android.util.EventLog Maven / Gradle / Ivy
Show all versions of android-all Show documentation
/*
* Copyright (C) 2007 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 java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Collection;
import java.util.HashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Access to the system diagnostic event record. System diagnostic events are
* used to record certain system-level events (such as garbage collection,
* activity manager state, system watchdogs, and other low level activity),
* which may be automatically collected and analyzed during system development.
*
* This is not the main "logcat" debugging log ({@link android.util.Log})!
* These diagnostic events are for system integrators, not application authors.
*
*
Events use integer tag codes corresponding to /system/etc/event-log-tags.
* They carry a payload of one or more int, long, or String values. The
* event-log-tags file defines the payload contents for each type code.
*/
public class EventLog {
/** @hide */ public EventLog() {}
private static final String TAG = "EventLog";
private static final String TAGS_FILE = "/system/etc/event-log-tags";
private static final String COMMENT_PATTERN = "^\\s*(#.*)?$";
private static final String TAG_PATTERN = "^\\s*(\\d+)\\s+(\\w+)\\s*(\\(.*\\))?\\s*$";
private static HashMap sTagCodes = null;
private static HashMap sTagNames = null;
/** A previously logged event read from the logs. */
public static final class Event {
private final ByteBuffer mBuffer;
// Layout of event log entry received from Android logger.
// see system/core/include/log/logger.h
private static final int LENGTH_OFFSET = 0;
private static final int HEADER_SIZE_OFFSET = 2;
private static final int PROCESS_OFFSET = 4;
private static final int THREAD_OFFSET = 8;
private static final int SECONDS_OFFSET = 12;
private static final int NANOSECONDS_OFFSET = 16;
// Layout for event log v1 format, v2 and v3 use HEADER_SIZE_OFFSET
private static final int V1_PAYLOAD_START = 20;
private static final int DATA_OFFSET = 4;
// Value types
private static final byte INT_TYPE = 0;
private static final byte LONG_TYPE = 1;
private static final byte STRING_TYPE = 2;
private static final byte LIST_TYPE = 3;
/** @param data containing event, read from the system */
/*package*/ Event(byte[] data) {
mBuffer = ByteBuffer.wrap(data);
mBuffer.order(ByteOrder.nativeOrder());
}
/** @return the process ID which wrote the log entry */
public int getProcessId() {
return mBuffer.getInt(PROCESS_OFFSET);
}
/** @return the thread ID which wrote the log entry */
public int getThreadId() {
return mBuffer.getInt(THREAD_OFFSET);
}
/** @return the wall clock time when the entry was written */
public long getTimeNanos() {
return mBuffer.getInt(SECONDS_OFFSET) * 1000000000l
+ mBuffer.getInt(NANOSECONDS_OFFSET);
}
/** @return the type tag code of the entry */
public int getTag() {
int offset = mBuffer.getShort(HEADER_SIZE_OFFSET);
if (offset == 0) {
offset = V1_PAYLOAD_START;
}
return mBuffer.getInt(offset);
}
/** @return one of Integer, Long, String, null, or Object[] of same. */
public synchronized Object getData() {
try {
int offset = mBuffer.getShort(HEADER_SIZE_OFFSET);
if (offset == 0) {
offset = V1_PAYLOAD_START;
}
mBuffer.limit(offset + mBuffer.getShort(LENGTH_OFFSET));
mBuffer.position(offset + DATA_OFFSET); // Just after the tag.
return decodeObject();
} catch (IllegalArgumentException e) {
Log.wtf(TAG, "Illegal entry payload: tag=" + getTag(), e);
return null;
} catch (BufferUnderflowException e) {
Log.wtf(TAG, "Truncated entry payload: tag=" + getTag(), e);
return null;
}
}
/** @return the loggable item at the current position in mBuffer. */
private Object decodeObject() {
byte type = mBuffer.get();
switch (type) {
case INT_TYPE:
return (Integer) mBuffer.getInt();
case LONG_TYPE:
return (Long) mBuffer.getLong();
case STRING_TYPE:
try {
int length = mBuffer.getInt();
int start = mBuffer.position();
mBuffer.position(start + length);
return new String(mBuffer.array(), start, length, "UTF-8");
} catch (UnsupportedEncodingException e) {
Log.wtf(TAG, "UTF-8 is not supported", e);
return null;
}
case LIST_TYPE:
int length = mBuffer.get();
if (length < 0) length += 256; // treat as signed byte
Object[] array = new Object[length];
for (int i = 0; i < length; ++i) array[i] = decodeObject();
return array;
default:
throw new IllegalArgumentException("Unknown entry type: " + type);
}
}
}
// We assume that the native methods deal with any concurrency issues.
/**
* Record an event log message.
* @param tag The event type tag code
* @param value A value to log
* @return The number of bytes written
*/
public static native int writeEvent(int tag, int value);
/**
* Record an event log message.
* @param tag The event type tag code
* @param value A value to log
* @return The number of bytes written
*/
public static native int writeEvent(int tag, long value);
/**
* Record an event log message.
* @param tag The event type tag code
* @param str A value to log
* @return The number of bytes written
*/
public static native int writeEvent(int tag, String str);
/**
* Record an event log message.
* @param tag The event type tag code
* @param list A list of values to log
* @return The number of bytes written
*/
public static native int writeEvent(int tag, Object... list);
/**
* Read events from the log, filtered by type.
* @param tags to search for
* @param output container to add events into
* @throws IOException if something goes wrong reading events
*/
public static native void readEvents(int[] tags, Collection output)
throws IOException;
/**
* Get the name associated with an event type tag code.
* @param tag code to look up
* @return the name of the tag, or null if no tag has that number
*/
public static String getTagName(int tag) {
readTagsFile();
return sTagNames.get(tag);
}
/**
* Get the event type tag code associated with an event name.
* @param name of event to look up
* @return the tag code, or -1 if no tag has that name
*/
public static int getTagCode(String name) {
readTagsFile();
Integer code = sTagCodes.get(name);
return code != null ? code : -1;
}
/**
* Read TAGS_FILE, populating sTagCodes and sTagNames, if not already done.
*/
private static synchronized void readTagsFile() {
if (sTagCodes != null && sTagNames != null) return;
sTagCodes = new HashMap();
sTagNames = new HashMap();
Pattern comment = Pattern.compile(COMMENT_PATTERN);
Pattern tag = Pattern.compile(TAG_PATTERN);
BufferedReader reader = null;
String line;
try {
reader = new BufferedReader(new FileReader(TAGS_FILE), 256);
while ((line = reader.readLine()) != null) {
if (comment.matcher(line).matches()) continue;
Matcher m = tag.matcher(line);
if (!m.matches()) {
Log.wtf(TAG, "Bad entry in " + TAGS_FILE + ": " + line);
continue;
}
try {
int num = Integer.parseInt(m.group(1));
String name = m.group(2);
sTagCodes.put(name, num);
sTagNames.put(num, name);
} catch (NumberFormatException e) {
Log.wtf(TAG, "Error in " + TAGS_FILE + ": " + line, e);
}
}
} catch (IOException e) {
Log.wtf(TAG, "Error reading " + TAGS_FILE, e);
// Leave the maps existing but unpopulated
} finally {
try { if (reader != null) reader.close(); } catch (IOException e) {}
}
}
}