core/java/android/util/Log.java - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2006 The Android Open Source Project
  *
  * Licensed 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 android.util;

 import android.os.DeadSystemException;

 import com.android.internal.os.RuntimeInit;
 import com.android.internal.util.FastPrintWriter;
 import com.android.internal.util.LineBreakBufferedWriter;

 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.io.Writer;
 import java.net.UnknownHostException;

 /**
  * API for sending log output.
  *
  * <p>Generally, you should use the {@link #v Log.v()}, {@link #d Log.d()},
  * {@link #i Log.i()}, {@link #w Log.w()}, and {@link #e Log.e()} methods to write logs.
  * You can then <a href="{@docRoot}studio/debug/am-logcat.html">view the logs in logcat</a>.
  *
  * <p>The order in terms of verbosity, from least to most is
  * ERROR, WARN, INFO, DEBUG, VERBOSE.  Verbose should never be compiled
  * into an application except during development.  Debug logs are compiled
  * in but stripped at runtime.  Error, warning and info logs are always kept.
  *
  * <p><b>Tip:</b> A good convention is to declare a <code>TAG</code> constant
  * in your class:
  *
  * <pre>private static final String TAG = "MyActivity";</pre>
  *
  * and use that in subsequent calls to the log methods.
  * </p>
  *
  * <p><b>Tip:</b> Don't forget that when you make a call like
  * <pre>Log.v(TAG, "index=" + i);</pre>
  * that when you're building the string to pass into Log.d, the compiler uses a
  * StringBuilder and at least three allocations occur: the StringBuilder
  * itself, the buffer, and the String object.  Realistically, there is also
  * another buffer allocation and copy, and even more pressure on the gc.
  * That means that if your log message is filtered out, you might be doing
  * significant work and incurring significant overhead.
  */
 public final class Log {

     /**
      * Priority constant for the println method; use Log.v.
      */
     public static final int VERBOSE = 2;

     /**
      * Priority constant for the println method; use Log.d.
      */
     public static final int DEBUG = 3;

     /**
      * Priority constant for the println method; use Log.i.
      */
     public static final int INFO = 4;

     /**
      * Priority constant for the println method; use Log.w.
      */
     public static final int WARN = 5;

     /**
      * Priority constant for the println method; use Log.e.
      */
     public static final int ERROR = 6;

     /**
      * Priority constant for the println method.
      */
     public static final int ASSERT = 7;

     /**
      * Exception class used to capture a stack trace in {@link #wtf}.
      * @hide
      */
     public static class TerribleFailure extends Exception {
         TerribleFailure(String msg, Throwable cause) { super(msg, cause); }
     }

     /**
      * Interface to handle terrible failures from {@link #wtf}.
      *
      * @hide
      */
     public interface TerribleFailureHandler {
         void onTerribleFailure(String tag, TerribleFailure what, boolean system);
     }

     private static TerribleFailureHandler sWtfHandler = new TerribleFailureHandler() {
             public void onTerribleFailure(String tag, TerribleFailure what, boolean system) {
                 RuntimeInit.wtf(tag, what, system);
             }
         };

     private Log() {
     }

     /**
      * Send a {@link #VERBOSE} log message.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      */
     public static int v(String tag, String msg) {
         return println_native(LOG_ID_MAIN, VERBOSE, tag, msg);
     }

     /**
      * Send a {@link #VERBOSE} log message and log the exception.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      * @param tr An exception to log
      */
     public static int v(String tag, String msg, Throwable tr) {
         return printlns(LOG_ID_MAIN, VERBOSE, tag, msg, tr);
     }

     /**
      * Send a {@link #DEBUG} log message.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      */
     public static int d(String tag, String msg) {
         return println_native(LOG_ID_MAIN, DEBUG, tag, msg);
     }

     /**
      * Send a {@link #DEBUG} log message and log the exception.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      * @param tr An exception to log
      */
     public static int d(String tag, String msg, Throwable tr) {
         return printlns(LOG_ID_MAIN, DEBUG, tag, msg, tr);
     }

     /**
      * Send an {@link #INFO} log message.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      */
     public static int i(String tag, String msg) {
         return println_native(LOG_ID_MAIN, INFO, tag, msg);
     }

     /**
      * Send a {@link #INFO} log message and log the exception.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      * @param tr An exception to log
      */
     public static int i(String tag, String msg, Throwable tr) {
         return printlns(LOG_ID_MAIN, INFO, tag, msg, tr);
     }

     /**
      * Send a {@link #WARN} log message.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      */
     public static int w(String tag, String msg) {
         return println_native(LOG_ID_MAIN, WARN, tag, msg);
     }

     /**
      * Send a {@link #WARN} log message and log the exception.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      * @param tr An exception to log
      */
     public static int w(String tag, String msg, Throwable tr) {
         return printlns(LOG_ID_MAIN, WARN, tag, msg, tr);
     }

     /**
      * Checks to see whether or not a log for the specified tag is loggable at the specified level.
      *
      *  The default level of any tag is set to INFO. This means that any level above and including
      *  INFO will be logged. Before you make any calls to a logging method you should check to see
      *  if your tag should be logged. You can change the default level by setting a system property:
      *      'setprop log.tag.&lt;YOUR_LOG_TAG> &lt;LEVEL>'
      *  Where level is either VERBOSE, DEBUG, INFO, WARN, ERROR, ASSERT, or SUPPRESS. SUPPRESS will
      *  turn off all logging for your tag. You can also create a local.prop file that with the
      *  following in it:
      *      'log.tag.&lt;YOUR_LOG_TAG>=&lt;LEVEL>'
      *  and place that in /data/local.prop.
      *
      * @param tag The tag to check.
      * @param level The level to check.
      * @return Whether or not that this is allowed to be logged.
      * @throws IllegalArgumentException is thrown if the tag.length() > 23
      *         for Nougat (7.0) releases (API <= 23) and prior, there is no
      *         tag limit of concern after this API level.
      */
     public static native boolean isLoggable(String tag, int level);

     /*
      * Send a {@link #WARN} log message and log the exception.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param tr An exception to log
      */
     public static int w(String tag, Throwable tr) {
         return printlns(LOG_ID_MAIN, WARN, tag, "", tr);
     }

     /**
      * Send an {@link #ERROR} log message.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      */
     public static int e(String tag, String msg) {
         return println_native(LOG_ID_MAIN, ERROR, tag, msg);
     }

     /**
      * Send a {@link #ERROR} log message and log the exception.
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      * @param tr An exception to log
      */
     public static int e(String tag, String msg, Throwable tr) {
         return printlns(LOG_ID_MAIN, ERROR, tag, msg, tr);
     }

     /**
      * What a Terrible Failure: Report a condition that should never happen.
      * The error will always be logged at level ASSERT with the call stack.
      * Depending on system configuration, a report may be added to the
      * {@link android.os.DropBoxManager} and/or the process may be terminated
      * immediately with an error dialog.
      * @param tag Used to identify the source of a log message.
      * @param msg The message you would like logged.
      */
     public static int wtf(String tag, String msg) {
         return wtf(LOG_ID_MAIN, tag, msg, null, false, false);
     }

     /**
      * Like {@link #wtf(String, String)}, but also writes to the log the full
      * call stack.
      * @hide
      */
     public static int wtfStack(String tag, String msg) {
         return wtf(LOG_ID_MAIN, tag, msg, null, true, false);
     }

     /**
      * What a Terrible Failure: Report an exception that should never happen.
      * Similar to {@link #wtf(String, String)}, with an exception to log.
      * @param tag Used to identify the source of a log message.
      * @param tr An exception to log.
      */
     public static int wtf(String tag, Throwable tr) {
         return wtf(LOG_ID_MAIN, tag, tr.getMessage(), tr, false, false);
     }

     /**
      * What a Terrible Failure: Report an exception that should never happen.
      * Similar to {@link #wtf(String, Throwable)}, with a message as well.
      * @param tag Used to identify the source of a log message.
      * @param msg The message you would like logged.
      * @param tr An exception to log.  May be null.
      */
     public static int wtf(String tag, String msg, Throwable tr) {
         return wtf(LOG_ID_MAIN, tag, msg, tr, false, false);
     }

     static int wtf(int logId, String tag, String msg, Throwable tr, boolean localStack,
             boolean system) {
         TerribleFailure what = new TerribleFailure(msg, tr);
         // Only mark this as ERROR, do not use ASSERT since that should be
         // reserved for cases where the system is guaranteed to abort.
         // The onTerribleFailure call does not always cause a crash.
         int bytes = printlns(logId, ERROR, tag, msg, localStack ? what : tr);
         sWtfHandler.onTerribleFailure(tag, what, system);
         return bytes;
     }

     static void wtfQuiet(int logId, String tag, String msg, boolean system) {
         TerribleFailure what = new TerribleFailure(msg, null);
         sWtfHandler.onTerribleFailure(tag, what, system);
     }

     /**
      * Sets the terrible failure handler, for testing.
      *
      * @return the old handler
      *
      * @hide
      */
     public static TerribleFailureHandler setWtfHandler(TerribleFailureHandler handler) {
         if (handler == null) {
             throw new NullPointerException("handler == null");
         }
         TerribleFailureHandler oldHandler = sWtfHandler;
         sWtfHandler = handler;
         return oldHandler;
     }

     /**
      * Handy function to get a loggable stack trace from a Throwable
      * @param tr An exception to log
      */
     public static String getStackTraceString(Throwable tr) {
         if (tr == null) {
             return "";
         }

         // This is to reduce the amount of log spew that apps do in the non-error
         // condition of the network being unavailable.
         Throwable t = tr;
         while (t != null) {
             if (t instanceof UnknownHostException) {
                 return "";
             }
             t = t.getCause();
         }

         StringWriter sw = new StringWriter();
         PrintWriter pw = new FastPrintWriter(sw, false, 256);
         tr.printStackTrace(pw);
         pw.flush();
         return sw.toString();
     }

     /**
      * Low-level logging call.
      * @param priority The priority/type of this log message
      * @param tag Used to identify the source of a log message.  It usually identifies
      *        the class or activity where the log call occurs.
      * @param msg The message you would like logged.
      * @return The number of bytes written.
      */
     public static int println(int priority, String tag, String msg) {
         return println_native(LOG_ID_MAIN, priority, tag, msg);
     }

     /** @hide */ public static final int LOG_ID_MAIN = 0;
     /** @hide */ public static final int LOG_ID_RADIO = 1;
     /** @hide */ public static final int LOG_ID_EVENTS = 2;
     /** @hide */ public static final int LOG_ID_SYSTEM = 3;
     /** @hide */ public static final int LOG_ID_CRASH = 4;

     /** @hide */ public static native int println_native(int bufID,
             int priority, String tag, String msg);

     /**
      * Return the maximum payload the log daemon accepts without truncation.
      * @return LOGGER_ENTRY_MAX_PAYLOAD.
      */
     private static native int logger_entry_max_payload_native();

     /**
      * Helper function for long messages. Uses the LineBreakBufferedWriter to break
      * up long messages and stacktraces along newlines, but tries to write in large
      * chunks. This is to avoid truncation.
      * @hide
      */
     public static int printlns(int bufID, int priority, String tag, String msg,
             Throwable tr) {
         ImmediateLogWriter logWriter = new ImmediateLogWriter(bufID, priority, tag);
         // Acceptable buffer size. Get the native buffer size, subtract two zero terminators,
         // and the length of the tag.
         // Note: we implicitly accept possible truncation for Modified-UTF8 differences. It
         //       is too expensive to compute that ahead of time.
         int bufferSize = PreloadHolder.LOGGER_ENTRY_MAX_PAYLOAD    // Base.
                 - 2                                                // Two terminators.
                 - (tag != null ? tag.length() : 0)                 // Tag length.
                 - 32;                                              // Some slack.
         // At least assume you can print *some* characters (tag is not too large).
         bufferSize = Math.max(bufferSize, 100);

         LineBreakBufferedWriter lbbw = new LineBreakBufferedWriter(logWriter, bufferSize);

         lbbw.println(msg);

         if (tr != null) {
             // This is to reduce the amount of log spew that apps do in the non-error
             // condition of the network being unavailable.
             Throwable t = tr;
             while (t != null) {
                 if (t instanceof UnknownHostException) {
                     break;
                 }
                 if (t instanceof DeadSystemException) {
                     lbbw.println("DeadSystemException: The system died; "
                             + "earlier logs will point to the root cause");
                     break;
                 }
                 t = t.getCause();
             }
             if (t == null) {
                 tr.printStackTrace(lbbw);
             }
         }

         lbbw.flush();

         return logWriter.getWritten();
     }

     /**
      * PreloadHelper class. Caches the LOGGER_ENTRY_MAX_PAYLOAD value to avoid
      * a JNI call during logging.
      */
     static class PreloadHolder {
         public final static int LOGGER_ENTRY_MAX_PAYLOAD =
                 logger_entry_max_payload_native();
     }

     /**
      * Helper class to write to the logcat. Different from LogWriter, this writes
      * the whole given buffer and does not break along newlines.
      */
     private static class ImmediateLogWriter extends Writer {

         private int bufID;
         private int priority;
         private String tag;

         private int written = 0;

         /**
          * Create a writer that immediately writes to the log, using the given
          * parameters.
          */
         public ImmediateLogWriter(int bufID, int priority, String tag) {
             this.bufID = bufID;
             this.priority = priority;
             this.tag = tag;
         }

         public int getWritten() {
             return written;
         }

         @Override
         public void write(char[] cbuf, int off, int len) {
             // Note: using String here has a bit of overhead as a Java object is created,
             //       but using the char[] directly is not easier, as it needs to be translated
             //       to a C char[] for logging.
             written += println_native(bufID, priority, tag, new String(cbuf, off, len));
         }

         @Override
         public void flush() {
             // Ignored.
         }

         @Override
         public void close() {
             // Ignored.
         }
     }
 }
	/*
	* Copyright (C) 2006 The Android Open Source Project
	*
	* Licensed 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 android.util;

	import android.os.DeadSystemException;

	import com.android.internal.os.RuntimeInit;
	import com.android.internal.util.FastPrintWriter;
	import com.android.internal.util.LineBreakBufferedWriter;

	import java.io.PrintWriter;
	import java.io.StringWriter;
	import java.io.Writer;
	import java.net.UnknownHostException;

	/**
	* API for sending log output.
	*
	* <p>Generally, you should use the {@link #v Log.v()}, {@link #d Log.d()},
	* {@link #i Log.i()}, {@link #w Log.w()}, and {@link #e Log.e()} methods to write logs.
	* You can then <a href="{@docRoot}studio/debug/am-logcat.html">view the logs in logcat</a>.
	*
	* <p>The order in terms of verbosity, from least to most is
	* ERROR, WARN, INFO, DEBUG, VERBOSE. Verbose should never be compiled
	* into an application except during development. Debug logs are compiled
	* in but stripped at runtime. Error, warning and info logs are always kept.
	*
	* <p><b>Tip:</b> A good convention is to declare a <code>TAG</code> constant
	* in your class:
	*
	* <pre>private static final String TAG = "MyActivity";</pre>
	*
	* and use that in subsequent calls to the log methods.
	* </p>
	*
	* <p><b>Tip:</b> Don't forget that when you make a call like
	* <pre>Log.v(TAG, "index=" + i);</pre>
	* that when you're building the string to pass into Log.d, the compiler uses a
	* StringBuilder and at least three allocations occur: the StringBuilder
	* itself, the buffer, and the String object. Realistically, there is also
	* another buffer allocation and copy, and even more pressure on the gc.
	* That means that if your log message is filtered out, you might be doing
	* significant work and incurring significant overhead.
	*/
	public final class Log {

	/**
	* Priority constant for the println method; use Log.v.
	*/
	public static final int VERBOSE = 2;

	/**
	* Priority constant for the println method; use Log.d.
	*/
	public static final int DEBUG = 3;

	/**
	* Priority constant for the println method; use Log.i.
	*/
	public static final int INFO = 4;

	/**
	* Priority constant for the println method; use Log.w.
	*/
	public static final int WARN = 5;

	/**
	* Priority constant for the println method; use Log.e.
	*/
	public static final int ERROR = 6;

	/**
	* Priority constant for the println method.
	*/
	public static final int ASSERT = 7;

	/**
	* Exception class used to capture a stack trace in {@link #wtf}.
	* @hide
	*/
	public static class TerribleFailure extends Exception {
	TerribleFailure(String msg, Throwable cause) { super(msg, cause); }
	}

	/**
	* Interface to handle terrible failures from {@link #wtf}.
	*
	* @hide
	*/
	public interface TerribleFailureHandler {
	void onTerribleFailure(String tag, TerribleFailure what, boolean system);
	}

	private static TerribleFailureHandler sWtfHandler = new TerribleFailureHandler() {
	public void onTerribleFailure(String tag, TerribleFailure what, boolean system) {
	RuntimeInit.wtf(tag, what, system);
	}
	};

	private Log() {
	}

	/**
	* Send a {@link #VERBOSE} log message.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	*/
	public static int v(String tag, String msg) {
	return println_native(LOG_ID_MAIN, VERBOSE, tag, msg);
	}

	/**
	* Send a {@link #VERBOSE} log message and log the exception.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	* @param tr An exception to log
	*/
	public static int v(String tag, String msg, Throwable tr) {
	return printlns(LOG_ID_MAIN, VERBOSE, tag, msg, tr);
	}

	/**
	* Send a {@link #DEBUG} log message.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	*/
	public static int d(String tag, String msg) {
	return println_native(LOG_ID_MAIN, DEBUG, tag, msg);
	}

	/**
	* Send a {@link #DEBUG} log message and log the exception.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	* @param tr An exception to log
	*/
	public static int d(String tag, String msg, Throwable tr) {
	return printlns(LOG_ID_MAIN, DEBUG, tag, msg, tr);
	}

	/**
	* Send an {@link #INFO} log message.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	*/
	public static int i(String tag, String msg) {
	return println_native(LOG_ID_MAIN, INFO, tag, msg);
	}

	/**
	* Send a {@link #INFO} log message and log the exception.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	* @param tr An exception to log
	*/
	public static int i(String tag, String msg, Throwable tr) {
	return printlns(LOG_ID_MAIN, INFO, tag, msg, tr);
	}

	/**
	* Send a {@link #WARN} log message.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	*/
	public static int w(String tag, String msg) {
	return println_native(LOG_ID_MAIN, WARN, tag, msg);
	}

	/**
	* Send a {@link #WARN} log message and log the exception.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	* @param tr An exception to log
	*/
	public static int w(String tag, String msg, Throwable tr) {
	return printlns(LOG_ID_MAIN, WARN, tag, msg, tr);
	}

	/**
	* Checks to see whether or not a log for the specified tag is loggable at the specified level.
	*
	* The default level of any tag is set to INFO. This means that any level above and including
	* INFO will be logged. Before you make any calls to a logging method you should check to see
	* if your tag should be logged. You can change the default level by setting a system property:
	* 'setprop log.tag.<YOUR_LOG_TAG> <LEVEL>'
	* Where level is either VERBOSE, DEBUG, INFO, WARN, ERROR, ASSERT, or SUPPRESS. SUPPRESS will
	* turn off all logging for your tag. You can also create a local.prop file that with the
	* following in it:
	* 'log.tag.<YOUR_LOG_TAG>=<LEVEL>'
	* and place that in /data/local.prop.
	*
	* @param tag The tag to check.
	* @param level The level to check.
	* @return Whether or not that this is allowed to be logged.
	* @throws IllegalArgumentException is thrown if the tag.length() > 23
	* for Nougat (7.0) releases (API <= 23) and prior, there is no
	* tag limit of concern after this API level.
	*/
	public static native boolean isLoggable(String tag, int level);

	/*
	* Send a {@link #WARN} log message and log the exception.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param tr An exception to log
	*/
	public static int w(String tag, Throwable tr) {
	return printlns(LOG_ID_MAIN, WARN, tag, "", tr);
	}

	/**
	* Send an {@link #ERROR} log message.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	*/
	public static int e(String tag, String msg) {
	return println_native(LOG_ID_MAIN, ERROR, tag, msg);
	}

	/**
	* Send a {@link #ERROR} log message and log the exception.
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	* @param tr An exception to log
	*/
	public static int e(String tag, String msg, Throwable tr) {
	return printlns(LOG_ID_MAIN, ERROR, tag, msg, tr);
	}

	/**
	* What a Terrible Failure: Report a condition that should never happen.
	* The error will always be logged at level ASSERT with the call stack.
	* Depending on system configuration, a report may be added to the
	* {@link android.os.DropBoxManager} and/or the process may be terminated
	* immediately with an error dialog.
	* @param tag Used to identify the source of a log message.
	* @param msg The message you would like logged.
	*/
	public static int wtf(String tag, String msg) {
	return wtf(LOG_ID_MAIN, tag, msg, null, false, false);
	}

	/**
	* Like {@link #wtf(String, String)}, but also writes to the log the full
	* call stack.
	* @hide
	*/
	public static int wtfStack(String tag, String msg) {
	return wtf(LOG_ID_MAIN, tag, msg, null, true, false);
	}

	/**
	* What a Terrible Failure: Report an exception that should never happen.
	* Similar to {@link #wtf(String, String)}, with an exception to log.
	* @param tag Used to identify the source of a log message.
	* @param tr An exception to log.
	*/
	public static int wtf(String tag, Throwable tr) {
	return wtf(LOG_ID_MAIN, tag, tr.getMessage(), tr, false, false);
	}

	/**
	* What a Terrible Failure: Report an exception that should never happen.
	* Similar to {@link #wtf(String, Throwable)}, with a message as well.
	* @param tag Used to identify the source of a log message.
	* @param msg The message you would like logged.
	* @param tr An exception to log. May be null.
	*/
	public static int wtf(String tag, String msg, Throwable tr) {
	return wtf(LOG_ID_MAIN, tag, msg, tr, false, false);
	}

	static int wtf(int logId, String tag, String msg, Throwable tr, boolean localStack,
	boolean system) {
	TerribleFailure what = new TerribleFailure(msg, tr);
	// Only mark this as ERROR, do not use ASSERT since that should be
	// reserved for cases where the system is guaranteed to abort.
	// The onTerribleFailure call does not always cause a crash.
	int bytes = printlns(logId, ERROR, tag, msg, localStack ? what : tr);
	sWtfHandler.onTerribleFailure(tag, what, system);
	return bytes;
	}

	static void wtfQuiet(int logId, String tag, String msg, boolean system) {
	TerribleFailure what = new TerribleFailure(msg, null);
	sWtfHandler.onTerribleFailure(tag, what, system);
	}

	/**
	* Sets the terrible failure handler, for testing.
	*
	* @return the old handler
	*
	* @hide
	*/
	public static TerribleFailureHandler setWtfHandler(TerribleFailureHandler handler) {
	if (handler == null) {
	throw new NullPointerException("handler == null");
	}
	TerribleFailureHandler oldHandler = sWtfHandler;
	sWtfHandler = handler;
	return oldHandler;
	}

	/**
	* Handy function to get a loggable stack trace from a Throwable
	* @param tr An exception to log
	*/
	public static String getStackTraceString(Throwable tr) {
	if (tr == null) {
	return "";
	}

	// This is to reduce the amount of log spew that apps do in the non-error
	// condition of the network being unavailable.
	Throwable t = tr;
	while (t != null) {
	if (t instanceof UnknownHostException) {
	return "";
	}
	t = t.getCause();
	}

	StringWriter sw = new StringWriter();
	PrintWriter pw = new FastPrintWriter(sw, false, 256);
	tr.printStackTrace(pw);
	pw.flush();
	return sw.toString();
	}

	/**
	* Low-level logging call.
	* @param priority The priority/type of this log message
	* @param tag Used to identify the source of a log message. It usually identifies
	* the class or activity where the log call occurs.
	* @param msg The message you would like logged.
	* @return The number of bytes written.
	*/
	public static int println(int priority, String tag, String msg) {
	return println_native(LOG_ID_MAIN, priority, tag, msg);
	}

	/** @hide */ public static final int LOG_ID_MAIN = 0;
	/** @hide */ public static final int LOG_ID_RADIO = 1;
	/** @hide */ public static final int LOG_ID_EVENTS = 2;
	/** @hide */ public static final int LOG_ID_SYSTEM = 3;
	/** @hide */ public static final int LOG_ID_CRASH = 4;

	/** @hide */ public static native int println_native(int bufID,
	int priority, String tag, String msg);

	/**
	* Return the maximum payload the log daemon accepts without truncation.
	* @return LOGGER_ENTRY_MAX_PAYLOAD.
	*/
	private static native int logger_entry_max_payload_native();

	/**
	* Helper function for long messages. Uses the LineBreakBufferedWriter to break
	* up long messages and stacktraces along newlines, but tries to write in large
	* chunks. This is to avoid truncation.
	* @hide
	*/
	public static int printlns(int bufID, int priority, String tag, String msg,
	Throwable tr) {
	ImmediateLogWriter logWriter = new ImmediateLogWriter(bufID, priority, tag);
	// Acceptable buffer size. Get the native buffer size, subtract two zero terminators,
	// and the length of the tag.
	// Note: we implicitly accept possible truncation for Modified-UTF8 differences. It
	// is too expensive to compute that ahead of time.
	int bufferSize = PreloadHolder.LOGGER_ENTRY_MAX_PAYLOAD // Base.
	- 2 // Two terminators.
	- (tag != null ? tag.length() : 0) // Tag length.
	- 32; // Some slack.
	// At least assume you can print some characters (tag is not too large).
	bufferSize = Math.max(bufferSize, 100);

	LineBreakBufferedWriter lbbw = new LineBreakBufferedWriter(logWriter, bufferSize);

	lbbw.println(msg);

	if (tr != null) {
	// This is to reduce the amount of log spew that apps do in the non-error
	// condition of the network being unavailable.
	Throwable t = tr;
	while (t != null) {
	if (t instanceof UnknownHostException) {
	break;
	}
	if (t instanceof DeadSystemException) {
	lbbw.println("DeadSystemException: The system died; "
	+ "earlier logs will point to the root cause");
	break;
	}
	t = t.getCause();
	}
	if (t == null) {
	tr.printStackTrace(lbbw);
	}
	}

	lbbw.flush();

	return logWriter.getWritten();
	}

	/**
	* PreloadHelper class. Caches the LOGGER_ENTRY_MAX_PAYLOAD value to avoid
	* a JNI call during logging.
	*/
	static class PreloadHolder {
	public final static int LOGGER_ENTRY_MAX_PAYLOAD =
	logger_entry_max_payload_native();
	}

	/**
	* Helper class to write to the logcat. Different from LogWriter, this writes
	* the whole given buffer and does not break along newlines.
	*/
	private static class ImmediateLogWriter extends Writer {

	private int bufID;
	private int priority;
	private String tag;

	private int written = 0;

	/**
	* Create a writer that immediately writes to the log, using the given
	* parameters.
	*/
	public ImmediateLogWriter(int bufID, int priority, String tag) {
	this.bufID = bufID;
	this.priority = priority;
	this.tag = tag;
	}

	public int getWritten() {
	return written;
	}

	@Override
	public void write(char[] cbuf, int off, int len) {
	// Note: using String here has a bit of overhead as a Java object is created,
	// but using the char[] directly is not easier, as it needs to be translated
	// to a C char[] for logging.
	written += println_native(bufID, priority, tag, new String(cbuf, off, len));
	}

	@Override
	public void flush() {
	// Ignored.
	}

	@Override
	public void close() {
	// Ignored.
	}
	}
	}