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Avoid extra allocations in RestGetAliasesAction #126177

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Merged
merged 11 commits into from
Apr 7, 2025
Merged

Avoid extra allocations in RestGetAliasesAction #126177

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2d824ba
Avoid extra allocations in RestGetAliasesAction
JeremyDahlgren Apr 3, 2025
ec666bf
Update docs/changelog/126177.yaml
JeremyDahlgren Apr 3, 2025
3694b13
Merge branch 'main' into get-alias-action-reduce-alloc
JeremyDahlgren Apr 3, 2025
7b00f2c
Delete docs/changelog/126177.yaml
JeremyDahlgren Apr 3, 2025
9bddef7
Address code review comments, add unit test case
JeremyDahlgren Apr 4, 2025
b7f0490
Merge branch 'main' into get-alias-action-reduce-alloc
JeremyDahlgren Apr 4, 2025
f117e48
Use for loops instead of streams
JeremyDahlgren Apr 5, 2025
632d818
Merge branch 'main' into get-alias-action-reduce-alloc
JeremyDahlgren Apr 5, 2025
980c8b4
Address code review comments
JeremyDahlgren Apr 7, 2025
f11e4a7
Merge branch 'main' into get-alias-action-reduce-alloc
JeremyDahlgren Apr 7, 2025
0660270
Merge branch 'main' into get-alias-action-reduce-alloc
JeremyDahlgren Apr 7, 2025
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29 changes: 19 additions & 10 deletions server/src/main/java/org/elasticsearch/rest/action/admin/indices/RestGetAliasesAction.java
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Original file line number Diff line number Diff line change
Expand Up @@ -84,19 +84,28 @@ static RestResponse buildRestResponse(
) throws Exception {
final Set<String> indicesToDisplay = new HashSet<>();
final Set<String> returnedAliasNames = new HashSet<>();
for (final Map.Entry<String, List<AliasMetadata>> cursor : responseAliasMap.entrySet()) {
for (final AliasMetadata aliasMetadata : cursor.getValue()) {
if (aliasesExplicitlyRequested) {
// only display indices that have aliases
indicesToDisplay.add(cursor.getKey());
if (aliasesExplicitlyRequested || requestedAliases.length > 0) {
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I've peered into the original code...
Does aliasesExplicitlyRequested have any influence? I think we can remove it (consider it either true or false in the original code).

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Yes, it can be true even when requestedAliases.length == 0 in the case _all is used for the name param. In prepareRequest() it uses request.paramAsStringArrayOrEmptyIfAll("name"). I originally wanted to eliminate aliasesExplicitlyRequested, but some tests broke even when the RestGetAliasesActionTests passed. An example was:

ClientYamlTestSuiteIT > test {yaml=indices.get_alias/10_basic/Get aliases via /_alias/_all} FAILED
    java.lang.AssertionError: Failure at [indices.get_alias/10_basic:70]: field [test_index_3] has a true value but it shouldn't

I added a new unit test case in RestGetAliasesActionTests that uses _all to cover this scenario.

I also refactored to simplify the code and just use aliasesExplicitlyRequested. Please let me know how this looks to you.

for (final Map.Entry<String, List<AliasMetadata>> cursor : responseAliasMap.entrySet()) {
final var aliases = cursor.getValue();
if (aliases.isEmpty() == false) {
if (aliasesExplicitlyRequested) {
// only display indices that have aliases
indicesToDisplay.add(cursor.getKey());
}
if (requestedAliases.length > 0) {
for (final AliasMetadata aliasMetadata : aliases) {
returnedAliasNames.add(aliasMetadata.alias());
}
}
}
returnedAliasNames.add(aliasMetadata.alias());
}
}
dataStreamAliases.entrySet()
.stream()
.flatMap(entry -> entry.getValue().stream())
.forEach(dataStreamAlias -> returnedAliasNames.add(dataStreamAlias.getName()));
if (requestedAliases.length > 0) {
dataStreamAliases.entrySet()
.stream()
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May as well destreamify this one here too.

.flatMap(entry -> entry.getValue().stream())
.forEach(dataStreamAlias -> returnedAliasNames.add(dataStreamAlias.getName()));
}

// compute explicitly requested aliases that have are not returned in the result
final SortedSet<String> missingAliases = new TreeSet<>();
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can we move the code that computes the missingAliases into a separate function.

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