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 #define LOG_TAG "Trace" 18 19 #include <cutils/properties.h> 20 #include <utils/Log.h> 21 #include <utils/Trace.h> 22 #include <utils/misc.h> 23 24 namespace android { 25 26 volatile int32_t Tracer::sIsReady = 0; 27 int Tracer::sTraceFD = -1; 28 uint64_t Tracer::sEnabledTags = 0; 29 Mutex Tracer::sMutex; 30 31 void Tracer::changeCallback() { 32 Mutex::Autolock lock(sMutex); 33 if (sIsReady && sTraceFD >= 0) { 34 loadSystemProperty(); 35 } 36 } 37 38 void Tracer::init() { 39 Mutex::Autolock lock(sMutex); 40 41 if (!sIsReady) { 42 add_sysprop_change_callback(changeCallback, 0); 43 44 const char* const traceFileName = 45 "/sys/kernel/debug/tracing/trace_marker"; 46 sTraceFD = open(traceFileName, O_WRONLY); 47 if (sTraceFD == -1) { 48 ALOGE("error opening trace file: %s (%d)", strerror(errno), errno); 49 // sEnabledTags remains zero indicating that no tracing can occur 50 } else { 51 loadSystemProperty(); 52 } 53 54 android_atomic_release_store(1, &sIsReady); 55 } 56 } 57 58 void Tracer::loadSystemProperty() { 59 char value[PROPERTY_VALUE_MAX]; 60 property_get("debug.atrace.tags.enableflags", value, "0"); 61 sEnabledTags = (strtoll(value, NULL, 0) & ATRACE_TAG_VALID_MASK) 62 | ATRACE_TAG_ALWAYS; 63 } 64 65 } // namespace andoid 66
