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Posted to commits@drill.apache.org by bo...@apache.org on 2019/01/09 04:12:01 UTC
[drill] 03/03: Changes following second code review
This is an automated email from the ASF dual-hosted git repository.
boaz pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/drill.git
commit fc1eacda8b181934eea811e5f228fff697f94549
Author: Ben-Zvi <bb...@mapr.com>
AuthorDate: Tue Jan 8 18:40:54 2019 -0800
Changes following second code review
---
.../exec/physical/impl/common/ChainedHashTable.java | 16 ++++++++--------
.../exec/physical/impl/common/HashTableTemplate.java | 7 +++++--
2 files changed, 13 insertions(+), 10 deletions(-)
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/ChainedHashTable.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/ChainedHashTable.java
index baed508..e7abd98 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/ChainedHashTable.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/ChainedHashTable.java
@@ -130,7 +130,7 @@ public class ChainedHashTable {
private RecordBatch incomingProbe;
private final RecordBatch outgoing;
- private enum setupWork {DO_BUILD, DO_PROBE, CHECK_BOTH_NULLS};
+ private enum SetupWork {DO_BUILD, DO_PROBE, CHECK_BOTH_NULLS};
public ChainedHashTable(HashTableConfig htConfig, FragmentContext context, BufferAllocator allocator,
RecordBatch incomingBuild, RecordBatch incomingProbe, RecordBatch outgoing) {
@@ -223,12 +223,12 @@ public class ChainedHashTable {
// (used by Hash-Join to avoid creating a long hash-table chain of null keys, which can lead to useless O(n^2) work on that chain.)
// The logic is: Nulls match on build, and don't match on probe. Note that this logic covers outer joins as well.
setupIsKeyMatchInternal(cgInner, bothKeysNullIncomingBuildMapping, bothKeysNullHtableMapping, keyExprsBuild,
- htConfig.getComparators(), htKeyFieldIds, setupWork.CHECK_BOTH_NULLS);
+ htConfig.getComparators(), htKeyFieldIds, SetupWork.CHECK_BOTH_NULLS);
// generate code for isKeyMatch(), setValue(), getHash() and outputRecordKeys()
setupIsKeyMatchInternal(cgInner, KeyMatchIncomingBuildMapping, KeyMatchHtableMapping, keyExprsBuild,
- htConfig.getComparators(), htKeyFieldIds, setupWork.DO_BUILD);
+ htConfig.getComparators(), htKeyFieldIds, SetupWork.DO_BUILD);
setupIsKeyMatchInternal(cgInner, KeyMatchIncomingProbeMapping, KeyMatchHtableProbeMapping, keyExprsProbe,
- htConfig.getComparators(), htKeyFieldIds, setupWork.DO_PROBE);
+ htConfig.getComparators(), htKeyFieldIds, SetupWork.DO_PROBE);
setupSetValue(cgInner, keyExprsBuild, htKeyFieldIds);
if (outgoing != null) {
@@ -249,9 +249,9 @@ public class ChainedHashTable {
}
private void setupIsKeyMatchInternal(ClassGenerator<HashTable> cg, MappingSet incomingMapping, MappingSet htableMapping,
- LogicalExpression[] keyExprs, List<Comparator> comparators, TypedFieldId[] htKeyFieldIds, setupWork work) {
+ LogicalExpression[] keyExprs, List<Comparator> comparators, TypedFieldId[] htKeyFieldIds, SetupWork work) {
- boolean checkIfBothNulls = work == setupWork.CHECK_BOTH_NULLS;
+ boolean checkIfBothNulls = work == SetupWork.CHECK_BOTH_NULLS;
// Regular key matching may return false in the middle (i.e., some pair of columns did not match), and true only if all matched;
// but "both nulls" check returns the opposite logic (i.e., true when one pair of nulls is found, need check no more)
@@ -277,7 +277,7 @@ public class ChainedHashTable {
JConditional jc;
- if ( work != setupWork.DO_BUILD ) { // BUILD runs this logic in a separate method - areBothKeysNull()
+ if ( work != SetupWork.DO_BUILD ) { // BUILD runs this logic in a separate method - areBothKeysNull()
// codegen for the special case when both columns are null (i.e., return early with midPointResult)
if (comparators.get(i) == Comparator.EQUALS
&& left.isOptional() && right.isOptional()) {
@@ -298,7 +298,7 @@ public class ChainedHashTable {
}
}
- // All key expressions compared equal, so return TRUE
+ // All key expressions compared the same way, so return the appropriate final result
cg.getEvalBlock()._return(finalResult);
}
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/HashTableTemplate.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/HashTableTemplate.java
index a064449..1d83239 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/HashTableTemplate.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/HashTableTemplate.java
@@ -230,8 +230,11 @@ public abstract class HashTableTemplate implements HashTable {
return isKeyMatchInternalBuild(incomingRowIdx, currentIdxWithinBatch);
}
- // This method should only be called following a "false" return from isKeyMatch()
- // It returns the next index in the hash chain (if any) so that next call to isKeyMatch() would compare the next link
+ // This method should only be used in an "iterator like" next() fashion, to traverse a hash table chain looking for a match.
+ // Starting from the first element (i.e., index) in the chain, _isKeyMatch()_ should be called on that element; if "false" is returned,
+ // then this method should be called to return the (index to the) next element in the chain (or an EMPTY_SLOT to terminate), and then
+ // _isKeyMatch()_ should be called on that next element; and so on until a match is found - where the loop is exited with the found result.
+ // (This was not implemented as a real Java iterator as each index may point to another BatchHolder).
private int nextLinkInHashChain(int currentIndex) {
return links.getAccessor().get(currentIndex & BATCH_MASK);
}