/*
- * Copyright (C) 2016 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
+ * SPDX-License-Identifier: LGPL-2.1-only
*
- * This library is free software; you can redistribute it and/or modify it
- * under the terms of the GNU Lesser General Public License, version 2.1 only,
- * as published by the Free Software Foundation.
- *
- * This library is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
- * for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this library; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ * Copyright (C) 2016 EfficiOS Inc.
+ * Copyright (C) 2016 Alexandre Montplaisir <alexmonthy@efficios.com>
*/
package org.lttng.ust.agent.context;
+import java.io.ByteArrayOutputStream;
+import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
* This class is used to serialize the list of "context info" objects to pass
* through JNI.
*
- * The protocol expects a single byte array parameter. This byte array consists
- * of a series of fixed-size entries, where each entry contains the following
- * elements (with their size in bytes in parenthesis):
+ * The protocol expects two byte array parameters, which are contained here in
+ * the {@link SerializedContexts} inner class.
+ *
+ * The first byte array is called the "entries array", and contains fixed-size
+ * entries, one per context element.
+ *
+ * The second one is the "strings array", it is of variable length and used to
+ * hold the variable-length strings. Each one of these strings is formatted as a
+ * UTF-8 C-string, meaning in will end with a "\0" byte to indicate its end.
+ * Entries in the first array may refer to offsets in the second array to point
+ * to relevant strings.
+ *
+ * The fixed-size entries in the entries array contain the following elements
+ * (size in bytes in parentheses):
*
* <ul>
- * <li>The full context name, like "$app.myprovider:mycontext" (256)</li>
+ * <li>The offset in the strings array pointing to the full context name, like
+ * "$app.myprovider:mycontext" (4)</li>
* <li>The context value type (1)</li>
- * <li>The context value itself(256)</li>
+ * <li>The context value itself (8)</li>
* </ul>
*
- * So the total size of each entry is 513 bytes. All unused bytes will be
- * zero'ed.
+ * The context value type will indicate how many bytes are used for the value.
+ * If the it is of String type, then we use 4 bytes to represent the offset in
+ * the strings array.
+ *
+ * So the total size of each entry is 13 bytes. All unused bytes (for context
+ * values shorter than 8 bytes for example) will be zero'ed.
*
* @author Alexandre Montplaisir
*/
}
}
+ /**
+ * Class used to wrap the two byte arrays returned by
+ * {@link #queryAndSerializeRequestedContexts}.
+ */
+ public static class SerializedContexts {
+
+ private final byte[] contextEntries;
+ private final byte[] contextStrings;
+
+ /**
+ * Constructor
+ *
+ * @param entries
+ * Arrays for the fixed-size context entries.
+ * @param strings
+ * Arrays for variable-length strings
+ */
+ public SerializedContexts(byte[] entries, byte[] strings) {
+ contextEntries = entries;
+ contextStrings = strings;
+ }
+
+ /**
+ * @return The entries array
+ */
+ public byte[] getEntriesArray() {
+ return contextEntries;
+ }
+
+ /**
+ * @return The strings array
+ */
+ public byte[] getStringsArray() {
+ return contextStrings;
+ }
+ }
+
private static final String UST_APP_CTX_PREFIX = "$app.";
- private static final int ELEMENT_LENGTH = 256;
- private static final int ENTRY_LENGTH = 513;
+ private static final int ENTRY_LENGTH = 13;
private static final ByteOrder NATIVE_ORDER = ByteOrder.nativeOrder();
private static final Charset UTF8_CHARSET = Charset.forName("UTF-8");
- private static final byte[] EMPTY_ARRAY = new byte[0];
+ private static final SerializedContexts EMPTY_CONTEXTS = new SerializedContexts(new byte[0], new byte[0]);
/**
* From the list of requested contexts in the tracing session, look them up
* @return The byte array representing the intersection of the requested and
* available contexts.
*/
- public static byte[] queryAndSerializeRequestedContexts(Collection<Map.Entry<String, Map<String, Integer>>> enabledContexts) {
+ public static SerializedContexts queryAndSerializeRequestedContexts(Collection<Map.Entry<String, Map<String, Integer>>> enabledContexts) {
if (enabledContexts.isEmpty()) {
/* Early return if there is no requested context information */
- return EMPTY_ARRAY;
- }
-
- /* Compute the total number of contexts (flatten the map) */
- int totalArraySize = 0;
- for (Map.Entry<String, Map<String, Integer>> contexts : enabledContexts) {
- totalArraySize += contexts.getValue().size() * ENTRY_LENGTH;
+ return EMPTY_CONTEXTS;
}
ContextInfoManager contextManager;
* The JNI library is not available, do not send any context
* information. No retriever could have been defined anyways.
*/
- return EMPTY_ARRAY;
+ return EMPTY_CONTEXTS;
}
- ByteBuffer buffer = ByteBuffer.allocate(totalArraySize);
- buffer.order(NATIVE_ORDER);
- buffer.clear();
-
- for (Map.Entry<String, Map<String, Integer>> entry : enabledContexts) {
- String requestedRetrieverName = entry.getKey();
- Map<String, Integer> requestedContexts = entry.getValue();
-
- IContextInfoRetriever retriever = contextManager.getContextInfoRetriever(requestedRetrieverName);
-
- for (String requestedContext : requestedContexts.keySet()) {
- Object contextInfo;
- if (retriever == null) {
- contextInfo = null;
- } else {
- contextInfo = retriever.retrieveContextInfo(requestedContext);
- /*
- * 'contextInfo' can still be null here, which would
- * indicate the retriever does not supply this context. We
- * will still write this information so that the tracer can
- * know about it.
- */
- }
+ /* Compute the total number of contexts (flatten the map) */
+ int totalArraySize = 0;
+ for (Map.Entry<String, Map<String, Integer>> contexts : enabledContexts) {
+ totalArraySize += contexts.getValue().size() * ENTRY_LENGTH;
+ }
+
+ /* Prepare the ByteBuffer that will generate the "entries" array */
+ ByteBuffer entriesBuffer = ByteBuffer.allocate(totalArraySize);
+ entriesBuffer.order(NATIVE_ORDER);
+ entriesBuffer.clear();
+
+ /* Prepare the streams that will generate the "strings" array */
+ ByteArrayOutputStream stringsBaos = new ByteArrayOutputStream();
+ DataOutputStream stringsDos = new DataOutputStream(stringsBaos);
- /* Serialize the result to the buffer */
- // FIXME Eventually pass the retriever name only once?
- String fullContextName = (UST_APP_CTX_PREFIX + requestedRetrieverName + ':' + requestedContext);
- byte[] strArray = fullContextName.getBytes(UTF8_CHARSET);
- int remainingBytes = ELEMENT_LENGTH - strArray.length;
- // FIXME Handle case where name is too long...
- buffer.put(strArray);
- buffer.position(buffer.position() + remainingBytes);
+ try {
+ for (Map.Entry<String, Map<String, Integer>> entry : enabledContexts) {
+ String requestedRetrieverName = entry.getKey();
+ Map<String, Integer> requestedContexts = entry.getValue();
+
+ IContextInfoRetriever retriever = contextManager.getContextInfoRetriever(requestedRetrieverName);
+
+ for (String requestedContext : requestedContexts.keySet()) {
+ Object contextInfo;
+ if (retriever == null) {
+ contextInfo = null;
+ } else {
+ contextInfo = retriever.retrieveContextInfo(requestedContext);
+ /*
+ * 'contextInfo' can still be null here, which would
+ * indicate the retriever does not supply this context.
+ * We will still write this information so that the
+ * tracer can know about it.
+ */
+ }
- LttngUstAgentLogger.log(ContextInfoSerializer.class,
- "ContextInfoSerializer: Context to be sent through JNI: " + fullContextName + '=' +
- (contextInfo == null ? "null" : contextInfo.toString()));
+ /* Serialize the result to the buffers */
+ // FIXME Eventually pass the retriever name only once?
+ String fullContextName = (UST_APP_CTX_PREFIX + requestedRetrieverName + ':' + requestedContext);
+ byte[] strArray = fullContextName.getBytes(UTF8_CHARSET);
- serializeContextInfo(buffer, contextInfo);
+ entriesBuffer.putInt(stringsDos.size());
+ stringsDos.write(strArray);
+ stringsDos.writeChar('\0');
+
+ LttngUstAgentLogger.log(ContextInfoSerializer.class,
+ "ContextInfoSerializer: Context to be sent through JNI: " + fullContextName + '=' +
+ (contextInfo == null ? "null" : contextInfo.toString()));
+
+ serializeContextInfo(entriesBuffer, stringsDos, contextInfo);
+ }
}
+
+ stringsDos.flush();
+ stringsBaos.flush();
+
+ } catch (IOException e) {
+ /*
+ * Should not happen because we are wrapping a
+ * ByteArrayOutputStream, which writes to memory
+ */
+ e.printStackTrace();
}
- return buffer.array();
+
+ byte[] entriesArray = entriesBuffer.array();
+ byte[] stringsArray = stringsBaos.toByteArray();
+ return new SerializedContexts(entriesArray, stringsArray);
}
- private static void serializeContextInfo(ByteBuffer buffer, Object contextInfo) {
+ private static final int CONTEXT_VALUE_LENGTH = 8;
+
+ private static void serializeContextInfo(ByteBuffer entriesBuffer, DataOutputStream stringsDos, Object contextInfo) throws IOException {
int remainingBytes;
if (contextInfo == null) {
- buffer.put(DataType.NULL.getValue());
- remainingBytes = ELEMENT_LENGTH;
+ entriesBuffer.put(DataType.NULL.getValue());
+ remainingBytes = CONTEXT_VALUE_LENGTH;
} else if (contextInfo instanceof Integer) {
- buffer.put(DataType.INTEGER.getValue());
- buffer.putInt(((Integer) contextInfo).intValue());
- remainingBytes = ELEMENT_LENGTH - 4;
+ entriesBuffer.put(DataType.INTEGER.getValue());
+ entriesBuffer.putInt(((Integer) contextInfo).intValue());
+ remainingBytes = CONTEXT_VALUE_LENGTH - 4;
} else if (contextInfo instanceof Long) {
- buffer.put(DataType.LONG.getValue());
- buffer.putLong(((Long) contextInfo).longValue());
- remainingBytes = ELEMENT_LENGTH - 8;
+ entriesBuffer.put(DataType.LONG.getValue());
+ entriesBuffer.putLong(((Long) contextInfo).longValue());
+ remainingBytes = CONTEXT_VALUE_LENGTH - 8;
} else if (contextInfo instanceof Double) {
- buffer.put(DataType.DOUBLE.getValue());
- buffer.putDouble(((Double) contextInfo).doubleValue());
- remainingBytes = ELEMENT_LENGTH - 8;
+ entriesBuffer.put(DataType.DOUBLE.getValue());
+ entriesBuffer.putDouble(((Double) contextInfo).doubleValue());
+ remainingBytes = CONTEXT_VALUE_LENGTH - 8;
} else if (contextInfo instanceof Float) {
- buffer.put(DataType.FLOAT.getValue());
- buffer.putFloat(((Float) contextInfo).floatValue());
- remainingBytes = ELEMENT_LENGTH - 4;
+ entriesBuffer.put(DataType.FLOAT.getValue());
+ entriesBuffer.putFloat(((Float) contextInfo).floatValue());
+ remainingBytes = CONTEXT_VALUE_LENGTH - 4;
} else if (contextInfo instanceof Byte) {
- buffer.put(DataType.BYTE.getValue());
- buffer.put(((Byte) contextInfo).byteValue());
- remainingBytes = ELEMENT_LENGTH - 1;
+ entriesBuffer.put(DataType.BYTE.getValue());
+ entriesBuffer.put(((Byte) contextInfo).byteValue());
+ remainingBytes = CONTEXT_VALUE_LENGTH - 1;
} else if (contextInfo instanceof Short) {
- buffer.put(DataType.SHORT.getValue());
- buffer.putShort(((Short) contextInfo).shortValue());
- remainingBytes = ELEMENT_LENGTH - 2;
+ entriesBuffer.put(DataType.SHORT.getValue());
+ entriesBuffer.putShort(((Short) contextInfo).shortValue());
+ remainingBytes = CONTEXT_VALUE_LENGTH - 2;
} else if (contextInfo instanceof Boolean) {
- buffer.put(DataType.BOOLEAN.getValue());
+ entriesBuffer.put(DataType.BOOLEAN.getValue());
boolean b = ((Boolean) contextInfo).booleanValue();
/* Converted to one byte, write 1 for true, 0 for false */
- buffer.put((byte) (b ? 1 : 0));
- remainingBytes = ELEMENT_LENGTH - 1;
+ entriesBuffer.put((byte) (b ? 1 : 0));
+ remainingBytes = CONTEXT_VALUE_LENGTH - 1;
} else {
- /* We'll write the object as a string. Also includes the case of Character. */
+ /* Also includes the case of Character. */
+ /*
+ * We'll write the object as a string, into the strings array. We
+ * will write the corresponding offset to the entries array.
+ */
String str = contextInfo.toString();
byte[] strArray = str.getBytes(UTF8_CHARSET);
- buffer.put(DataType.STRING.getValue());
- if (strArray.length >= ELEMENT_LENGTH) {
- /* Trim the string to the max allowed length */
- buffer.put(strArray, 0, ELEMENT_LENGTH);
- remainingBytes = 0;
- } else {
- buffer.put(strArray);
- remainingBytes = ELEMENT_LENGTH - strArray.length;
- }
+ entriesBuffer.put(DataType.STRING.getValue());
+
+ entriesBuffer.putInt(stringsDos.size());
+ stringsDos.write(strArray);
+ stringsDos.writeChar('\0');
+
+ remainingBytes = CONTEXT_VALUE_LENGTH - 4;
}
- buffer.position(buffer.position() + remainingBytes);
+ entriesBuffer.position(entriesBuffer.position() + remainingBytes);
}
}
projects / lttng-ust.git / blobdiff