* Speed up ExpressionSelectors.makeExprEvalSelector
Addresses performance bottlenecks observed when running a search query
with an expression filter and granularity set to none by caching and
changing streams to for-loops. After changes, the query was observed to
run 2-3x faster.
Also fixes various IntelliJ inspection warnings.
* Fix static analysis errors
JVMMonitor requires access to jdk.internal.perf.Perf to enable GC
counters, which requires additional JVM arguments with JDK11.
This change adds a fallback in case GC counters cannot be initialized,
and logs a warning message explaining how GC counters can be enabled.
* Fallback to parsing classpath for hadoop task in Java 9+
In Java 9 and above we cannot assume that the system classloader is an
instance of URLClassLoader. This change adds a fallback method to parse
the system classpath in that case, and adds a unit test to validate it matches
what JDK8 would do.
Note: This has not been tested in an actual hadoop setup, so this is mostly
to help us pass unit tests.
* Remove granularity test of dubious value
One of our granularity tests relies on system classloader being a URLClassLoaders to
catch a bug related to class initialization and static initializers using a subclass (see
#2979)
This test was added to catch a potential regression, but it assumes we would add back
the same type of static initializers to this specific class, so it seems to be of dubious value
as a unit test and mostly serves to illustrate the bug.
relates to #5589
* check ctyle for constant field name
* check ctyle for constant field name
* check ctyle for constant field name
* check ctyle for constant field name
* check ctyle for constant field name
* check ctyle for constant field name
* check ctyle for constant field name
* check ctyle for constant field name
* check ctyle for constant field name
* merging with upstream
* review-1
* unknow changes
* unknow changes
* review-2
* merging with master
* review-2 1 changes
* review changes-2 2
* bug fix
* Add group_id to overlord tasks API and sys.tasks table
* adjust test
* modify docs
* Make groupId nullable
* fix integration test
* fix toString
* Remove groupId from TaskInfo
* Modify docs and tests
* modify TaskMonitorTest
* Enable code coverage
Code coverage was disabled via
https://github.com/apache/incubator-druid/pull/3122 due to an issue with
cobertura in Travis CI. Switch code coverage tool from cobertura to
jacoco to avoid issue and re-enable coveralls for Travis CI.
* Exclude non-production code
* Exclude benchmark generated code
* Exclude DruidTestRunnerFactory
* Add TaskResourceCleaner; fix a couple of concurrency bugs in batch tasks
* kill runner when it's ready
* add comment
* kill run thread
* fix test
* Take closeable out of Appenderator
* add javadoc
* fix test
* fix test
* update javadoc
* add javadoc about killed task
* address comment
* Add support for parallel native indexing with shuffle for perfect rollup.
* Add comment about volatiles
* fix test
* fix test
* handling missing exceptions
* more clear javadoc for stopGracefully
* unused import
* update javadoc
* Add missing statement in javadoc
* address comments; fix doc
* add javadoc for isGuaranteedRollup
* Rename confusing variable name and fix typos
* fix typos; move fetch() to a better home; fix the expiration time
* add support https
* make double sum/min/max agg work on string columns
* style and compilation fixes
* fix tests
* address review comments
* add comment on SimpleDoubleAggregatorFactory
* make checkstyle happy
After enabling parallel builds for "mvn install", the sigar dependency
would sometimes resolve to the incorrect artifact repo for some of the
maven modules. This issue seems to be fixed by moving the definition of
the sigar dependency's artifact repo to the root POM.
Also, depending on network speeds, "mvn -q install" may take longer than
the default 10 minute timeout to print any output. Use travis_wait to
extend the timeout to 15 minutes.
* Use partitionsSpec for all task types
* fix doc
* fix typos and revert to use isPushRequired
* address comments
* move partitionsSpec to core
* remove hadoopPartitionsSpec
* firehose doc adjustments
* fix typo
* additional information on parser types in ingestion docs
* clarify ingest segment firehose docs, add sql firehose examples to sql extension pages
* fixit
* make sql firehose more forgiving my always constructing a MapInputRowParser from the parseSpec of whatever actual InputRowParser impl is provided, remove doc references to map based parsers
* transforms
* fix tests
* Fix dependency analyze warnings
Update the maven dependency plugin to the latest version and fix all
warnings for unused declared and used undeclared dependencies in the
compile scope. Added new travis job to add the check to CI. Also fixed
some source code files to use the correct packages for their imports.
* Fix licenses and dependencies
* Fix licenses and dependencies again
* Fix integration test dependency
* Address review comments
* Fix unit test dependencies
* Fix integration test dependency
* Fix integration test dependency again
* Fix integration test dependency third time
* Fix integration test dependency fourth time
* Fix compile error
* Fix assert package
* add CachingClusteredClient benchmark, refactor some stuff
* revert WeightedServerSelectorStrategy to ConnectionCountServerSelectorStrategy and remove getWeight since felt artificial, default mergeResults in toolchest implementation for topn, search, select
* adjust javadoc
* adjustments
* oops
* use it
* use BinaryOperator, remove CombiningFunction, use Comparator instead of Ordering, other review adjustments
* rename createComparator to createResultComparator, fix typo, firstNonNull nullable parameters
* doc updates and changes to use the CollectionUtils.mapValues utility method
* Add Structural Search patterns to intelliJ
* refactoring from PR comments
* put -> putIfAbsent
* do single key lookup
* Benchmarks: New SqlBenchmark, add caching & vectorization to some others.
- Introduce a new SqlBenchmark geared towards benchmarking a wide
variety of SQL queries. Rename the old SqlBenchmark to
SqlVsNativeBenchmark.
- Add (optional) caching to SegmentGenerator to enable easier
benchmarking of larger segments.
- Add vectorization to FilteredAggregatorBenchmark and GroupByBenchmark.
* Query vectorization.
This patch includes vectorized timeseries and groupBy engines, as well
as some analogs of your favorite Druid classes:
- VectorCursor is like Cursor. (It comes from StorageAdapter.makeVectorCursor.)
- VectorColumnSelectorFactory is like ColumnSelectorFactory, and it has
methods to create analogs of the column selectors you know and love.
- VectorOffset and ReadableVectorOffset are like Offset and ReadableOffset.
- VectorAggregator is like BufferAggregator.
- VectorValueMatcher is like ValueMatcher.
There are some noticeable differences between vectorized and regular
execution:
- Unlike regular cursors, vector cursors do not understand time
granularity. They expect query engines to handle this on their own,
which a new VectorCursorGranularizer class helps with. This is to
avoid too much batch-splitting and to respect the fact that vector
selectors are somewhat more heavyweight than regular selectors.
- Unlike FilteredOffset, FilteredVectorOffset does not leverage indexes
for filters that might partially support them (like an OR of one
filter that supports indexing and another that doesn't). I'm not sure
that this behavior is desirable anyway (it is potentially too eager)
but, at any rate, it'd be better to harmonize it between the two
classes. Potentially they should both do some different thing that
is smarter than what either of them is doing right now.
- When vector cursors are created by QueryableIndexCursorSequenceBuilder,
they use a morphing binary-then-linear search to find their start and
end rows, rather than linear search.
Limitations in this patch are:
- Only timeseries and groupBy have vectorized engines.
- GroupBy doesn't handle multi-value dimensions yet.
- Vector cursors cannot handle virtual columns or descending order.
- Only some filters have vectorized matchers: "selector", "bound", "in",
"like", "regex", "search", "and", "or", and "not".
- Only some aggregators have vectorized implementations: "count",
"doubleSum", "floatSum", "longSum", "hyperUnique", and "filtered".
- Dimension specs other than "default" don't work yet (no extraction
functions or filtered dimension specs).
Currently, the testing strategy includes adding vectorization-enabled
tests to TimeseriesQueryRunnerTest, GroupByQueryRunnerTest,
GroupByTimeseriesQueryRunnerTest, CalciteQueryTest, and all of the
filtering tests that extend BaseFilterTest. In all of those classes,
there are some test cases that don't support vectorization. They are
marked by special function calls like "cannotVectorize" or "skipVectorize"
that tell the test harness to either expect an exception or to skip the
test case.
Testing should be expanded in the future -- a project in and of itself.
Related to #3011.
* WIP
* Adjustments for unused things.
* Adjust javadocs.
* DimensionDictionarySelector adjustments.
* Add "clone" to BatchIteratorAdapter.
* ValueMatcher javadocs.
* Fix benchmark.
* Fixups post-merge.
* Expect exception on testGroupByWithStringVirtualColumn for IncrementalIndex.
* BloomDimFilterSqlTest: Tag two non-vectorizable tests.
* Minor adjustments.
* Update surefire, bump up Xmx in Travis.
* Some more adjustments.
* Javadoc adjustments
* AggregatorAdapters adjustments.
* Additional comments.
* Remove switching search.
* Only missiles.
Make static imports forbidden in tests and remove all occurrences to be
consistent with the non-test code.
Also, various changes to files affected by above:
- Reformat to adhere to druid style guide
- Fix various IntelliJ warnings
- Fix various SonarLint warnings (e.g., the expected/actual args to
Assert.assertEquals() were flipped)
* more sql support for expression array functions
* prepend/slice
* doc fixes
* fix imports
* fix tests
* add null numeric expr for proper conversions between ExprEval and Expr and back to ExprEval
* re-arrange
* imports :(
* add append/prepend test
* array support for expression language for multi-value string columns
* fix tests?
* fixes
* more tests
* fixes
* cleanup
* more better, more test
* ignore inspection
* license
* license fix
* inspection
* remove dumb import
* more better
* some comments
* add expr rewrite for arrayfn args for more magic, tests
* test stuff
* more tests
* fix test
* fix test
* castfunc can deal with arrays
* needs more empty array
* more tests, make cast to long array more forgiving
* refactor
* simplify ExprMacro Expr implementations with base classes in core
* oops
* more test
* use Shuttle for Parser.flatten, javadoc, cleanup
* fixes and more tests
* unused import
* fixes
* javadocs, cleanup, refactors
* fix imports
* more javadoc
* more javadoc
* more
* more javadocs, nonnullbydefault, minor refactor
* markdown fix
* adjustments
* more doc
* move initial filter out
* docs
* map empty arg lambda, apply function argument validation
* check function args at parse time instead of eval time
* more immutable
* more more immutable
* clarify grammar
* fix docs
* empty array is string test, we need a way to make arrays better maybe in the future, or define empty arrays as other types..
* Add state and error tracking for seekable stream supervisors
* Fixed nits in docs
* Made inner class static and updated spec test with jackson inject
* Review changes
* Remove redundant config param in supervisor
* Style
* Applied some of Jon's recommendations
* Add transience field
* write test
* implement code review changes except for reconsidering logic of markRunFinishedAndEvaluateHealth()
* remove transience reporting and fix SeekableStreamSupervisorStateManager impl
* move call to stateManager.markRunFinished() from RunNotice to runInternal() for tests
* remove stateHistory because it wasn't adding much value, some fixes, and add more tests
* fix tests
* code review changes and add HTTP health check status
* fix test failure
* refactor to split into a generic SupervisorStateManager and a specific SeekableStreamSupervisorStateManager
* fixup after merge
* code review changes - add additional docs
* cleanup KafkaIndexTaskTest
* add additional documentation for Kinesis indexing
* remove unused throws class
Recently we've been talking about using SegmentIds as map keys rather than
DataSegments, because its sense of equality is more well-defined. This is
a refactor that does this in the druid-sql module, which mostly involves
DruidSchema and some related classes. It should have no user-visible effects.
* Add checkstyle for "Local variable names shouldn't start with capital"
* Adjust some local variables to constants
* Replace StringUtils.LINE_SEPARATOR with System.lineSeparator()
* Bump Checkstyle to 8.20
Moderate severity vulnerability that affects:
com.puppycrawl.tools:checkstyle
Checkstyle prior to 8.18 loads external DTDs by default,
which can potentially lead to denial of service attacks
or the leaking of confidential information.
Affected versions: < 8.18
* Oops, missed one
* Oops, missed a few
* update easymock / powermock for to 4.0.2 / 2.0.2 for JDK11 support
* update tests to use new easymock interfaces
* fix tests failing due to easymock fixes
* remove dependency on jmockit
* fix race condition in ResourcePoolTest
* sampler initial check-in
fix checkstyle issues
add sampler fix to process CSV files from cache properly
change to composition and rename some classes
add tests and report num rows read and indexed
remove excludedByFilter flag and don't send filtered out data
fix tests to handle both settings for druid.generic.useDefaultValueForNull
* wrap sampler firehose in TimedShutoffFirehoseFactory to support timeouts
* code review changes - add additional comments, limit maxRows
* Java 9 compatible specialized class compilation
We currently use Unsafe.defineClass to compile specialized classes,
which has been removed in Java 9 and above. This change switches to
MethodHandles.Lookup.defineClass at runtime, which provides similar
functionality in newer JDK versions.
* add comments
* fix incorrect comment
* add unsafe utility class
* make comments java-doc style
* fix checkstyle errors
* rename unsafe -> unsafeutil
* move defineClass method to utility class
* rename unsafeutil -> unsafeutils to match other utility class names
* remove extra lookup method
* add utiliy class docs
* more comments
* minor comments and formatting
Java 9 removed support for sun.misc.Cleaner in favor of
java.lang.ref.Cleaner. This change adds a thin abstraction to switch
between Cleaner implementations based on JDK version at runtime
* Implement round function in druid-sql
* Return value according to the type of argument
* Fix codes for abnoraml inputs, updated math-expr.md
* Fix assert text
* Fix error messages and refactor codes
* Fix compile error, update sql.md, refactor codes and format tests
* Enhnace the HttpFirehose to work with both insecure URIs and URIs requiring basic authentication
* Improve security of enhanced HttpFirehoseFactory by not logging auth credentials
* Fix checkstyle failure in HttpFirehoseFactory.java
* Update docs and fix TeamCity build with required noinspection
* Indentation cleanup and logic modification for HttpFirehose object stream
* Remove default Empty string password provider in http firehose
* Add JavaDoc for MixIn describing its intended use
* Reverting documentation notation for json code to be inline with rest of doc
* Improve instantiation of ObjectMappers that require MixIn for redacting password from task logs
* Add comment to clarify fully qualified references of Objects in SQLMetadataStorageActionHandler
The current bytebuffer unmap operations are not compatible with Java 9
and above. This change adapts the code from Apache Kafka to perform the
appropriate unmap operation based on JDK version at runtime.
see e554dc518e
* orc extension reworked to use apache orc map-reduce lib, moved to core extensions, support for flattenSpec, tests, docs
* change binary handling to be compatible with avro and parquet, Rows.objectToStrings now converts byte[] to base64, change date handling
* better docs and tests
* fix it
* formatting
* doc fix
* fix it
* exclude redundant dependencies
* use latest orc-mapreduce, add hadoop jobProperties recommendations to docs
* doc fix
* review stuff and fix binaryAsString
* cache for root level fields
* more better
* Moved Scan Builder to Druids class and started on Scan Benchmark setup
* Need to form queries
* It runs.
* Stuff for time-ordered scan query
* Move ScanResultValue timestamp comparator to a separate class for testing
* Licensing stuff
* Change benchmark
* Remove todos
* Added TimestampComparator tests
* Change number of benchmark iterations
* Added time ordering to the scan benchmark
* Changed benchmark params
* More param changes
* Benchmark param change
* Made Jon's changes and removed TODOs
* Broke some long lines into two lines
* nit
* Decrease segment size for less memory usage
* Wrote tests for heapsort scan result values and fixed bug where iterator
wasn't returning elements in correct order
* Wrote more tests for scan result value sort
* Committing a param change to kick teamcity
* Fixed codestyle and forbidden API errors
* .
* Improved conciseness
* nit
* Created an error message for when someone tries to time order a result
set > threshold limit
* Set to spaces over tabs
* Fixing tests WIP
* Fixed failing calcite tests
* Kicking travis with change to benchmark param
* added all query types to scan benchmark
* Fixed benchmark queries
* Renamed sort function
* Added javadoc on ScanResultValueTimestampComparator
* Unused import
* Added more javadoc
* improved doc
* Removed unused import to satisfy PMD check
* Small changes
* Changes based on Gian's comments
* Fixed failing test due to null resultFormat
* Added config and get # of segments
* Set up time ordering strategy decision tree
* Refactor and pQueue works
* Cleanup
* Ordering is correct on n-way merge -> still need to batch events into
ScanResultValues
* WIP
* Sequence stuff is so dirty :(
* Fixed bug introduced by replacing deque with list
* Wrote docs
* Multi-historical setup works
* WIP
* Change so batching only occurs on broker for time-ordered scans
Restricted batching to broker for time-ordered queries and adjusted
tests
Formatting
Cleanup
* Fixed mistakes in merge
* Fixed failing tests
* Reset config
* Wrote tests and added Javadoc
* Nit-change on javadoc
* Checkstyle fix
* Improved test and appeased TeamCity
* Sorry, checkstyle
* Applied Jon's recommended changes
* Checkstyle fix
* Optimization
* Fixed tests
* Updated error message
* Added error message for UOE
* Renaming
* Finish rename
* Smarter limiting for pQueue method
* Optimized n-way merge strategy
* Rename segment limit -> segment partitions limit
* Added a bit of docs
* More comments
* Fix checkstyle and test
* Nit comment
* Fixed failing tests -> allow usage of all types of segment spec
* Fixed failing tests -> allow usage of all types of segment spec
* Revert "Fixed failing tests -> allow usage of all types of segment spec"
This reverts commit ec470288c7.
* Revert "Merge branch '6088-Time-Ordering-On-Scans-N-Way-Merge' of github.com:justinborromeo/incubator-druid into 6088-Time-Ordering-On-Scans-N-Way-Merge"
This reverts commit 57033f36df, reversing
changes made to 8f01d8dd16.
* Check type of segment spec before using for time ordering
* Fix bug in numRowsScanned
* Fix bug messing up count of rows
* Fix docs and flipped boolean in ScanQueryLimitRowIterator
* Refactor n-way merge
* Added test for n-way merge
* Refixed regression
* Checkstyle and doc update
* Modified sequence limit to accept longs and added test for long limits
* doc fix
* Implemented Clint's recommendations
* Avoid many unnecessary materializations of collections of 'all segments in cluster' cardinality
* Fix DruidCoordinatorTest; Renamed DruidCoordinator.getReplicationStatus() to computeUnderReplicationCountsPerDataSourcePerTier()
* More Javadocs, typos, refactor DruidCoordinatorRuntimeParams.createAvailableSegmentsSet()
* Style
* typo
* Disable StaticPseudoFunctionalStyleMethod inspection because of too much false positives
* Fixes
* Throw caught exception.
* Throw caught exceptions.
* Related checkstyle rule is added to prevent further bugs.
* RuntimeException() is used instead of Throwables.propagate().
* Missing import is added.
* Throwables are propogated if possible.
* Throwables are propogated if possible.
* Throwables are propogated if possible.
* Throwables are propogated if possible.
* * Checkstyle definition is improved.
* Throwables.propagate() usages are removed.
* Checkstyle pattern is changed for only scanning "Throwables.propagate(" instead of checking lookbehind.
* Throwable is kept before firing a Runtime Exception.
* Fix unused assignments.
#### `EventReceiverFirehoseFactory`
Fixed several concurrency bugs in `EventReceiverFirehoseFactory`:
- Race condition over putting an entry into `producerSequences` in `checkProducerSequence()`.
- `Stopwatch` used to measure time across threads, but it's a non-thread-safe class.
- Use `System.nanoTime()` instead of `System.currentTimeMillis()` because the latter are [not suitable](https://stackoverflow.com/a/351571/648955) for measuring time intervals.
- `close()` was not synchronized by could be called from multiple threads concurrently.
Removed unnecessary `readLock` (protecting `hasMore()` and `nextRow()` which are always called from a single thread). Removed unnecessary `volatile` modifiers.
Documented threading model and concurrent control flow of `EventReceiverFirehose` instances.
**Important:** please read the updated Javadoc for `EventReceiverFirehose.addAll()`. It allows events from different requests (batches) to be interleaved in the buffer. Is this OK?
#### `TimedShutoffFirehoseFactory`
- Fixed a race condition that was possible because `close()` that was not properly synchronized.
Documented threading model and concurrent control flow of `TimedShutoffFirehose` instances.
#### `Firehose`
Refined concurrency contract of `Firehose` based on `EventReceiverFirehose` implementation. Importantly, now it states that `close()` doesn't affect `hasMore()` and `nextRow()` and could be called concurrently with them. In other words, specified that `close()` is for "row supply" side rather than "row consume" side. However, I didn't check that other `Firehose` implementatations adhere to this contract.
<hr>
This issue is the result of reviewing `EventReceiverFirehose` and `TimedShutoffFirehose` using [this checklist](https://medium.com/@leventov/code-review-checklist-java-concurrency-49398c326154).
* [#1332] Fix - select failing if milis used for idx.
* Formating correction.
* Address comment: throw original exception.
* Using constant values in tests
- Try converting to Integer and then multiply by 1000L to achieve milis.
- If not successful try converting to Long or rethrow original
exception.
* DateTime#of has to support "2011-01-01T00:00:00"
- in addition to seconds and milisecs, this method currently supports
even a date string.
* Handle only milisec timestamps and ISO8601 strings
* Remove DataSegmentFinder, InsertSegmentToDb, and descriptor.json file
* delete descriptor.file when killing segments
* fix test
* Add doc for ha
* improve warning
* document middle manager api
* re-arrange
* correction
* document more missing overlord api calls, minor re-arrange of some code i was referencing
* fix it
* this will fix it
* fixup
* link to other docs
* Prohibit assigning concurrent maps into Map-types variables and fields; Fix a race condition in CoordinatorRuleManager; improve logic in DirectDruidClient and ResourcePool
* Enforce that if compute(), computeIfAbsent(), computeIfPresent() or merge() is called on a ConcurrentHashMap, it's stored in a ConcurrentHashMap-typed variable, not ConcurrentMap; add comments explaining get()-before-computeIfAbsent() optimization; refactor Counters; fix a race condition in Intialization.java
* Remove unnecessary comment
* Checkstyle
* Fix getFromExtensions()
* Add a reference to the comment about guarded computeIfAbsent() optimization; IdentityHashMap optimization
* Fix UriCacheGeneratorTest
* Workaround issue with MaterializedViewQueryQueryToolChest
* Strengthen Appenderator's contract regarding concurrency
* * Add few methods about base64 into StringUtils
* Use `java.util.Base64` instead of others
* Add org.apache.commons.codec.binary.Base64 & com.google.common.io.BaseEncoding into druid-forbidden-apis
* Rename encodeBase64String & decodeBase64String
* Update druid-forbidden-apis
* Use multi-guava version friendly direct executor implementation
* Don't use a singleton
* Fix strict compliation complaints
* Copy Guava's DirectExecutor
* Fix javadoc
* Imports are the devil
* FilteredRequestLogger: Fix start/stop, invalid delegate behavior.
Fixes two bugs:
1) FilteredRequestLogger did not start/stop the delegate.
2) FilteredRequestLogger would ignore an invalid delegate type, and
instead silently substitute the "noop" logger. This was due to a larger
problem with RequestLoggerProvider setup in general; the fix here is
to remove "defaultImpl" from the RequestLoggerProvider interface, and
instead have JsonConfigurator be responsible for creating the
default implementations. It is stricter about things than the old system
was, and is only willing to make a noop logger if it doesn't see any
request logger configs. Otherwise, it'll raise a provision error.
* Remove unneeded annotations.
* FileUtils: Sync directory entry too on writeAtomically.
See the fsync(2) man page for why this is important:
https://linux.die.net/man/2/fsync
This also plumbs CompressionUtils's "zip" function through
writeAtomically, so the code for handling atomic local filesystem
writes is all done in the same place.
* Remove unused import.
* Avoid FileOutputStream.
* Allow non-atomic writes to overwrite.
* Add some comments. And no need to flush an unbuffered stream.
* autosize processing buffers based on direct memory sizing
* remove oops, more test
* max 1gb autosize buffers, test, start of docs
* fix oops
* revert accidental change
* print buffer size in exception
* change the things
Not putting this to 0.13 milestone because the found bugs are not critical (one is a harmless DI config duplicate, and another is in a benchmark.
Change in `DumpSegment` is just an indentation change.
* Add checkstyle rules about imports and empty lines between members
* Add suppressions
* Update Eclipse import order
* Add empty line
* Fix StatsDEmitter
Also add a "fromIndex" argument to the strpos expression function. There
are some -1 and +1 adjustment terms due to the fact that the strpos
expression behaves like Java indexOf (0-indexed), but the POSITION SQL
function is 1-indexed.
* Optimization for expressions that hit a single long column.
There was previously a single-long-input optimization that applied only
to the time column. These have been combined together. Also adds
type-specific value caching to ExprEval, which allowed simplifying
the SingleLongInputCachingExpressionColumnValueSelector code.
* Add more benchmarks.
* Don't use LRU cache for __time.
* Simplify a bit.
* Let the cache grow.
* move parquet-extensions from contrib to core, adds new hadoop parquet parser that does not convert to avro first and supports flattenSpec and int96 columns, add support for flattenSpec for parquet-avro conversion parser, much test with a bunch of files lifted from spark-sql
* fix avro flattener to support nullable primitives for auto discovery and now only supports primitive arrays instead of all arrays
* remove leftover print
* convert micro timestamp to millis
* checkstyle
* add ignore for .parquet and .parq to rat exclude
* fix legit test failure from avro flattern behavior change
* fix rebase
* add exclusions to pom to cut down on redundant jars
* refactor tests, add support for unwrapping lists for parquet-avro, review comments
* more comment
* fix oops
* tweak parquet-avro list handling
* more docs
* fix style
* grr styles
* Prohibit some guava collection APIs and use JDK APIs directly
* reset files that changed by accident
* sort codestyle/druid-forbidden-apis.txt alphabetically
@gianm gauge `emitter/buffers/failed` and `emitter/buffers/totalAllocated` metrics proved to be very inconvenient in practice: they are not additive across a fleet of nodes, are randomly reset when a JVM restarts (that may be completely independent from metrics emitting issues). Regarding [problem identification](https://github.com/apache/incubator-druid/pull/4973#issuecomment-338119125), `emitter/buffers/dropped` serves this well.
Currently in this PR I added `/delta` vs. `/total` metrics, but if there are no objections I would remove `/total` and so align `emitter/buffers/allocated` and `/failed` with `/dropped` and `/events/emitted` which are already delta-only.
Chi Cao Minh
Xavier Léauté
SandishKumarHN
Surekha
Clint Wylie
Benedict Jin
Jihoon Son
Jonathan Wei
Fokko Driesprong
Himanshu
Artiom Darie
Roman Leventov
Gian Merlino
Sashidhar Thallam
Xue Yu
Fokko Driesprong
Clint Wylie
Justin Borromeo
Gian Merlino
Merlin Lee
Xue Yu
David Lim
Xavier Léauté
Kazuhito Takeuchi
Lucas Capistrant
Furkan KAMACI
Mirko Jotic
Egor Riashin
Charles Allen
David Glasser
Mingming Qiu
seoeun
David Lim
patelh