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Side by Side Diff: content/browser/tracing/arc_tracing_agent.cc

Issue 2400163003: arc: enable Android tracing in verified-boot mode (Closed)
Patch Set: rebase to tot Created 3 years, 8 months ago
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1 // Copyright 2017 The Chromium Authors. All rights reserved. 1 // Copyright 2017 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #include "content/browser/tracing/arc_tracing_agent.h" 5 #include "content/browser/tracing/arc_tracing_agent.h"
6 6
7 #include <memory>
7 #include <string> 8 #include <string>
9 #include <utility>
10 #include <vector>
8 11
9 #include "base/bind.h" 12 #include "base/bind.h"
13 #include "base/bind_helpers.h"
14 #include "base/files/file.h"
15 #include "base/files/file_descriptor_watcher_posix.h"
10 #include "base/logging.h" 16 #include "base/logging.h"
17 #include "base/memory/ptr_util.h"
11 #include "base/memory/singleton.h" 18 #include "base/memory/singleton.h"
12 #include "base/threading/thread_checker.h" 19 #include "base/memory/weak_ptr.h"
20 #include "base/posix/unix_domain_socket_linux.h"
21 #include "base/threading/sequenced_task_runner_handle.h"
13 #include "base/threading/thread_task_runner_handle.h" 22 #include "base/threading/thread_task_runner_handle.h"
23 #include "base/time/time.h"
24 #include "cc/base/ring_buffer.h"
25 #include "content/public/browser/browser_thread.h"
14 26
15 namespace content { 27 namespace content {
16 28
17 namespace { 29 namespace {
18 30
31 // The maximum size used to store one trace event. The ad hoc trace format for
32 // atrace is 1024 bytes. Here we add additional size as we're using JSON and
33 // have additional data fields.
34 constexpr size_t kArcTraceMessageLength = 1024 + 512;
35
19 constexpr char kArcTracingAgentName[] = "arc"; 36 constexpr char kArcTracingAgentName[] = "arc";
20 constexpr char kArcTraceLabel[] = "ArcTraceEvents"; 37 constexpr char kArcTraceLabel[] = "ArcTraceEvents";
21 38
22 void OnStopTracing(bool success) { 39 // Number of events for the ring buffer.
23 DLOG_IF(WARNING, !success) << "Failed to stop ARC tracing."; 40 constexpr size_t kTraceEventBufferSize = 64000;
24 } 41
42 // A helper class for reading trace data from the client side. We separate this
43 // from |ArcTracingAgentImpl| to isolate the logic that runs on browser's IO
44 // thread. All the functions in this class except for constructor, destructor,
45 // and |GetWeakPtr| are expected to be run on browser's IO thread.
46 class ArcTracingReader {
47 public:
48 using StopTracingCallback =
49 base::Callback<void(const scoped_refptr<base::RefCountedString>&)>;
50
51 ArcTracingReader() : weak_ptr_factory_(this) {}
52
53 void StartTracing(base::ScopedFD read_fd) {
54 DCHECK_CURRENTLY_ON(BrowserThread::IO);
55 read_fd_ = std::move(read_fd);
56 // We don't use the weak pointer returned by |GetWeakPtr| to avoid using it
57 // on different task runner. Instead, we use |base::Unretained| here as
58 // |fd_watcher_| is always destroyed before |this| is destroyed.
59 fd_watcher_ = base::FileDescriptorWatcher::WatchReadable(
60 read_fd_.get(), base::Bind(&ArcTracingReader::OnTraceDataAvailable,
61 base::Unretained(this)));
62 }
63
64 void OnTraceDataAvailable() {
65 DCHECK_CURRENTLY_ON(BrowserThread::IO);
66
67 char buf[kArcTraceMessageLength];
68 std::vector<base::ScopedFD> unused_fds;
69 ssize_t n = base::UnixDomainSocket::RecvMsg(
70 read_fd_.get(), buf, kArcTraceMessageLength, &unused_fds);
71 // When EOF, return and do nothing. The clean up is done in StopTracing.
72 if (n == 0)
73 return;
74
75 if (n < 0) {
76 DPLOG(WARNING) << "Unexpected error while reading trace from client.";
77 // Do nothing here as StopTracing will do the clean up and the existing
78 // trace logs will be returned.
79 return;
80 }
81
82 if (n > static_cast<ssize_t>(kArcTraceMessageLength)) {
83 DLOG(WARNING) << "Unexpected data size when reading trace from client.";
84 return;
85 }
86 ring_buffer_.SaveToBuffer(std::string(buf, n));
87 }
88
89 void StopTracing(const StopTracingCallback& callback) {
90 DCHECK_CURRENTLY_ON(BrowserThread::IO);
91 fd_watcher_.reset();
92 read_fd_.reset();
93
94 bool append_comma = false;
95 std::string data;
96 for (auto it = ring_buffer_.Begin(); it; ++it) {
97 if (append_comma)
98 data.append(",");
99 else
100 append_comma = true;
101 data.append(**it);
102 }
103 ring_buffer_.Clear();
104
105 BrowserThread::PostTask(
106 BrowserThread::IO, FROM_HERE,
107 base::Bind(callback, base::RefCountedString::TakeString(&data)));
108 }
109
110 base::WeakPtr<ArcTracingReader> GetWeakPtr() {
111 return weak_ptr_factory_.GetWeakPtr();
112 }
113
114 private:
115 base::ScopedFD read_fd_;
116 std::unique_ptr<base::FileDescriptorWatcher::Controller> fd_watcher_;
117 cc::RingBuffer<std::string, kTraceEventBufferSize> ring_buffer_;
118 // NOTE: Weak pointers must be invalidated before all other member variables
119 // so it must be the last member.
120 base::WeakPtrFactory<ArcTracingReader> weak_ptr_factory_;
121
122 DISALLOW_COPY_AND_ASSIGN(ArcTracingReader);
123 };
25 124
26 class ArcTracingAgentImpl : public ArcTracingAgent { 125 class ArcTracingAgentImpl : public ArcTracingAgent {
27 public: 126 public:
28 // base::trace_event::TracingAgent overrides: 127 // base::trace_event::TracingAgent overrides:
29 std::string GetTracingAgentName() override { return kArcTracingAgentName; } 128 std::string GetTracingAgentName() override { return kArcTracingAgentName; }
30 129
31 std::string GetTraceEventLabel() override { return kArcTraceLabel; } 130 std::string GetTraceEventLabel() override { return kArcTraceLabel; }
32 131
33 void StartAgentTracing(const base::trace_event::TraceConfig& trace_config, 132 void StartAgentTracing(const base::trace_event::TraceConfig& trace_config,
34 const StartAgentTracingCallback& callback) override { 133 const StartAgentTracingCallback& callback) override {
35 DCHECK(thread_checker_.CalledOnValidThread()); 134 DCHECK_CURRENTLY_ON(BrowserThread::UI);
135
36 // delegate_ may be nullptr if ARC is not enabled on the system. In such 136 // delegate_ may be nullptr if ARC is not enabled on the system. In such
37 // case, simply do nothing. 137 // case, simply do nothing.
38 if (!delegate_) { 138 bool success = (delegate_ != nullptr);
139
140 base::ScopedFD write_fd, read_fd;
141 success = success && CreateSocketPair(&read_fd, &write_fd);
142
143 if (!success) {
39 // Use PostTask as the convention of TracingAgent. The caller expects 144 // Use PostTask as the convention of TracingAgent. The caller expects
40 // callback to be called after this function returns. 145 // callback to be called after this function returns.
41 base::ThreadTaskRunnerHandle::Get()->PostTask( 146 base::ThreadTaskRunnerHandle::Get()->PostTask(
42 FROM_HERE, base::Bind(callback, GetTracingAgentName(), false)); 147 FROM_HERE, base::Bind(callback, GetTracingAgentName(), false));
43 return; 148 return;
44 } 149 }
45 150
46 delegate_->StartTracing(trace_config, 151 BrowserThread::PostTask(
152 BrowserThread::IO, FROM_HERE,
153 base::Bind(&ArcTracingReader::StartTracing, reader_.GetWeakPtr(),
154 base::Passed(&read_fd)));
155
156 delegate_->StartTracing(trace_config, std::move(write_fd),
47 base::Bind(callback, GetTracingAgentName())); 157 base::Bind(callback, GetTracingAgentName()));
48 } 158 }
49 159
50 void StopAgentTracing(const StopAgentTracingCallback& callback) override { 160 void StopAgentTracing(const StopAgentTracingCallback& callback) override {
51 DCHECK(thread_checker_.CalledOnValidThread()); 161 DCHECK_CURRENTLY_ON(BrowserThread::UI);
52 if (delegate_)
53 delegate_->StopTracing(base::Bind(OnStopTracing));
54 162
55 // Trace data is collect via systrace (debugd) in dev-mode. Simply 163 if (is_stopping_) {
56 // return empty data here. 164 DLOG(WARNING) << "Already working on stopping ArcTracingAgent.";
57 std::string no_data; 165 return;
58 base::ThreadTaskRunnerHandle::Get()->PostTask( 166 }
59 FROM_HERE, 167 is_stopping_ = true;
60 base::Bind(callback, GetTracingAgentName(), GetTraceEventLabel(), 168 if (delegate_) {
61 base::RefCountedString::TakeString(&no_data))); 169 delegate_->StopTracing(
170 base::Bind(&ArcTracingAgentImpl::OnArcTracingStopped,
171 weak_ptr_factory_.GetWeakPtr(), callback));
172 }
62 } 173 }
63 174
64 // ArcTracingAgent overrides: 175 // ArcTracingAgent overrides:
65 void SetDelegate(Delegate* delegate) override { 176 void SetDelegate(Delegate* delegate) override {
66 DCHECK(thread_checker_.CalledOnValidThread()); 177 DCHECK_CURRENTLY_ON(BrowserThread::UI);
67 delegate_ = delegate; 178 delegate_ = delegate;
68 } 179 }
69 180
70 static ArcTracingAgentImpl* GetInstance() { 181 static ArcTracingAgentImpl* GetInstance() {
71 return base::Singleton<ArcTracingAgentImpl>::get(); 182 return base::Singleton<ArcTracingAgentImpl>::get();
72 } 183 }
73 184
74 private: 185 private:
75 // This allows constructor and destructor to be private and usable only 186 // This allows constructor and destructor to be private and usable only
76 // by the Singleton class. 187 // by the Singleton class.
77 friend struct base::DefaultSingletonTraits<ArcTracingAgentImpl>; 188 friend struct base::DefaultSingletonTraits<ArcTracingAgentImpl>;
78 189
79 ArcTracingAgentImpl() = default; 190 ArcTracingAgentImpl() : weak_ptr_factory_(this) {}
191
80 ~ArcTracingAgentImpl() override = default; 192 ~ArcTracingAgentImpl() override = default;
81 193
194 void OnArcTracingStopped(const StopAgentTracingCallback& callback,
195 bool success) {
196 DCHECK_CURRENTLY_ON(BrowserThread::UI);
197 if (!success) {
198 DLOG(WARNING) << "Failed to stop ARC tracing.";
199 callback.Run(GetTracingAgentName(), GetTraceEventLabel(),
200 new base::RefCountedString());
201 is_stopping_ = false;
202 return;
203 }
204 BrowserThread::PostTask(
205 BrowserThread::IO, FROM_HERE,
206 base::Bind(&ArcTracingReader::StopTracing, reader_.GetWeakPtr(),
207 base::Bind(&ArcTracingAgentImpl::OnTracingReaderStopped,
208 weak_ptr_factory_.GetWeakPtr(), callback)));
209 }
210
211 void OnTracingReaderStopped(
212 const StopAgentTracingCallback& callback,
213 const scoped_refptr<base::RefCountedString>& data) {
214 DCHECK_CURRENTLY_ON(BrowserThread::UI);
215 callback.Run(GetTracingAgentName(), GetTraceEventLabel(), data);
216 is_stopping_ = false;
217 }
218
82 Delegate* delegate_ = nullptr; // Owned by ArcServiceLauncher. 219 Delegate* delegate_ = nullptr; // Owned by ArcServiceLauncher.
83 base::ThreadChecker thread_checker_; 220 // We use |reader_.GetWeakPtr()| when binding callbacks with its functions.
221 // Notes that the weak pointer returned by it can only be deferenced or
222 // invalided in the same task runner to avoid racing condition. The
223 // destruction of |reader_| is also a source of invalidation. However, we're
224 // lucky as we're using |ArcTracingAgentImpl| as a singleton, the
225 // destruction is always performed after all MessageLoops are destroyed, and
226 // thus there are no race conditions in such situation.
227 ArcTracingReader reader_;
228 bool is_stopping_ = false;
229 // NOTE: Weak pointers must be invalidated before all other member variables
230 // so it must be the last member.
231 base::WeakPtrFactory<ArcTracingAgentImpl> weak_ptr_factory_;
84 232
85 DISALLOW_COPY_AND_ASSIGN(ArcTracingAgentImpl); 233 DISALLOW_COPY_AND_ASSIGN(ArcTracingAgentImpl);
86 }; 234 };
87 235
88 } // namespace 236 } // namespace
89 237
90 // static 238 // static
91 ArcTracingAgent* ArcTracingAgent::GetInstance() { 239 ArcTracingAgent* ArcTracingAgent::GetInstance() {
92 return ArcTracingAgentImpl::GetInstance(); 240 return ArcTracingAgentImpl::GetInstance();
93 } 241 }
94 242
95 ArcTracingAgent::ArcTracingAgent() = default; 243 ArcTracingAgent::ArcTracingAgent() = default;
96 ArcTracingAgent::~ArcTracingAgent() = default; 244 ArcTracingAgent::~ArcTracingAgent() = default;
97 245
98 ArcTracingAgent::Delegate::~Delegate() = default; 246 ArcTracingAgent::Delegate::~Delegate() = default;
99 247
100 } // namespace content 248 } // namespace content
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