// GetOrCreateShard will return the shard object, or create one if it doesn't // already exist. Note the shard creation is protected by a keyspace Lock. func GetOrCreateShard(ctx context.Context, ts topo.Server, keyspace, shard string) (*topo.ShardInfo, error) { si, finalErr := ts.GetShard(ctx, keyspace, shard) if finalErr == topo.ErrNoNode { // create the keyspace, maybe it already exists if err := ts.CreateKeyspace(ctx, keyspace, &pb.Keyspace{}); err != nil && err != topo.ErrNodeExists { return nil, fmt.Errorf("CreateKeyspace(%v) failed: %v", keyspace, err) } // now we can lock the keyspace node := actionnode.KeyspaceCreateShard() lockPath, err := node.LockKeyspace(ctx, ts, keyspace) if err != nil { return nil, fmt.Errorf("LockKeyspace failed: %v", err) } // now try to create within the lock, may already exist if err := ts.CreateShard(ctx, keyspace, shard); err != nil && err != topo.ErrNodeExists { return nil, node.UnlockKeyspace(ctx, ts, keyspace, lockPath, fmt.Errorf("CreateShard(%v/%v) failed: %v", keyspace, shard, err)) } // try to read the shard again, maybe someone created it // in between the original GetShard and the LockKeyspace si, finalErr = ts.GetShard(ctx, keyspace, shard) // and unlock if err := node.UnlockKeyspace(ctx, ts, keyspace, lockPath, finalErr); err != nil { return nil, fmt.Errorf("UnlockKeyspace failed: %v", err) } } return si, finalErr }
// CreateShard will create the shard, while holding the keyspace lock func CreateShard(ctx context.Context, ts topo.Server, keyspace, shard string) error { // Lock the keyspace node := actionnode.KeyspaceCreateShard() lockPath, err := node.LockKeyspace(ctx, ts, keyspace) if err != nil { return fmt.Errorf("LockKeyspace failed: %v", err) } // now try to create within the lock, may already exist err = ts.CreateShard(ctx, keyspace, shard) // and unlock and return return node.UnlockKeyspace(ctx, ts, keyspace, lockPath, err) }
// CopyShards will create the keyspaces in the destination topo func CopyShards(fromTS, toTS topo.Server, deleteKeyspaceShards bool) { keyspaces, err := fromTS.GetKeyspaces() if err != nil { relog.Fatal("fromTS.GetKeyspaces failed: %v", err) } wg := sync.WaitGroup{} rec := concurrency.AllErrorRecorder{} for _, keyspace := range keyspaces { wg.Add(1) go func(keyspace string) { defer wg.Done() shards, err := fromTS.GetShardNames(keyspace) if err != nil { rec.RecordError(err) return } if deleteKeyspaceShards { if err := toTS.DeleteKeyspaceShards(keyspace); err != nil { rec.RecordError(err) return } } for _, shard := range shards { wg.Add(1) go func(keyspace, shard string) { defer wg.Done() if err := toTS.CreateShard(keyspace, shard); err != nil { if err == topo.ErrNodeExists { relog.Warning("shard %v/%v already exists", keyspace, shard) } else { rec.RecordError(err) } } }(keyspace, shard) } }(keyspace) } wg.Wait() if rec.HasErrors() { relog.Fatal("copyShards failed: %v", rec.Error()) } }