* introducing CuratorLoadQueuePeon
* HttpLoadQueuePeon based off of current code
* Revert "Remove SegmentLoaderConfig.numLoadingThreads config (#4829)"
This reverts commit d8b3bfa63c.
* SegmentLoadDropHandler copy/pasted from ZkCoordinator
* Revert "1-based counts in ZkCoordinator (#4917)"
This reverts commit e725ff4146.
* remove non-zk part from ZkCoordinator
* remove zk part from SegmentLoadDropHandler
* additional changes for segment load/drop management with http
* address review comments
* add some more logs
* Execs class is moved
* Only consider loaded replicants when computing replication status.
This affects the computation of segment/underReplicated/count and
segment/unavailable/count, as well as the loadstatus?simple and
loadstatus?full APIs.
I'm not sure why they currently consider segments in the load
queues, but it would make more sense to me if they only considered
segments that are actually loaded.
* Fix tests.
* Fix imports.
* Changes for lookup synchronization
* Refactor of Lookup classes
* Minor refactors and doc update
* Change coordinator instance to be retrieved by DruidLeaderClient
* Wait before thread shutdown
* Make disablelookups flag true by default
* Update docs
* Rename flag
* Move executorservice shutdown to finally block
* Update LookupConfig
* Refactoring and doc changes
* Remove lookup config constructor
* Revert Lookupconfig constructor changes
* Add tests to LookupConfig
* Make executorservice local
* Update LRM
* Move ListeningScheduledExecutorService to ExecutorCompletionService
* Move exception to outer block
* Remove check to see future is done
* Remove unnecessary assignment
* Add logging
* Add ability to optionally specify a sequence identifier to reduce the possibility of duplicate events entering the event receiver firehose
* Add ability to optionally specify a sequence identifier to reduce the possibility of duplicate events entering the event receiver firehose
* Add a hard coded limit to the maximum number of possible producer IDs to prevent a malicious (or uninformed) client from overflowing the heap
* add configs to enable fast request failure on broker
* address review comments
* fix styling error
* fix style error
* have enableRequestLimit config instead of having user specify max limit
* add comment
* fix style error
* add UT fo LimitRequestsFilter
* address review comments
* fix test
* make LimitRequestsFilterTest more robust
* fix JettyQosTest
* Fix#4647
* NPE protect bucketInterval as well
* Add test to verify timezone as well
* Also handle case when intervals are already present
* Fix checkstyle error
* Use factory method instead for Datetime
* Use Intervals factory method
* Priority on loading for primary replica
* Simplicity fixes
* Fix on skipping drop for quick return.
* change to debug logging for no replicants.
* Fix on filter logic
* swapping if-else
* Fix on wrong "hasTier" logic
* Refactoring of LoadRule
* Rename createPredicate to createLoadQueueSizeLimitingPredicate
* Rename getHolderList to getFilteredHolders
* remove varargs
* extract out currentReplicantsInTier
* rename holders to holdersInTier
* don't do temporary removal of tier.
* rename primaryTier to tierToSkip
* change LinkedList to ArrayList
* Change MinMaxPriorityQueue in DruidCluster to TreeSet.
* Adding some comments.
* Modify log messages in light of predicates.
* Add in-method comments
* Don't create new Object2IntOpenHashMap for each run() call.
* Cache result from strategy call in the primary assignment to be reused during the same run.
* Spelling mistake
* Cleaning up javadoc.
* refactor out loading in progress check.
* Removed redundant comment.
* Removed forbidden API
* Correct non-forbidden API.
* Precision in variable type for NavigableSet.
* Obsolete comment.
* Clarity in method call and moving retrieval of ServerHolder into method call.
* Comment on mutability of CoordinatoorStats.
* Added auxiliary fixture for dropping.
* Add identity to query metrics, logs.
Also fix a bug where unauthorized requests would not emit any logs or metrics,
and instead would log a "Tried to emit logs and metrics twice" warning.
Also rename QueryResource's "getServer" to "cancelQuery", because that's what
it does.
* Do not emit identity by default.
* remove ServerConfig from DruidNode as all information needs to be present in DruidNode serialized form
* sanitize output of /druid/coordinator/v1/cluster endpoint
* Added org.joda.time.DateTime#(java.lang.String) to forbidden API.
* Added org.joda.time.DateTime#(java.lang.String, org.joda.time.format.DateTimeFormatter) to forbidden API.
* Add additional APIs that may create DateTime with default time zone
* Add helper function that accepts formatter to parse String.
* Add additional forbidden APIs
* Replace existing usage of forbidden APIs
* Use wrapper class to enforce Chronology on DateTimeFormatter.
* Creates constant UtcFormatter for constant ISODateTimeFormat.
* Move caffeine out of extension.
* Remove `JsonTypeName` from the class itself
* Fix bad docs
* Fix distribution pom
* Fix unused import
* Make caffeine default
* Address code comments
* Add more description around the jre version in the readme
* Add suggested comments
* Move emitters from io.druid.server.initialization to the dedicated io.druid.server.emitter package; Update emitter library to 0.6.0; Add support for ParametrizedUriEmitter; Support hierarical properties in JsonConfigurator (was needed for ParametrizedUriEmitter)
* Log created RequestLoggers
* Fix forbidden API
* Test fix
* More Http and Parametrized Http Emitter docs
* Switch to debug level
* fixes HttpServerInventoryView to call server/segment callbacks correctly and Unit Tests for the class
* fix checkstyle and forbidden-api errors
* HttpServerInventoryView to finish start() only after server inventory is initialized
* fix compilation errors
* address review comments
* add exponential backoff instead of fixed 5 secs on successive failures
* update test to exercise server fail scenarios
* use AtomicInteger for requestNum and increment only once
* Move scan-query from a contrib extension into core.
Based on a proposal at: https://groups.google.com/d/topic/druid-development/ME_OatUDnbk/discussion
This patch also adds support for virtual columns to the Scan query,
and updates Druid SQL to use Scan instead of Select.
This patch also makes some behavioral changes to handling of the __time
column. In particular, it is now is returned as "__time" rather than
"timestamp"; it is no longer included if you do not specifically ask for
it in your "columns"; and it is returned as a long rather than a string.
Users can revert time handling to the legacy extension behavior by
setting "legacy" : true in their queries, or setting the property
druid.query.scan.legacy = true. This is meant to provide a migration
path for users that were formerly using the contrib extension.
* Adjustments from review.
* Add back Select query.
* Adjust SQL docs.
* Restore SelectQuery link.
* SQL: Full TRIM support.
- Support trimming arbitrary characters
- Support BOTH, LEADING, and TRAILING
* Remove unused import.
* Fix tests, add RTRIM / LTRIM.
* Remove unused imports.
* BTRIM and docs.
* Replace for with foreach.
* Use internal-discovery and http for talking to overlord/coordinator leaders
* CuratorDruidNodeDiscovery.getAllNodes() best effort 30 sec wait for cache initialization
* DruidLeaderClientProvider to eagerly instantiate DruidNodeDiscovery when needed so that DruidNodeDiscovery impl cache gets initialized well in time
* Revert "DruidLeaderClientProvider to eagerly instantiate DruidNodeDiscovery when needed so that DruidNodeDiscovery impl cache gets initialized well in time"
This reverts commit f1a2432614ba56ddc2d55fe47e990d17fcfd6129.
* add lifecycle to DruidLeaderClient to early initialize DruidNodeDiscovery so that it has its cache update well in time
Expose version property for so that it may serialize/deserialize correctly
Expose version property for `CustomVersioningPolicy` so that it may serialize/deserialize correctly
Expose version property for CustomVersioningPolicy so that it may serialize/deserialize correctly
Expose version property for `CustomVersioningPolicy` so that it may serialize/deserialize correctly
* DruidLeaderSelector interface for leader election and Curator based impl. DruidCoordinator/TaskMaster are updated to use the new interface.
* add fake DruidNode binding in integration-tests module
* add docs on DruidLeaderSelector interface
* remove start/stop and keep register/unregister Listener in DruidLeaderSelector interface
* updated comments on DruidLeaderSelector
* cache the listener executor in CuratorDruidLeaderSelector
* use same latch owner name that was used before
* remove stuff related to druid.zk.paths.indexer.leaderLatchPath config
* randomize the delay when giving up leadership and restarting leader latch
* Factor QueryableIndexColumnSelectorFactory and IncrementalIndexColumnSelectorFactory out of QueryableIndexStorageAdapter and IncrementalIndexStorageAdapter; Add Offset.getBaseReadableOffset(); Remove OffsetHolder interface; Replace Cursor extends ColumnSelectorFactory with composition; Reduce indirection in ColumnValueSelectors created by QueryableIndexColumnSelectorFactory
* Don't override clone() in FilteredOffset (the prev. implementation was broken); Some warnings fixed
* Simplify Cursors in QueryableIndexStorageAdapter
* Address comments
* Remove unused and unimplemented methods from GenericColumn interface
* Comments
* Add @ExtensionPoint and @PublicApi annotations.
* Clean up wording.
* Remove unused import.
* Remove unused imports.
* Only types can be extension points.
* Adjust annotations some more.
* Remove unused import.
* Make ServletFilterHolder an extension point.
* Add a couple extension points, and update docs.
* Do not remove segment that should not be moved from currentlyMovingSegments (segments are removed by callbacks or not inserted)
* Mark segments that are going to be dropped from server and use this information in CostBalancerStrategy
* Fix tests
* update LookupCoordinatorManager to use internal discovery to discover lookup nodes
* router:use internal-discovery to discover brokers
* minor [Curator]DruidDiscoveryProvider refactoring
* add initialized() method to DruidNodeDiscovery.Listener
* update HttpServerInventoryView to use initialized() and call segment callback initialization asynchronously
* Revert "update HttpServerInventoryView to use initialized() and call segment callback initialization asynchronously"
This reverts commit f796e441221fe8b0e9df87fdec6c9f47bcedd890.
* Revert "add initialized() method to DruidNodeDiscovery.Listener"
This reverts commit f0661541d073683f28fce2dd4f30ec37db90deb0.
* minor refactoring removing synchronized from DruidNodeDiscoveryProvider
* updated DruidNodeDiscovery.Listener contract to take List of nodes and first call marks initialization
* update HttpServerInventoryView to handle new contract and handle initialization
* router update to handle updated listener contract
* document DruidNodeDiscovery.Listener contract
* fix forbidden-api error
* change log level to info for unknown path children cache events in CuratorDruidNodeDiscoveryProvider
* announce broker only after segment inventory is initialized
* internal-discovery: interfaces for announcement/discovery, curator impls
* more tests
* address some review comments
* more fixes
* address more review comments
* simplify ObjectMapper setup in CuratorDruidNodeAnnouncerAndDiscoveryTest
* fix KafkaIndexTaskTest
* make lookupTier overridable via RealtimeIndexTask and KafkaIndexTask context
* make teamcity build happy
* Do not remove segment that should not be moved from currentlyMovingSegments (segments are removed by callbacks or not inserted)
* Replace putIfAbsent with computeIfAbsent in DruidBalancer
* Refactoring
* make BrokerQueryResource instantiation singleton
* fix druid.router.http.* handling so that they are actually used and introduce numRequestsQueued for jetty http client at router
* address comments
* address review comment
* Use ConcurrentHashMap to store segment servers or else getInventory() would need to clone the values list
* introduce unstableTimeout for segment servers
* address review comment
* add HttpServerInventoryViewConfigTest
* Add metrics to the native queries underpinning SQL.
This is done by factoring out the metrics and request log emitting
code from QueryResource into a new QueryLifecycle class. That class
is used by both QueryResource and the SQL DruidSchema and QueryMaker.
Also fixes a couple of bugs in QueryResource:
- RequestLogLine start time was set to `TimeUnit.NANOSECONDS.toMillis(startNs)`,
which is incorrect since absolute nanos cannot be converted to millis.
- DruidMetrics.makeRequestMetrics was called with null `query` on
unparseable queries, which led to spurious "Unable to log query"
errors.
Partial fix for #4047.
* Code style
* Remove unused imports.
* Fix tests.
* Remove unused import.
* Fixes and improvements to SQL metadata caching.
Also adds support for MultipleSpecificSegmentSpec to CachingClusteredClient.
SQL changes:
- Cache metadata on a per-segment level, in addition to per-dataSource, so
we don't need to re-query all segments whenever a single new one appears.
This should lower the load placed on the cluster by metadata queries.
- Fix race condition in DruidSchema that can cause us to miss metadata. It was
possible to notice new segments, then issue a query, and have that query
not actually hit those segments, and not notice that it didn't hit those segments.
Then, the metadata from those segments would be ignored.
- Fix assumption in DruidSchema that all segments are immutable. Now, mutable
segments are periodically re-queried.
- Fix inappropriate re-use of SchemaPlus. Now we create one for each planning
cycle, rather than sharing one. It caches table objects, which we want to
avoid, since it can cause stale metadata. We do the caching in DruidSchema
so we don't need the SchemaPlus caching.
Server changes:
- Add a TimelineCallback to TimelineServerView, for callers that want to get updates
when the timeline has been modified.
- Change CachingClusteredClient from a QueryRunner to a QuerySegmentWalker. This
allows it to accept queries that are segment-descriptor-based rather than
intervals-based. In particular it will now support MultipleSpecificSegmentSpec.
* Fix DruidSchema, and unused imports.
* Remove unused import.
* Fix SqlBenchmark.
* Rename ResourceManagementStrategy to ProvisioningStrategy, similarly for related classes. Make ProvisioningService non-global, created per RemoteTaskRunner instead. Add OverlordBlinkLeadershipTest.
* Fix RemoteTaskRunnerFactoryTest.testExecNotSharedBetweenRunners()
* Small fix
* Make SimpleProvisioner and PendingProvisioner more similar in details
* Fix executor name
* Style fixes
* Use LifecycleLock in RemoteTaskRunner
* Remove some unnecessary use of boxed types.
* Fix some incorrect format strings.
* Enable IDEA's MalformedFormatString inspection.
* Add a Checkstyle check for finding uses of incorrect logging packages.
* Fix some incorrect usages of the metamx logger.
* Bypass incorrect logger Checkstyle check where using the correct logger is not simple.
* Fix some more places where the wrong number of arguments are provided to format strings.
* Suppress `MalformedFormatString` inspection on legacy logging test.
* Use @SuppressWarnings rather than a noinspection suppression comment.
* Fix some more incorrect format strings.
* Suppress some more incorrect format string warnings where the incorrect string is intentional.
* Log the aggregator when closing it fails.
* Remove some unneeded log lines.
* Early publishing segments in the middle of data ingestion
* Remove unnecessary logs
* Address comments
* Refactoring the patch according to #4292 and address comments
* Set the total shard number of NumberedShardSpec to 0
* refactoring
* Address comments
* Fix tests
* Address comments
* Fix sync problem of committer and retry push only
* Fix doc
* Fix build failure
* Address comments
* Fix compilation failure
* Fix transient test failure
* Avoid usages of Default system Locale and printing to System.out or System.err in production code
* Fix Charset in DruidKerberosUtil
* Remove redundant string format in GenericIndexed
* Rename StringUtils.safeFormat() to unimportantSafeFormat(); add StringUtils.format() which fails as well as String.format()
* Fix testSafeFormat()
* More fixes of redundant StringUtils.format() inside ISE
* Rename unimportantSafeFormat() to nonStrictFormat()
* Add some new expression functions and macros.
See misc/math-expr.md for the list of added functions, except for
"like", which previously existed but was not documented.
* Add easymock to datasketches tests.
* Add easymock to distinctcount tests.
* Add easymock to virtual-columns tests.
* Code review comments.
* Clean up code a bit.
* Add easymock to scan-query tests.
* Rework ExprMacros that have multiple impls.
* Improve test coverage.
* Remove DruidProcessingModule, QueryableModule and QueryRunnerFactoryModule from DI for coordinator, overlord, middle-manager. Add RouterDruidProcessing not to allocate processing resources on router
* Fix examples
* Fixes
* Revert Peon configs and add comments
* Remove qualifier
* Add maxSegmentsInQueue parameter to CoordinatorDinamicConfig and use it in LoadRule to improve segments loading and replication time
* Rename maxSegmentsInQueue to maxSegmentsInNodeLoadingQueue
* Make CoordinatorDynamicConfig constructor private; add/fix tests; set default maxSegmentsInNodeLoadingQueue to 0 (unbounded)
* Docs added for maxSegmentsInNodeLoadingQueue parameter in CoordinatorDynamicConfig
* More docs for maxSegmentsInNodeLoadingQueue and style fixes
* Remove ability to create segments in v8 format
* Fix IndexGeneratorJobTest
* Fix parameterized test name in IndexMergerTest
* Remove extra legacy merging stuff
* Remove legacy serializer builders
* Remove ConciseBitmapIndexMergerTest and RoaringBitmapIndexMergerTest
* Adding a flag to indicate when ObjectCachingColumnSelectorFactory need not be threadsafe.
* - Use of computeIfAbsent over putIfAbsent
- Replace Maps.newXXXMap() with normal instantiation
- Documentations on when is thread-safe required.
- Use Builders for On/OffheapIncrementalIndex
* - Optimization on computeIfAbsent
- Constant EMPTY DimensionsSpec
- Improvement on IncrementalIndexSchema.Builder
- Remove setting of default values
- Use var args for metrics
- Correction on On/OffheapIncrementalIndex Builders
- Combine On/OffheapIncrementalIndex Builders
* - Removing unused imports.
* - Helper method for testing with IncrementalIndex.Builder
* - Correction on javadoc.
* Style fix
* Make PolyBind to fail if property value is not found
* Fix test
* Add onHeap option in NamespaceExtractionModule
* Add PolyBind.createChoiceWithDefaultNoScope()
* Fix NPE
* Fix
* Configure MetadataStorageProvider option for MySQL, PostgreSQL and SQLServer
* Deprecate PolyBind.createChoiceWithDefault form with unused defaultKey
* Fix NPE
* Expressions: Add ExprMacros, which have the same syntax as functions, but
can convert themselves to any kind of Expr at parse-time.
ExprMacroTable is an extension point for adding new ExprMacros. Anything
that might need to parse expressions needs an ExprMacroTable, which can
be injected through Guice.
* Address code review comments.
* Enable most IntelliJ 'Probable bugs' inspections
* Fix in RemoteTestNG
* Fix IndexSpec's equals() and hashCode() to include longEncoding
* Fix inspection errors
* Extract global isntance of natural().nullsFirst(); address comments
* Fix
* Use noinspection comments instead of SuppressWarnings on method for IntelliJ-specific inspections
* Prohibit Ordering.natural().nullsFirst() using Checkstyle
* Make using implicit system charset an error
* Use StringUtils.toUtf8() and fromUtf8() instead of String.getBytes() and new String()
* Use English locale in StringUtils.safeFormat()
* Restore comment
* Adding s3a schema and s3a implem to hdfs storage module.
* use 2.7.3
* use segment pusher to make loadspec
* move getStorageDir and makeLoad spec under DataSegmentPusher
* fix uts
* fix comment part1
* move to hadoop 2.8
* inject deep storage properties
* set version to 2.7.3
* fix build issue about static class
* fix comments
* fix default hadoop default coordinate
* fix create filesytem
* downgrade aws sdk
* bump the version
* fix TestKafkaExtractionCluster fail due to port already used
* explicitly unmap hydrant files when abandonSegment to recyle mmap memory
* address the comments
* apply to AppenderatorImpl
* Refactoring Appenderator
1) Added publishExecutor and handoffExecutor for background publishing and handing segments off
2) Change add() to not move segments out in it
* Address comments
1) Remove publishTimeout for KafkaIndexTask
2) Simplifying registerHandoff()
3) Add increamental handoff test
* Remove unused variable
* Add persist() to Appenderator and more tests for AppenderatorDriver
* Remove unused imports
* Fix strict build
* Address comments
* move ProtoBufInputRowParser from processing module to protobuf extensions
* Ported PR #3509
* add DynamicMessage
* fix local test stuff that slipped in
* add license header
* removed redundant type name
* removed commented code
* fix code style
* rename ProtoBuf -> Protobuf
* pom.xml: shade protobuf classes, handle .desc resource file as binary file
* clean up error messages
* pick first message type from descriptor if not specified
* fix protoMessageType null check. add test case
* move protobuf-extension from contrib to core
* document: add new configuration keys, and descriptions
* update document. add examples
* move protobuf-extension from contrib to core (2nd try)
* touch
* include protobuf extensions in the distribution
* fix whitespace
* include protobuf example in the distribution
* example: create new pb obj everytime
* document: use properly quoted json
* fix whitespace
* bump parent version to 0.10.1-SNAPSHOT
* ignore Override check
* touch
* Do not re-create prioritized servers on each call in server selector and extend TierSelectorStrategy interface with a method to pick multiple elements at once
* Fix compilation
* Replaces use of CountingMap with Object2LongMap from fastutil.
* Remove CountingMap classes and minor fixes
* Added additional test cases for DatasourceInputFormat.
* Added additional test cases for CoordinatorStats.
* Not materializing segment list.
* Put in this fix because it is failing the test on its expected behavior.
* Added missing header.
* Improve concurrency of SegmentManager
* Fix SegmentManager and add more tests
* Add more tests
* Add null check to TimelineEntry
* Remove empty data source and check null in getTimeline()
* Add a comment for returning null in compute()
* Make SegmentManager LazySingleton
* Timeout and maxScatterGatherBytes handling for queries run by Druid SQL
* Address PR comments
* Fix contexts in CalciteQueryTest
* Fix contexts in QuantileSqlAggregatorTest
* Add a ServerType for peons
* Add toString() method, toString() test, unsupported type check
* Use ServerType enum in DruidServer and DruidServerMetadata
* Don't pass QueryMetrics down in concurrent and async QueryRunners
* Rename QueryPlus.threadSafe() to withoutThreadUnsafeState(); Update QueryPlus.withQueryMetrics() Javadocs; Fix generics in MetricsEmittingQueryRunner and CpuTimeMetricQueryRunner; Make DefaultQueryMetrics to fail fast on modifications from concurrent threads
This is useful for putting them behind load balancers or proxies, as it lets
the load balancer know which server is currently active through an http health
check.
Also makes the method naming a little more consistent between coordinator and
overlord code.
* Optional long-polling based segment announcement via HTTP instead of Zookeeper
* address review comments
* make endpoint /druid-internal/v1 instead of /druid/internal so that jetty qos filters can be configured easily when needed
* update segment callback initialization to be called only after first segment list fetch has been succeeded from all servers
* address review comments
* remove size check not required anymore as only segment servers announce themselves and not all peon processes
* annouce segment server on historical only after cached segments are loaded
* fix checkstyle errors
* Fix lz4 library incompatibility in kafka-indexing-service extension #3266
* Bumped Kafka version to 0.10.2.0 for : Fix lz4 library incompatibility in kafka-indexing-service extension #3266
* Replaced Lists.newArrayList() with Collections.singletonList() For Fix lz4 library incompatibility in kafka-indexing-service extension #4115
* Fixed: Average Server Percent Used: NaN% Error when server startup is in progress #4214
* Make Errorprone the default compiler
* Address comments
* Make Error Prone's ClassCanBeStatic rule a error
* Preconditions allow only %s pattern
* Fix DruidCoordinatorBalancerTester
* Try to give the compiler more memory
* Remove distribution module activation on jdk 1.8 because only jdk 1.8 is used now
* Don't show compiler warnings
* Try different travis script
* Fix travis.yml
* Make Error Prone optional again
* For error-prone compiler
* Increase compiler's maxmem
* Don't run Error Prone for benchmarks because of OOM
* Skip install step in Travis
* Remove MetricHolder.writeToChannel()
* In travis.yml, check compilation before tests, because it may fail faster
* Add QueryPlus. Add QueryRunner.run(QueryPlus, Map) method with default implementation, to replace QueryRunner.run(Query, Map).
* Fix GroupByMergingQueryRunnerV2
* Fix QueryResourceTest
* Expand the comment to Query.run(walker, context)
* Remove legacy version of BySegmentSkippingQueryRunner.doRun()
* Add LegacyApiQueryRunnerTest and be more specific about legacy API removal plans in Druid 0.11 in Javadocs
* Ignore misnamed segment cache info files.
Fixes a bug where historical nodes could announce the same segment twice,
ultimately leading to historicals and their watchers (like coordinators
and brokers) being out of sync about which segments are served.
This could be caused if Druid is switched from local time to UTC, because
that causes the same segment descriptors to lead to different identifiers
(an identifier with local time interval before the switch, and UTC interval
after the switch). In turn this causes that segment descriptor to be written
to multiple segment cache info files and potentially get announced twice.
Later, if the historical receives a drop request, it drops the segment and
unannounces it once, but the other announcement would stick around in an
ephemeral znode forever, confusing coordinators and brokers.
* Only alert once.
* coordinator lookups mgmt improvements
* revert replaces removal, deprecate it instead
* convert and use older specs stored in db
* more tests and updates
* review comments
* add behavior for 0.10.0 to 0.9.2 downgrade
* incorporating more review comments
* remove explicit lock and use LifecycleLock in LookupReferencesManager. use LifecycleLock in LookupCoordinatorManager as well
* wip on LookupCoordinatorManager
* lifecycle lock
* refactor thread creation into utility method
* more review comments addressed
* support smooth roll back of lookup snapshots from 0.10.0 to 0.9.2
* correctly use LifecycleLock in LookupCoordinatorManager and remove synchronization from start/stop
* run lookup mgmt on leader coordinator only
* wip: changes to do multiple start() and stop() on LookupCoordinatorManager
* lifecycleLock fix usage in LookupReferencesManagerTest
* add LifecycleLock back
* fix license hdr
* some fixes
* make LookupReferencesManager.getAllLookupsState() consistent while still being lockless
* address review comments
* addressing leventov's comments
* address charle's comments
* add IOE.java
* for safety in LookupReferencesManager mainThread check for lifecycle started state on each loop in addition to interrupt
* move thread creation utility method to Execs
* fix names
* add tests for LookupCoordinatorManager.lookupManagementLoop()
* add further tests for figuring out toBeLoaded and toBeDropped on LookupCoordinatorManager
* address leventov comments
* remove LookupsStateWithMap and parameterize LookupsState
* address review comments
* address more review comments
* misc fixes
Roman Leventov
Himanshu
Gian Merlino
Jihoon Son
Atul Mohan
Kevin Conaway
Parag Jain
praveev
Akash Dwivedi
Jonathan Wei
Niketh Sabbineni
Goh Wei Xiang
Charles Allen
dgolitsyn
Egor Riashin
Slim
Chris Gavin
kaijianding
Kenji Noguchi
Benedict Jin
satishbhor
David Lim