OO-3562: don't reuse the support NGramProfil across request but create a

new one every time

src/main/java/org/olat/core/commons/services/text/impl/nutch/LanguageIdentifier.java

@@ -66,8 +66,7 @@ public class LanguageIdentifier {
   /** A global index of ngrams of all supported languages */
   private Map<CharSequence, NGramEntry[]> ngramsIdx = new HashMap<CharSequence, NGramEntry[]>();
 
-  /** The NGramProfile used for identification */
-  private NGramProfile suspect = null;
+
 
 
   /**
@@ -136,7 +135,6 @@ public class LanguageIdentifier {
       }
       log.info(list.toString());
       // Create the suspect profile
-      suspect = new NGramProfile("suspect", minLength, maxLength);
     } catch (Exception e) {
       log.error("", e);
     }
@@ -172,6 +170,7 @@ public class LanguageIdentifier {
         text.setLength(analyzeLength);
     }
 
+    NGramProfile suspect = new NGramProfile("suspect", minLength, maxLength);
     suspect.analyze(text);
     Iterator<NGramEntry> iter = suspect.getSorted().iterator();
     float topscore = Float.MIN_VALUE;

src/main/java/org/olat/core/commons/services/text/impl/nutch/NGramProfile.java

@@ -127,7 +127,7 @@ public class NGramProfile {
    * 
    * @param w is the word to add
    */
-  public void add(StringBuffer w) {
+  public void add(StringBuilder w) {
     for (int i=minLength; (i <= maxLength) && (i < w.length()); i++) {
       add(w, i);
     }
@@ -203,7 +203,7 @@ public class NGramProfile {
    * @param w
    * @param n sequence length
    */
-  private void add(StringBuffer w, int n) {
+  private void add(StringBuilder w, int n) {
     for (int i=0; i <= w.length()-n; i++) {
       add(w.subSequence(i, i + n));
     }
@@ -254,9 +254,10 @@ public class NGramProfile {
   }
   
   // Inherited JavaDoc
+  @Override
   public String toString() {
 
-    StringBuffer s = new StringBuffer().append("NGramProfile: ")
+    StringBuilder s = new StringBuilder().append("NGramProfile: ")
                                        .append(name).append("\n");
 
     Iterator<NGramEntry> i = getSorted().iterator();
@@ -543,7 +544,7 @@ public class NGramProfile {
      * @param count is the number of occurences of this ngram
      */
     public NGramEntry(String seq, int count) {
-      this.seq = new StringBuffer(seq).subSequence(0, seq.length());
+      this.seq = new StringBuilder(seq).subSequence(0, seq.length());
       this.count = count;
     }
 

src/test/java/org/olat/core/commons/services/text/TextServiceTest.java

+package org.olat.core.commons.services.text;
+
+import java.util.Locale;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.olat.core.logging.OLog;
+import org.olat.core.logging.Tracing;
+import org.olat.test.OlatTestCase;
+import org.springframework.beans.factory.annotation.Autowired;
+
+/**
+ * 
+ * Initial date: 29 juin 2018<br>
+ * @author srosse, stephane.rosse@frentix.com, http://www.frentix.com
+ *
+ */
+public class TextServiceTest extends OlatTestCase {
+
+	private static final OLog log = Tracing.createLoggerFor(TextServiceTest.class);
+	
+	@Autowired
+	private TextService textService;
+	
+	@Test
+	public void detectLocale_french() {
+		Locale locale = textService.detectLocale("Bonjour, je parle français.");
+		Assert.assertNotNull(locale);
+		Assert.assertEquals("fr", locale.getLanguage());
+	}
+	
+	@Test
+	public void detectLocale_english() {
+		Locale locale = textService.detectLocale("Hi, I speak British english.");
+		Assert.assertNotNull(locale);
+		Assert.assertEquals("en", locale.getLanguage());
+	}
+	
+	@Test
+	public void concurrentDetection() throws InterruptedException {
+		int numOfThreads = 10;
+		CountDownLatch latch = new CountDownLatch(numOfThreads);
+		NGramThread[] threads = new NGramThread[numOfThreads];
+		for(int i=numOfThreads; i-->0; ) {
+			threads[i] = new NGramThread(textService, latch);
+		}
+		
+		for(int i=numOfThreads; i-->0; ) {
+			threads[i].start();
+		}
+
+		latch.await(120, TimeUnit.SECONDS);
+		
+		for(int i=numOfThreads; i-->0; ) {
+			if(threads[i].getException() != null) {
+				log.error("", threads[i].getException());
+			}
+			Assert.assertNull(threads[i].getException());
+		}
+	}
+
+	private static class NGramThread extends Thread {
+
+		private final TextService service;
+		private final CountDownLatch latch;
+		
+		private Exception exception;
+		
+		public NGramThread(TextService service, CountDownLatch latch) {
+			this.service = service;
+			this.latch = latch;
+		}
+		
+		public Exception getException() {
+			return exception;
+		}
+
+		@Override
+		public void run() {
+			try {
+				Thread.sleep(100);
+				for(int i=0; i<2500; i++) {
+					Locale locale = service.detectLocale("Bonjour, je parle français.");
+					Assert.assertNotNull(locale);
+					
+				}
+			} catch (Exception e) {
+				exception = e;
+			} finally {
+				latch.countDown();
+			}
+		}
+	}
+
+}

src/test/java/org/olat/test/AllTestsJunit4.java

@@ -109,6 +109,7 @@ import org.junit.runners.Suite;
 	org.olat.core.commons.services.sms.manager.MessageLogDAOTest.class,
 	org.olat.core.commons.services.taskexecutor.PersistentTaskDAOTest.class,
 	org.olat.core.commons.services.taskexecutor.TaskExecutorManagerTest.class,
+	org.olat.core.commons.services.text.TextServiceTest.class,
 	org.olat.admin.user.delete.service.UserDeletionManagerTest.class,
 	org.olat.group.BusinessGroupManagedFlagsTest.class,
 	org.olat.group.test.BGRightManagerTest.class,