(opennlp) branch OPENNLP-1678-Add-thread-safe-version-of-LanguageDetectorME created (now 3b615f6c)

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      at 3b615f6c OPENNLP-1678 Add thread-safe version of LanguageDetectorME

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     new 3b615f6c OPENNLP-1678 Add thread-safe version of LanguageDetectorME

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(opennlp) 01/01: OPENNLP-1678 Add thread-safe version of LanguageDetectorME

[ma...@apache.org]

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mawiesne pushed a commit to branch OPENNLP-1678-Add-thread-safe-version-of-LanguageDetectorME
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commit 3b615f6c414dc1626300f5e0cb3fa32ed78cc46d
Author: Martin Wiesner <ma...@hs-heilbronn.de>
AuthorDate: Sat Dec 21 10:17:02 2024 +0100

    OPENNLP-1678 Add thread-safe version of LanguageDetectorME
---
 .../langdetect/ThreadSafeLanguageDetectorME.java   | 84 ++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/opennlp-tools/src/main/java/opennlp/tools/langdetect/ThreadSafeLanguageDetectorME.java b/opennlp-tools/src/main/java/opennlp/tools/langdetect/ThreadSafeLanguageDetectorME.java
new file mode 100644
index 00000000..c8058d65
--- /dev/null
+++ b/opennlp-tools/src/main/java/opennlp/tools/langdetect/ThreadSafeLanguageDetectorME.java
@@ -0,0 +1,84 @@
+/*
+ * 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.langdetect;
+
+import opennlp.tools.commons.ThreadSafe;
+
+/**
+ * A thread-safe version of the {@link LanguageDetectorME}. 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 LanguageDetector
+ * @see LanguageDetectorME
+ */
+@ThreadSafe
+public class ThreadSafeLanguageDetectorME implements LanguageDetector, AutoCloseable {
+
+  private final LanguageDetectorModel model;
+
+  private final ThreadLocal<LanguageDetectorME> threadLocal = new ThreadLocal<>();
+
+  /**
+   * Initializes a {@link ThreadSafeLanguageDetectorME} with the specified {@code model}.
+   *
+   * @param model A valid {@link LanguageDetectorModel}.
+   */
+  public ThreadSafeLanguageDetectorME(LanguageDetectorModel model) {
+    super();
+    this.model = model;
+  }
+
+  private LanguageDetectorME getLanguageDetector() {
+    LanguageDetectorME ld = threadLocal.get();
+    if (ld == null) {
+      ld = new LanguageDetectorME(model);
+      threadLocal.set(ld);
+    }
+    return ld;
+  }
+
+  @Override
+  public Language[] predictLanguages(CharSequence content) {
+    return getLanguageDetector().predictLanguages(content);
+  }
+
+  @Override
+  public Language predictLanguage(CharSequence content) {
+    return getLanguageDetector().predictLanguage(content);
+  }
+
+  @Override
+  public String[] getSupportedLanguages() {
+    return getLanguageDetector().getSupportedLanguages();
+  }
+
+  @Override
+  public void close() {
+    threadLocal.remove();
+  }
+
+}