galera SST scripts: removing obsolete xtrabackup_pid support

Removed handling of the long-unsupported xtrabackup_pid file,
as it is not even created by modern versions of mariabackup.
Instead, added stopping of the asynchronous process that
mariabackup runs (if it is still active) to the exception
handler.

scripts/wsrep_sst_mariabackup.sh

@@ -687,16 +687,16 @@ cleanup_at_exit()
     fi
 
     if [ "$WSREP_SST_OPT_ROLE" = 'joiner' ]; then
+        if [ -n "$BACKUP_PID" ]; then
+            if ps -p $BACKUP_PID >/dev/null 2>&1; then
+                wsrep_log_error \
+                    "mariadb-backup process is still running. Killing..."
+                cleanup_pid $CHECK_PID
+            fi
+        fi
         wsrep_log_info "Removing the sst_in_progress file"
         wsrep_cleanup_progress_file
     else
-        if [ -n "$BACKUP_PID" ]; then
-            if check_pid "$BACKUP_PID" 1; then
-                wsrep_log_error \
-                    "mariadb-backup process is still running. Killing..."
-                cleanup_pid $CHECK_PID "$BACKUP_PID"
-            fi
-        fi
         [ -f "$DATA/$IST_FILE" ] && rm -f "$DATA/$IST_FILE" || :
     fi
 
@@ -906,14 +906,14 @@ monitor_process()
     local sst_stream_pid=$1
 
     while :; do
-        if ! ps -p "$WSREP_SST_OPT_PARENT" >/dev/null 2>&1; then
+        if ! ps -p $WSREP_SST_OPT_PARENT >/dev/null 2>&1; then
             wsrep_log_error \
                 "Parent mysqld process (PID: $WSREP_SST_OPT_PARENT)" \
                 "terminated unexpectedly."
-            kill -- -"$WSREP_SST_OPT_PARENT"
+            kill -- -$WSREP_SST_OPT_PARENT
             exit 32
         fi
-        if ! ps -p "$sst_stream_pid" >/dev/null 2>&1; then
+        if ! ps -p $sst_stream_pid >/dev/null 2>&1; then
             break
         fi
         sleep 0.1
@@ -1073,7 +1073,7 @@ SST_PID="$DATA/wsrep_sst.pid"
 
 # give some time for previous SST to complete:
 check_round=0
-while check_pid "$SST_PID" 0; do
+while check_pid "$SST_PID"; do
     wsrep_log_info "previous SST is not completed, waiting for it to exit"
     check_round=$(( check_round+1 ))
     if [ $check_round -eq 30 ]; then
@@ -1220,9 +1220,6 @@ if [ "$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"
@@ -1402,7 +1399,7 @@ else # joiner
         fi
         mkdir -p "$DATA/.sst"
         (recv_joiner "$DATA/.sst" "$stagemsg-SST" 0 0 0) &
-        jpid=$!
+        BACKUP_PID=$!
         wsrep_log_info "Proceeding with SST"
 
         get_binlog
@@ -1447,6 +1444,7 @@ else # joiner
 
         # Deleting files from previous SST and legacy files from old versions:
         [ -f "$DATA/xtrabackup_binary" ]      && rm -f "$DATA/xtrabackup_binary"
+        [ -f "$DATA/xtrabackup_pid" ]         && rm -f "$DATA/xtrabackup_pid"
         [ -f "$DATA/xtrabackup_checkpoints" ] && rm -f "$DATA/xtrabackup_checkpoints"
         [ -f "$DATA/xtrabackup_info" ]        && rm -f "$DATA/xtrabackup_info"
         [ -f "$DATA/xtrabackup_slave_info" ]  && rm -f "$DATA/xtrabackup_slave_info"
@@ -1457,7 +1455,8 @@ else # joiner
         MAGIC_FILE="$DATA/$INFO_FILE"
 
         wsrep_log_info "Waiting for SST streaming to complete!"
-        monitor_process $jpid
+        monitor_process $BACKUP_PID
+        BACKUP_PID=""
 
         if [ ! -s "$DATA/xtrabackup_checkpoints" ]; then
             wsrep_log_error "xtrabackup_checkpoints missing," \

scripts/wsrep_sst_rsync.sh

@@ -351,7 +351,7 @@ SST_PID="$DATA/wsrep_sst.pid"
 
 # give some time for previous SST to complete:
 check_round=0
-while check_pid "$SST_PID" 0; do
+while check_pid "$SST_PID"; do
     wsrep_log_info "Previous SST is not completed, waiting for it to exit"
     check_round=$(( check_round+1 ))
     if [ $check_round -eq 20 ]; then
@@ -866,19 +866,18 @@ EOF
 
     echo "ready $ADDR:$RSYNC_PORT/$MODULE"
 
-    MYSQLD_PID="$WSREP_SST_OPT_PARENT"
-
     # wait for SST to complete by monitoring magic file
     while [ ! -r "$MAGIC_FILE" ] && check_pid "$TRANSFER_PID" && \
-          ps -p $MYSQLD_PID >/dev/null 2>&1
+          ps -p $WSREP_SST_OPT_PARENT >/dev/null 2>&1
     do
         sleep 1
     done
 
-    if ! ps -p $MYSQLD_PID >/dev/null 2>&1; then
+    if ! ps -p $WSREP_SST_OPT_PARENT >/dev/null 2>&1; then
         wsrep_log_error \
-            "Parent mysqld process (PID: $MYSQLD_PID) terminated unexpectedly."
-        kill -- -$MYSQLD_PID
+            "Parent mysqld process (PID: $WSREP_SST_OPT_PARENT)" \
+            "terminated unexpectedly."
+        kill -- -$WSREP_SST_OPT_PARENT
         sleep 1
         exit 32
     fi