Class: Kafka::OffsetManager
- Inherits:
-
Object
- Object
- Kafka::OffsetManager
- Defined in:
- lib/kafka/offset_manager.rb
Overview
Manages a consumer's position in partitions, figures out where to resume processing from, etc.
Constant Summary collapse
- DEFAULT_RETENTION_TIME =
The default broker setting for offsets.retention.minutes is 1440.
1440 * 60
Instance Method Summary collapse
-
#clear_offsets ⇒ nil
Clear all stored offset information.
-
#clear_offsets_excluding(excluded) ⇒ nil
Clear stored offset information for all partitions except those specified in
excluded
. -
#commit_offsets(recommit = false) ⇒ nil
Commit offsets of messages that have been marked as processed.
-
#commit_offsets_if_necessary ⇒ nil
Commit offsets if necessary, according to the offset commit policy specified when initializing the class.
-
#initialize(cluster:, group:, logger:, commit_interval:, commit_threshold:, offset_retention_time:) ⇒ OffsetManager
constructor
A new instance of OffsetManager.
-
#mark_as_processed(topic, partition, offset) ⇒ nil
Mark a message as having been processed.
-
#next_offset_for(topic, partition) ⇒ Integer
Return the next offset that should be fetched for the specified partition.
-
#seek_to(topic, partition, offset) ⇒ nil
Move the consumer's position in the partition to the specified offset.
-
#seek_to_default(topic, partition) ⇒ nil
Move the consumer's position in the partition back to the configured default offset, either the first or latest in the partition.
-
#set_default_offset(topic, default_offset) ⇒ nil
Set the default offset for a topic.
Constructor Details
#initialize(cluster:, group:, logger:, commit_interval:, commit_threshold:, offset_retention_time:) ⇒ OffsetManager
Returns a new instance of OffsetManager.
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# File 'lib/kafka/offset_manager.rb', line 10 def initialize(cluster:, group:, logger:, commit_interval:, commit_threshold:, offset_retention_time:) @cluster = cluster @group = group @logger = logger @commit_interval = commit_interval @commit_threshold = commit_threshold @uncommitted_offsets = 0 @processed_offsets = {} @default_offsets = {} @committed_offsets = nil @resolved_offsets = {} @last_commit = Time.now @last_recommit = nil @recommit_interval = (offset_retention_time || DEFAULT_RETENTION_TIME) / 2 end |
Instance Method Details
#clear_offsets ⇒ nil
Clear all stored offset information.
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# File 'lib/kafka/offset_manager.rb', line 144 def clear_offsets @processed_offsets.clear @resolved_offsets.clear # Clear the cached commits from the brokers. @committed_offsets = nil end |
#clear_offsets_excluding(excluded) ⇒ nil
Clear stored offset information for all partitions except those specified
in excluded
.
offset_manager.clear_offsets_excluding("my-topic" => [1, 2, 3])
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# File 'lib/kafka/offset_manager.rb', line 158 def clear_offsets_excluding(excluded) # Clear all offsets that aren't in `excluded`. @processed_offsets.each do |topic, partitions| partitions.keep_if do |partition, _| excluded.fetch(topic, []).include?(partition) end end # Clear the cached commits from the brokers. @committed_offsets = nil @resolved_offsets.clear end |
#commit_offsets(recommit = false) ⇒ nil
Commit offsets of messages that have been marked as processed.
If recommit
is set to true, we will also commit the existing positions
even if no messages have been processed on a partition. This is done
in order to avoid the offset information expiring in cases where messages
are very rare -- it's essentially a keep-alive.
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# File 'lib/kafka/offset_manager.rb', line 115 def commit_offsets(recommit = false) offsets = offsets_to_commit(recommit) unless offsets.empty? @logger.info "Committing offsets#{recommit ? ' with recommit' : ''}: #{prettify_offsets(offsets)}" @group.commit_offsets(offsets) @last_commit = Time.now @last_recommit = Time.now if recommit @uncommitted_offsets = 0 @committed_offsets = nil end end |
#commit_offsets_if_necessary ⇒ nil
Commit offsets if necessary, according to the offset commit policy specified when initializing the class.
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# File 'lib/kafka/offset_manager.rb', line 134 def commit_offsets_if_necessary recommit = recommit_timeout_reached? if recommit || commit_timeout_reached? || commit_threshold_reached? commit_offsets(recommit) end end |
#mark_as_processed(topic, partition, offset) ⇒ nil
Mark a message as having been processed.
When offsets are committed, the message's offset will be stored in Kafka so that we can resume from this point at a later time.
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# File 'lib/kafka/offset_manager.rb', line 49 def mark_as_processed(topic, partition, offset) @uncommitted_offsets += 1 @processed_offsets[topic] ||= {} # The committed offset should always be the offset of the next message that the # application will read, thus adding one to the last message processed. @processed_offsets[topic][partition] = offset + 1 @logger.debug "Marking #{topic}/#{partition}:#{offset} as processed" end |
#next_offset_for(topic, partition) ⇒ Integer
Return the next offset that should be fetched for the specified partition.
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# File 'lib/kafka/offset_manager.rb', line 90 def next_offset_for(topic, partition) offset = @processed_offsets.fetch(topic, {}).fetch(partition) { committed_offset_for(topic, partition) } # A negative offset means that no offset has been committed, so we need to # resolve the default offset for the topic. if offset < 0 resolve_offset(topic, partition) else # The next offset is the last offset. offset end end |
#seek_to(topic, partition, offset) ⇒ nil
Move the consumer's position in the partition to the specified offset.
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# File 'lib/kafka/offset_manager.rb', line 80 def seek_to(topic, partition, offset) @processed_offsets[topic] ||= {} @processed_offsets[topic][partition] = offset end |
#seek_to_default(topic, partition) ⇒ nil
Move the consumer's position in the partition back to the configured default offset, either the first or latest in the partition.
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# File 'lib/kafka/offset_manager.rb', line 65 def seek_to_default(topic, partition) # Remove any cached offset, in case things have changed broker-side. clear_resolved_offset(topic) offset = resolve_offset(topic, partition) seek_to(topic, partition, offset) end |
#set_default_offset(topic, default_offset) ⇒ nil
Set the default offset for a topic.
When the consumer is started for the first time, or in cases where it gets stuck and has to reset its position, it must start either with the earliest messages or with the latest, skipping to the very end of each partition.
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# File 'lib/kafka/offset_manager.rb', line 36 def set_default_offset(topic, default_offset) @default_offsets[topic] = default_offset end |