1.6 and superior.

For older versions (peersv1), this inconsistent state should not generate side
effects because chunks are not used and a next acknowlegement message resets
the pointer in a valid state.

diff --git a/src/peers.c b/src/peers.c
index b3a14e6a7a2c4835c9fd76240f2dd12112fc5950..6f88c192518e210879eeffb60a3e259041885032 100644 (file)
--- a/src/peers.c
+++ b/src/peers.c
@@ -886,6 +886,7 @@ switchstate:
                                                curpeer->confirm++;
                                        }
                                        else if (msg_head[1] == PEER_MSG_CTRL_RESYNCCONFIRM)  {
+                                               struct shared_table *st;
 
                                                /* If stopping state */
                                                if (stopping) {
@@ -894,6 +895,10 @@ switchstate:
                                                        appctx->st0 = PEER_SESS_ST_END;
                                                        goto switchstate;
                                                }
+                                               for (st = curpeer->tables; st; st = st->next) {
+                                                       st->update = st->last_pushed = st->teaching_origin;
+                                                       st->flags = 0;
+                                               }
 
                                                 /* reset teaching flags to 0 */
                                                curpeer->flags &= PEER_TEACH_RESET;
@@ -1224,25 +1229,6 @@ incomplete:
                                }
 
 
-                               /* Confirm finished or partial messages */
-                               while (curpeer->confirm) {
-                                       unsigned char msg[2];
-
-                                       /* There is a confirm messages to send */
-                                       msg[0] = PEER_MSG_CLASS_CONTROL;
-                                       msg[1] = PEER_MSG_CTRL_RESYNCCONFIRM;
-
-                                       /* message to buffer */
-                                       repl = bi_putblk(si_ic(si), (char *)msg, sizeof(msg));
-                                       if (repl <= 0) {
-                                               /* no more write possible */
-                                               if (repl == -1)
-                                                       goto full;
-                                               appctx->st0 = PEER_SESS_ST_END;
-                                               goto switchstate;
-                                       }
-                                       curpeer->confirm--;
-                               }
 
 
                                /* Need to request a resync */
@@ -1491,7 +1477,6 @@ incomplete:
                                                                        /* push local updates */
                                                                        if (!eb || eb->key > st->teaching_origin) {
                                                                                st->flags |= SHTABLE_F_TEACH_STAGE2;
-                                                                               st->last_pushed = st->teaching_origin;
                                                                                break;
                                                                        }
 
@@ -1548,6 +1533,26 @@ incomplete:
                                        curpeer->flags |= PEER_F_TEACH_FINISHED;
                                }
 
+                               /* Confirm finished or partial messages */
+                               while (curpeer->confirm) {
+                                       unsigned char msg[2];
+
+                                       /* There is a confirm messages to send */
+                                       msg[0] = PEER_MSG_CLASS_CONTROL;
+                                       msg[1] = PEER_MSG_CTRL_RESYNCCONFIRM;
+
+                                       /* message to buffer */
+                                       repl = bi_putblk(si_ic(si), (char *)msg, sizeof(msg));
+                                       if (repl <= 0) {
+                                               /* no more write possible */
+                                               if (repl == -1)
+                                                       goto full;
+                                               appctx->st0 = PEER_SESS_ST_END;
+                                               goto switchstate;
+                                       }
+                                       curpeer->confirm--;
+                               }
+
                                /* noting more to do */
                                goto out;
                        }