[8.0] Use Java 14 switch expressions (#82178) (#82355)

JEP 361[https://openjdk.java.net/jeps/361] added support for switch expressions
which can be much more terse and less error-prone than switch statements.

Another useful feature of switch expressions is exhaustiveness: we can make
sure that an enum switch expression covers all the cases at compile time.

(cherry picked from commit 0699c93)

* Rollback switch expressions for the SQL plugin (#82349)

It was updated to Java 8 compatibility in #82274

(cherry picked from commit 78509f4)

benchmarks/src/main/java/org/elasticsearch/benchmark/indices/common/RoundingBenchmark.java

@@ -89,16 +89,11 @@ public void buildDates() {
             roundingBuilder = Rounding.builder(TimeValue.parseTimeValue(interval, "interval"));
         }
         Rounding rounding = roundingBuilder.timeZone(ZoneId.of(zone)).build();
-        switch (rounder) {
-            case "java time":
-                rounderBuilder = rounding::prepareJavaTime;
-                break;
-            case "es":
-                rounderBuilder = () -> rounding.prepare(min, max);
-                break;
-            default:
-                throw new IllegalArgumentException("Expectd rounder to be [java time] or [es]");
-        }
+        rounderBuilder = switch (rounder) {
+            case "java time" -> rounding::prepareJavaTime;
+            case "es" -> () -> rounding.prepare(min, max);
+            default -> throw new IllegalArgumentException("Expected rounder to be [java time] or [es]");
+        };
     }
 
     @Benchmark

benchmarks/src/main/java/org/elasticsearch/benchmark/script/ScriptScoreBenchmark.java

@@ -101,28 +101,19 @@ public class ScriptScoreBenchmark {
 
     @Setup
     public void setupScript() {
-        switch (script) {
-            case "expression":
-                factory = scriptModule.engines.get("expression").compile("test", "doc['n'].value", ScoreScript.CONTEXT, Map.of());
-                break;
-            case "metal":
-                factory = bareMetalScript();
-                break;
-            case "painless_cast":
-                factory = scriptModule.engines.get("painless")
-                    .compile(
-                        "test",
-                        "((org.elasticsearch.index.fielddata.ScriptDocValues.Longs)doc['n']).value",
-                        ScoreScript.CONTEXT,
-                        Map.of()
-                    );
-                break;
-            case "painless_def":
-                factory = scriptModule.engines.get("painless").compile("test", "doc['n'].value", ScoreScript.CONTEXT, Map.of());
-                break;
-            default:
-                throw new IllegalArgumentException("Don't know how to implement script [" + script + "]");
-        }
+        factory = switch (script) {
+            case "expression" -> scriptModule.engines.get("expression").compile("test", "doc['n'].value", ScoreScript.CONTEXT, Map.of());
+            case "metal" -> bareMetalScript();
+            case "painless_cast" -> scriptModule.engines.get("painless")
+                .compile(
+                    "test",
+                    "((org.elasticsearch.index.fielddata.ScriptDocValues.Longs)doc['n']).value",
+                    ScoreScript.CONTEXT,
+                    Map.of()
+                );
+            case "painless_def" -> scriptModule.engines.get("painless").compile("test", "doc['n'].value", ScoreScript.CONTEXT, Map.of());
+            default -> throw new IllegalArgumentException("Don't know how to implement script [" + script + "]");
+        };
     }
 
     @Setup

benchmarks/src/main/java/org/elasticsearch/benchmark/search/aggregations/AggConstructionContentionBenchmark.java

@@ -107,20 +107,12 @@ public class AggConstructionContentionBenchmark {
 
     @Setup
     public void setup() {
-        switch (breaker) {
-            case "real":
-                breakerService = new HierarchyCircuitBreakerService(Settings.EMPTY, List.of(), clusterSettings);
-                break;
-            case "preallocate":
-                preallocateBreaker = true;
-                breakerService = new HierarchyCircuitBreakerService(Settings.EMPTY, List.of(), clusterSettings);
-                break;
-            case "noop":
-                breakerService = new NoneCircuitBreakerService();
-                break;
-            default:
-                throw new UnsupportedOperationException();
-        }
+        breakerService = switch (breaker) {
+            case "real", "preallocate" -> new HierarchyCircuitBreakerService(Settings.EMPTY, List.of(), clusterSettings);
+            case "noop" -> new NoneCircuitBreakerService();
+            default -> throw new UnsupportedOperationException();
+        };
+        preallocateBreaker = breaker.equals("preallocate");
         bigArrays = new BigArrays(recycler, breakerService, "request");
     }
 

benchmarks/src/main/java/org/elasticsearch/benchmark/search/fetch/subphase/FetchSourcePhaseBenchmark.java

@@ -53,22 +53,13 @@ public class FetchSourcePhaseBenchmark {
 
     @Setup
     public void setup() throws IOException {
-        switch (source) {
-            case "tiny":
-                sourceBytes = new BytesArray("{\"message\": \"short\"}");
-                break;
-            case "short":
-                sourceBytes = read300BytesExample();
-                break;
-            case "one_4k_field":
-                sourceBytes = buildBigExample("huge".repeat(1024));
-                break;
-            case "one_4m_field":
-                sourceBytes = buildBigExample("huge".repeat(1024 * 1024));
-                break;
-            default:
-                throw new IllegalArgumentException("Unknown source [" + source + "]");
-        }
+        sourceBytes = switch (source) {
+            case "tiny" -> new BytesArray("{\"message\": \"short\"}");
+            case "short" -> read300BytesExample();
+            case "one_4k_field" -> buildBigExample("huge".repeat(1024));
+            case "one_4m_field" -> buildBigExample("huge".repeat(1024 * 1024));
+            default -> throw new IllegalArgumentException("Unknown source [" + source + "]");
+        };
         fetchContext = new FetchSourceContext(
             true,
             Strings.splitStringByCommaToArray(includes),

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/SymbolicLinkPreservingTar.java

@@ -44,18 +44,11 @@ public class SymbolicLinkPreservingTar extends Tar {
 
     @Override
     protected CopyAction createCopyAction() {
-        final ArchiveOutputStreamFactory compressor;
-        switch (getCompression()) {
-            case BZIP2:
-                compressor = Bzip2Archiver.getCompressor();
-                break;
-            case GZIP:
-                compressor = GzipArchiver.getCompressor();
-                break;
-            default:
-                compressor = new SimpleCompressor();
-                break;
-        }
+        final ArchiveOutputStreamFactory compressor = switch (getCompression()) {
+            case BZIP2 -> Bzip2Archiver.getCompressor();
+            case GZIP -> GzipArchiver.getCompressor();
+            default -> new SimpleCompressor();
+        };
         return new SymbolicLinkPreservingTarCopyAction(getArchiveFile(), compressor, isPreserveFileTimestamps());
     }
 

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/docker/TransformLog4jConfigFilter.java

@@ -87,23 +87,17 @@ static List<String> transformConfig(List<String> lines) {
                 }
 
                 switch (keyParts[2]) {
-                    case "type":
+                    case "type" -> {
                         if (value.equals("RollingFile")) {
                             value = "Console";
                         }
                         line = key + " = " + value;
-                        break;
-
-                    case "fileName":
-                    case "filePattern":
-                    case "policies":
-                    case "strategy":
+                    }
+                    case "fileName", "filePattern", "policies", "strategy" -> {
                         // No longer applicable. Omit it.
                         skipNext = line.endsWith("\\");
                         continue;
-
-                    default:
-                        break;
+                    }
                 }
             } else if (line.startsWith("rootLogger.appenderRef")) {
                 String[] parts = line.split("\\s*=\\s*");

build-tools/src/main/java/org/elasticsearch/gradle/Architecture.java

@@ -21,15 +21,11 @@ public enum Architecture {
 
     public static Architecture current() {
         final String architecture = System.getProperty("os.arch", "");
-        switch (architecture) {
-            case "amd64":
-            case "x86_64":
-                return X64;
-            case "aarch64":
-                return AARCH64;
-            default:
-                throw new IllegalArgumentException("can not determine architecture from [" + architecture + "]");
-        }
+        return switch (architecture) {
+            case "amd64", "x86_64" -> X64;
+            case "aarch64" -> AARCH64;
+            default -> throw new IllegalArgumentException("can not determine architecture from [" + architecture + "]");
+        };
     }
 
 }

client/benchmark/src/main/java/org/elasticsearch/client/benchmark/AbstractBenchmark.java

@@ -36,16 +36,12 @@ public final void run(String[] args) throws Exception {
             System.exit(1);
         }
         switch (args[0]) {
-            case "search":
-                runSearchBenchmark(args);
-                break;
-            case "bulk":
-                runBulkIndexBenchmark(args);
-                break;
-            default:
+            case "search" -> runSearchBenchmark(args);
+            case "bulk" -> runBulkIndexBenchmark(args);
+            default -> {
                 System.err.println("Unknown benchmark type [" + args[0] + "]");
                 System.exit(1);
-
+            }
         }
 
     }

client/benchmark/src/main/java/org/elasticsearch/client/benchmark/BenchmarkMain.java

@@ -16,15 +16,14 @@ public class BenchmarkMain {
     @SuppressForbidden(reason = "system out is ok for a command line tool")
     public static void main(String[] args) throws Exception {
         String type = args[0];
-        AbstractBenchmark<?> benchmark = null;
-        switch (type) {
-            case "rest":
-                benchmark = new RestClientBenchmark();
-                break;
-            default:
+        AbstractBenchmark<?> benchmark = switch (type) {
+            case "rest" -> new RestClientBenchmark();
+            default -> {
                 System.err.println("Unknown client type [" + type + "]");
                 System.exit(1);
-        }
+                yield null;
+            }
+        };
         benchmark.run(Arrays.copyOfRange(args, 1, args.length));
     }
 }

client/rest-high-level/src/main/java/org/elasticsearch/client/ccr/FollowInfoResponse.java

@@ -163,14 +163,11 @@ public String getName() {
         }
 
         public static Status fromString(String value) {
-            switch (value) {
-                case "active":
-                    return Status.ACTIVE;
-                case "paused":
-                    return Status.PAUSED;
-                default:
-                    throw new IllegalArgumentException("unexpected status value [" + value + "]");
-            }
+            return switch (value) {
+                case "active" -> Status.ACTIVE;
+                case "paused" -> Status.PAUSED;
+                default -> throw new IllegalArgumentException("unexpected status value [" + value + "]");
+            };
         }
     }
 }

client/rest-high-level/src/main/java/org/elasticsearch/client/indices/GetIndexResponse.java

@@ -149,20 +149,11 @@ private static IndexEntry parseIndexEntry(XContentParser parser) throws IOExcept
             parser.nextToken();
             if (parser.currentToken() == Token.START_OBJECT) {
                 switch (parser.currentName()) {
-                    case "aliases":
-                        indexAliases = parseAliases(parser);
-                        break;
-                    case "mappings":
-                        indexMappings = parseMappings(parser);
-                        break;
-                    case "settings":
-                        indexSettings = Settings.fromXContent(parser);
-                        break;
-                    case "defaults":
-                        indexDefaultSettings = Settings.fromXContent(parser);
-                        break;
-                    default:
-                        parser.skipChildren();
+                    case "aliases" -> indexAliases = parseAliases(parser);
+                    case "mappings" -> indexMappings = parseMappings(parser);
+                    case "settings" -> indexSettings = Settings.fromXContent(parser);
+                    case "defaults" -> indexDefaultSettings = Settings.fromXContent(parser);
+                    default -> parser.skipChildren();
                 }
             } else if (parser.currentToken() == Token.VALUE_STRING) {
                 if (parser.currentName().equals("data_stream")) {

client/rest-high-level/src/main/java/org/elasticsearch/client/license/LicenseStatus.java

@@ -27,15 +27,11 @@ public String label() {
     }
 
     public static LicenseStatus fromString(String value) {
-        switch (value) {
-            case "active":
-                return ACTIVE;
-            case "invalid":
-                return INVALID;
-            case "expired":
-                return EXPIRED;
-            default:
-                throw new IllegalArgumentException("unknown license status [" + value + "]");
-        }
+        return switch (value) {
+            case "active" -> ACTIVE;
+            case "invalid" -> INVALID;
+            case "expired" -> EXPIRED;
+            default -> throw new IllegalArgumentException("unknown license status [" + value + "]");
+        };
     }
 }

client/rest-high-level/src/main/java/org/elasticsearch/client/license/LicensesStatus.java

@@ -42,15 +42,11 @@ public String toString() {
     }
 
     public static LicensesStatus fromString(String value) {
-        switch (value) {
-            case "valid":
-                return VALID;
-            case "invalid":
-                return INVALID;
-            case "expired":
-                return EXPIRED;
-            default:
-                throw new IllegalArgumentException("unknown licenses status [" + value + "]");
-        }
+        return switch (value) {
+            case "valid" -> VALID;
+            case "invalid" -> INVALID;
+            case "expired" -> EXPIRED;
+            default -> throw new IllegalArgumentException("unknown licenses status [" + value + "]");
+        };
     }
 }

client/rest-high-level/src/main/java/org/elasticsearch/client/security/support/expressiondsl/parser/RoleMapperExpressionParser.java

@@ -164,25 +164,16 @@ private <T> List<T> parseArray(ParseField field, XContentParser parser, CheckedF
     }
 
     private Object parseFieldValue(XContentParser parser) throws IOException {
-        switch (parser.currentToken()) {
-            case VALUE_STRING:
-                return parser.text();
-
-            case VALUE_BOOLEAN:
-                return parser.booleanValue();
-
-            case VALUE_NUMBER:
-                return parser.longValue();
-
-            case VALUE_NULL:
-                return null;
-
-            default:
-                throw new ElasticsearchParseException(
-                    "failed to parse rules expression. expected a field value but found [{}] instead",
-                    parser.currentToken()
-                );
-        }
+        return switch (parser.currentToken()) {
+            case VALUE_STRING -> parser.text();
+            case VALUE_BOOLEAN -> parser.booleanValue();
+            case VALUE_NUMBER -> parser.longValue();
+            case VALUE_NULL -> null;
+            default -> throw new ElasticsearchParseException(
+                "failed to parse rules expression. expected a field value but found [{}] instead",
+                parser.currentToken()
+            );
+        };
     }
 
 }

client/rest-high-level/src/main/java/org/elasticsearch/client/transform/transforms/pivot/GroupConfig.java

@@ -75,24 +75,17 @@ public static GroupConfig fromXContent(final XContentParser parser) throws IOExc
                 continue;
             }
 
-            SingleGroupSource groupSource = null;
-            switch (groupType) {
-                case "terms":
-                    groupSource = TermsGroupSource.fromXContent(parser);
-                    break;
-                case "histogram":
-                    groupSource = HistogramGroupSource.fromXContent(parser);
-                    break;
-                case "date_histogram":
-                    groupSource = DateHistogramGroupSource.fromXContent(parser);
-                    break;
-                case "geotile_grid":
-                    groupSource = GeoTileGroupSource.fromXContent(parser);
-                    break;
-                default:
+            SingleGroupSource groupSource = switch (groupType) {
+                case "terms" -> TermsGroupSource.fromXContent(parser);
+                case "histogram" -> HistogramGroupSource.fromXContent(parser);
+                case "date_histogram" -> DateHistogramGroupSource.fromXContent(parser);
+                case "geotile_grid" -> GeoTileGroupSource.fromXContent(parser);
+                default -> {
                     // not a valid group source. Consume up to the dest field end object
                     consumeUntilEndObject(parser, 2);
-            }
+                    yield null;
+                }
+            };
 
             if (groupSource != null) {
                 groups.put(destinationFieldName, groupSource);