1 /*
2 * Copyright (C) 2019 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 "perfetto/base/build_config.h"
18
19 #if PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX) || \
20 PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID) || \
21 PERFETTO_BUILDFLAG(PERFETTO_OS_FUCHSIA) || \
22 PERFETTO_BUILDFLAG(PERFETTO_OS_APPLE)
23
24 #include "perfetto/ext/base/file_utils.h"
25 #include "perfetto/ext/base/thread_task_runner.h"
26 #include "perfetto/tracing/internal/tracing_tls.h"
27 #include "perfetto/tracing/platform.h"
28 #include "perfetto/tracing/trace_writer_base.h"
29
30 #include <pthread.h>
31 #include <stdlib.h>
32
33 namespace perfetto {
34
35 namespace {
36
37 class PlatformPosix : public Platform {
38 public:
39 PlatformPosix();
40 ~PlatformPosix() override;
41
42 ThreadLocalObject* GetOrCreateThreadLocalObject() override;
43
44 std::unique_ptr<base::TaskRunner> CreateTaskRunner(
45 const CreateTaskRunnerArgs&) override;
46 std::string GetCurrentProcessName() override;
47 void Shutdown() override;
48
49 private:
50 pthread_key_t tls_key_{};
51 };
52
53 PlatformPosix* g_instance = nullptr;
54
55 using ThreadLocalObject = Platform::ThreadLocalObject;
56
PlatformPosix()57 PlatformPosix::PlatformPosix() {
58 PERFETTO_CHECK(!g_instance);
59 g_instance = this;
60 auto tls_dtor = [](void* obj) {
61 // The Posix TLS implementation resets the key before calling this dtor.
62 // Here we re-reset it to the object we are about to delete. This is to
63 // handle re-entrant usages of tracing in the PostTask done during the dtor
64 // (see comments in TracingTLS::~TracingTLS()). Chromium's platform
65 // implementation (which does NOT use this platform impl) has a similar
66 // workaround (https://crrev.com/c/2748300).
67 pthread_setspecific(g_instance->tls_key_, obj);
68 delete static_cast<ThreadLocalObject*>(obj);
69 pthread_setspecific(g_instance->tls_key_, nullptr);
70 };
71 PERFETTO_CHECK(pthread_key_create(&tls_key_, tls_dtor) == 0);
72 }
73
~PlatformPosix()74 PlatformPosix::~PlatformPosix() {
75 // pthread_key_delete doesn't call destructors, so do it manually for the
76 // calling thread.
77 void* tls_ptr = pthread_getspecific(tls_key_);
78 delete static_cast<ThreadLocalObject*>(tls_ptr);
79
80 pthread_key_delete(tls_key_);
81 g_instance = nullptr;
82 }
83
Shutdown()84 void PlatformPosix::Shutdown() {
85 PERFETTO_CHECK(g_instance == this);
86 delete this;
87 PERFETTO_CHECK(!g_instance);
88 // We're not clearing out the instance in GetDefaultPlatform() since it's not
89 // possible to re-initialize Perfetto after calling this function anyway.
90 }
91
GetOrCreateThreadLocalObject()92 ThreadLocalObject* PlatformPosix::GetOrCreateThreadLocalObject() {
93 // In chromium this should be implemented using base::ThreadLocalStorage.
94 void* tls_ptr = pthread_getspecific(tls_key_);
95
96 // This is needed to handle re-entrant calls during TLS dtor.
97 // See comments in platform.cc and aosp/1712371 .
98 ThreadLocalObject* tls = static_cast<ThreadLocalObject*>(tls_ptr);
99 if (!tls) {
100 tls = ThreadLocalObject::CreateInstance().release();
101 pthread_setspecific(tls_key_, tls);
102 }
103 return tls;
104 }
105
CreateTaskRunner(const CreateTaskRunnerArgs & args)106 std::unique_ptr<base::TaskRunner> PlatformPosix::CreateTaskRunner(
107 const CreateTaskRunnerArgs& args) {
108 return std::unique_ptr<base::TaskRunner>(new base::ThreadTaskRunner(
109 base::ThreadTaskRunner::CreateAndStart(args.name_for_debugging)));
110 }
111
GetCurrentProcessName()112 std::string PlatformPosix::GetCurrentProcessName() {
113 #if PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX) || \
114 PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID)
115 std::string cmdline;
116 base::ReadFile("/proc/self/cmdline", &cmdline);
117 return cmdline.substr(0, cmdline.find('\0'));
118 #elif PERFETTO_BUILDFLAG(PERFETTO_OS_APPLE)
119 return std::string(getprogname());
120 #else
121 return "unknown_producer";
122 #endif
123 }
124
125 } // namespace
126
127 // static
GetDefaultPlatform()128 Platform* Platform::GetDefaultPlatform() {
129 static PlatformPosix* instance = new PlatformPosix();
130 return instance;
131 }
132
133 } // namespace perfetto
134 #endif // OS_LINUX || OS_ANDROID || OS_APPLE || OS_FUCHSIA
135