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8ab5c06b AM |
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 | ||
b1ca4c5f AM |
20 | import java.io.ByteArrayOutputStream; |
21 | import java.io.DataOutputStream; | |
8ab5c06b AM |
22 | import java.io.IOException; |
23 | import java.nio.ByteBuffer; | |
24 | import java.nio.ByteOrder; | |
25 | import java.nio.charset.Charset; | |
26 | import java.util.Collection; | |
27 | import java.util.Map; | |
28 | ||
cbe2ebd6 AM |
29 | import org.lttng.ust.agent.utils.LttngUstAgentLogger; |
30 | ||
8ab5c06b AM |
31 | /** |
32 | * This class is used to serialize the list of "context info" objects to pass | |
33 | * through JNI. | |
34 | * | |
b1ca4c5f AM |
35 | * The protocol expects two byte array parameters, which are contained here in |
36 | * the {@link SerializedContexts} inner class. | |
37 | * | |
38 | * The first byte array is called the "entries array", and contains fixed-size | |
39 | * entries, one per context element. | |
40 | * | |
41 | * The second one is the "strings array", it is of variable length and used to | |
42 | * hold the variable-length strings. Each one of these strings is formatted as a | |
43 | * UTF-8 C-string, meaning in will end with a "\0" byte to indicate its end. | |
44 | * Entries in the first array may refer to offsets in the second array to point | |
45 | * to relevant strings. | |
46 | * | |
47 | * The fixed-size entries in the entries array contain the following elements | |
48 | * (size in bytes in parentheses): | |
8ab5c06b AM |
49 | * |
50 | * <ul> | |
b1ca4c5f AM |
51 | * <li>The offset in the strings array pointing to the full context name, like |
52 | * "$app.myprovider:mycontext" (4)</li> | |
8ab5c06b | 53 | * <li>The context value type (1)</li> |
b1ca4c5f | 54 | * <li>The context value itself (8)</li> |
8ab5c06b AM |
55 | * </ul> |
56 | * | |
b1ca4c5f AM |
57 | * The context value type will indicate how many bytes are used for the value. |
58 | * If the it is of String type, then we use 4 bytes to represent the offset in | |
59 | * the strings array. | |
60 | * | |
61 | * So the total size of each entry is 13 bytes. All unused bytes (for context | |
62 | * values shorter than 8 bytes for example) will be zero'ed. | |
8ab5c06b AM |
63 | * |
64 | * @author Alexandre Montplaisir | |
65 | */ | |
66 | public class ContextInfoSerializer { | |
67 | ||
68 | private enum DataType { | |
69 | NULL(0), | |
70 | INTEGER(1), | |
71 | LONG(2), | |
72 | DOUBLE(3), | |
73 | FLOAT(4), | |
74 | BYTE(5), | |
75 | SHORT(6), | |
76 | BOOLEAN(7), | |
77 | STRING(8); | |
78 | ||
79 | private final byte value; | |
80 | ||
81 | private DataType(int value) { | |
82 | this.value = (byte) value; | |
83 | } | |
84 | ||
85 | public byte getValue() { | |
86 | return value; | |
87 | } | |
88 | } | |
89 | ||
b1ca4c5f AM |
90 | /** |
91 | * Class used to wrap the two byte arrays returned by | |
92 | * {@link #queryAndSerializeRequestedContexts}. | |
93 | */ | |
94 | public static class SerializedContexts { | |
95 | ||
96 | private final byte[] contextEntries; | |
97 | private final byte[] contextStrings; | |
98 | ||
99 | /** | |
100 | * Constructor | |
101 | * | |
102 | * @param entries | |
103 | * Arrays for the fixed-size context entries. | |
104 | * @param strings | |
105 | * Arrays for variable-length strings | |
106 | */ | |
107 | public SerializedContexts(byte[] entries, byte[] strings) { | |
108 | contextEntries = entries; | |
109 | contextStrings = strings; | |
110 | } | |
111 | ||
112 | /** | |
113 | * @return The entries array | |
114 | */ | |
115 | public byte[] getEntriesArray() { | |
116 | return contextEntries; | |
117 | } | |
118 | ||
119 | /** | |
120 | * @return The strings array | |
121 | */ | |
122 | public byte[] getStringsArray() { | |
123 | return contextStrings; | |
124 | } | |
125 | } | |
126 | ||
8ab5c06b | 127 | private static final String UST_APP_CTX_PREFIX = "$app."; |
b1ca4c5f | 128 | private static final int ENTRY_LENGTH = 13; |
8ab5c06b AM |
129 | private static final ByteOrder NATIVE_ORDER = ByteOrder.nativeOrder(); |
130 | private static final Charset UTF8_CHARSET = Charset.forName("UTF-8"); | |
b1ca4c5f | 131 | private static final SerializedContexts EMPTY_CONTEXTS = new SerializedContexts(new byte[0], new byte[0]); |
8ab5c06b AM |
132 | |
133 | /** | |
134 | * From the list of requested contexts in the tracing session, look them up | |
135 | * in the {@link ContextInfoManager}, retrieve the available ones, and | |
136 | * serialize them into a byte array. | |
137 | * | |
138 | * @param enabledContexts | |
139 | * The contexts that are enabled in the tracing session (indexed | |
140 | * first by retriever name, then by index names). Should come | |
141 | * from the LTTng Agent. | |
142 | * @return The byte array representing the intersection of the requested and | |
143 | * available contexts. | |
144 | */ | |
b1ca4c5f | 145 | public static SerializedContexts queryAndSerializeRequestedContexts(Collection<Map.Entry<String, Map<String, Integer>>> enabledContexts) { |
8ab5c06b AM |
146 | if (enabledContexts.isEmpty()) { |
147 | /* Early return if there is no requested context information */ | |
b1ca4c5f | 148 | return EMPTY_CONTEXTS; |
8ab5c06b AM |
149 | } |
150 | ||
151 | ContextInfoManager contextManager; | |
152 | try { | |
153 | contextManager = ContextInfoManager.getInstance(); | |
154 | } catch (IOException e) { | |
155 | /* | |
156 | * The JNI library is not available, do not send any context | |
157 | * information. No retriever could have been defined anyways. | |
158 | */ | |
b1ca4c5f | 159 | return EMPTY_CONTEXTS; |
8ab5c06b AM |
160 | } |
161 | ||
b1ca4c5f AM |
162 | /* Compute the total number of contexts (flatten the map) */ |
163 | int totalArraySize = 0; | |
164 | for (Map.Entry<String, Map<String, Integer>> contexts : enabledContexts) { | |
165 | totalArraySize += contexts.getValue().size() * ENTRY_LENGTH; | |
166 | } | |
167 | ||
168 | /* Prepare the ByteBuffer that will generate the "entries" array */ | |
169 | ByteBuffer entriesBuffer = ByteBuffer.allocate(totalArraySize); | |
170 | entriesBuffer.order(NATIVE_ORDER); | |
171 | entriesBuffer.clear(); | |
172 | ||
173 | /* Prepare the streams that will generate the "strings" array */ | |
174 | ByteArrayOutputStream stringsBaos = new ByteArrayOutputStream(); | |
175 | DataOutputStream stringsDos = new DataOutputStream(stringsBaos); | |
176 | ||
177 | try { | |
178 | for (Map.Entry<String, Map<String, Integer>> entry : enabledContexts) { | |
179 | String requestedRetrieverName = entry.getKey(); | |
180 | Map<String, Integer> requestedContexts = entry.getValue(); | |
181 | ||
182 | IContextInfoRetriever retriever = contextManager.getContextInfoRetriever(requestedRetrieverName); | |
183 | ||
184 | for (String requestedContext : requestedContexts.keySet()) { | |
185 | Object contextInfo; | |
186 | if (retriever == null) { | |
187 | contextInfo = null; | |
188 | } else { | |
189 | contextInfo = retriever.retrieveContextInfo(requestedContext); | |
190 | /* | |
191 | * 'contextInfo' can still be null here, which would | |
192 | * indicate the retriever does not supply this context. | |
193 | * We will still write this information so that the | |
194 | * tracer can know about it. | |
195 | */ | |
196 | } | |
8ab5c06b | 197 | |
b1ca4c5f AM |
198 | /* Serialize the result to the buffers */ |
199 | // FIXME Eventually pass the retriever name only once? | |
200 | String fullContextName = (UST_APP_CTX_PREFIX + requestedRetrieverName + ':' + requestedContext); | |
201 | byte[] strArray = fullContextName.getBytes(UTF8_CHARSET); | |
8ab5c06b | 202 | |
b1ca4c5f AM |
203 | entriesBuffer.putInt(stringsDos.size()); |
204 | stringsDos.write(strArray); | |
205 | stringsDos.writeChar('\0'); | |
cbe2ebd6 | 206 | |
b1ca4c5f AM |
207 | LttngUstAgentLogger.log(ContextInfoSerializer.class, |
208 | "ContextInfoSerializer: Context to be sent through JNI: " + fullContextName + '=' + | |
209 | (contextInfo == null ? "null" : contextInfo.toString())); | |
210 | ||
211 | serializeContextInfo(entriesBuffer, stringsDos, contextInfo); | |
212 | } | |
8ab5c06b | 213 | } |
b1ca4c5f AM |
214 | |
215 | stringsDos.flush(); | |
216 | stringsBaos.flush(); | |
217 | ||
218 | } catch (IOException e) { | |
219 | /* | |
220 | * Should not happen because we are wrapping a | |
221 | * ByteArrayOutputStream, which writes to memory | |
222 | */ | |
223 | e.printStackTrace(); | |
8ab5c06b | 224 | } |
b1ca4c5f AM |
225 | |
226 | byte[] entriesArray = entriesBuffer.array(); | |
227 | byte[] stringsArray = stringsBaos.toByteArray(); | |
228 | return new SerializedContexts(entriesArray, stringsArray); | |
8ab5c06b AM |
229 | } |
230 | ||
b1ca4c5f AM |
231 | private static final int CONTEXT_VALUE_LENGTH = 8; |
232 | ||
233 | private static void serializeContextInfo(ByteBuffer entriesBuffer, DataOutputStream stringsDos, Object contextInfo) throws IOException { | |
8ab5c06b AM |
234 | int remainingBytes; |
235 | if (contextInfo == null) { | |
b1ca4c5f AM |
236 | entriesBuffer.put(DataType.NULL.getValue()); |
237 | remainingBytes = CONTEXT_VALUE_LENGTH; | |
8ab5c06b AM |
238 | |
239 | } else if (contextInfo instanceof Integer) { | |
b1ca4c5f AM |
240 | entriesBuffer.put(DataType.INTEGER.getValue()); |
241 | entriesBuffer.putInt(((Integer) contextInfo).intValue()); | |
242 | remainingBytes = CONTEXT_VALUE_LENGTH - 4; | |
8ab5c06b AM |
243 | |
244 | } else if (contextInfo instanceof Long) { | |
b1ca4c5f AM |
245 | entriesBuffer.put(DataType.LONG.getValue()); |
246 | entriesBuffer.putLong(((Long) contextInfo).longValue()); | |
247 | remainingBytes = CONTEXT_VALUE_LENGTH - 8; | |
8ab5c06b AM |
248 | |
249 | } else if (contextInfo instanceof Double) { | |
b1ca4c5f AM |
250 | entriesBuffer.put(DataType.DOUBLE.getValue()); |
251 | entriesBuffer.putDouble(((Double) contextInfo).doubleValue()); | |
252 | remainingBytes = CONTEXT_VALUE_LENGTH - 8; | |
8ab5c06b AM |
253 | |
254 | } else if (contextInfo instanceof Float) { | |
b1ca4c5f AM |
255 | entriesBuffer.put(DataType.FLOAT.getValue()); |
256 | entriesBuffer.putFloat(((Float) contextInfo).floatValue()); | |
257 | remainingBytes = CONTEXT_VALUE_LENGTH - 4; | |
8ab5c06b AM |
258 | |
259 | } else if (contextInfo instanceof Byte) { | |
b1ca4c5f AM |
260 | entriesBuffer.put(DataType.BYTE.getValue()); |
261 | entriesBuffer.put(((Byte) contextInfo).byteValue()); | |
262 | remainingBytes = CONTEXT_VALUE_LENGTH - 1; | |
8ab5c06b AM |
263 | |
264 | } else if (contextInfo instanceof Short) { | |
b1ca4c5f AM |
265 | entriesBuffer.put(DataType.SHORT.getValue()); |
266 | entriesBuffer.putShort(((Short) contextInfo).shortValue()); | |
267 | remainingBytes = CONTEXT_VALUE_LENGTH - 2; | |
8ab5c06b AM |
268 | |
269 | } else if (contextInfo instanceof Boolean) { | |
b1ca4c5f | 270 | entriesBuffer.put(DataType.BOOLEAN.getValue()); |
8ab5c06b AM |
271 | boolean b = ((Boolean) contextInfo).booleanValue(); |
272 | /* Converted to one byte, write 1 for true, 0 for false */ | |
b1ca4c5f AM |
273 | entriesBuffer.put((byte) (b ? 1 : 0)); |
274 | remainingBytes = CONTEXT_VALUE_LENGTH - 1; | |
8ab5c06b AM |
275 | |
276 | } else { | |
b1ca4c5f AM |
277 | /* Also includes the case of Character. */ |
278 | /* | |
279 | * We'll write the object as a string, into the strings array. We | |
280 | * will write the corresponding offset to the entries array. | |
281 | */ | |
8ab5c06b AM |
282 | String str = contextInfo.toString(); |
283 | byte[] strArray = str.getBytes(UTF8_CHARSET); | |
284 | ||
b1ca4c5f AM |
285 | entriesBuffer.put(DataType.STRING.getValue()); |
286 | ||
287 | entriesBuffer.putInt(stringsDos.size()); | |
288 | stringsDos.write(strArray); | |
289 | stringsDos.writeChar('\0'); | |
290 | ||
291 | remainingBytes = CONTEXT_VALUE_LENGTH - 4; | |
8ab5c06b | 292 | } |
b1ca4c5f | 293 | entriesBuffer.position(entriesBuffer.position() + remainingBytes); |
8ab5c06b AM |
294 | } |
295 | } |