1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.os; 18 19 import dalvik.annotation.optimization.FastNative; 20 21 /** 22 * Writes trace events to the system trace buffer. These trace events can be 23 * collected and visualized using the Systrace tool. 24 * 25 * <p>This tracing mechanism is independent of the method tracing mechanism 26 * offered by {@link Debug#startMethodTracing}. In particular, it enables 27 * tracing of events that occur across multiple processes. 28 * <p>For information about using the Systrace tool, read <a 29 * href="{@docRoot}tools/debugging/systrace.html">Analyzing Display and Performance 30 * with Systrace</a>. 31 */ 32 public final class Trace { 33 /* 34 * Writes trace events to the kernel trace buffer. These trace events can be 35 * collected using the "atrace" program for offline analysis. 36 */ 37 38 private static final String TAG = "Trace"; 39 40 // These tags must be kept in sync with system/core/include/cutils/trace.h. 41 // They should also be added to frameworks/native/cmds/atrace/atrace.cpp. 42 /** @hide */ 43 public static final long TRACE_TAG_NEVER = 0; 44 /** @hide */ 45 public static final long TRACE_TAG_ALWAYS = 1L << 0; 46 /** @hide */ 47 public static final long TRACE_TAG_GRAPHICS = 1L << 1; 48 /** @hide */ 49 public static final long TRACE_TAG_INPUT = 1L << 2; 50 /** @hide */ 51 public static final long TRACE_TAG_VIEW = 1L << 3; 52 /** @hide */ 53 public static final long TRACE_TAG_WEBVIEW = 1L << 4; 54 /** @hide */ 55 public static final long TRACE_TAG_WINDOW_MANAGER = 1L << 5; 56 /** @hide */ 57 public static final long TRACE_TAG_ACTIVITY_MANAGER = 1L << 6; 58 /** @hide */ 59 public static final long TRACE_TAG_SYNC_MANAGER = 1L << 7; 60 /** @hide */ 61 public static final long TRACE_TAG_AUDIO = 1L << 8; 62 /** @hide */ 63 public static final long TRACE_TAG_VIDEO = 1L << 9; 64 /** @hide */ 65 public static final long TRACE_TAG_CAMERA = 1L << 10; 66 /** @hide */ 67 public static final long TRACE_TAG_HAL = 1L << 11; 68 /** @hide */ 69 public static final long TRACE_TAG_APP = 1L << 12; 70 /** @hide */ 71 public static final long TRACE_TAG_RESOURCES = 1L << 13; 72 /** @hide */ 73 public static final long TRACE_TAG_DALVIK = 1L << 14; 74 /** @hide */ 75 public static final long TRACE_TAG_RS = 1L << 15; 76 /** @hide */ 77 public static final long TRACE_TAG_BIONIC = 1L << 16; 78 /** @hide */ 79 public static final long TRACE_TAG_POWER = 1L << 17; 80 /** @hide */ 81 public static final long TRACE_TAG_PACKAGE_MANAGER = 1L << 18; 82 /** @hide */ 83 public static final long TRACE_TAG_SYSTEM_SERVER = 1L << 19; 84 /** @hide */ 85 public static final long TRACE_TAG_DATABASE = 1L << 20; 86 /** @hide */ 87 public static final long TRACE_TAG_NETWORK = 1L << 21; 88 /** @hide */ 89 public static final long TRACE_TAG_ADB = 1L << 22; 90 91 private static final long TRACE_TAG_NOT_READY = 1L << 63; 92 private static final int MAX_SECTION_NAME_LEN = 127; 93 94 // Must be volatile to avoid word tearing. 95 private static volatile long sEnabledTags = TRACE_TAG_NOT_READY; 96 97 private static native long nativeGetEnabledTags(); 98 private static native void nativeSetAppTracingAllowed(boolean allowed); 99 private static native void nativeSetTracingEnabled(boolean allowed); 100 101 @FastNative 102 private static native void nativeTraceCounter(long tag, String name, int value); 103 @FastNative 104 private static native void nativeTraceBegin(long tag, String name); 105 @FastNative 106 private static native void nativeTraceEnd(long tag); 107 @FastNative 108 private static native void nativeAsyncTraceBegin(long tag, String name, int cookie); 109 @FastNative 110 private static native void nativeAsyncTraceEnd(long tag, String name, int cookie); 111 112 static { 113 // We configure two separate change callbacks, one in Trace.cpp and one here. The 114 // native callback reads the tags from the system property, and this callback 115 // reads the value that the native code retrieved. It's essential that the native 116 // callback executes first. 117 // 118 // The system provides ordering through a priority level. Callbacks made through 119 // SystemProperties.addChangeCallback currently have a negative priority, while 120 // our native code is using a priority of zero. 121 SystemProperties.addChangeCallback(new Runnable() { 122 @Override public void run() { 123 cacheEnabledTags(); 124 } 125 }); 126 } 127 128 private Trace() { 129 } 130 131 /** 132 * Caches a copy of the enabled-tag bits. The "master" copy is held by the native code, 133 * and comes from the PROPERTY_TRACE_TAG_ENABLEFLAGS property. 134 * <p> 135 * If the native code hasn't yet read the property, we will cause it to do one-time 136 * initialization. We don't want to do this during class init, because this class is 137 * preloaded, so all apps would be stuck with whatever the zygote saw. (The zygote 138 * doesn't see the system-property update broadcasts.) 139 * <p> 140 * We want to defer initialization until the first use by an app, post-zygote. 141 * <p> 142 * We're okay if multiple threads call here simultaneously -- the native state is 143 * synchronized, and sEnabledTags is volatile (prevents word tearing). 144 */ 145 private static long cacheEnabledTags() { 146 long tags = nativeGetEnabledTags(); 147 sEnabledTags = tags; 148 return tags; 149 } 150 151 /** 152 * Returns true if a trace tag is enabled. 153 * 154 * @param traceTag The trace tag to check. 155 * @return True if the trace tag is valid. 156 * 157 * @hide 158 */ 159 public static boolean isTagEnabled(long traceTag) { 160 long tags = sEnabledTags; 161 if (tags == TRACE_TAG_NOT_READY) { 162 tags = cacheEnabledTags(); 163 } 164 return (tags & traceTag) != 0; 165 } 166 167 /** 168 * Writes trace message to indicate the value of a given counter. 169 * 170 * @param traceTag The trace tag. 171 * @param counterName The counter name to appear in the trace. 172 * @param counterValue The counter value. 173 * 174 * @hide 175 */ 176 public static void traceCounter(long traceTag, String counterName, int counterValue) { 177 if (isTagEnabled(traceTag)) { 178 nativeTraceCounter(traceTag, counterName, counterValue); 179 } 180 } 181 182 /** 183 * Set whether application tracing is allowed for this process. This is intended to be set 184 * once at application start-up time based on whether the application is debuggable. 185 * 186 * @hide 187 */ 188 public static void setAppTracingAllowed(boolean allowed) { 189 nativeSetAppTracingAllowed(allowed); 190 191 // Setting whether app tracing is allowed may change the tags, so we update the cached 192 // tags here. 193 cacheEnabledTags(); 194 } 195 196 /** 197 * Set whether tracing is enabled in this process. Tracing is disabled shortly after Zygote 198 * initializes and re-enabled after processes fork from Zygote. This is done because Zygote 199 * has no way to be notified about changes to the tracing tags, and if Zygote ever reads and 200 * caches the tracing tags, forked processes will inherit those stale tags. 201 * 202 * @hide 203 */ 204 public static void setTracingEnabled(boolean enabled) { 205 nativeSetTracingEnabled(enabled); 206 207 // Setting whether tracing is enabled may change the tags, so we update the cached tags 208 // here. 209 cacheEnabledTags(); 210 } 211 212 /** 213 * Writes a trace message to indicate that a given section of code has 214 * begun. Must be followed by a call to {@link #traceEnd} using the same 215 * tag. 216 * 217 * @param traceTag The trace tag. 218 * @param methodName The method name to appear in the trace. 219 * 220 * @hide 221 */ 222 public static void traceBegin(long traceTag, String methodName) { 223 if (isTagEnabled(traceTag)) { 224 nativeTraceBegin(traceTag, methodName); 225 } 226 } 227 228 /** 229 * Writes a trace message to indicate that the current method has ended. 230 * Must be called exactly once for each call to {@link #traceBegin} using the same tag. 231 * 232 * @param traceTag The trace tag. 233 * 234 * @hide 235 */ 236 public static void traceEnd(long traceTag) { 237 if (isTagEnabled(traceTag)) { 238 nativeTraceEnd(traceTag); 239 } 240 } 241 242 /** 243 * Writes a trace message to indicate that a given section of code has 244 * begun. Must be followed by a call to {@link #asyncTraceEnd} using the same 245 * tag. Unlike {@link #traceBegin(long, String)} and {@link #traceEnd(long)}, 246 * asynchronous events do not need to be nested. The name and cookie used to 247 * begin an event must be used to end it. 248 * 249 * @param traceTag The trace tag. 250 * @param methodName The method name to appear in the trace. 251 * @param cookie Unique identifier for distinguishing simultaneous events 252 * 253 * @hide 254 */ 255 public static void asyncTraceBegin(long traceTag, String methodName, int cookie) { 256 if (isTagEnabled(traceTag)) { 257 nativeAsyncTraceBegin(traceTag, methodName, cookie); 258 } 259 } 260 261 /** 262 * Writes a trace message to indicate that the current method has ended. 263 * Must be called exactly once for each call to {@link #asyncTraceBegin(long, String, int)} 264 * using the same tag, name and cookie. 265 * 266 * @param traceTag The trace tag. 267 * @param methodName The method name to appear in the trace. 268 * @param cookie Unique identifier for distinguishing simultaneous events 269 * 270 * @hide 271 */ 272 public static void asyncTraceEnd(long traceTag, String methodName, int cookie) { 273 if (isTagEnabled(traceTag)) { 274 nativeAsyncTraceEnd(traceTag, methodName, cookie); 275 } 276 } 277 278 /** 279 * Writes a trace message to indicate that a given section of code has begun. This call must 280 * be followed by a corresponding call to {@link #endSection()} on the same thread. 281 * 282 * <p class="note"> At this time the vertical bar character '|', newline character '\n', and 283 * null character '\0' are used internally by the tracing mechanism. If sectionName contains 284 * these characters they will be replaced with a space character in the trace. 285 * 286 * @param sectionName The name of the code section to appear in the trace. This may be at 287 * most 127 Unicode code units long. 288 */ 289 public static void beginSection(String sectionName) { 290 if (isTagEnabled(TRACE_TAG_APP)) { 291 if (sectionName.length() > MAX_SECTION_NAME_LEN) { 292 throw new IllegalArgumentException("sectionName is too long"); 293 } 294 nativeTraceBegin(TRACE_TAG_APP, sectionName); 295 } 296 } 297 298 /** 299 * Writes a trace message to indicate that a given section of code has ended. This call must 300 * be preceeded by a corresponding call to {@link #beginSection(String)}. Calling this method 301 * will mark the end of the most recently begun section of code, so care must be taken to 302 * ensure that beginSection / endSection pairs are properly nested and called from the same 303 * thread. 304 */ 305 public static void endSection() { 306 if (isTagEnabled(TRACE_TAG_APP)) { 307 nativeTraceEnd(TRACE_TAG_APP); 308 } 309 } 310 } 311
