Remove Strings#splitStringToArray

This commit removes the method Strings#splitStringToArray and replaces
the call sites with invocations to String#split. There are only two
explanations for the existence of this method. The first is that
String#split is slightly tricky in that it accepts a regular expression
rather than a character to split on. This means that if s is a string,
s.split(".")  does not split on the character '.', but rather splits on
the regular expression '.' which splits on every character (of course,
this is easily fixed by invoking s.split("\\.") instead). The second
possible explanation is that (again) String#split accepts a regular
expression. This means that there could be a performance concern
compared to just splitting on a single character. However, it turns out
that String#split has a fast path for the case of splitting on a single
character and microbenchmarks show that String#split has 1.5x--2x the
throughput of Strings#splitStringToArray. There is a slight behavior
difference between Strings#splitStringToArray and String#split: namely,
the former would return an empty array in cases when the input string
was null or empty but String#split will just NPE at the call site on
null and return a one-element array containing the empty string when the
input string is empty. There was only one place relying on this behavior
and the call site has been modified accordingly.

core/src/main/java/org/elasticsearch/action/search/TransportSearchHelper.java

@@ -24,7 +24,6 @@
 import org.elasticsearch.cluster.routing.ShardRouting;
 import org.elasticsearch.common.Base64;
 import org.elasticsearch.common.Nullable;
-import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.util.concurrent.AtomicArray;
 import org.elasticsearch.search.SearchPhaseResult;
 import org.elasticsearch.search.internal.InternalScrollSearchRequest;
@@ -89,7 +88,7 @@ static ParsedScrollId parseScrollId(String scrollId) {
         } catch (Exception e) {
             throw new IllegalArgumentException("Failed to decode scrollId", e);
         }
-        String[] elements = Strings.splitStringToArray(spare.get(), ';');
+        String[] elements = spare.get().toString().split(";");
         if (elements.length < 2) {
             throw new IllegalArgumentException("Malformed scrollId [" + scrollId + "]");
         }

core/src/main/java/org/elasticsearch/common/Strings.java

@@ -38,7 +38,6 @@
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Properties;
-import java.util.Random;
 import java.util.Set;
 import java.util.StringTokenizer;
 import java.util.TreeSet;
@@ -557,7 +556,8 @@ public static String cleanPath(String path) {
     }
 
     public static String[] splitStringByCommaToArray(final String s) {
-        return splitStringToArray(s, ',');
+        if (s == null || s.isEmpty()) return Strings.EMPTY_ARRAY;
+        else return s.split(",");
     }
 
     public static Set<String> splitStringToSet(final String s, final char c) {
@@ -588,42 +588,6 @@ public static String cleanPath(String path) {
         return result;
     }
 
-    public static String[] splitStringToArray(final CharSequence s, final char c) {
-        if (s == null || s.length() == 0) {
-            return Strings.EMPTY_ARRAY;
-        }
-        int count = 1;
-        for (int i = 0; i < s.length(); i++) {
-            if (s.charAt(i) == c) {
-                count++;
-            }
-        }
-        final String[] result = new String[count];
-        final StringBuilder builder = new StringBuilder();
-        int res = 0;
-        for (int i = 0; i < s.length(); i++) {
-            if (s.charAt(i) == c) {
-                if (builder.length() > 0) {
-                    result[res++] = builder.toString();
-                    builder.setLength(0);
-                }
-
-            } else {
-                builder.append(s.charAt(i));
-            }
-        }
-        if (builder.length() > 0) {
-            result[res++] = builder.toString();
-        }
-        if (res != count) {
-            // we have empty strings, copy over to a new array
-            String[] result1 = new String[res];
-            System.arraycopy(result, 0, result1, 0, res);
-            return result1;
-        }
-        return result;
-    }
-
     /**
      * Split a String at the first occurrence of the delimiter.
      * Does not include the delimiter in the result.

core/src/main/java/org/elasticsearch/common/Table.java

@@ -149,7 +149,7 @@ public Table addCell(Object value, String attributes) {
                 // get the attributes of the header cell we are going to add
                 mAttr.putAll(headers.get(currentCells.size()).attr);
             }
-            String[] sAttrs = Strings.splitStringToArray(attributes, ';');
+            String[] sAttrs = attributes.split(";");
             for (String sAttr : sAttrs) {
                 if (sAttr.length() == 0) {
                     continue;

core/src/main/java/org/elasticsearch/common/path/PathTrie.java

@@ -19,8 +19,6 @@
 
 package org.elasticsearch.common.path;
 
-import org.elasticsearch.common.Strings;
-
 import java.util.HashMap;
 import java.util.Map;
 
@@ -38,7 +36,7 @@
 
     private final Decoder decoder;
     private final TrieNode root;
-    private final char separator;
+    private final String separator;
     private T rootValue;
 
     public PathTrie(Decoder decoder) {
@@ -47,8 +45,9 @@ public PathTrie(Decoder decoder) {
 
     public PathTrie(char separator, String wildcard, Decoder decoder) {
         this.decoder = decoder;
-        this.separator = separator;
-        root = new TrieNode(new String(new char[]{separator}), null, wildcard);
+        final String separatorAsString = new String(new char[]{separator});
+        this.separator = separatorAsString;
+        root = new TrieNode(separatorAsString, null, wildcard);
     }
 
     public class TrieNode {
@@ -196,7 +195,7 @@ public String toString() {
     }
 
     public void insert(String path, T value) {
-        String[] strings = Strings.splitStringToArray(path, separator);
+        String[] strings = path.split(separator);
         if (strings.length == 0) {
             rootValue = value;
             return;
@@ -217,7 +216,7 @@ public T retrieve(String path, Map<String, String> params) {
         if (path.length() == 0) {
             return rootValue;
         }
-        String[] strings = Strings.splitStringToArray(path, separator);
+        String[] strings = path.split(separator);
         if (strings.length == 0) {
             return rootValue;
         }

core/src/main/java/org/elasticsearch/common/settings/Settings.java

@@ -899,19 +899,6 @@ public Builder put(Dictionary<Object,Object> properties) {
             return this;
         }
 
-        public Builder loadFromDelimitedString(String value, char delimiter) {
-            String[] values = Strings.splitStringToArray(value, delimiter);
-            for (String s : values) {
-                int index = s.indexOf('=');
-                if (index == -1) {
-                    throw new IllegalArgumentException(
-                            "value [" + s + "] for settings loaded with delimiter [" + delimiter + "] is malformed, missing =");
-                }
-                map.put(s.substring(0, index), s.substring(index + 1));
-            }
-            return this;
-        }
-
         /**
          * Loads settings from the actual string content that represents them using the
          * {@link SettingsLoaderFactory#loaderFromSource(String)}.

core/src/main/java/org/elasticsearch/common/util/BloomFilter.java

@@ -24,7 +24,6 @@
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.RamUsageEstimator;
 import org.elasticsearch.common.Nullable;
-import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.hash.MurmurHash3;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
@@ -75,7 +74,7 @@ public static Factory buildFromString(@Nullable String config) {
             if (config == null) {
                 return buildDefault();
             }
-            String[] sEntries = Strings.splitStringToArray(config, ',');
+            String[] sEntries = config.split(",");
             if (sEntries.length == 0) {
                 if (config.length() > 0) {
                     return new Factory(new Entry[]{new Entry(0, Double.parseDouble(config))});

core/src/main/java/org/elasticsearch/common/xcontent/support/XContentMapValues.java

@@ -40,7 +40,7 @@
      */
     public static List<Object> extractRawValues(String path, Map<String, Object> map) {
         List<Object> values = new ArrayList<>();
-        String[] pathElements = Strings.splitStringToArray(path, '.');
+        String[] pathElements = path.split("\\.");
         if (pathElements.length == 0) {
             return values;
         }
@@ -93,7 +93,7 @@ private static void extractRawValues(List values, List<Object> part, String[] pa
     }
 
     public static Object extractValue(String path, Map<String, Object> map) {
-        String[] pathElements = Strings.splitStringToArray(path, '.');
+        String[] pathElements = path.split("\\.");
         if (pathElements.length == 0) {
             return null;
         }

core/src/main/java/org/elasticsearch/index/mapper/DocumentParser.java

@@ -19,13 +19,6 @@
 
 package org.elasticsearch.index.mapper;
 
-import java.io.IOException;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.List;
-
 import org.apache.lucene.document.Field;
 import org.apache.lucene.index.IndexableField;
 import org.elasticsearch.Version;
@@ -51,6 +44,13 @@
 import org.elasticsearch.index.mapper.object.ArrayValueMapperParser;
 import org.elasticsearch.index.mapper.object.ObjectMapper;
 
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+
 /** A parser for documents, given mappings from a DocumentMapper */
 final class DocumentParser {
 
@@ -829,8 +829,7 @@ private static void parseCopy(String field, ParseContext context) throws IOExcep
             // The path of the dest field might be completely different from the current one so we need to reset it
             context = context.overridePath(new ContentPath(0));
 
-            // TODO: why Strings.splitStringToArray instead of String.split?
-            final String[] paths = Strings.splitStringToArray(field, '.');
+            final String[] paths = field.split("\\.");
             final String fieldName = paths[paths.length-1];
             ObjectMapper mapper = context.root();
             ObjectMapper[] mappers = new ObjectMapper[paths.length-1];

core/src/main/java/org/elasticsearch/index/query/GeoShapeQueryBuilder.java

@@ -33,7 +33,6 @@
 import org.elasticsearch.client.Client;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.ParsingException;
-import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.geo.ShapeRelation;
 import org.elasticsearch.common.geo.ShapesAvailability;
 import org.elasticsearch.common.geo.SpatialStrategy;
@@ -379,7 +378,7 @@ private ShapeBuilder fetch(Client client, GetRequest getRequest, String path) th
             throw new IllegalArgumentException("Shape with ID [" + getRequest.id() + "] in type [" + getRequest.type() + "] not found");
         }
 
-        String[] pathElements = Strings.splitStringToArray(path, '.');
+        String[] pathElements = path.split("\\.");
         int currentPathSlot = 0;
 
         try (XContentParser parser = XContentHelper.createParser(response.getSourceAsBytesRef())) {

core/src/main/java/org/elasticsearch/ingest/core/IngestDocument.java

@@ -622,8 +622,8 @@ private FieldPath(String path) {
                     newPath = path;
                 }
             }
-            this.pathElements = Strings.splitStringToArray(newPath, '.');
-            if (pathElements.length == 0) {
+            this.pathElements = newPath.split("\\.");
+            if (pathElements.length == 1 && pathElements[0].isEmpty()) {
                 throw new IllegalArgumentException("path [" + path + "] is not valid");
             }
         }

core/src/test/java/org/elasticsearch/action/admin/cluster/node/tasks/TasksIT.java

@@ -492,7 +492,7 @@ public void tearDown() throws Exception {
     private void registerTaskManageListeners(String actionMasks) {
         for (String nodeName : internalCluster().getNodeNames()) {
             DiscoveryNode node = internalCluster().getInstance(ClusterService.class, nodeName).localNode();
-            RecordingTaskManagerListener listener = new RecordingTaskManagerListener(node, Strings.splitStringToArray(actionMasks, ','));
+            RecordingTaskManagerListener listener = new RecordingTaskManagerListener(node, actionMasks.split(","));
             ((MockTaskManager) internalCluster().getInstance(TransportService.class, nodeName).getTaskManager()).addListener(listener);
             RecordingTaskManagerListener oldListener = listeners.put(new Tuple<>(node.getName(), actionMasks), listener);
             assertNull(oldListener);

core/src/test/java/org/elasticsearch/common/settings/SettingsTests.java

@@ -38,24 +38,6 @@
 
 public class SettingsTests extends ESTestCase {
 
-    public void testLoadFromDelimitedString() {
-        Settings settings = Settings.builder()
-                .loadFromDelimitedString("key1=value1;key2=value2", ';')
-                .build();
-        assertThat(settings.get("key1"), equalTo("value1"));
-        assertThat(settings.get("key2"), equalTo("value2"));
-        assertThat(settings.getAsMap().size(), equalTo(2));
-        assertThat(settings.toDelimitedString(';'), equalTo("key1=value1;key2=value2;"));
-
-        settings = Settings.builder()
-                .loadFromDelimitedString("key1=value1;key2=value2;", ';')
-                .build();
-        assertThat(settings.get("key1"), equalTo("value1"));
-        assertThat(settings.get("key2"), equalTo("value2"));
-        assertThat(settings.getAsMap().size(), equalTo(2));
-        assertThat(settings.toDelimitedString(';'), equalTo("key1=value1;key2=value2;"));
-    }
-
     public void testReplacePropertiesPlaceholderSystemProperty() {
         String value = System.getProperty("java.home");
         assertFalse(value.isEmpty());

plugins/discovery-gce/src/main/java/org/elasticsearch/cloud/gce/network/GceNameResolver.java

@@ -92,7 +92,7 @@ public GceNameResolver(Settings settings, GceComputeService gceComputeService) {
         } else if (value.startsWith(GceAddressResolverType.PRIVATE_IP.configName)) {
             // We extract the network interface from gce:privateIp:XX
             String network = "0";
-            String[] privateIpConfig = Strings.splitStringToArray(value, ':');
+            String[] privateIpConfig = value.split(":");
             if (privateIpConfig != null && privateIpConfig.length == 3) {
                 network = privateIpConfig[2];
             }

plugins/repository-azure/src/main/java/org/elasticsearch/repositories/azure/AzureRepository.java

@@ -116,7 +116,7 @@ public AzureRepository(RepositoryName name, RepositorySettings repositorySetting
             // Remove starting / if any
             basePath = Strings.trimLeadingCharacter(basePath, '/');
             BlobPath path = new BlobPath();
-            for(String elem : Strings.splitStringToArray(basePath, '/')) {
+            for(String elem : basePath.split("/")) {
                 path = path.add(elem);
             }
             this.basePath = path;

plugins/repository-s3/src/main/java/org/elasticsearch/repositories/s3/S3Repository.java

@@ -287,7 +287,7 @@ public S3Repository(RepositoryName name, RepositorySettings repositorySettings,
         String basePath = getValue(repositorySettings, Repository.BASE_PATH_SETTING, Repositories.BASE_PATH_SETTING);
         if (Strings.hasLength(basePath)) {
             BlobPath path = new BlobPath();
-            for(String elem : Strings.splitStringToArray(basePath, '/')) {
+            for(String elem : basePath.split("/")) {
                 path = path.add(elem);
             }
             this.basePath = path;

test/framework/src/main/java/org/elasticsearch/ingest/RandomDocumentPicks.java

@@ -22,8 +22,6 @@
 import com.carrotsearch.randomizedtesting.generators.RandomInts;
 import com.carrotsearch.randomizedtesting.generators.RandomPicks;
 import com.carrotsearch.randomizedtesting.generators.RandomStrings;
-import org.elasticsearch.common.Strings;
-import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.ingest.core.IngestDocument;
 
 import java.util.ArrayList;
@@ -105,7 +103,7 @@ public static String addRandomField(Random random, IngestDocument ingestDocument
      * that each node of the tree either doesn't exist or is a map, otherwise new fields cannot be added.
      */
     public static boolean canAddField(String path, IngestDocument ingestDocument) {
-        String[] pathElements = Strings.splitStringToArray(path, '.');
+        String[] pathElements = path.split("\\.");
         Map<String, Object> innerMap = ingestDocument.getSourceAndMetadata();
         if (pathElements.length > 1) {
             for (int i = 0; i < pathElements.length - 1; i++) {