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java/org/apache/tomcat/dbcp/pool2/impl/ThrowableCallStack.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.tomcat.dbcp.pool2.impl;
+
+import java.io.PrintWriter;
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+
+/**
+ * CallStack strategy that uses the stack trace from a {@link Throwable}. This strategy, while slower than the
+ * SecurityManager implementation, provides call stack method names and other metadata in addition to the call stack
+ * of classes.
+ *
+ * @see Throwable#fillInStackTrace()
+ * @since 2.4.3
+ */
+public class ThrowableCallStack implements CallStack {
+
+    private final String messageFormat;
+    //@GuardedBy("dateFormat")
+    private final DateFormat dateFormat;
+
+    private volatile Snapshot snapshot;
+
+    /**
+     * Create a new instance.
+     *
+     * @param messageFormat message format
+     * @param useTimestamp whether to format the dates in the output message or not
+     */
+    public ThrowableCallStack(final String messageFormat, final boolean useTimestamp) {
+        this.messageFormat = messageFormat;
+        this.dateFormat = useTimestamp ? new SimpleDateFormat(messageFormat) : null;
+    }
+
+    @Override
+    public synchronized boolean printStackTrace(final PrintWriter writer) {
+        final Snapshot snapshotRef = this.snapshot;
+        if (snapshotRef == null) {
+            return false;
+        }
+        final String message;
+        if (dateFormat == null) {
+            message = messageFormat;
+        } else {
+            synchronized (dateFormat) {
+                message = dateFormat.format(Long.valueOf(snapshotRef.timestamp));
+            }
+        }
+        writer.println(message);
+        snapshotRef.printStackTrace(writer);
+        return true;
+    }
+
+    @Override
+    public void fillInStackTrace() {
+        snapshot = new Snapshot();
+    }
+
+    @Override
+    public void clear() {
+        snapshot = null;
+    }
+
+    /**
+     * A snapshot of a throwable.
+     */
+    private static class Snapshot extends Throwable {
+        private static final long serialVersionUID = 1L;
+        private final long timestamp = System.currentTimeMillis();
+    }
+}