| 1 | /* |
| 2 | * Copyright (C) 2016 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com> |
| 3 | * |
| 4 | * This library is free software; you can redistribute it and/or modify it |
| 5 | * under the terms of the GNU Lesser General Public License, version 2.1 only, |
| 6 | * as published by the Free Software Foundation. |
| 7 | * |
| 8 | * This library is distributed in the hope that it will be useful, but WITHOUT |
| 9 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 10 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License |
| 11 | * for more details. |
| 12 | * |
| 13 | * You should have received a copy of the GNU Lesser General Public License |
| 14 | * along with this library; if not, write to the Free Software Foundation, |
| 15 | * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 16 | */ |
| 17 | |
| 18 | package org.lttng.ust.agent.context; |
| 19 | |
| 20 | import java.io.IOException; |
| 21 | import java.nio.ByteBuffer; |
| 22 | import java.nio.ByteOrder; |
| 23 | import java.nio.charset.Charset; |
| 24 | import java.util.Collection; |
| 25 | import java.util.Map; |
| 26 | |
| 27 | import org.lttng.ust.agent.utils.LttngUstAgentLogger; |
| 28 | |
| 29 | /** |
| 30 | * This class is used to serialize the list of "context info" objects to pass |
| 31 | * through JNI. |
| 32 | * |
| 33 | * The protocol expects a single byte array parameter. This byte array consists |
| 34 | * of a series of fixed-size entries, where each entry contains the following |
| 35 | * elements (with their size in bytes in parenthesis): |
| 36 | * |
| 37 | * <ul> |
| 38 | * <li>The full context name, like "$app.myprovider:mycontext" (256)</li> |
| 39 | * <li>The context value type (1)</li> |
| 40 | * <li>The context value itself(256)</li> |
| 41 | * </ul> |
| 42 | * |
| 43 | * So the total size of each entry is 513 bytes. All unused bytes will be |
| 44 | * zero'ed. |
| 45 | * |
| 46 | * @author Alexandre Montplaisir |
| 47 | */ |
| 48 | public class ContextInfoSerializer { |
| 49 | |
| 50 | private enum DataType { |
| 51 | NULL(0), |
| 52 | INTEGER(1), |
| 53 | LONG(2), |
| 54 | DOUBLE(3), |
| 55 | FLOAT(4), |
| 56 | BYTE(5), |
| 57 | SHORT(6), |
| 58 | BOOLEAN(7), |
| 59 | STRING(8); |
| 60 | |
| 61 | private final byte value; |
| 62 | |
| 63 | private DataType(int value) { |
| 64 | this.value = (byte) value; |
| 65 | } |
| 66 | |
| 67 | public byte getValue() { |
| 68 | return value; |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | private static final String UST_APP_CTX_PREFIX = "$app."; |
| 73 | private static final int ELEMENT_LENGTH = 256; |
| 74 | private static final int ENTRY_LENGTH = 513; |
| 75 | private static final ByteOrder NATIVE_ORDER = ByteOrder.nativeOrder(); |
| 76 | private static final Charset UTF8_CHARSET = Charset.forName("UTF-8"); |
| 77 | private static final byte[] EMPTY_ARRAY = new byte[0]; |
| 78 | |
| 79 | /** |
| 80 | * From the list of requested contexts in the tracing session, look them up |
| 81 | * in the {@link ContextInfoManager}, retrieve the available ones, and |
| 82 | * serialize them into a byte array. |
| 83 | * |
| 84 | * @param enabledContexts |
| 85 | * The contexts that are enabled in the tracing session (indexed |
| 86 | * first by retriever name, then by index names). Should come |
| 87 | * from the LTTng Agent. |
| 88 | * @return The byte array representing the intersection of the requested and |
| 89 | * available contexts. |
| 90 | */ |
| 91 | public static byte[] queryAndSerializeRequestedContexts(Collection<Map.Entry<String, Map<String, Integer>>> enabledContexts) { |
| 92 | if (enabledContexts.isEmpty()) { |
| 93 | /* Early return if there is no requested context information */ |
| 94 | return EMPTY_ARRAY; |
| 95 | } |
| 96 | |
| 97 | /* Compute the total number of contexts (flatten the map) */ |
| 98 | int totalArraySize = 0; |
| 99 | for (Map.Entry<String, Map<String, Integer>> contexts : enabledContexts) { |
| 100 | totalArraySize += contexts.getValue().size() * ENTRY_LENGTH; |
| 101 | } |
| 102 | |
| 103 | ContextInfoManager contextManager; |
| 104 | try { |
| 105 | contextManager = ContextInfoManager.getInstance(); |
| 106 | } catch (IOException e) { |
| 107 | /* |
| 108 | * The JNI library is not available, do not send any context |
| 109 | * information. No retriever could have been defined anyways. |
| 110 | */ |
| 111 | return EMPTY_ARRAY; |
| 112 | } |
| 113 | |
| 114 | ByteBuffer buffer = ByteBuffer.allocate(totalArraySize); |
| 115 | buffer.order(NATIVE_ORDER); |
| 116 | buffer.clear(); |
| 117 | |
| 118 | for (Map.Entry<String, Map<String, Integer>> entry : enabledContexts) { |
| 119 | String requestedRetrieverName = entry.getKey(); |
| 120 | Map<String, Integer> requestedContexts = entry.getValue(); |
| 121 | |
| 122 | IContextInfoRetriever retriever = contextManager.getContextInfoRetriever(requestedRetrieverName); |
| 123 | |
| 124 | for (String requestedContext : requestedContexts.keySet()) { |
| 125 | Object contextInfo; |
| 126 | if (retriever == null) { |
| 127 | contextInfo = null; |
| 128 | } else { |
| 129 | contextInfo = retriever.retrieveContextInfo(requestedContext); |
| 130 | /* |
| 131 | * 'contextInfo' can still be null here, which would |
| 132 | * indicate the retriever does not supply this context. We |
| 133 | * will still write this information so that the tracer can |
| 134 | * know about it. |
| 135 | */ |
| 136 | } |
| 137 | |
| 138 | /* Serialize the result to the buffer */ |
| 139 | // FIXME Eventually pass the retriever name only once? |
| 140 | String fullContextName = (UST_APP_CTX_PREFIX + requestedRetrieverName + ':' + requestedContext); |
| 141 | byte[] strArray = fullContextName.getBytes(UTF8_CHARSET); |
| 142 | int remainingBytes = ELEMENT_LENGTH - strArray.length; |
| 143 | // FIXME Handle case where name is too long... |
| 144 | buffer.put(strArray); |
| 145 | buffer.position(buffer.position() + remainingBytes); |
| 146 | |
| 147 | LttngUstAgentLogger.log(ContextInfoSerializer.class, |
| 148 | "ContextInfoSerializer: Context to be sent through JNI: " + fullContextName + '=' + |
| 149 | (contextInfo == null ? "null" : contextInfo.toString())); |
| 150 | |
| 151 | serializeContextInfo(buffer, contextInfo); |
| 152 | } |
| 153 | } |
| 154 | return buffer.array(); |
| 155 | } |
| 156 | |
| 157 | private static void serializeContextInfo(ByteBuffer buffer, Object contextInfo) { |
| 158 | int remainingBytes; |
| 159 | if (contextInfo == null) { |
| 160 | buffer.put(DataType.NULL.getValue()); |
| 161 | remainingBytes = ELEMENT_LENGTH; |
| 162 | |
| 163 | } else if (contextInfo instanceof Integer) { |
| 164 | buffer.put(DataType.INTEGER.getValue()); |
| 165 | buffer.putInt(((Integer) contextInfo).intValue()); |
| 166 | remainingBytes = ELEMENT_LENGTH - 4; |
| 167 | |
| 168 | } else if (contextInfo instanceof Long) { |
| 169 | buffer.put(DataType.LONG.getValue()); |
| 170 | buffer.putLong(((Long) contextInfo).longValue()); |
| 171 | remainingBytes = ELEMENT_LENGTH - 8; |
| 172 | |
| 173 | } else if (contextInfo instanceof Double) { |
| 174 | buffer.put(DataType.DOUBLE.getValue()); |
| 175 | buffer.putDouble(((Double) contextInfo).doubleValue()); |
| 176 | remainingBytes = ELEMENT_LENGTH - 8; |
| 177 | |
| 178 | } else if (contextInfo instanceof Float) { |
| 179 | buffer.put(DataType.FLOAT.getValue()); |
| 180 | buffer.putFloat(((Float) contextInfo).floatValue()); |
| 181 | remainingBytes = ELEMENT_LENGTH - 4; |
| 182 | |
| 183 | } else if (contextInfo instanceof Byte) { |
| 184 | buffer.put(DataType.BYTE.getValue()); |
| 185 | buffer.put(((Byte) contextInfo).byteValue()); |
| 186 | remainingBytes = ELEMENT_LENGTH - 1; |
| 187 | |
| 188 | } else if (contextInfo instanceof Short) { |
| 189 | buffer.put(DataType.SHORT.getValue()); |
| 190 | buffer.putShort(((Short) contextInfo).shortValue()); |
| 191 | remainingBytes = ELEMENT_LENGTH - 2; |
| 192 | |
| 193 | } else if (contextInfo instanceof Boolean) { |
| 194 | buffer.put(DataType.BOOLEAN.getValue()); |
| 195 | boolean b = ((Boolean) contextInfo).booleanValue(); |
| 196 | /* Converted to one byte, write 1 for true, 0 for false */ |
| 197 | buffer.put((byte) (b ? 1 : 0)); |
| 198 | remainingBytes = ELEMENT_LENGTH - 1; |
| 199 | |
| 200 | } else { |
| 201 | /* We'll write the object as a string. Also includes the case of Character. */ |
| 202 | String str = contextInfo.toString(); |
| 203 | byte[] strArray = str.getBytes(UTF8_CHARSET); |
| 204 | |
| 205 | buffer.put(DataType.STRING.getValue()); |
| 206 | if (strArray.length >= ELEMENT_LENGTH) { |
| 207 | /* Trim the string to the max allowed length */ |
| 208 | buffer.put(strArray, 0, ELEMENT_LENGTH); |
| 209 | remainingBytes = 0; |
| 210 | } else { |
| 211 | buffer.put(strArray); |
| 212 | remainingBytes = ELEMENT_LENGTH - strArray.length; |
| 213 | } |
| 214 | } |
| 215 | buffer.position(buffer.position() + remainingBytes); |
| 216 | } |
| 217 | } |