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