// NewPartitionConsumer creates a new partition consumer instance
func NewPartitionConsumer(group *ConsumerGroup, partition int32) (*PartitionConsumer, error) {
config := sarama.ConsumerConfig{
DefaultFetchSize: group.config.DefaultFetchSize,
EventBufferSize: group.config.EventBufferSize,
MaxMessageSize: group.config.MaxMessageSize,
MaxWaitTime: group.config.MaxWaitTime,
MinFetchSize: group.config.MinFetchSize,
OffsetMethod: sarama.OffsetMethodOldest,
}
offset, err := group.Offset(partition)
if err != nil {
return nil, err
} else if offset > 0 {
config.OffsetMethod = sarama.OffsetMethodManual
config.OffsetValue = offset
}
stream, err := sarama.NewConsumer(group.client, group.topic, partition, group.name, &config)
if err != nil {
return nil, err
}
return &PartitionConsumer{
stream: stream,
topic: group.topic,
partition: partition,
}, nil
}
// Validate consumer config, maybe sarama can expose a public ConsumerConfig.Validate() one day
func validateConsumerConfig(config *sarama.ConsumerConfig) error {
if config.DefaultFetchSize < 0 {
return sarama.ConfigurationError("Invalid DefaultFetchSize")
} else if config.DefaultFetchSize == 0 {
config.DefaultFetchSize = 1024
}
if config.MinFetchSize < 0 {
return sarama.ConfigurationError("Invalid MinFetchSize")
} else if config.MinFetchSize == 0 {
config.MinFetchSize = 1
}
if config.MaxWaitTime <= 0 {
return sarama.ConfigurationError("Invalid MaxWaitTime")
} else if config.MaxWaitTime < 100 {
sarama.Logger.Println("ConsumerConfig.MaxWaitTime is very low, which can cause high CPU and network usage. See sarama documentation for details.")
}
if config.MaxMessageSize < 0 {
return sarama.ConfigurationError("Invalid MaxMessageSize")
} else if config.EventBufferSize < 0 {
return sarama.ConfigurationError("Invalid EventBufferSize")
}
return nil
}