src/com/android/traceur/PerfettoUtils.java - platform/packages/apps/Traceur - Git at Google

 /*
  * Copyright (C) 2015 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 com.android.traceur;

 import android.system.Os;
 import android.util.Log;

 import java.io.File;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.Collection;
 import java.util.List;
 import java.util.TreeMap;
 import java.util.concurrent.TimeUnit;

 import perfetto.protos.DataSourceDescriptorOuterClass.DataSourceDescriptor;
 import perfetto.protos.FtraceDescriptorOuterClass.FtraceDescriptor.AtraceCategory;
 import perfetto.protos.TracingServiceStateOuterClass.TracingServiceState;
 import perfetto.protos.TracingServiceStateOuterClass.TracingServiceState.DataSource;

 /**
  * Utility functions for calling Perfetto
  */
 public class PerfettoUtils implements TraceUtils.TraceEngine {

     static final String TAG = "Traceur";
     public static final String NAME = "PERFETTO";

     private static final String OUTPUT_EXTENSION = "perfetto-trace";
     private static final String TEMP_DIR= "/data/local/traces/";
     private static final String TEMP_TRACE_LOCATION = "/data/local/traces/.trace-in-progress.trace";

     private static final String PERFETTO_TAG = "traceur";
     private static final String MARKER = "PERFETTO_ARGUMENTS";
     private static final int LIST_TIMEOUT_MS = 10000;
     private static final int STARTUP_TIMEOUT_MS = 10000;
     private static final int STOP_TIMEOUT_MS = 30000;
     private static final long MEGABYTES_TO_BYTES = 1024L * 1024L;
     private static final long MINUTES_TO_MILLISECONDS = 60L * 1000L;

     // The total amount of memory allocated to the two target buffers will be divided according to a
     // ratio of (BUFFER_SIZE_RATIO - 1) to 1.
     private static final int BUFFER_SIZE_RATIO = 64;

     // atrace trace categories that will result in added data sources in the Perfetto config.
     private static final String CAMERA_TAG = "camera";
     private static final String GFX_TAG = "gfx";
     private static final String MEMORY_TAG = "memory";
     private static final String POWER_TAG = "power";
     private static final String SCHED_TAG = "sched";
     private static final String WEBVIEW_TAG = "webview";

     // Custom trace categories.
     private static final String SYS_STATS_TAG = "sys_stats";

     public String getName() {
         return NAME;
     }

     public String getOutputExtension() {
         return OUTPUT_EXTENSION;
     }

     public boolean traceStart(Collection<String> tags, int bufferSizeKb, boolean apps,
             boolean attachToBugreport, boolean longTrace, int maxLongTraceSizeMb,
             int maxLongTraceDurationMinutes) {
         if (isTracingOn()) {
             Log.e(TAG, "Attempting to start perfetto trace but trace is already in progress");
             return false;
         } else {
             // If a temporary trace file already exists, save it before beginning a new trace.
             File recoveredFile = TraceUtils.getOutputFile(
                     TraceUtils.getRecoveredFilename());
             if (!traceDump(recoveredFile)) {
                 Log.w(TAG, "Failed to recover in-progress trace.");
             }
         }

         // The user chooses a per-CPU buffer size due to atrace limitations.
         // So we use this to ensure that we reserve the correctly-sized buffer.
         int numCpus = Runtime.getRuntime().availableProcessors();

         // Allots 1 / BUFFER_SIZE_RATIO to the small buffer and the remainder to the large buffer.
         int totalBufferSizeKb = numCpus * bufferSizeKb;
         int targetBuffer1Kb = totalBufferSizeKb / BUFFER_SIZE_RATIO;
         int targetBuffer0Kb = totalBufferSizeKb - targetBuffer1Kb;

         // Build the perfetto config that will be passed on the command line.
         StringBuilder config = new StringBuilder()
             .append("write_into_file: true\n")
             // Ensure that we flush ftrace data every 30s even if cpus are idle.
             .append("flush_period_ms: 30000\n");

             // If the user has flagged that in-progress trace sessions should be grabbed
             // during bugreports, and BetterBug is present.
             if (attachToBugreport) {
                 config.append("bugreport_score: 500\n");
             }

             // Indicates that perfetto should notify Traceur if the tracing session's status
             // changes.
             config.append("notify_traceur: true\n");

             if (longTrace) {
                 if (maxLongTraceSizeMb != 0) {
                     config.append("max_file_size_bytes: "
                         + (maxLongTraceSizeMb * MEGABYTES_TO_BYTES) + "\n");
                 }

                 if (maxLongTraceDurationMinutes != 0) {
                     config.append("duration_ms: "
                         + (maxLongTraceDurationMinutes * MINUTES_TO_MILLISECONDS)
                         + "\n");
                 }

                 // Default value for long traces to write to file.
                 config.append("file_write_period_ms: 1000\n");
             } else {
                 // For short traces, we don't write to the file.
                 // So, always use the maximum value here: 7 days.
                 config.append("file_write_period_ms: 604800000\n");
             }

         config.append("incremental_state_config {\n")
             .append("  clear_period_ms: 15000\n")
             .append("} \n")
             // This is target_buffer: 0, which is used for ftrace and the ftrace-derived
             // android.gpu.memory.
             .append("buffers {\n")
             .append("  size_kb: " + targetBuffer0Kb + "\n")
             .append("  fill_policy: RING_BUFFER\n")
             .append("} \n")
             // This is target_buffer: 1, which is used for additional data sources.
             .append("buffers {\n")
             .append("  size_kb: " + targetBuffer1Kb + "\n")
             .append("  fill_policy: RING_BUFFER\n")
             .append("} \n")
             .append("data_sources {\n")
             .append("  config {\n")
             .append("    name: \"linux.ftrace\"\n")
             .append("    target_buffer: 0\n")
             .append("    ftrace_config {\n")
             .append("      symbolize_ksyms: true\n");

         for (String tag : tags) {
             // Tags are expected to be only letters, numbers, and underscores.
             String cleanTag = tag.replaceAll("[^a-zA-Z0-9_]", "");
             if (!cleanTag.equals(tag)) {
                 Log.w(TAG, "Attempting to use an invalid tag: " + tag);
             }
             config.append("      atrace_categories: \"" + cleanTag + "\"\n");
         }

         if (apps) {
             config.append("      atrace_apps: \"*\"\n");
         }

         // Request a dense encoding of the common sched events (sched_switch, sched_waking).
         if (tags.contains(SCHED_TAG)) {
             config.append("      compact_sched {\n");
             config.append("        enabled: true\n");
             config.append("      }\n");
         }

         // These parameters affect only the kernel trace buffer size and how
         // frequently it gets moved into the userspace buffer defined above.
         config.append("      buffer_size_kb: 8192\n")
             .append("      drain_period_ms: 1000\n")
             .append("    }\n")
             .append("  }\n")
             .append("}\n")
             .append(" \n");

         // Captures initial counter values, updates are captured in ftrace.
         if (tags.contains(MEMORY_TAG) || tags.contains(GFX_TAG)) {
              config.append("data_sources: {\n")
                 .append("  config { \n")
                 .append("    name: \"android.gpu.memory\"\n")
                 .append("    target_buffer: 0\n")
                 .append("  }\n")
                 .append("}\n");
         }

         // For process association. If the memory tag is enabled,
         // poll periodically instead of just once at the beginning.
         config.append("data_sources {\n")
             .append("  config {\n")
             .append("    name: \"linux.process_stats\"\n")
             .append("    target_buffer: 1\n");
         if (tags.contains(MEMORY_TAG)) {
             config.append("    process_stats_config {\n")
                 .append("      proc_stats_poll_ms: 60000\n")
                 .append("    }\n");
         }
         config.append("  }\n")
             .append("} \n");

         if (tags.contains(POWER_TAG)) {
             config.append("data_sources: {\n")
                 .append("  config { \n")
                 .append("    name: \"android.power\"\n")
                 .append("    target_buffer: 1\n")
                 .append("    android_power_config {\n");
             if (longTrace) {
                 config.append("      battery_poll_ms: 5000\n");
             } else {
                 config.append("      battery_poll_ms: 1000\n");
             }
             config.append("      collect_power_rails: true\n")
                 .append("      battery_counters: BATTERY_COUNTER_CAPACITY_PERCENT\n")
                 .append("      battery_counters: BATTERY_COUNTER_CHARGE\n")
                 .append("      battery_counters: BATTERY_COUNTER_CURRENT\n")
                 .append("    }\n")
                 .append("  }\n")
                 .append("}\n");
         }

         if (tags.contains(SYS_STATS_TAG)) {
             config.append("data_sources: {\n")
                 .append("  config { \n")
                 .append("    name: \"linux.sys_stats\"\n")
                 .append("    target_buffer: 1\n")
                 .append("    sys_stats_config {\n")
                 .append("      meminfo_period_ms: 1000\n")
                 .append("      vmstat_period_ms: 1000\n")
                 .append("    }\n")
                 .append("  }\n")
                 .append("}\n");
         }

         if (tags.contains(GFX_TAG)) {
           config.append("data_sources: {\n")
               .append("  config { \n")
               .append("    name: \"android.surfaceflinger.frametimeline\"\n")
               .append("  }\n")
               .append("}\n");
         }

         if (tags.contains(CAMERA_TAG)) {
           config.append("data_sources: {\n")
               .append("  config { \n")
               .append("    name: \"android.hardware.camera\"\n")
               .append("    target_buffer: 1\n")
               .append("  }\n")
               .append("}\n");
         }

         // Also enable Chrome events when the WebView tag is enabled.
         if (tags.contains(WEBVIEW_TAG)) {
             String chromeTraceConfig =  "{" +
                 "\\\"record_mode\\\":\\\"record-continuously\\\"," +
                 "\\\"included_categories\\\":[\\\"*\\\"]" +
                 "}";
             config.append("data_sources: {\n")
                 .append("  config {\n")
                 .append("    name: \"org.chromium.trace_event\"\n")
                 .append("    chrome_config {\n")
                 .append("      trace_config: \"" + chromeTraceConfig + "\"\n")
                 .append("    }\n")
                 .append("  }\n")
                 .append("}\n")
                 .append("data_sources: {\n")
                 .append("  config {\n")
                 .append("    name: \"org.chromium.trace_metadata\"\n")
                 .append("      chrome_config {\n")
                 .append("        trace_config: \"" + chromeTraceConfig + "\"\n")
                 .append("      }\n")
                 .append("  }\n")
                 .append("}\n");
         }

         String configString = config.toString();

         // If the here-doc ends early, within the config string, exit immediately.
         // This should never happen.
         if (configString.contains(MARKER)) {
             throw new RuntimeException("The arguments to the Perfetto command are malformed.");
         }

         String cmd = "perfetto --detach=" + PERFETTO_TAG
             + " -o " + TEMP_TRACE_LOCATION
             + " -c - --txt"
             + " <<" + MARKER +"\n" + configString + "\n" + MARKER;

         Log.v(TAG, "Starting perfetto trace.");
         try {
             Process process = TraceUtils.execWithTimeout(cmd, TEMP_DIR, STARTUP_TIMEOUT_MS);
             if (process == null) {
                 return false;
             } else if (process.exitValue() != 0) {
                 Log.e(TAG, "perfetto traceStart failed with: " + process.exitValue());
                 return false;
             }
         } catch (Exception e) {
             throw new RuntimeException(e);
         }

         Log.v(TAG, "perfetto traceStart succeeded!");
         return true;
     }

     public void traceStop() {
         Log.v(TAG, "Stopping perfetto trace.");

         if (!isTracingOn()) {
             Log.w(TAG, "No trace appears to be in progress. Stopping perfetto trace may not work.");
         }

         String cmd = "perfetto --stop --attach=" + PERFETTO_TAG;
         try {
             Process process = TraceUtils.execWithTimeout(cmd, null, STOP_TIMEOUT_MS);
             if (process != null && process.exitValue() != 0) {
                 Log.e(TAG, "perfetto traceStop failed with: " + process.exitValue());
             }
         } catch (Exception e) {
             throw new RuntimeException(e);
         }
     }

     public boolean traceDump(File outFile) {
         traceStop();

         // Short-circuit if a trace was not stopped.
         if (isTracingOn()) {
             Log.e(TAG, "Trace was not stopped successfully, aborting trace dump.");
             return false;
         }

         // Short-circuit if the file we're trying to dump to doesn't exist.
         if (!Files.exists(Paths.get(TEMP_TRACE_LOCATION))) {
             Log.e(TAG, "In-progress trace file doesn't exist, aborting trace dump.");
             return false;
         }

         Log.v(TAG, "Saving perfetto trace to " + outFile);

         try {
             Os.rename(TEMP_TRACE_LOCATION, outFile.getCanonicalPath());
         } catch (Exception e) {
             throw new RuntimeException(e);
         }

         outFile.setReadable(true, false); // (readable, ownerOnly)
         outFile.setWritable(true, false); // (readable, ownerOnly)
         return true;
     }

     public boolean isTracingOn() {
         String cmd = "perfetto --is_detached=" + PERFETTO_TAG;

         try {
             Process process = TraceUtils.exec(cmd);

             // 0 represents a detached process exists with this name
             // 2 represents no detached process with this name
             // 1 (or other error code) represents an error
             int result = process.waitFor();
             if (result == 0) {
                 return true;
             } else if (result == 2) {
                 return false;
             } else {
                 throw new RuntimeException("Perfetto error: " + result);
             }
         } catch (Exception e) {
             throw new RuntimeException(e);
         }
     }

     public static TreeMap<String,String> perfettoListCategories() {
         String cmd = "perfetto --query-raw";

         Log.v(TAG, "Listing tags: " + cmd);
         try {

             TreeMap<String, String> result = new TreeMap<>();

             // execWithTimeout() cannot be used because stdout must be consumed before the process
             // is terminated.
             Process perfetto = TraceUtils.exec(cmd, null, false);
             TracingServiceState serviceState =
                     TracingServiceState.parseFrom(perfetto.getInputStream());

             // Destroy the perfetto process if it times out.
             if (!perfetto.waitFor(LIST_TIMEOUT_MS, TimeUnit.MILLISECONDS)) {
                 Log.e(TAG, "perfettoListCategories timed out after " + LIST_TIMEOUT_MS + " ms.");
                 perfetto.destroyForcibly();
                 return result;
             }

             // The perfetto process completed and failed, but does not need to be destroyed.
             if (perfetto.exitValue() != 0) {
                 Log.e(TAG, "perfettoListCategories failed with: " + perfetto.exitValue());
             }

             List<AtraceCategory> categories = null;

             for (DataSource dataSource : serviceState.getDataSourcesList()) {
                 DataSourceDescriptor dataSrcDescriptor = dataSource.getDsDescriptor();
                 if (dataSrcDescriptor.getName().equals("linux.ftrace")){
                     categories = dataSrcDescriptor.getFtraceDescriptor().getAtraceCategoriesList();
                     break;
                 }
             }

             if (categories != null) {
                 for (AtraceCategory category : categories) {
                     result.put(category.getName(), category.getDescription());
                 }
             }
             return result;
         } catch (Exception e) {
             throw new RuntimeException(e);
         }
     }
 }
	/*
	* Copyright (C) 2015 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 com.android.traceur;

	import android.system.Os;
	import android.util.Log;

	import java.io.File;
	import java.nio.file.Files;
	import java.nio.file.Paths;
	import java.util.Collection;
	import java.util.List;
	import java.util.TreeMap;
	import java.util.concurrent.TimeUnit;

	import perfetto.protos.DataSourceDescriptorOuterClass.DataSourceDescriptor;
	import perfetto.protos.FtraceDescriptorOuterClass.FtraceDescriptor.AtraceCategory;
	import perfetto.protos.TracingServiceStateOuterClass.TracingServiceState;
	import perfetto.protos.TracingServiceStateOuterClass.TracingServiceState.DataSource;

	/**
	* Utility functions for calling Perfetto
	*/
	public class PerfettoUtils implements TraceUtils.TraceEngine {

	static final String TAG = "Traceur";
	public static final String NAME = "PERFETTO";

	private static final String OUTPUT_EXTENSION = "perfetto-trace";
	private static final String TEMP_DIR= "/data/local/traces/";
	private static final String TEMP_TRACE_LOCATION = "/data/local/traces/.trace-in-progress.trace";

	private static final String PERFETTO_TAG = "traceur";
	private static final String MARKER = "PERFETTO_ARGUMENTS";
	private static final int LIST_TIMEOUT_MS = 10000;
	private static final int STARTUP_TIMEOUT_MS = 10000;
	private static final int STOP_TIMEOUT_MS = 30000;
	private static final long MEGABYTES_TO_BYTES = 1024L * 1024L;
	private static final long MINUTES_TO_MILLISECONDS = 60L * 1000L;

	// The total amount of memory allocated to the two target buffers will be divided according to a
	// ratio of (BUFFER_SIZE_RATIO - 1) to 1.
	private static final int BUFFER_SIZE_RATIO = 64;

	// atrace trace categories that will result in added data sources in the Perfetto config.
	private static final String CAMERA_TAG = "camera";
	private static final String GFX_TAG = "gfx";
	private static final String MEMORY_TAG = "memory";
	private static final String POWER_TAG = "power";
	private static final String SCHED_TAG = "sched";
	private static final String WEBVIEW_TAG = "webview";

	// Custom trace categories.
	private static final String SYS_STATS_TAG = "sys_stats";

	public String getName() {
	return NAME;
	}

	public String getOutputExtension() {
	return OUTPUT_EXTENSION;
	}

	public boolean traceStart(Collection<String> tags, int bufferSizeKb, boolean apps,
	boolean attachToBugreport, boolean longTrace, int maxLongTraceSizeMb,
	int maxLongTraceDurationMinutes) {
	if (isTracingOn()) {
	Log.e(TAG, "Attempting to start perfetto trace but trace is already in progress");
	return false;
	} else {
	// If a temporary trace file already exists, save it before beginning a new trace.
	File recoveredFile = TraceUtils.getOutputFile(
	TraceUtils.getRecoveredFilename());
	if (!traceDump(recoveredFile)) {
	Log.w(TAG, "Failed to recover in-progress trace.");
	}
	}

	// The user chooses a per-CPU buffer size due to atrace limitations.
	// So we use this to ensure that we reserve the correctly-sized buffer.
	int numCpus = Runtime.getRuntime().availableProcessors();

	// Allots 1 / BUFFER_SIZE_RATIO to the small buffer and the remainder to the large buffer.
	int totalBufferSizeKb = numCpus * bufferSizeKb;
	int targetBuffer1Kb = totalBufferSizeKb / BUFFER_SIZE_RATIO;
	int targetBuffer0Kb = totalBufferSizeKb - targetBuffer1Kb;

	// Build the perfetto config that will be passed on the command line.
	StringBuilder config = new StringBuilder()
	.append("write_into_file: true\n")
	// Ensure that we flush ftrace data every 30s even if cpus are idle.
	.append("flush_period_ms: 30000\n");

	// If the user has flagged that in-progress trace sessions should be grabbed
	// during bugreports, and BetterBug is present.
	if (attachToBugreport) {
	config.append("bugreport_score: 500\n");
	}

	// Indicates that perfetto should notify Traceur if the tracing session's status
	// changes.
	config.append("notify_traceur: true\n");

	if (longTrace) {
	if (maxLongTraceSizeMb != 0) {
	config.append("max_file_size_bytes: "
	+ (maxLongTraceSizeMb * MEGABYTES_TO_BYTES) + "\n");
	}

	if (maxLongTraceDurationMinutes != 0) {
	config.append("duration_ms: "
	+ (maxLongTraceDurationMinutes * MINUTES_TO_MILLISECONDS)
	+ "\n");
	}

	// Default value for long traces to write to file.
	config.append("file_write_period_ms: 1000\n");
	} else {
	// For short traces, we don't write to the file.
	// So, always use the maximum value here: 7 days.
	config.append("file_write_period_ms: 604800000\n");
	}

	config.append("incremental_state_config {\n")
	.append(" clear_period_ms: 15000\n")
	.append("} \n")
	// This is target_buffer: 0, which is used for ftrace and the ftrace-derived
	// android.gpu.memory.
	.append("buffers {\n")
	.append(" size_kb: " + targetBuffer0Kb + "\n")
	.append(" fill_policy: RING_BUFFER\n")
	.append("} \n")
	// This is target_buffer: 1, which is used for additional data sources.
	.append("buffers {\n")
	.append(" size_kb: " + targetBuffer1Kb + "\n")
	.append(" fill_policy: RING_BUFFER\n")
	.append("} \n")
	.append("data_sources {\n")
	.append(" config {\n")
	.append(" name: \"linux.ftrace\"\n")
	.append(" target_buffer: 0\n")
	.append(" ftrace_config {\n")
	.append(" symbolize_ksyms: true\n");

	for (String tag : tags) {
	// Tags are expected to be only letters, numbers, and underscores.
	String cleanTag = tag.replaceAll("[^a-zA-Z0-9_]", "");
	if (!cleanTag.equals(tag)) {
	Log.w(TAG, "Attempting to use an invalid tag: " + tag);
	}
	config.append(" atrace_categories: \"" + cleanTag + "\"\n");
	}

	if (apps) {
	config.append(" atrace_apps: \"*\"\n");
	}

	// Request a dense encoding of the common sched events (sched_switch, sched_waking).
	if (tags.contains(SCHED_TAG)) {
	config.append(" compact_sched {\n");
	config.append(" enabled: true\n");
	config.append(" }\n");
	}

	// These parameters affect only the kernel trace buffer size and how
	// frequently it gets moved into the userspace buffer defined above.
	config.append(" buffer_size_kb: 8192\n")
	.append(" drain_period_ms: 1000\n")
	.append(" }\n")
	.append(" }\n")
	.append("}\n")
	.append(" \n");

	// Captures initial counter values, updates are captured in ftrace.
	if (tags.contains(MEMORY_TAG) \|\| tags.contains(GFX_TAG)) {
	config.append("data_sources: {\n")
	.append(" config { \n")
	.append(" name: \"android.gpu.memory\"\n")
	.append(" target_buffer: 0\n")
	.append(" }\n")
	.append("}\n");
	}

	// For process association. If the memory tag is enabled,
	// poll periodically instead of just once at the beginning.
	config.append("data_sources {\n")
	.append(" config {\n")
	.append(" name: \"linux.process_stats\"\n")
	.append(" target_buffer: 1\n");
	if (tags.contains(MEMORY_TAG)) {
	config.append(" process_stats_config {\n")
	.append(" proc_stats_poll_ms: 60000\n")
	.append(" }\n");
	}
	config.append(" }\n")
	.append("} \n");

	if (tags.contains(POWER_TAG)) {
	config.append("data_sources: {\n")
	.append(" config { \n")
	.append(" name: \"android.power\"\n")
	.append(" target_buffer: 1\n")
	.append(" android_power_config {\n");
	if (longTrace) {
	config.append(" battery_poll_ms: 5000\n");
	} else {
	config.append(" battery_poll_ms: 1000\n");
	}
	config.append(" collect_power_rails: true\n")
	.append(" battery_counters: BATTERY_COUNTER_CAPACITY_PERCENT\n")
	.append(" battery_counters: BATTERY_COUNTER_CHARGE\n")
	.append(" battery_counters: BATTERY_COUNTER_CURRENT\n")
	.append(" }\n")
	.append(" }\n")
	.append("}\n");
	}

	if (tags.contains(SYS_STATS_TAG)) {
	config.append("data_sources: {\n")
	.append(" config { \n")
	.append(" name: \"linux.sys_stats\"\n")
	.append(" target_buffer: 1\n")
	.append(" sys_stats_config {\n")
	.append(" meminfo_period_ms: 1000\n")
	.append(" vmstat_period_ms: 1000\n")
	.append(" }\n")
	.append(" }\n")
	.append("}\n");
	}

	if (tags.contains(GFX_TAG)) {
	config.append("data_sources: {\n")
	.append(" config { \n")
	.append(" name: \"android.surfaceflinger.frametimeline\"\n")
	.append(" }\n")
	.append("}\n");
	}

	if (tags.contains(CAMERA_TAG)) {
	config.append("data_sources: {\n")
	.append(" config { \n")
	.append(" name: \"android.hardware.camera\"\n")
	.append(" target_buffer: 1\n")
	.append(" }\n")
	.append("}\n");
	}

	// Also enable Chrome events when the WebView tag is enabled.
	if (tags.contains(WEBVIEW_TAG)) {
	String chromeTraceConfig = "{" +
	"\\\"record_mode\\\":\\\"record-continuously\\\"," +
	"\\\"included_categories\\\":[\\\"*\\\"]" +
	"}";
	config.append("data_sources: {\n")
	.append(" config {\n")
	.append(" name: \"org.chromium.trace_event\"\n")
	.append(" chrome_config {\n")
	.append(" trace_config: \"" + chromeTraceConfig + "\"\n")
	.append(" }\n")
	.append(" }\n")
	.append("}\n")
	.append("data_sources: {\n")
	.append(" config {\n")
	.append(" name: \"org.chromium.trace_metadata\"\n")
	.append(" chrome_config {\n")
	.append(" trace_config: \"" + chromeTraceConfig + "\"\n")
	.append(" }\n")
	.append(" }\n")
	.append("}\n");
	}

	String configString = config.toString();

	// If the here-doc ends early, within the config string, exit immediately.
	// This should never happen.
	if (configString.contains(MARKER)) {
	throw new RuntimeException("The arguments to the Perfetto command are malformed.");
	}

	String cmd = "perfetto --detach=" + PERFETTO_TAG
	+ " -o " + TEMP_TRACE_LOCATION
	+ " -c - --txt"
	+ " <<" + MARKER +"\n" + configString + "\n" + MARKER;

	Log.v(TAG, "Starting perfetto trace.");
	try {
	Process process = TraceUtils.execWithTimeout(cmd, TEMP_DIR, STARTUP_TIMEOUT_MS);
	if (process == null) {
	return false;
	} else if (process.exitValue() != 0) {
	Log.e(TAG, "perfetto traceStart failed with: " + process.exitValue());
	return false;
	}
	} catch (Exception e) {
	throw new RuntimeException(e);
	}

	Log.v(TAG, "perfetto traceStart succeeded!");
	return true;
	}

	public void traceStop() {
	Log.v(TAG, "Stopping perfetto trace.");

	if (!isTracingOn()) {
	Log.w(TAG, "No trace appears to be in progress. Stopping perfetto trace may not work.");
	}

	String cmd = "perfetto --stop --attach=" + PERFETTO_TAG;
	try {
	Process process = TraceUtils.execWithTimeout(cmd, null, STOP_TIMEOUT_MS);
	if (process != null && process.exitValue() != 0) {
	Log.e(TAG, "perfetto traceStop failed with: " + process.exitValue());
	}
	} catch (Exception e) {
	throw new RuntimeException(e);
	}
	}

	public boolean traceDump(File outFile) {
	traceStop();

	// Short-circuit if a trace was not stopped.
	if (isTracingOn()) {
	Log.e(TAG, "Trace was not stopped successfully, aborting trace dump.");
	return false;
	}

	// Short-circuit if the file we're trying to dump to doesn't exist.
	if (!Files.exists(Paths.get(TEMP_TRACE_LOCATION))) {
	Log.e(TAG, "In-progress trace file doesn't exist, aborting trace dump.");
	return false;
	}

	Log.v(TAG, "Saving perfetto trace to " + outFile);

	try {
	Os.rename(TEMP_TRACE_LOCATION, outFile.getCanonicalPath());
	} catch (Exception e) {
	throw new RuntimeException(e);
	}

	outFile.setReadable(true, false); // (readable, ownerOnly)
	outFile.setWritable(true, false); // (readable, ownerOnly)
	return true;
	}

	public boolean isTracingOn() {
	String cmd = "perfetto --is_detached=" + PERFETTO_TAG;

	try {
	Process process = TraceUtils.exec(cmd);

	// 0 represents a detached process exists with this name
	// 2 represents no detached process with this name
	// 1 (or other error code) represents an error
	int result = process.waitFor();
	if (result == 0) {
	return true;
	} else if (result == 2) {
	return false;
	} else {
	throw new RuntimeException("Perfetto error: " + result);
	}
	} catch (Exception e) {
	throw new RuntimeException(e);
	}
	}

	public static TreeMap<String,String> perfettoListCategories() {
	String cmd = "perfetto --query-raw";

	Log.v(TAG, "Listing tags: " + cmd);
	try {

	TreeMap<String, String> result = new TreeMap<>();

	// execWithTimeout() cannot be used because stdout must be consumed before the process
	// is terminated.
	Process perfetto = TraceUtils.exec(cmd, null, false);
	TracingServiceState serviceState =
	TracingServiceState.parseFrom(perfetto.getInputStream());

	// Destroy the perfetto process if it times out.
	if (!perfetto.waitFor(LIST_TIMEOUT_MS, TimeUnit.MILLISECONDS)) {
	Log.e(TAG, "perfettoListCategories timed out after " + LIST_TIMEOUT_MS + " ms.");
	perfetto.destroyForcibly();
	return result;
	}

	// The perfetto process completed and failed, but does not need to be destroyed.
	if (perfetto.exitValue() != 0) {
	Log.e(TAG, "perfettoListCategories failed with: " + perfetto.exitValue());
	}

	List<AtraceCategory> categories = null;

	for (DataSource dataSource : serviceState.getDataSourcesList()) {
	DataSourceDescriptor dataSrcDescriptor = dataSource.getDsDescriptor();
	if (dataSrcDescriptor.getName().equals("linux.ftrace")){
	categories = dataSrcDescriptor.getFtraceDescriptor().getAtraceCategoriesList();
	break;
	}
	}

	if (categories != null) {
	for (AtraceCategory category : categories) {
	result.put(category.getName(), category.getDescription());
	}
	}
	return result;
	} catch (Exception e) {
	throw new RuntimeException(e);
	}
	}
	}