From 885060b939c05ca539eb415189aaeb59456ff48f Mon Sep 17 00:00:00 2001
From: Nik Everett <nik9000@gmail.com>
Date: Tue, 9 Jun 2020 13:15:21 -0400
Subject: [PATCH] Deprecte Rounding#round (#57845)

This deprecates `Rounding#round` and `Rounding#nextRoundingValue` in
favor of calling
```
Rounding.Prepared prepared = rounding.prepare(min, max);
...
prepared.round(val)

``` because it is always going to be faster to prepare once. There
are going to be some cases where we won't know what to prepare *for*
and in those cases you can call `prepareForUnknown` and stil be faster
than calling the deprecated method over and over and over again.

Ultimately, this is important because it doesn't look like there is an
easy way to cache `Rounding.Prepared` or any of its precursors like
`LocalTimeOffset.Lookup`. Instead, we can just build it at most once per
request.

Relates to #56124
---
 .../org/elasticsearch/common/Rounding.java    |  8 ++---
 .../common/rounding/RoundingDuelTests.java    |  6 ++--
 .../InternalAutoDateHistogramTests.java       | 21 ++++++-------
 .../histogram/InternalDateHistogramTests.java | 11 +++++--
 .../rollup/job/DateHistogramGroupConfig.java  |  6 ++--
 .../pivot/DateHistogramGroupSource.java       | 30 +++++++++++--------
 .../job/RollupIndexerIndexingTests.java       |  4 +--
 7 files changed, 48 insertions(+), 38 deletions(-)

diff --git a/server/src/main/java/org/elasticsearch/common/Rounding.java b/server/src/main/java/org/elasticsearch/common/Rounding.java
index ebfa043333ade..c795fa8cd3ca2 100644
--- a/server/src/main/java/org/elasticsearch/common/Rounding.java
+++ b/server/src/main/java/org/elasticsearch/common/Rounding.java
@@ -240,9 +240,9 @@ public interface Prepared {
 
     /**
      * Rounds the given value.
-     * <p>
-     * Prefer {@link #prepare(long, long)} if rounding many values.
+     * @deprecated Prefer {@link #prepare} and then {@link Prepared#round(long)}
      */
+    @Deprecated
     public final long round(long utcMillis) {
         return prepare(utcMillis, utcMillis).round(utcMillis);
     }
@@ -252,9 +252,9 @@ public final long round(long utcMillis) {
      * {@link #round(long)}, returns the next rounding value. For
      * example, with interval based rounding, if the interval is
      * 3, {@code nextRoundValue(6) = 9}.
-     * <p>
-     * Prefer {@link #prepare(long, long)} if rounding many values.
+     * @deprecated Prefer {@link #prepare} and then {@link Prepared#nextRoundingValue(long)}
      */
+    @Deprecated
     public final long nextRoundingValue(long utcMillis) {
         return prepare(utcMillis, utcMillis).nextRoundingValue(utcMillis);
     }
diff --git a/server/src/test/java/org/elasticsearch/common/rounding/RoundingDuelTests.java b/server/src/test/java/org/elasticsearch/common/rounding/RoundingDuelTests.java
index b791d0e3ce9dd..2bba52a0b7591 100644
--- a/server/src/test/java/org/elasticsearch/common/rounding/RoundingDuelTests.java
+++ b/server/src/test/java/org/elasticsearch/common/rounding/RoundingDuelTests.java
@@ -60,16 +60,16 @@ public void testSerialization() throws Exception {
     public void testDuellingImplementations() {
         org.elasticsearch.common.Rounding.DateTimeUnit randomDateTimeUnit =
             randomFrom(org.elasticsearch.common.Rounding.DateTimeUnit.values());
-        org.elasticsearch.common.Rounding rounding;
+        org.elasticsearch.common.Rounding.Prepared rounding;
         Rounding roundingJoda;
 
         if (randomBoolean()) {
-            rounding = org.elasticsearch.common.Rounding.builder(randomDateTimeUnit).timeZone(ZoneOffset.UTC).build();
+            rounding = org.elasticsearch.common.Rounding.builder(randomDateTimeUnit).timeZone(ZoneOffset.UTC).build().prepareForUnknown();
             DateTimeUnit dateTimeUnit = DateTimeUnit.resolve(randomDateTimeUnit.getId());
             roundingJoda = Rounding.builder(dateTimeUnit).timeZone(DateTimeZone.UTC).build();
         } else {
             TimeValue interval = timeValue();
-            rounding = org.elasticsearch.common.Rounding.builder(interval).timeZone(ZoneOffset.UTC).build();
+            rounding = org.elasticsearch.common.Rounding.builder(interval).timeZone(ZoneOffset.UTC).build().prepareForUnknown();
             roundingJoda = Rounding.builder(interval).timeZone(DateTimeZone.UTC).build();
         }
 
diff --git a/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogramTests.java b/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogramTests.java
index fd49e57e7c9aa..4d7e9b731a56e 100644
--- a/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogramTests.java
+++ b/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalAutoDateHistogramTests.java
@@ -157,6 +157,7 @@ protected void assertReduced(InternalAutoDateHistogram reduced, List<InternalAut
 
         int roundingIndex = reduced.getBucketInfo().roundingIdx;
         RoundingInfo roundingInfo = AutoDateHistogramAggregationBuilder.buildRoundings(null, null)[roundingIndex];
+        Rounding.Prepared prepared = roundingInfo.rounding.prepare(lowest, highest);
 
         long normalizedDuration = (highest - lowest) / roundingInfo.getRoughEstimateDurationMillis();
         int innerIntervalIndex = 0;
@@ -185,7 +186,7 @@ protected void assertReduced(InternalAutoDateHistogram reduced, List<InternalAut
         } else {
             do {
                 innerIntervalToUse = roundingInfo.innerIntervals[innerIntervalIndex];
-                int bucketCountAtInterval = getBucketCount(lowest, highest, roundingInfo.rounding, innerIntervalToUse);
+                int bucketCountAtInterval = getBucketCount(lowest, highest, prepared, innerIntervalToUse);
                 if (bucketCountAtInterval == reduced.getBuckets().size()) {
                     break;
                 }
@@ -199,11 +200,11 @@ protected void assertReduced(InternalAutoDateHistogram reduced, List<InternalAut
         assertThat(reduced.getInterval().toString(), equalTo(innerIntervalToUse + roundingInfo.unitAbbreviation));
         Map<Instant, Long> expectedCounts = new TreeMap<>();
         if (totalBucketConut > 0) {
-            long keyForBucket = roundingInfo.rounding.round(lowest);
-            while (keyForBucket <= roundingInfo.rounding.round(highest)) {
+            long keyForBucket = prepared.round(lowest);
+            while (keyForBucket <= prepared.round(highest)) {
                 long nextKey = keyForBucket;
                 for (int i = 0; i < innerIntervalToUse; i++) {
-                    nextKey = roundingInfo.rounding.nextRoundingValue(nextKey);
+                    nextKey = prepared.nextRoundingValue(nextKey);
                 }
                 Instant key = Instant.ofEpochMilli(keyForBucket);
                 expectedCounts.put(key, 0L);
@@ -214,7 +215,7 @@ protected void assertReduced(InternalAutoDateHistogram reduced, List<InternalAut
 
                 for (InternalAutoDateHistogram histogram : inputs) {
                     for (Histogram.Bucket bucket : histogram.getBuckets()) {
-                        long roundedBucketKey = roundingInfo.rounding.round(((ZonedDateTime) bucket.getKey()).toInstant().toEpochMilli());
+                        long roundedBucketKey = prepared.round(((ZonedDateTime) bucket.getKey()).toInstant().toEpochMilli());
                         long docCount = bucket.getDocCount();
                         if (roundedBucketKey >= keyForBucket && roundedBucketKey < nextKey) {
                             expectedCounts.compute(key,
@@ -227,8 +228,8 @@ protected void assertReduced(InternalAutoDateHistogram reduced, List<InternalAut
 
             // If there is only a single bucket, and we haven't added it above, add a bucket with no documents.
             // this step is necessary because of the roundedBucketKey < keyForBucket + intervalInMillis above.
-            if (roundingInfo.rounding.round(lowest) == roundingInfo.rounding.round(highest) && expectedCounts.isEmpty()) {
-                expectedCounts.put(Instant.ofEpochMilli(roundingInfo.rounding.round(lowest)), 0L);
+            if (prepared.round(lowest) == prepared.round(highest) && expectedCounts.isEmpty()) {
+                expectedCounts.put(Instant.ofEpochMilli(prepared.round(lowest)), 0L);
             }
         }
 
@@ -249,12 +250,12 @@ protected void assertReduced(InternalAutoDateHistogram reduced, List<InternalAut
         assertThat(reduced.getInterval(), equalTo(expectedInterval));
     }
 
-    private int getBucketCount(long min, long max, Rounding rounding, int interval) {
+    private int getBucketCount(long min, long max, Rounding.Prepared prepared, int interval) {
         int bucketCount = 0;
-        long key = rounding.round(min);
+        long key = prepared.round(min);
         while (key < max) {
             for (int i = 0; i < interval; i++) {
-                key = rounding.nextRoundingValue(key);
+                key = prepared.nextRoundingValue(key);
             }
             bucketCount++;
         }
diff --git a/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalDateHistogramTests.java b/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalDateHistogramTests.java
index 3a4ed0006b47c..d1d402e9d5e98 100644
--- a/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalDateHistogramTests.java
+++ b/server/src/test/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalDateHistogramTests.java
@@ -58,7 +58,8 @@ public void setUp() throws Exception {
         long interval = randomIntBetween(1, 3);
         intervalMillis = randomFrom(timeValueSeconds(interval), timeValueMinutes(interval), timeValueHours(interval)).getMillis();
         Rounding rounding = Rounding.builder(TimeValue.timeValueMillis(intervalMillis)).build();
-        baseMillis = rounding.round(System.currentTimeMillis());
+        long now = System.currentTimeMillis();
+        baseMillis = rounding.prepare(now, now).round(now);
         if (randomBoolean()) {
             minDocCount = randomIntBetween(1, 10);
             emptyBucketInfo = null;
@@ -108,8 +109,12 @@ protected void assertReduced(InternalDateHistogram reduced, List<InternalDateHis
             long minBound = -1;
             long maxBound = -1;
             if (emptyBucketInfo.bounds != null) {
-                minBound = emptyBucketInfo.rounding.round(emptyBucketInfo.bounds.getMin());
-                maxBound = emptyBucketInfo.rounding.round(emptyBucketInfo.bounds.getMax());
+                Rounding.Prepared prepared = emptyBucketInfo.rounding.prepare(
+                    emptyBucketInfo.bounds.getMin(),
+                    emptyBucketInfo.bounds.getMax()
+                );
+                minBound = prepared.round(emptyBucketInfo.bounds.getMin());
+                maxBound = prepared.round(emptyBucketInfo.bounds.getMax());
                 if (expectedCounts.isEmpty() && minBound <= maxBound) {
                     expectedCounts.put(minBound, 0L);
                 }
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/DateHistogramGroupConfig.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/DateHistogramGroupConfig.java
index 4db5966671df4..e8f67c8ac3932 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/DateHistogramGroupConfig.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/DateHistogramGroupConfig.java
@@ -304,7 +304,7 @@ public String getTimeZone() {
     /**
      * Create the rounding for this date histogram
      */
-    public Rounding createRounding() {
+    public Rounding.Prepared createRounding() {
         return createRounding(interval.toString(), timeZone);
     }
 
@@ -363,7 +363,7 @@ public static DateHistogramGroupConfig fromXContent(final XContentParser parser)
         return PARSER.parse(parser, null);
     }
 
-    private static Rounding createRounding(final String expr, final String timeZone) {
+    private static Rounding.Prepared createRounding(final String expr, final String timeZone) {
         Rounding.DateTimeUnit timeUnit = DateHistogramAggregationBuilder.DATE_FIELD_UNITS.get(expr);
         final Rounding.Builder rounding;
         if (timeUnit != null) {
@@ -372,6 +372,6 @@ private static Rounding createRounding(final String expr, final String timeZone)
             rounding = new Rounding.Builder(TimeValue.parseTimeValue(expr, "createRounding"));
         }
         rounding.timeZone(ZoneId.of(timeZone, ZoneId.SHORT_IDS));
-        return rounding.build();
+        return rounding.build().prepareForUnknown();
     }
 }
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/transform/transforms/pivot/DateHistogramGroupSource.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/transform/transforms/pivot/DateHistogramGroupSource.java
index f61497e31d3e6..08277310e76a8 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/transform/transforms/pivot/DateHistogramGroupSource.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/transform/transforms/pivot/DateHistogramGroupSource.java
@@ -209,13 +209,27 @@ private void writeInterval(Interval interval, StreamOutput out) throws IOExcepti
 
     private final Interval interval;
     private final ZoneId timeZone;
-    private Rounding rounding;
+    private final Rounding.Prepared rounding;
 
     public DateHistogramGroupSource(String field, ScriptConfig scriptConfig, Interval interval, ZoneId timeZone) {
         super(field, scriptConfig);
         this.interval = interval;
         this.timeZone = timeZone;
+        rounding = buildRounding();
+    }
+
+    public DateHistogramGroupSource(StreamInput in) throws IOException {
+        super(in);
+        this.interval = readInterval(in);
+        this.timeZone = in.readOptionalZoneId();
+        // Format was optional in 7.2.x, removed in 7.3+
+        if (in.getVersion().before(Version.V_7_3_0)) {
+            in.readOptionalString();
+        }
+        rounding = buildRounding();
+    }
 
+    private Rounding.Prepared buildRounding() {
         Rounding.DateTimeUnit timeUnit = DateHistogramAggregationBuilder.DATE_FIELD_UNITS.get(interval.toString());
         final Rounding.Builder roundingBuilder;
         if (timeUnit != null) {
@@ -227,17 +241,7 @@ public DateHistogramGroupSource(String field, ScriptConfig scriptConfig, Interva
         if (timeZone != null) {
             roundingBuilder.timeZone(timeZone);
         }
-        this.rounding = roundingBuilder.build();
-    }
-
-    public DateHistogramGroupSource(StreamInput in) throws IOException {
-        super(in);
-        this.interval = readInterval(in);
-        this.timeZone = in.readOptionalZoneId();
-        // Format was optional in 7.2.x, removed in 7.3+
-        if (in.getVersion().before(Version.V_7_3_0)) {
-            in.readOptionalString();
-        }
+        return roundingBuilder.build().prepareForUnknown();
     }
 
     private static ConstructingObjectParser<DateHistogramGroupSource, Void> createParser(boolean lenient) {
@@ -296,7 +300,7 @@ public ZoneId getTimeZone() {
         return timeZone;
     }
 
-    public Rounding getRounding() {
+    Rounding.Prepared getRounding() {
         return rounding;
     }
 
diff --git a/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/rollup/job/RollupIndexerIndexingTests.java b/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/rollup/job/RollupIndexerIndexingTests.java
index 8ab5b68b7ae7c..673c49122bc12 100644
--- a/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/rollup/job/RollupIndexerIndexingTests.java
+++ b/x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/rollup/job/RollupIndexerIndexingTests.java
@@ -283,7 +283,7 @@ public void testSimpleDateHistoWithDelay() throws Exception {
                         asMap("the_histo", now)
                 )
         );
-        final Rounding rounding = dateHistoConfig.createRounding();
+        final Rounding.Prepared rounding = dateHistoConfig.createRounding();
         executeTestCase(dataset, job, now, (resp) -> {
             assertThat(resp.size(), equalTo(3));
             IndexRequest request = resp.get(0);
@@ -350,7 +350,7 @@ public void testSimpleDateHistoWithOverlappingDelay() throws Exception {
                 asMap("the_histo", now)
             )
         );
-        final Rounding rounding = dateHistoConfig.createRounding();
+        final Rounding.Prepared rounding = dateHistoConfig.createRounding();
         executeTestCase(dataset, job, now, (resp) -> {
             assertThat(resp.size(), equalTo(2));
             IndexRequest request = resp.get(0);