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Java bindings for cudf::hash_join (#9080)
Adds Java APIs to build a hash table for the right side table in a join and re-use it to join against a series of left probe tables. It also exposes the ability to compute the join output row count and pass that count to a subsequent call to produce the join gather maps to avoid redundant computation when the output row count must be examined before manifesting the gather maps. Authors: - Jason Lowe (https://github.com/jlowe) Approvers: - Robert (Bobby) Evans (https://github.com/revans2) URL: #9080
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| /* | ||
| * Copyright (c) 2021, NVIDIA CORPORATION. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
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| package ai.rapids.cudf; | ||
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| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
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| /** | ||
| * This class represents a hash table built from the join keys of the right-side table for a | ||
| * join operation. This hash table can then be reused across a series of left probe tables | ||
| * to compute gather maps for joins more efficiently when the right-side table is not changing. | ||
| * It can also be used to query the output row count of a join and then pass that result to the | ||
| * operation that generates the join gather maps to avoid redundant computation when the output | ||
| * row count must be checked before manifesting the join gather maps. | ||
| */ | ||
| public class HashJoin implements AutoCloseable { | ||
| static { | ||
| NativeDepsLoader.loadNativeDeps(); | ||
| } | ||
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| private static final Logger log = LoggerFactory.getLogger(HashJoin.class); | ||
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| private static class HashJoinCleaner extends MemoryCleaner.Cleaner { | ||
| private Table buildKeys; | ||
| private long nativeHandle; | ||
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| HashJoinCleaner(Table buildKeys, long nativeHandle) { | ||
| this.buildKeys = buildKeys; | ||
| this.nativeHandle = nativeHandle; | ||
| addRef(); | ||
| } | ||
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| @Override | ||
| protected synchronized boolean cleanImpl(boolean logErrorIfNotClean) { | ||
| long origAddress = nativeHandle; | ||
| boolean neededCleanup = nativeHandle != 0; | ||
| if (neededCleanup) { | ||
| try { | ||
| destroy(nativeHandle); | ||
| buildKeys.close(); | ||
| buildKeys = null; | ||
| } finally { | ||
| nativeHandle = 0; | ||
| } | ||
| if (logErrorIfNotClean) { | ||
| log.error("A HASH TABLE WAS LEAKED (ID: " + id + " " + Long.toHexString(origAddress)); | ||
| } | ||
| } | ||
| return neededCleanup; | ||
| } | ||
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| @Override | ||
| public boolean isClean() { | ||
| return nativeHandle == 0; | ||
| } | ||
| } | ||
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| private final HashJoinCleaner cleaner; | ||
| private final boolean compareNulls; | ||
| private boolean isClosed = false; | ||
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| /** | ||
| * Construct a hash table for a join from a table representing the join key columns from the | ||
| * right-side table in the join. The resulting instance must be closed to release the | ||
| * GPU resources associated with the instance. | ||
| * @param buildKeys table view containing the join keys for the right-side join table | ||
| * @param compareNulls true if null key values should match otherwise false | ||
| */ | ||
| public HashJoin(Table buildKeys, boolean compareNulls) { | ||
| this.compareNulls = compareNulls; | ||
| Table buildTable = new Table(buildKeys.getColumns()); | ||
| try { | ||
| long handle = create(buildTable.getNativeView(), compareNulls); | ||
| this.cleaner = new HashJoinCleaner(buildTable, handle); | ||
| MemoryCleaner.register(this, cleaner); | ||
| } catch (Throwable t) { | ||
| try { | ||
| buildTable.close(); | ||
| } catch (Throwable t2) { | ||
| t.addSuppressed(t2); | ||
| } | ||
| throw t; | ||
| } | ||
| } | ||
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| @Override | ||
| public synchronized void close() { | ||
| cleaner.delRef(); | ||
| if (isClosed) { | ||
| cleaner.logRefCountDebug("double free " + this); | ||
| throw new IllegalStateException("Close called too many times " + this); | ||
| } | ||
| cleaner.clean(false); | ||
| isClosed = true; | ||
| } | ||
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| long getNativeView() { | ||
| return cleaner.nativeHandle; | ||
| } | ||
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| /** Get the number of join key columns for the table that was used to generate the has table. */ | ||
| public long getNumberOfColumns() { | ||
| return cleaner.buildKeys.getNumberOfColumns(); | ||
| } | ||
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| /** Returns true if the hash table was built to match on nulls otherwise false. */ | ||
| public boolean getCompareNulls() { | ||
| return compareNulls; | ||
| } | ||
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| private static native long create(long tableView, boolean nullEqual); | ||
| private static native void destroy(long handle); | ||
| } |
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