// forceMasterSnapshot: Normally a master is not a viable tablet to snapshot.
// However, there are degenerate cases where you need to override this, for
// instance the initial clone of a new master.
func (wr *Wrangler) PartialSnapshot(tabletAlias topo.TabletAlias, keyName string, startKey, endKey key.HexKeyspaceId, forceMasterSnapshot bool, concurrency int) (manifest string, parent topo.TabletAlias, err error) {
restoreAfterSnapshot, err := wr.prepareToSnapshot(tabletAlias, forceMasterSnapshot)
if err != nil {
return
}
defer func() {
err = replaceError(err, restoreAfterSnapshot())
}()
actionPath, err := wr.ai.PartialSnapshot(tabletAlias, &tm.PartialSnapshotArgs{keyName, startKey, endKey, concurrency})
if err != nil {
return
}
results, actionErr := wr.ai.WaitForCompletionReply(actionPath, wr.actionTimeout())
var reply *tm.SnapshotReply
if actionErr != nil {
relog.Error("PartialSnapshot failed, still restoring tablet type: %v", actionErr)
reply = &tm.SnapshotReply{}
} else {
reply = results.(*tm.SnapshotReply)
tm.BackfillAlias(reply.ZkParentPath, &reply.ParentAlias)
}
return reply.ManifestPath, reply.ParentAlias, actionErr
}
// forceMasterSnapshot: Normally a master is not a viable tablet to snapshot.
// However, there are degenerate cases where you need to override this, for
// instance the initial clone of a new master.
func (wr *Wrangler) Snapshot(tabletAlias topo.TabletAlias, forceMasterSnapshot bool, snapshotConcurrency int, serverMode bool) (manifest string, parent topo.TabletAlias, slaveStartRequired, readOnly bool, originalType topo.TabletType, err error) {
var ti *topo.TabletInfo
ti, err = wr.ts.GetTablet(tabletAlias)
if err != nil {
return
}
originalType = ti.Tablet.Type
if ti.Tablet.Type == topo.TYPE_MASTER && forceMasterSnapshot {
// In this case, we don't bother recomputing the serving graph.
// All queries will have to fail anyway.
log.Infof("force change type master -> backup: %v", tabletAlias)
// There is a legitimate reason to force in the case of a single
// master.
ti.Tablet.Type = topo.TYPE_BACKUP
err = topo.UpdateTablet(wr.ts, ti)
} else {
err = wr.ChangeType(ti.Alias(), topo.TYPE_BACKUP, false)
}
if err != nil {
return
}
var actionPath string
actionPath, err = wr.ai.Snapshot(tabletAlias, &tm.SnapshotArgs{snapshotConcurrency, serverMode})
if err != nil {
return
}
// wait for completion, and save the error
results, actionErr := wr.ai.WaitForCompletionReply(actionPath, wr.actionTimeout())
var reply *tm.SnapshotReply
newType := originalType
if actionErr != nil {
log.Errorf("snapshot failed, still restoring tablet type: %v", actionErr)
reply = &tm.SnapshotReply{}
} else {
reply = results.(*tm.SnapshotReply)
tm.BackfillAlias(reply.ZkParentPath, &reply.ParentAlias)
if serverMode {
log.Infof("server mode specified, switching tablet to snapshot_source mode")
newType = topo.TYPE_SNAPSHOT_SOURCE
}
}
// Go back to original type, or go to SNAPSHOT_SOURCE
log.Infof("change type after snapshot: %v %v", tabletAlias, newType)
if ti.Tablet.Parent.Uid == topo.NO_TABLET && forceMasterSnapshot && newType != topo.TYPE_SNAPSHOT_SOURCE {
log.Infof("force change type backup -> master: %v", tabletAlias)
ti.Tablet.Type = topo.TYPE_MASTER
err = topo.UpdateTablet(wr.ts, ti)
} else {
err = wr.ChangeType(ti.Alias(), newType, false)
}
if err != nil {
// failure in changing the topology type is probably worse,
// so returning that (we logged actionErr anyway)
return
}
return reply.ManifestPath, reply.ParentAlias, reply.SlaveStartRequired, reply.ReadOnly, originalType, actionErr
}