vitess.io/vitess@v0.16.2/go/vt/vtgate/resolver.go (about) 1 /* 2 Copyright 2019 The Vitess Authors. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package vtgate 18 19 import ( 20 "context" 21 22 "vitess.io/vitess/go/sqltypes" 23 "vitess.io/vitess/go/vt/key" 24 topodatapb "vitess.io/vitess/go/vt/proto/topodata" 25 "vitess.io/vitess/go/vt/srvtopo" 26 ) 27 28 // Resolver is the layer to resolve KeyspaceIds and KeyRanges 29 // to shards. It will try to re-resolve shards if ScatterConn 30 // returns retryable error, which may imply horizontal or vertical 31 // resharding happened. It is implemented using a srvtopo.Resolver. 32 type Resolver struct { 33 scatterConn *ScatterConn 34 resolver *srvtopo.Resolver 35 toposerv srvtopo.Server 36 cell string 37 } 38 39 // NewResolver creates a new Resolver. 40 func NewResolver(resolver *srvtopo.Resolver, serv srvtopo.Server, cell string, sc *ScatterConn) *Resolver { 41 return &Resolver{ 42 scatterConn: sc, 43 resolver: resolver, 44 toposerv: serv, 45 cell: cell, 46 } 47 } 48 49 // MessageStream streams messages. 50 func (res *Resolver) MessageStream(ctx context.Context, keyspace string, shard string, keyRange *topodatapb.KeyRange, name string, callback func(*sqltypes.Result) error) error { 51 var destination key.Destination 52 if shard != "" { 53 // If we pass in a shard, resolve the keyspace/shard 54 // following redirects. 55 destination = key.DestinationShard(shard) 56 } else { 57 // If we pass in a KeyRange, resolve it to the proper shards. 58 // Note we support multiple shards here, we will just aggregate 59 // the message streams. 60 destination = key.DestinationExactKeyRange{KeyRange: keyRange} 61 } 62 rss, err := res.resolver.ResolveDestination(ctx, keyspace, topodatapb.TabletType_PRIMARY, destination) 63 if err != nil { 64 return err 65 } 66 return res.scatterConn.MessageStream(ctx, rss, name, callback) 67 } 68 69 // GetGatewayCacheStatus returns a displayable version of the Gateway cache. 70 func (res *Resolver) GetGatewayCacheStatus() TabletCacheStatusList { 71 return res.scatterConn.GetGatewayCacheStatus() 72 }