github.com/adnan-c/fabric_e2e_couchdb@v0.6.1-preview.0.20170228180935-21ce6b23cf91/orderer/kafka/broker.go (about) 1 /* 2 Copyright IBM Corp. 2016 All Rights Reserved. 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 kafka 18 19 import ( 20 "fmt" 21 22 "github.com/Shopify/sarama" 23 ) 24 25 // Broker allows the caller to get info on the cluster's partitions 26 type Broker interface { 27 GetOffset(cp ChainPartition, req *sarama.OffsetRequest) (int64, error) 28 Closeable 29 } 30 31 type brokerImpl struct { 32 broker *sarama.Broker 33 } 34 35 // Connects to the broker that handles all produce and consume 36 // requests for the given chain (Partition Leader Replica) 37 func newBroker(brokers []string, cp ChainPartition) (Broker, error) { 38 var candidateBroker, connectedBroker, leaderBroker *sarama.Broker 39 40 // Connect to one of the given brokers 41 for _, hostPort := range brokers { 42 candidateBroker = sarama.NewBroker(hostPort) 43 if err := candidateBroker.Open(nil); err != nil { 44 logger.Warningf("Failed to connect to broker %s: %s", hostPort, err) 45 continue 46 } 47 if connected, err := candidateBroker.Connected(); !connected { 48 logger.Warningf("Failed to connect to broker %s: %s", hostPort, err) 49 continue 50 } 51 connectedBroker = candidateBroker 52 break 53 } 54 55 if connectedBroker == nil { 56 return nil, fmt.Errorf("Failed to connect to any of the given brokers (%v) for metadata request", brokers) 57 } 58 logger.Debugf("Connected to broker %s", connectedBroker.Addr()) 59 60 // Get metadata for the topic that corresponds to this chain 61 metadata, err := connectedBroker.GetMetadata(&sarama.MetadataRequest{Topics: []string{cp.Topic()}}) 62 if err != nil { 63 return nil, fmt.Errorf("Failed to get metadata for topic %s: %s", cp, err) 64 } 65 66 // Get the leader broker for this chain partition 67 if (cp.Partition() >= 0) && (cp.Partition() < int32(len(metadata.Topics[0].Partitions))) { 68 leaderBrokerID := metadata.Topics[0].Partitions[cp.Partition()].Leader 69 logger.Debugf("Leading broker for chain %s is broker ID %d", cp, leaderBrokerID) 70 for _, availableBroker := range metadata.Brokers { 71 if availableBroker.ID() == leaderBrokerID { 72 leaderBroker = availableBroker 73 break 74 } 75 } 76 } 77 78 if leaderBroker == nil { 79 return nil, fmt.Errorf("Can't find leader for chain %s", cp) 80 } 81 82 // Connect to broker 83 if err := leaderBroker.Open(nil); err != nil { 84 return nil, fmt.Errorf("Failed to connect ho Kafka broker: %s", err) 85 } 86 if connected, err := leaderBroker.Connected(); !connected { 87 return nil, fmt.Errorf("Failed to connect to Kafka broker: %s", err) 88 } 89 90 return &brokerImpl{broker: leaderBroker}, nil 91 } 92 93 // GetOffset retrieves the offset number that corresponds 94 // to the requested position in the log. 95 func (b *brokerImpl) GetOffset(cp ChainPartition, req *sarama.OffsetRequest) (int64, error) { 96 resp, err := b.broker.GetAvailableOffsets(req) 97 if err != nil { 98 return int64(-1), err 99 } 100 return resp.GetBlock(cp.Topic(), cp.Partition()).Offsets[0], nil 101 } 102 103 // Close terminates the broker. 104 // This is invoked by the session deliverer's getOffset method. 105 func (b *brokerImpl) Close() error { 106 return b.broker.Close() 107 }