OPENNLP-1667: Add thread-safe version of ChunkerME

opennlp-tools/src/main/java/opennlp/tools/chunker/ThreadSafeChunkerME.java

@@ -0,0 +1,91 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package opennlp.tools.chunker;
+
+import opennlp.tools.commons.ThreadSafe;
+import opennlp.tools.util.Sequence;
+import opennlp.tools.util.Span;
+
+/**
+ * A thread-safe version of the {@link ChunkerME}. Using it is completely transparent.
+ * You can use it in a single-threaded context as well, it only incurs a minimal overhead.
+ *
+ * @implNote
+ * This implementation uses a {@link ThreadLocal}. Although the implementation is
+ * lightweight because the model is not duplicated, if you have many long-running threads,
+ * you may run into memory problems.
+ * <p>
+ * Be careful when using this in a Jakarta EE application, for example.
+ * </p>
+ * The user is responsible for clearing the {@link ThreadLocal}.
+ *
+ * @see Chunker
+ * @see ChunkerME
+ */
+@ThreadSafe
+public class ThreadSafeChunkerME implements Chunker, AutoCloseable {
+
+  private final ChunkerModel model;
+
+  private final ThreadLocal<ChunkerME> threadLocal = new ThreadLocal<>();
+
+  /**
+   * Initializes a {@link ThreadSafeChunkerME} with the specified {@code model}.
+   *
+   * @param model A valid {@link ChunkerModel}.
+   */
+  public ThreadSafeChunkerME(ChunkerModel model) {
+    super();
+    this.model = model;
+  }
+
+  private ChunkerME getChunker() {
+    ChunkerME c = threadLocal.get();
+    if (c == null) {
+      c = new ChunkerME(model);
+      threadLocal.set(c);
+    }
+    return c;
+  }
+
+  @Override
+  public String[] chunk(String[] toks, String[] tags) {
+    return getChunker().chunk(toks, tags);
+  }
+
+  @Override
+  public Span[] chunkAsSpans(String[] toks, String[] tags) {
+    return getChunker().chunkAsSpans(toks, tags);
+  }
+
+  @Override
+  public Sequence[] topKSequences(String[] sentence, String[] tags) {
+    return getChunker().topKSequences(sentence, tags);
+  }
+
+  @Override
+  public Sequence[] topKSequences(String[] sentence, String[] tags, double minSequenceScore) {
+    return getChunker().topKSequences(sentence, tags, minSequenceScore);
+  }
+
+  @Override
+  public void close() {
+    threadLocal.remove();
+  }
+
+}

opennlp-tools/src/main/java/opennlp/tools/lemmatizer/ThreadSafeLemmatizerME.java

@@ -55,12 +55,12 @@ public ThreadSafeLemmatizerME(LemmatizerModel model) {
   }
 
   private LemmatizerME getLemmatizer() {
-    LemmatizerME tagger = threadLocal.get();
-    if (tagger == null) {
-      tagger = new LemmatizerME(model);
-      threadLocal.set(tagger);
+    LemmatizerME l = threadLocal.get();
+    if (l == null) {
+      l = new LemmatizerME(model);
+      threadLocal.set(l);
     }
-    return tagger;
+    return l;
   }
 
   @Override

opennlp-tools/src/main/java/opennlp/tools/namefind/ThreadSafeNameFinderME.java

@@ -55,17 +55,12 @@ public ThreadSafeNameFinderME(TokenNameFinderModel model) {
 
   // If a thread-local version exists, return it. Otherwise, create, then return.
   private NameFinderME getNameFinder() {
-    NameFinderME sd = threadLocal.get();
-    if (sd == null) {
-      sd = new NameFinderME(model);
-      threadLocal.set(sd);
+    NameFinderME nf = threadLocal.get();
+    if (nf == null) {
+      nf = new NameFinderME(model);
+      threadLocal.set(nf);
     }
-    return sd;
-  }
-
-  @Override
-  public void close() {
-    threadLocal.remove();
+    return nf;
   }
 
   @Override
@@ -77,4 +72,9 @@ public Span[] find(String[] tokens) {
   public void clearAdaptiveData() {
     getNameFinder().clearAdaptiveData();
   }
+
+  @Override
+  public void close() {
+    threadLocal.remove();
+  }
 }