refactor like a mastor

1 files changed, 114 insertions, 47 deletions

diff --git a/src/mariadb-push-replica.sh b/src/mariadb-push-replica.sh
index 7134864..e133fad 100755
--- a/src/mariadb-push-replica.sh
+++ b/src/mariadb-push-replica.sh
@@ -124,18 +124,18 @@ stop_mariadb_server_and_remove_database_files()
 {
         livedb=/var/lib/mysql
         set -e
-        if [ -e "$livedb" ]
+        set -o pipefail
+        [ -e "$livedb" ] || return 0
+
+        if [ "$(systemctl is-active mariadb)" = active ]
         then
-                if [ "$(systemctl is-active mariadb)" = active ]
-                then
-                        systemctl stop mariadb
-                fi
-                livedb_backup=$livedb~$(date -Ins)
-                mv -v -T -- "$livedb" "$livedb_backup"
-                mkdir "$livedb"
-                chown --reference="$livedb_backup" "$livedb"
-                chmod --reference="$livedb_backup" "$livedb"
+                systemctl stop mariadb
         fi
+        livedb_backup=$livedb~$(date -Ins)
+        mv -v -T -- "$livedb" "$livedb_backup"
+        mkdir "$livedb"
+        chown --reference="$livedb_backup" "$livedb"
+        chmod --reference="$livedb_backup" "$livedb"
 }
 
 restore_from_backup()
@@ -321,56 +321,117 @@ printarray()
 
 # Call run_replica from here to avoid
 # piping the database back to caller
-# unnecessarily
+# unnecessarily.  Better would be
+# a direct connect from mariadb client
+# to remote mariadb server; but that
+# requires transmitting credentials.
+# Credential-transporter.  Transporter-transporter.
+# Well, a transporter protein is more like a provenance tag,
+# and the transporter code is the receptor to the transporter
+# which is the provenance checker.  But anyway we have that
+# with ssh, except we don't: we are assuming the primary
+# has the ssh root of the replica!  Insanity!  Now this only works
+# because the code runs on the primary; unless we forward the
+# ssh auth with the ssh agent; but that only makes the security
+# flaw temporary not solved; in fact, the replica should receive
+# the transmission on some limited authorization channel; which
+# _could_ be ssh; in fact, the dump could transparently be either
+# live or else cached on the server side; it could be the
+# rsync.net backup even; but ... it needs to include
+# the btrfs snap similarly ... .
 send_mariadb_dump()
 {
-        (set -x
-        mariadb-dump "${@:2}") |
-        replica_host="$1" run_replica pipe_into_mariadb
+        (
+                set -x
+                mariadb-dump "${@:2}"
+        ) |
+        replica_host="$1" run_replica receive_mariadb_dump
 }
 
-pipe_into_mariadb()
+receive_mariadb_dump()
 {
-        pv -f | mariadb
+        pv -f | mariadb --skip-reconnect
 }
 
-mariadbdump_transfer_missing_databases()
+save_array()
 {
-        declare -a primary_dbs
-        mapfile -t primary_dbs < \
-                <(</dev/null run_primary \
-                        mariadb_list_databases | sort -u)
-
-        declare -a replica_dbs
-        mapfile -t replica_dbs < \
-                <(</dev/null run_replica \
-                        mariadb_list_databases | sort -u)
+        declare -n _to_save="$1"
+        case "$2 $3" in
+                'from zfile' )
+                        mapfile -d '' -t _to_save < "$4"
+                        ;;
+                'from lines' )
+                        mapfile -t _to_save < "$4"
+                        ;;
+                * )
+                        false
+                        ;;
+        esac
+}
 
-        declare -a dbs_missing_from_replica
-        mapfile -t dbs_missing_from_replica < \
-                <(comm -23 -- \
-                        <(printarray primary_dbs) \
-                        <(printarray replica_dbs))
+mariadb_scan_databases()
+{
+        declare -g -a primary_dbs
+        save_array primary_dbs from lines <(
+                run_primary mariadb_list_databases </dev/null |
+                sort -u
+        )
+
+        declare -g -a replica_dbs
+        save_array replica_dbs from lines <(
+                run_replica mariadb_list_databases </dev/null |
+                sort -u
+        )
+
+        declare -g -a primary_dbs_not_on_replica
+        save_array primary_dbs_not_on_replica from zfile <(
+                subtract_arrays primary_dbs replica_dbs
+        )
+}
 
+mariadbdump_transfer_missing_databases()
+{
+        mariadb_scan_databases
         declare -a to_replicate
         if [ $# = 0 ]
         then
-                to_replicate=("${dbs_missing_from_replica[@]}")
+                to_replicate=("${primary_dbs_not_on_replica[@]}")
+                printf "Missing on ${replica_host}: %s\n" \
+                        "${to_replicate[@]}"
+                exit
         else
-                mapfile -t to_replicate < \
-                        <(comm -12 -- \
-                                <(printarray dbs_missing_from_replica) \
-                                <(printlines "$@"))
-        fi
-        if [ ${#to_replicate[@]} -gt 0 ]
-        then
-                run_primary \
-                        send_mariadb_dump "$replica_host" \
-                        --master-data \
-                        --gtid \
-                        --single-transaction \
-                        --databases "${to_replicate[@]}"
+                save_array to_replicate from lines \
+                        <(intersection_lines \
+                                <(printarray primary_dbs_not_on_replica) \
+                                <(printlines "$@" | sort -u))
         fi
+        mariadbdump_transfer_databases \
+                "$replica_host" \
+                "${to_replicate[@]}"
+}
+
+mariadbdump_transfer_databases()
+{
+        [ $# -ge 2 ] || return
+        run_primary \
+                send_mariadb_dump "$1" \
+                --master-data \
+                --gtid \
+                --single-transaction \
+                --databases "${@:2}"
+}
+
+intersection_lines()
+{
+        comm -12 -- "$1" "$2"
+}
+
+subtract_arrays()
+{
+        declare -n _a="$1" _b="$2"
+        comm -z -23 -- \
+                <(printf '%s\0' "${_a[@]}") \
+                <(printf '%s\0' "${_b[@]}")
 }
 
 main()
@@ -398,8 +459,14 @@ list_databases()
 {
 mariadb -t "$@" <<.
 select
-        @@hostname,
-        @@server_id,
+        @@hostname
+,       @@server_id
+,       count(schema_name) as 'databases'
+,       @@gtid_slave_pos
+from
+        information_schema.schemata
+;
+select
         schema_name as 'database'
 from
         information_schema.schemata