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 = ATRACE_TAG_NOT_READY;
29 Mutex Tracer::sMutex;
30
changeCallback()31 void Tracer::changeCallback() {
32 Mutex::Autolock lock(sMutex);
33 if (sIsReady && sTraceFD >= 0) {
34 loadSystemProperty();
35 }
36 }
37
init()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 = 0; // no tracing can occur
50 } else {
51 loadSystemProperty();
52 }
53
54 android_atomic_release_store(1, &sIsReady);
55 }
56 }
57
loadSystemProperty()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