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split.go
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split.go
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// Copyright 2012, Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package wrangler
import (
"fmt"
"golang.org/x/net/context"
pb "github.com/youtube/vitess/go/vt/proto/topodata"
)
// SetSourceShards is a utility function to override the SourceShards fields
// on a Shard.
func (wr *Wrangler) SetSourceShards(ctx context.Context, keyspace, shard string, sources []*pb.TabletAlias, tables []string) error {
// read the shard
shardInfo, err := wr.ts.GetShard(ctx, keyspace, shard)
if err != nil {
return err
}
// If the shard already has sources, maybe it's already been restored,
// so let's be safe and abort right here.
if len(shardInfo.SourceShards) > 0 {
return fmt.Errorf("Shard %v/%v already has SourceShards, not overwriting them", keyspace, shard)
}
// read the source tablets
sourceTablets, err := wr.ts.GetTabletMap(ctx, sources)
if err != nil {
return err
}
// Insert their KeyRange in the SourceShards array.
// We use a linear 0-based id, that matches what mysqlctld/split.go
// inserts into _vt.blp_checkpoint.
shardInfo.SourceShards = make([]*pb.Shard_SourceShard, len(sourceTablets))
i := 0
for _, ti := range sourceTablets {
shardInfo.SourceShards[i] = &pb.Shard_SourceShard{
Uid: uint32(i),
Keyspace: ti.Keyspace,
Shard: ti.Shard,
KeyRange: ti.KeyRange,
Tables: tables,
}
i++
}
// and write the shard
if err = wr.ts.UpdateShard(ctx, shardInfo); err != nil {
return err
}
return nil
}