X-Git-Url: http://source.jalview.org/gitweb/?p=jalview.git;a=blobdiff_plain;f=srcjar%2Forg%2Fapache%2Flog4j%2FMDC.java;fp=srcjar%2Forg%2Fapache%2Flog4j%2FMDC.java;h=c07efed0f078081e9352fc377483295e5b4e6759;hp=0000000000000000000000000000000000000000;hb=2d6292c0377bc6b773c6844a45d3f2c5fac352c7;hpb=954af328a2a6a0055572cd1a09ee035301222574

diff --git a/srcjar/org/apache/log4j/MDC.java b/srcjar/org/apache/log4j/MDC.java
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+/*
+ * 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 org.apache.log4j;
+
+import org.apache.log4j.helpers.Loader;
+import org.apache.log4j.helpers.ThreadLocalMap;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Hashtable;
+
+/**
+ * The MDC class is similar to the {@link NDC} class except that it is
+ * based on a map instead of a stack. It provides <em>mapped
+ * diagnostic contexts</em>. A <em>Mapped Diagnostic Context</em>, or
+ * MDC in short, is an instrument for distinguishing interleaved log
+ * output from different sources. Log output is typically interleaved
+ * when a server handles multiple clients near-simultaneously.
+ * <p/>
+ * <p><b><em>The MDC is managed on a per thread basis</em></b>. A
+ * child thread automatically inherits a <em>copy</em> of the mapped
+ * diagnostic context of its parent.
+ * <p/>
+ * <p>The MDC class requires JDK 1.2 or above. Under JDK 1.1 the MDC
+ * will always return empty values but otherwise will not affect or
+ * harm your application.</p>
+ *
+ * <p>Attention: the application is required to clean up. In web applications
+ * this can happen with creating a Servlet Filter and overriding the
+ * onFilter method like:</p>
+ *
+ * <pre>
+ * try {
+ *    MDC.put(myKey);
+ *    chain.doFilter(request, response);
+ * } finally {
+ *    MDC.remove(myKey);
+ * }
+ * </pre>
+ *
+ * <p>Please also see: {@link http://logging.apache.org/log4j/1.2/faq.html#mdcmemoryleak}</p>
+ *
+ * @author Ceki G&uuml;lc&uuml;
+ * @since 1.2
+ */
+public class MDC {
+
+    final static MDC mdc = new MDC();
+
+    static final int HT_SIZE = 7;
+
+    boolean java1;
+
+    Object tlm;
+
+    private Method removeMethod;
+
+    private MDC() {
+        java1 = Loader.isJava1();
+        if (!java1) {
+            tlm = new ThreadLocalMap();
+        }
+
+        try {
+            removeMethod = ThreadLocal.class.getMethod("remove", null);
+        } catch (NoSuchMethodException e) {
+            // don't do anything - java prior 1.5
+        }
+    }
+
+    /**
+     * Put a context value (the <code>o</code> parameter) as identified
+     * with the <code>key</code> parameter into the current thread's
+     * context map.
+     * <p/>
+     * <p>If the current thread does not have a context map it is
+     * created as a side effect.
+     */
+    public static void put(String key, Object o) {
+        if (mdc != null) {
+            mdc.put0(key, o);
+        }
+    }
+
+    /**
+     * Get the context identified by the <code>key</code> parameter.
+     * <p/>
+     * <p>This method has no side effects.
+     */
+    public static Object get(String key) {
+        if (mdc != null) {
+            return mdc.get0(key);
+        }
+        return null;
+    }
+
+    /**
+     * Remove the the context identified by the <code>key</code>
+     * parameter.
+     */
+    public static void remove(String key) {
+        if (mdc != null) {
+            mdc.remove0(key);
+        }
+    }
+
+
+    /**
+     * Get the current thread's MDC as a hashtable. This method is
+     * intended to be used internally.
+     */
+    public static Hashtable getContext() {
+        if (mdc != null) {
+            return mdc.getContext0();
+        } else {
+            return null;
+        }
+    }
+
+    /**
+     * Remove all values from the MDC.
+     *
+     * @since 1.2.16
+     */
+    public static void clear() {
+        if (mdc != null) {
+            mdc.clear0();
+        }
+    }
+
+
+    private void put0(String key, Object o) {
+        if (java1 || tlm == null) {
+            return;
+        } else {
+            Hashtable ht = (Hashtable) ((ThreadLocalMap) tlm).get();
+            if (ht == null) {
+                ht = new Hashtable(HT_SIZE);
+                ((ThreadLocalMap) tlm).set(ht);
+            }
+            ht.put(key, o);
+        }
+    }
+
+    private Object get0(String key) {
+        if (java1 || tlm == null) {
+            return null;
+        } else {
+            Hashtable ht = (Hashtable) ((ThreadLocalMap) tlm).get();
+            if (ht != null && key != null) {
+                return ht.get(key);
+            } else {
+                return null;
+            }
+        }
+    }
+
+    private void remove0(String key) {
+        if (!java1 && tlm != null) {
+            Hashtable ht = (Hashtable) ((ThreadLocalMap) tlm).get();
+            if (ht != null) {
+                ht.remove(key);
+                // clean up if this was the last key
+                if (ht.isEmpty()) {
+                        clear0();
+                }
+            }
+        }
+    }
+
+    private Hashtable getContext0() {
+        if (java1 || tlm == null) {
+            return null;
+        } else {
+            return (Hashtable) ((ThreadLocalMap) tlm).get();
+        }
+    }
+
+    private void clear0() {
+        if (!java1 && tlm != null) {
+            Hashtable ht = (Hashtable) ((ThreadLocalMap) tlm).get();
+            if (ht != null) {
+                ht.clear();
+            }
+            if (removeMethod != null) {
+                // java 1.3/1.4 does not have remove - will suffer from a memory leak
+                try {
+                    removeMethod.invoke(tlm, null);
+                } catch (IllegalAccessException e) {
+                    // should not happen
+                } catch (InvocationTargetException e) {
+                    // should not happen
+                }
+            }
+        }
+    }
+}