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.apache.lucene.util.CharsRefBuilder;
 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 @@ final class TransportSearchHelper {
         } 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.Iterator;
 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 class Strings {
     }
 
     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 class Strings {
         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 class Table {
                 // 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 @@ public class PathTrie<T> {
 
     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 class PathTrie<T> {
 
     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 class PathTrie<T> {
     }
 
     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 class PathTrie<T> {
         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 final class Settings implements ToXContent {
             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.store.IndexInput;
 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 class BloomFilter {
             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 class XContentMapValues {
      */
     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 @@ public class XContentMapValues {
     }
 
     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.internal.UidFieldMapper;
 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 @@ final class DocumentParser {
             // 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.action.get.GetResponse;
 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 @@ public class GeoShapeQueryBuilder extends AbstractQueryBuilder<GeoShapeQueryBuil
             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 @@ public final class IngestDocument {
                     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 class TasksIT extends ESIntegTestCase {
     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 @@ import static org.hamcrest.Matchers.nullValue;
 
 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 class GceNameResolver extends AbstractComponent implements CustomNameReso
         } 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 class AzureRepository extends BlobStoreRepository {
             // 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 class S3Repository extends BlobStoreRepository {
         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 @@ package org.elasticsearch.ingest;
 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 final class RandomDocumentPicks {
      * 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++) {