MDEV-30822: Adjust wsrep_sst_mariabackup.sh to understand both pre-MDEV-18931...

MDEV-30822: Adjust wsrep_sst_mariabackup.sh to understand both pre-MDEV-18931 and post-MDEV-18931 file naming

This commit adds support for legacy names for files such
as mariadb_backup_galera_info, mariadb_backup_checkpoints
and mariabackup_binlog_info to allow upgrading from old
to new server versions without stopping the galera cluster.

In addition, improved handling of errors to prevent hangs
detected during stress testing of the updated SST script
for mariabackup (when conditions for hangs at the mariabackup
stage were artificially created).

scripts/wsrep_sst_mariabackup.sh

@@ -846,7 +846,13 @@ recv_joiner()
     done
 
     if [ $checkf -eq 1 ]; then
-        if [ ! -r "$MAGIC_FILE" ]; then
+        if [ -r "$MAGIC_FILE" ]; then
+            :
+        elif [ -r "$STATDIR/xtrabackup_galera_info" ]; then
+            mv "$STATDIR/xtrabackup_galera_info" "$MAGIC_FILE"
+            wsrep_log_info "the SST donor uses an old version" \
+                           "of mariabackup or xtrabackup"
+        else
             # this message should cause joiner to abort:
             wsrep_log_error "receiving process ended without creating" \
                             "magic file ($MAGIC_FILE)"
@@ -919,9 +925,6 @@ monitor_process()
     done
 }
 
-[ -f "$MAGIC_FILE" ] && rm -f "$MAGIC_FILE"
-[ -f "$DONOR_MAGIC_FILE" ] && rm -rf "$DONOR_MAGIC_FILE"
-
 read_cnf
 setup_ports
 
@@ -1071,6 +1074,23 @@ get_transfer
 findopt='-L'
 [ "$OS" = 'FreeBSD' ] && findopt="$findopt -E"
 
+SST_PID="$DATA/wsrep_sst.pid"
+
+# give some time for previous SST to complete:
+check_round=0
+while check_pid "$SST_PID" 0; do
+    wsrep_log_info "previous SST is not completed, waiting for it to exit"
+    check_round=$(( check_round+1 ))
+    if [ $check_round -eq 30 ]; then
+       wsrep_log_error "previous SST script still running."
+       exit 114 # EALREADY
+    fi
+    sleep 1
+done
+
+[ -f "$MAGIC_FILE" ] && rm -f "$MAGIC_FILE"
+[ -f "$DONOR_MAGIC_FILE" ] && rm -f "$DONOR_MAGIC_FILE"
+
 if [ "$WSREP_SST_OPT_ROLE" = 'donor' ]; then
 
     trap cleanup_at_exit EXIT
@@ -1185,6 +1205,9 @@ if [ "$WSREP_SST_OPT_ROLE" = 'donor' ]; then
 
         setup_commands
 
+        # mariadb-backup implicitly writes PID to fixed location in $xtmpdir
+        BACKUP_PID="$xtmpdir/xtrabackup_pid"
+
         set +e
         timeit "$stagemsg-SST" "$INNOBACKUP | $tcmd; RC=( "\${PIPESTATUS[@]}" )"
         set -e
@@ -1198,9 +1221,6 @@ if [ "$WSREP_SST_OPT_ROLE" = 'donor' ]; then
             exit 22
         fi
 
-        # mariadb-backup implicitly writes PID to fixed location in $xtmpdir
-        BACKUP_PID="$xtmpdir/xtrabackup_pid"
-
     else # BYPASS FOR IST
 
         wsrep_log_info "Bypassing the SST for IST"
@@ -1313,20 +1333,6 @@ else # joiner
         impts="--parallel=$backup_threads${impts:+ }$impts"
     fi
 
-    SST_PID="$DATA/wsrep_sst.pid"
-
-    # give some time for previous SST to complete:
-    check_round=0
-    while check_pid "$SST_PID" 0; do
-        wsrep_log_info "previous SST is not completed, waiting for it to exit"
-        check_round=$(( check_round+1 ))
-        if [ $check_round -eq 10 ]; then
-            wsrep_log_error "previous SST script still running."
-            exit 114 # EALREADY
-        fi
-        sleep 1
-    done
-
     trap simple_cleanup EXIT
     echo $$ > "$SST_PID"
 
@@ -1336,10 +1342,6 @@ else # joiner
 
     [ -f "$DATA/$IST_FILE" ] && rm -f "$DATA/$IST_FILE"
 
-    # May need mariadb_backup_checkpoints later on
-    [ -f "$DATA/xtrabackup_binary" ]      && rm -f "$DATA/xtrabackup_binary"
-    [ -f "$DATA/mariadb_backup_galera_info" ] && rm -f "$DATA/mariadb_backup_galera_info"
-
     ADDR="$WSREP_SST_OPT_HOST"
 
     if [ "${tmode#VERIFY}" != "$tmode" ]; then
@@ -1443,6 +1445,9 @@ else # joiner
                 "$DATA" -mindepth 1 -prune -regex "$cpat" \
                 -o -exec rm -rf {} >&2 \+
 
+        [ -f "$DATA/xtrabackup_checkpoints" ]     && rm -f "$DATA/xtrabackup_checkpoints"
+        [ -f "$DATA/mariadb_backup_checkpoints" ] && rm -f "$DATA/mariadb_backup_checkpoints"
+
         TDATA="$DATA"
         DATA="$DATA/.sst"
         MAGIC_FILE="$DATA/$INFO_FILE"
@@ -1450,6 +1455,16 @@ else # joiner
         wsrep_log_info "Waiting for SST streaming to complete!"
         monitor_process $jpid
 
+        # An old version of the donor may send a checkpoints
+        # list file under an outdated name:
+        if [ ! -f "$DATA/mariadb_backup_checkpoints" -a \
+               -f "$DATA/xtrabackup_checkpoints" ]
+        then
+            mv "$DATA/xtrabackup_checkpoints" "$DATA/mariadb_backup_checkpoints"
+            wsrep_log_info "list of checkpoints with a legacy" \
+                           "name has been renamed"
+        fi
+
         if [ ! -s "$DATA/mariadb_backup_checkpoints" ]; then
             wsrep_log_error "mariadb_backup_checkpoints missing," \
                             "failed mariadb-backup/SST on donor"
@@ -1509,6 +1524,16 @@ else # joiner
             fi
         fi
 
+        # An old version of the donor may send a binary logs
+        # list file under an outdated name:
+        if [ ! -f "$DATA/mariadb_backup_binlog_info" -a \
+               -f "$DATA/xtrabackup_binlog_info" ]
+        then
+            mv "$DATA/xtrabackup_binlog_info" "$DATA/mariadb_backup_binlog_info"
+            wsrep_log_info "list of binary logs with a legacy" \
+                           "name has been renamed"
+        fi
+
         wsrep_log_info "Preparing the backup at $DATA"
         setup_commands
         timeit 'mariadb-backup prepare stage' "$INNOAPPLY"
@@ -1579,11 +1604,6 @@ else # joiner
 
     fi
 
-    if [ ! -r "$MAGIC_FILE" ]; then
-        wsrep_log_error "SST magic file '$MAGIC_FILE' not found/readable"
-        exit 2
-    fi
-
     # use donor magic file, if present
     # if IST was used, donor magic file was not created
     # Remove special tags from the magic file, and from the output: