simplify: Partition() can never return a non-nil error

cluster/partitioner/partitioner.go

@@ -12,7 +12,7 @@ import (
 
 type Partitioner interface {
 	Key(schema.PartitionedMetric, []byte) []byte
-	Partition(schema.PartitionedMetric, int32) (int32, error)
+	Partition(schema.PartitionedMetric, int32) int32
 }
 
 // NewKafka returns the appropriate kafka partitioner
@@ -42,17 +42,14 @@ func (k KafkaByOrg) Key(m schema.PartitionedMetric, b []byte) []byte {
 }
 
 // Partition partitions just like sarama.HashPartitioner but without needing a *sarama.ProducerMessage
-func (k KafkaByOrg) Partition(m schema.PartitionedMetric, numPartitions int32) (int32, error) {
+func (k KafkaByOrg) Partition(m schema.PartitionedMetric, numPartitions int32) int32 {
 	k.hasher.Reset()
-	_, err := k.hasher.Write(k.Key(m, nil))
-	if err != nil {
-		return -1, err
-	}
+	k.hasher.Write(k.Key(m, nil)) // fnv can never return a non-nil error
 	partition := int32(k.hasher.Sum32()) % numPartitions
 	if partition < 0 {
 		partition = -partition
 	}
-	return partition, nil
+	return partition
 }
 
 // KafkaBySeries partitions a schema.PartitionedMetric by Series name, using hashing equivalent to sarama.HashPartitioner
@@ -65,17 +62,14 @@ func (k KafkaBySeries) Key(m schema.PartitionedMetric, b []byte) []byte {
 }
 
 // Partition partitions just like sarama.HashPartitioner but without needing a *sarama.ProducerMessage
-func (k KafkaBySeries) Partition(m schema.PartitionedMetric, numPartitions int32) (int32, error) {
+func (k KafkaBySeries) Partition(m schema.PartitionedMetric, numPartitions int32) int32 {
 	k.hasher.Reset()
-	_, err := k.hasher.Write(k.Key(m, nil))
-	if err != nil {
-		return -1, err
-	}
+	k.hasher.Write(k.Key(m, nil)) // fnv can never return a non-nil error
 	partition := int32(k.hasher.Sum32()) % numPartitions
 	if partition < 0 {
 		partition = -partition
 	}
-	return partition, nil
+	return partition
 }
 
 // KafkaBySeriesWithTags partitions a schema.PartitionedMetric by nameWithTags, using a custom xxhash+jump hashing scheme
@@ -87,7 +81,7 @@ func (k KafkaBySeriesWithTags) Key(m schema.PartitionedMetric, b []byte) []byte
 }
 
 // Partition partitions using a custom xxhash+jump hashing scheme
-func (k KafkaBySeriesWithTags) Partition(m schema.PartitionedMetric, numPartitions int32) (int32, error) {
+func (k KafkaBySeriesWithTags) Partition(m schema.PartitionedMetric, numPartitions int32) int32 {
 	jumpKey := xxhash.Sum64(k.Key(m, nil))
-	return jump.Hash(jumpKey, int(numPartitions)), nil
+	return jump.Hash(jumpKey, int(numPartitions))
 }

cmd/mt-index-migrate/main.go

@@ -181,12 +181,7 @@ func getDefs(session *gocql.Session, defsChan chan *schema.MetricDefinition) {
 		if *numPartitions == 1 {
 			mdef.Partition = 0
 		} else {
-			p, err := partitioner.Partition(&mdef, int32(*numPartitions))
-			if err != nil {
-				log.Fatalf("failed to get partition id of metric. %s", err.Error())
-			} else {
-				mdef.Partition = p
-			}
+			mdef.Partition = partitioner.Partition(&mdef, int32(*numPartitions))
 		}
 		defsChan <- &mdef
 	}

cmd/mt-whisper-importer-writer/main.go

@@ -238,11 +238,7 @@ func (s *Server) chunksHandler(w http.ResponseWriter, req *http.Request) {
 		throwError(fmt.Sprintf("Invalid MetricData.Id: %s", err))
 	}
 
-	partition, err := s.Partitioner.Partition(&metric.MetricData, int32(*numPartitions))
-	if err != nil {
-		throwError(fmt.Sprintf("Error partitioning: %q", err))
-		return
-	}
+	partition := s.Partitioner.Partition(&metric.MetricData, int32(*numPartitions))
 	s.Index.AddOrUpdate(mkey, &metric.MetricData, partition)
 
 	for archiveIdx, a := range metric.Archives {