Cassandra Community Webinar: Apache Cassandra Internals

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Apache Cassandra solves many interesting problems to provide a scalable, distributed, fault tolerant database. Cluster wide operations track node membership, direct requests and implement consistency guarantees. At the node level, the Log Structured storage engine provides high performance reads and writes. All of this is implemented in a Java code base that has greatly matured over the past few years.

In this webinar Aaron Morton will step through read and write requests, automatic processes and manual maintenance tasks. He will also discuss the general approach to solving the problem and drill down to the code responsible for implementation.

Speaker: Aaron Morton, Apache Cassandra Committer
Aaron Morton is a Freelance Developer based in New Zealand, and a Committer on the Apache Cassandra project. In 2010 he gave up the RDBMS world for the scale and reliability of Cassandra. He now spends his time advancing the Cassandra project and helping others get the best out of it.

Published in: Technology

Cassandra Community Webinar: Apache Cassandra Internals

  1. 1. CASSANDRA COMMUNITY WEBINARS AUGUST 2013 CASSANDRA INTERNALS Aaron Morton @aaronmorton Co-Founder & Principal Consultant www.thelastpickle.com Licensed under a Creative Commons Attribution-NonCommercial 3.0 New Zealand License
  2. 2. AboutThe Last Pickle Work with clients to deliver and improve Apache Cassandra based solutions. Apache Cassandra Committer, DataStax MVP, Hector Maintainer, 6+ years combined Cassandra experience. Based in New Zealand & Austin,TX.
  3. 3. Architecture Code www.thelastpickle.com
  4. 4. Cassandra Architecture API's Cluster Aware Cluster Unaware Clients Disk www.thelastpickle.com
  5. 5. Cassandra Cluster Architecture API's Cluster Aware Cluster Unaware Clients Disk API's Cluster Aware Cluster Unaware Disk Node 1 Node 2 www.thelastpickle.com
  6. 6. Dynamo Cluster Architecture API's Dynamo Database Clients Disk API's Dynamo Database Disk Node 1 Node 2 www.thelastpickle.com
  7. 7. Architecture API Dynamo Database www.thelastpickle.com
  8. 8. APITransports Thrift Native Binary www.thelastpickle.com
  9. 9. ThriftTransport //Custom TServer implementations o.a.c.thrift.CustomTThreadPoolServer o.a.c.thrift.CustomTNonBlockingServer o.a.c.thrift.CustomTHsHaServer www.thelastpickle.com
  10. 10. APITransports Thrift Native Binary www.thelastpickle.com
  11. 11. Native BinaryTransport Beta in Cassandra 1.2 Uses Netty Enabled with start_native_transport (Disabled by default) www.thelastpickle.com
  12. 12. o.a.c.transport.Server.run() //Setup the Netty server new ExecutionHandler() new NioServerSocketChannelFactory() ServerBootstrap.setPipelineFactory() www.thelastpickle.com
  13. 13. o.a.c.transport.Message.Dispatcher.messageReceived() //Process message from client ServerConnection.validateNewMessage() Request.execute() ServerConnection.applyStateTransition() Channel.write() www.thelastpickle.com
  14. 14. Messages Defined in the Native Binary Protocol $SRC/doc/native_protocol.spec www.thelastpickle.com
  15. 15. API Services JMX Thrift CQL 3 www.thelastpickle.com
  16. 16. JMX Management Beans Spread around the code base. Interfaces named *MBean www.thelastpickle.com
  17. 17. JMX Management Beans Registered with names such as org.apache.cassandra.db: type=StorageProxy www.thelastpickle.com
  18. 18. API Services JMX Thrift CQL 3 www.thelastpickle.com
  19. 19. o.a.c.thrift.CassandraServer // Implements Thrift Interface // Access control // Input validation // Mapping to/from Thrift and internal types www.thelastpickle.com
  20. 20. Thrift Interface Thrift IDL $SRC/interface/cassandra.thrift www.thelastpickle.com
  21. 21. o.a.c.thrift.CassandraServer.get_slice() // get columns for one row Tracing.begin() ClientState cState = state() cState.hasColumnFamilyAccess() multigetSliceInternal() www.thelastpickle.com
  22. 22. CassandraServer.multigetSliceInternal() // get columns for may rows ThriftValidation.validate*() // Create ReadCommands getSlice() www.thelastpickle.com
  23. 23. CassandraServer.getSlice() // Process ReadCommands // return Thrift types readColumnFamily() thriftifyColumnFamily() www.thelastpickle.com
  24. 24. CassandraServer.readColumnFamily() // Process ReadCommands // Return ColumnFamilies StorageProxy.read() www.thelastpickle.com
  25. 25. API Services JMX Thrift CQL 3 www.thelastpickle.com
  26. 26. o.a.c.cql3.QueryProcessor // Prepares and executes CQL3 statements // Used by Thrift & Native transports // Access control // Input validation // Returns transport.ResultMessage www.thelastpickle.com
  27. 27. CQL3 Grammar ANTLR Grammar $SRC/o.a.c.cql3/Cql.g www.thelastpickle.com
  28. 28. o.a.c.cql3.statements.ParsedStatement // Subclasses generated by ANTLR // Tracks bound term count // Prepare CQLStatement prepare() www.thelastpickle.com
  29. 29. o.a.c.cql3.statements.CQLStatement checkAccess(ClientState state) validate(ClientState state) execute(ConsistencyLevel cl, QueryState state, List<ByteBuffer> variables) www.thelastpickle.com
  30. 30. statements.SelectStatement.RawStatement // Implements ParsedStatement // Input validation prepare() www.thelastpickle.com
  31. 31. statements.SelectStatement.execute() // Create ReadCommands StorageProxy.read() www.thelastpickle.com
  32. 32. Architecture API Dynamo Database www.thelastpickle.com
  33. 33. Dynamo Layer o.a.c.service o.a.c.net o.a.c.dht o.a.c.gms o.a.c.locator o.a.c.stream www.thelastpickle.com
  34. 34. o.a.c.service.StorageProxy // Cluster wide storage operations // Select endpoints & check CL available // Send messages to Stages // Wait for response // Store Hints www.thelastpickle.com
  35. 35. o.a.c.service.StorageService // Ring operations // Track ring state // Start & stop ring membership // Node & token queries www.thelastpickle.com
  36. 36. o.a.c.service.IResponseResolver preprocess(MessageIn<T> message) resolve() throws DigestMismatchException RowDigestResolver RowDataResolver RangeSliceResponseResolver www.thelastpickle.com
  37. 37. Response Handlers / Callback implements IAsyncCallback<T> response(MessageIn<T> msg) www.thelastpickle.com
  38. 38. o.a.c.service.ReadCallback.get() //Wait for blockfor & data condition.await(timeout, TimeUnit.MILLISECONDS) throw ReadTimeoutException() resolver.resolve() www.thelastpickle.com
  39. 39. o.a.c.service.StorageProxy.fetchRows() getLiveSortedEndpoints() new RowDigestResolver() new ReadCallback() MessagingService.sendRR() --------------------------------------- ReadCallback.get() # blocking catch (DigestMismatchException ex) catch (ReadTimeoutException ex) www.thelastpickle.com
  40. 40. Dynamo Layer o.a.c.service o.a.c.net o.a.c.dht o.a.c.gms o.a.c.locator o.a.c.stream www.thelastpickle.com
  41. 41. o.a.c.net.MessagingService.verb<<enum>> MUTATION READ REQUEST_RESPONSE TREE_REQUEST TREE_RESPONSE (And more...) www.thelastpickle.com
  42. 42. o.a.c.net.MessagingService.verbHandlers new EnumMap<Verb, IVerbHandler>(Verb.class) www.thelastpickle.com
  43. 43. o.a.c.net.IVerbHandler<T> doVerb(MessageIn<T> message, String id); www.thelastpickle.com
  44. 44. o.a.c.net.MessagingService.verbStages new EnumMap<MessagingService.Verb, Stage>(MessagingService.Verb.class) www.thelastpickle.com
  45. 45. o.a.c.net.MessagingService.receive() runnable = new MessageDeliveryTask( message, id, timestamp); StageManager.getStage( message.getMessageType()); stage.execute(runnable); www.thelastpickle.com
  46. 46. o.a.c.net.MessageDeliveryTask.run() // If dropable and rpc_timeout MessagingService.incrementDroppedMessag es(verb); MessagingService.getVerbHandler(verb) verbHandler.doVerb(message, id) www.thelastpickle.com
  47. 47. Architecture API Layer Dynamo Layer Database Layer www.thelastpickle.com
  48. 48. Database Layer o.a.c.concurrent o.a.c.db o.a.c.cache o.a.c.io o.a.c.trace www.thelastpickle.com
  49. 49. o.a.c.concurrent.StageManager stages = new EnumMap<Stage, ThreadPoolExecutor>(Stage.class); getStage(Stage stage) www.thelastpickle.com
  50. 50. o.a.c.concurrent.Stage READ MUTATION GOSSIP REQUEST_RESPONSE ANTI_ENTROPY (And more...) www.thelastpickle.com
  51. 51. Database Layer o.a.c.concurrent o.a.c.db o.a.c.cache o.a.c.io o.a.c.trace www.thelastpickle.com
  52. 52. o.a.c.db.Table // Keyspace open(String table) getColumnFamilyStore(String cfName) getRow(QueryFilter filter) apply(RowMutation mutation, boolean writeCommitLog) www.thelastpickle.com
  53. 53. o.a.c.db.ColumnFamilyStore // Column Family getColumnFamily(QueryFilter filter) getTopLevelColumns(...) apply(DecoratedKey key, ColumnFamily columnFamily, SecondaryIndexManager.Updater indexer) www.thelastpickle.com
  54. 54. o.a.c.db.IColumnContainer addColumn(IColumn column) remove(ByteBuffer columnName) ColumnFamily SuperColumn www.thelastpickle.com
  55. 55. o.a.c.db.ISortedColumns addColumn(IColumn column, Allocator allocator) removeColumn(ByteBuffer name) ArrayBackedSortedColumns AtomicSortedColumns TreeMapBackedSortedColumns www.thelastpickle.com
  56. 56. o.a.c.db.Memtable put(DecoratedKey key, ColumnFamily columnFamily, SecondaryIndexManager.Updater indexer) flushAndSignal(CountDownLatch latch, Future<ReplayPosition> context) www.thelastpickle.com
  57. 57. o.a.c.db.ReadCommand getRow(Table table) SliceByNamesReadCommand SliceFromReadCommand www.thelastpickle.com
  58. 58. o.a.c.db.IDiskAtomFilter getMemtableColumnIterator(...) getSSTableColumnIterator(...) IdentityQueryFilter NamesQueryFilter SliceQueryFilter www.thelastpickle.com
  59. 59. Summary CustomTThreadPoolServer Message.Dispatcher CassandraServer QueryProcessor ReadCommand StorageProxy IResponseResolver IAsyncCallback MessagingService IVerbHandler Table ColumnFamilyStore IDiskAtomFilter API Dynamo Database www.thelastpickle.com
  60. 60. Thanks. www.thelastpickle.com
  61. 61. Aaron Morton @aaronmorton Co-Founder & Principal Consultant www.thelastpickle.com Licensed under a Creative Commons Attribution-NonCommercial 3.0 New Zealand License

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