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java/org/apache/tomcat/util/log/UserDataHelper.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.util.log;
+
+import org.apache.juli.logging.Log;
+
+/**
+ * This helper class assists with the logging associated with invalid input
+ * data. A developer may want all instances of invalid input data logged to
+ * assist with debugging whereas in production it is likely to be desirable not
+ * to log anything for invalid data. The following settings may be used:
+ * <ul>
+ * <li>NOTHING: Log nothing.</li>
+ * <li>DEBUG_ALL: Log all problems at DEBUG log level.</li>
+ * <li>INFO_THEN_DEBUG: Log first problem at INFO log level and any further
+ *     issues in the following TBD (configurable) seconds at DEBUG level</li>
+ * <li>INFO_ALL: Log all problems at INFO log level.</li>
+ * </ul>
+ * By default, INFO_THEN_DEBUG is used with a suppression time of 24 hours.
+ *
+ * NOTE: This class is not completely thread-safe. When using INFO_THEN_DEBUG it
+ * is possible that several INFO messages will be logged before dropping to
+ * DEBUG.
+ */
+public class UserDataHelper {
+
+    private final Log log;
+
+    private final Config config;
+
+    // A value of 0 is equivalent to using INFO_ALL
+    // A negative value will trigger infinite suppression
+    // The value is milliseconds
+    private final long suppressionTime;
+
+    private volatile long lastInfoTime = 0;
+
+
+    public UserDataHelper(Log log) {
+        this.log = log;
+
+        Config tempConfig;
+        String configString = System.getProperty(
+                "org.apache.juli.logging.UserDataHelper.CONFIG");
+        if (configString == null) {
+            tempConfig = Config.INFO_THEN_DEBUG;
+        } else {
+            try {
+                tempConfig = Config.valueOf(configString);
+            } catch (IllegalArgumentException iae) {
+                // Ignore - use default
+                tempConfig = Config.INFO_THEN_DEBUG;
+            }
+        }
+
+        // Default suppression time of 1 day.
+        suppressionTime = Integer.getInteger(
+                "org.apache.juli.logging.UserDataHelper.SUPPRESSION_TIME",
+                60 * 60 * 24).intValue() * 1000L;
+
+        if (suppressionTime == 0) {
+            tempConfig = Config.INFO_ALL;
+        }
+
+        config = tempConfig;
+    }
+
+
+    /**
+     * Returns log mode for the next log message, or <code>null</code> if the
+     * message should not be logged.
+     *
+     * <p>
+     * If <code>INFO_THEN_DEBUG</code> configuration option is enabled, this
+     * method might change internal state of this object.
+     *
+     * @return Log mode, or <code>null</code>
+     */
+    public Mode getNextMode() {
+        if (Config.NONE == config) {
+            return null;
+        } else if (Config.DEBUG_ALL == config) {
+            return log.isDebugEnabled() ? Mode.DEBUG : null;
+        } else if (Config.INFO_THEN_DEBUG == config) {
+            if (logAtInfo()) {
+                return log.isInfoEnabled() ? Mode.INFO_THEN_DEBUG : null;
+            } else {
+                return log.isDebugEnabled() ? Mode.DEBUG : null;
+            }
+        } else if (Config.INFO_ALL == config) {
+            return log.isInfoEnabled() ? Mode.INFO : null;
+        }
+        // Should never happen
+        return null;
+    }
+
+
+    /*
+     * Not completely thread-safe but good enough for this use case. I couldn't
+     * see a simple enough way to make it completely thread-safe that was not
+     * likely to compromise performance.
+     */
+    private boolean logAtInfo() {
+
+        if (suppressionTime < 0 && lastInfoTime > 0) {
+            return false;
+        }
+
+        long now = System.currentTimeMillis();
+
+        if (lastInfoTime + suppressionTime > now) {
+            return false;
+        }
+
+        lastInfoTime = now;
+        return true;
+    }
+
+
+    private enum Config {
+        NONE,
+        DEBUG_ALL,
+        INFO_THEN_DEBUG,
+        INFO_ALL
+    }
+
+    /**
+     * Log mode for the next log message.
+     */
+    public enum Mode {
+        DEBUG,
+        INFO_THEN_DEBUG,
+        INFO
+    }
+}