dsync: Debug logging improvements and comment clarifications.

diff --git a/src/doveadm/dsync/dsync-mailbox-import.c b/src/doveadm/dsync/dsync-mailbox-import.c
index f12757b25d840eefc49cc7ee66ed8aab0b32b1ab..12f534471d6adac086fb22409b20ff64df93aee5 100644 (file)
--- a/src/doveadm/dsync/dsync-mailbox-import.c
+++ b/src/doveadm/dsync/dsync-mailbox-import.c
@@ -1370,12 +1370,14 @@ dsync_mailbox_import_match_msg(struct dsync_mailbox_importer *importer,
 
 static bool
 dsync_mailbox_find_common_expunged_uid(struct dsync_mailbox_importer *importer,
-                                      const struct dsync_mail_change *change)
+                                      const struct dsync_mail_change *change,
+                                      const char **result_r)
 {
        const struct dsync_mail_change *local_change;
 
        if (*change->guid == '\0') {
                /* remote doesn't support GUIDs, can't verify expunge */
+               *result_r = "GUIDs not supported, can't verify expunge";
                return FALSE;
        }
 
@@ -1385,20 +1387,27 @@ dsync_mailbox_find_common_expunged_uid(struct dsync_mailbox_importer *importer,
           GUID string to 128bit GUID first. */
        local_change = hash_table_lookup(importer->local_changes,
                                         POINTER_CAST(change->uid));
-       if (local_change == NULL || local_change->guid == NULL)
+       if (local_change == NULL || local_change->guid == NULL) {
+               *result_r = "Expunged local mail's GUID not found";
                return FALSE;
+       }
 
        i_assert(local_change->type == DSYNC_MAIL_CHANGE_TYPE_EXPUNGE);
        if (dsync_mail_change_guid_equals(importer, local_change,
-                                         change->guid, NULL))
+                                         change->guid, NULL)) {
                importer->last_common_uid = change->uid;
-       else if (change->type != DSYNC_MAIL_CHANGE_TYPE_EXPUNGE)
+               *result_r = "Expunged local mail's GUID matches remote";
+       } else if (change->type != DSYNC_MAIL_CHANGE_TYPE_EXPUNGE) {
                dsync_mailbox_common_uid_found(importer);
-       else {
+               *result_r = "Expunged local mail's GUID doesn't match remote GUID";
+       } else {
                /* GUID mismatch for two expunged mails. dsync can't update
                   GUIDs for already expunged messages, so we can't immediately
                   determine that the rest of the messages are a mismatch. so
                   for now we'll just skip over this pair. */
+               *result_r = "Expunged mails' GUIDs don't match - delaying decision";
+               /* NOTE: the return value here doesn't matter, because the only
+                  caller that checks for it never reaches this code path */
        }
        return TRUE;
 }
@@ -1436,20 +1445,22 @@ dsync_mailbox_find_common_uid(struct dsync_mailbox_importer *importer,
                        *result_r = "Expunged mail not found locally";
                        return;
                }
-               if (importer->revert_local_changes &&
-                   importer->local_uid_next > change->uid) {
+               i_assert(change->guid != NULL);
+               if (importer->local_uid_next <= change->uid) {
+                       dsync_mailbox_common_uid_found(importer);
+                       *result_r = "Mail's UID is above local UIDNEXT";
+               } else if (importer->revert_local_changes) {
                        dsync_mailbox_revert_missing(importer, change);
                        *result_r = "Reverting local change by deleting mailbox";
-               } else if (change->guid == NULL ||
-                        !dsync_mailbox_find_common_expunged_uid(importer, change)) {
-                       /* couldn't match it for an expunged mail. use the last
-                          message with a matching GUID as the last common
+               } else if (!dsync_mailbox_find_common_expunged_uid(importer, change, result_r)) {
+                       /* it's unknown if this mail existed locally and was
+                          expunged. since we don't want to lose any mails,
+                          assume that we need to preserve the mail. use the
+                          last message with a matching GUID as the last common
                           UID. */
                        dsync_mailbox_common_uid_found(importer);
-                       *result_r = "No more local mails found";
-               } else {
-                       *result_r = "Mail expunged locally";
                }
+               *result_r = t_strdup_printf("%s - No more local mails found", *result_r);
                return;
        }
 
@@ -1478,10 +1489,8 @@ dsync_mailbox_find_common_uid(struct dsync_mailbox_importer *importer,
            change->type != DSYNC_MAIL_CHANGE_TYPE_EXPUNGE) {
                dsync_mailbox_revert_missing(importer, change);
                *result_r = "Reverting local change by deleting mailbox";
-       } else if (dsync_mailbox_find_common_expunged_uid(importer, change)) {
-               *result_r = "Mail expunged locally";
        } else {
-               *result_r = "Mail not found locally";
+               (void)dsync_mailbox_find_common_expunged_uid(importer, change, result_r);
        }
        *result_r = t_strdup_printf("%s (next local mail UID=%u)",
                                    *result_r, importer->cur_mail->uid);