1 /*
2 * Copyright 2017 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 #include <dlfcn.h>
18 #include "logging_macros.h"
19 #include <cstdio>
20 #include "trace.h"
21
22 static const int TRACE_MAX_SECTION_NAME_LENGTH = 100;
23
24 // Tracing functions
25 static void *(*ATrace_beginSection)(const char *sectionName);
26
27 static void *(*ATrace_endSection)(void);
28
29 static bool *(*ATrace_isEnabled)(void);
30
31 typedef void *(*fp_ATrace_beginSection)(const char *sectionName);
32
33 typedef void *(*fp_ATrace_endSection)(void);
34
35 typedef bool *(*fp_ATrace_isEnabled)(void);
36
37 bool Trace::is_enabled_ = false;
38 bool Trace::has_error_been_shown_ = false;
39
beginSection(const char * fmt,...)40 void Trace::beginSection(const char *fmt, ...) {
41
42 if (is_enabled_) {
43 static char buff[TRACE_MAX_SECTION_NAME_LENGTH];
44 va_list args;
45 va_start(args, fmt);
46 vsprintf(buff, fmt, args);
47 va_end(args);
48 ATrace_beginSection(buff);
49 } else if (!has_error_been_shown_) {
50 LOGE("Tracing is either not initialized (call Trace::initialize()) "
51 "or not supported on this device");
52 has_error_been_shown_ = true;
53 }
54 }
55
endSection()56 void Trace::endSection() {
57
58 if (is_enabled_) {
59 ATrace_endSection();
60 }
61 }
62
initialize()63 void Trace::initialize() {
64
65 // Using dlsym allows us to use tracing on API 21+ without needing android/trace.h which wasn't
66 // published until API 23
67 void *lib = dlopen("libandroid.so", RTLD_NOW | RTLD_LOCAL);
68 if (lib == nullptr) {
69 LOGE("Could not open libandroid.so to dynamically load tracing symbols");
70 } else {
71 ATrace_beginSection =
72 reinterpret_cast<fp_ATrace_beginSection >(
73 dlsym(lib, "ATrace_beginSection"));
74 ATrace_endSection =
75 reinterpret_cast<fp_ATrace_endSection >(
76 dlsym(lib, "ATrace_endSection"));
77 ATrace_isEnabled =
78 reinterpret_cast<fp_ATrace_isEnabled >(
79 dlsym(lib, "ATrace_isEnabled"));
80
81 if (ATrace_isEnabled != nullptr && ATrace_isEnabled()) {
82 is_enabled_ = true;
83 }
84 }
85 }
86