1 /*
2 * Copyright (C) 2022 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 "src/traced/probes/android_system_property/android_system_property_data_source.h"
18 #include <optional>
19
20 #include "perfetto/base/task_runner.h"
21 #include "perfetto/base/time.h"
22 #include "perfetto/ext/base/android_utils.h"
23 #include "perfetto/ext/base/string_utils.h"
24 #include "perfetto/tracing/core/data_source_config.h"
25
26 #include "protos/perfetto/config/android/android_system_property_config.pbzero.h"
27 #include "protos/perfetto/trace/android/android_system_property.pbzero.h"
28 #include "protos/perfetto/trace/trace_packet.pbzero.h"
29
30 namespace perfetto {
31
32 // static
33 const AndroidSystemPropertyDataSource::Descriptor
34 AndroidSystemPropertyDataSource::descriptor = {
35 /* name */ "android.system_property",
36 /* flags */ Descriptor::kFlagsNone,
37 /*fill_descriptor_func*/ nullptr,
38 };
39
40 constexpr const char* REQUIRED_NAME_PREFIX = "debug.tracing.";
41
AndroidSystemPropertyDataSource(base::TaskRunner * task_runner,const DataSourceConfig & ds_config,TracingSessionID session_id,std::unique_ptr<TraceWriter> writer)42 AndroidSystemPropertyDataSource::AndroidSystemPropertyDataSource(
43 base::TaskRunner* task_runner,
44 const DataSourceConfig& ds_config,
45 TracingSessionID session_id,
46 std::unique_ptr<TraceWriter> writer)
47 : ProbesDataSource(session_id, &descriptor),
48 task_runner_(task_runner),
49 writer_(std::move(writer)),
50 weak_factory_(this) {
51 protos::pbzero::AndroidSystemPropertyConfig::Decoder cfg(
52 ds_config.android_system_property_config_raw());
53 poll_period_ms_ = cfg.poll_ms();
54 if (poll_period_ms_ > 0 && poll_period_ms_ < 100) {
55 PERFETTO_ILOG("poll_ms %" PRIu32
56 " is less than minimum of 100ms. Increasing to 100ms.",
57 poll_period_ms_);
58 poll_period_ms_ = 100;
59 }
60 for (auto name_chars = cfg.property_name(); name_chars; ++name_chars) {
61 auto name = (*name_chars).ToStdString();
62 if (base::StartsWith(name, REQUIRED_NAME_PREFIX)) {
63 property_names_.push_back(name);
64 } else {
65 PERFETTO_ELOG("Property %s lacks required prefix %s", name.c_str(),
66 REQUIRED_NAME_PREFIX);
67 }
68 }
69 }
70
Start()71 void AndroidSystemPropertyDataSource::Start() {
72 Tick();
73 }
74
75 base::WeakPtr<AndroidSystemPropertyDataSource>
GetWeakPtr() const76 AndroidSystemPropertyDataSource::GetWeakPtr() const {
77 return weak_factory_.GetWeakPtr();
78 }
79
Tick()80 void AndroidSystemPropertyDataSource::Tick() {
81 if (poll_period_ms_) {
82 auto weak_this = GetWeakPtr();
83
84 uint32_t delay_ms =
85 poll_period_ms_ -
86 static_cast<uint32_t>(base::GetWallTimeMs().count() % poll_period_ms_);
87 task_runner_->PostDelayedTask(
88 [weak_this]() -> void {
89 if (weak_this) {
90 weak_this->Tick();
91 }
92 },
93 delay_ms);
94 }
95 WriteState();
96 }
97
WriteState()98 void AndroidSystemPropertyDataSource::WriteState() {
99 auto packet = writer_->NewTracePacket();
100 packet->set_timestamp(static_cast<uint64_t>(base::GetBootTimeNs().count()));
101 auto* properties = packet->set_android_system_property();
102 for (const auto& name : property_names_) {
103 const std::optional<std::string> value = ReadProperty(name);
104 if (value) {
105 auto* property = properties->add_values();
106 property->set_name(name);
107 property->set_value(*value);
108 }
109 }
110 packet->Finalize();
111 // For most data sources we would not want to flush every time we have
112 // something to write. However this source tends to emit very slowly and it is
113 // very possible that it would only flush at the end of the trace - at which
114 // point it might not be able to write anything (e.g. DISCARD buffer might be
115 // full). Taking the hit of 4kB each time we write seems reasonable to make
116 // this behave more predictably.
117 writer_->Flush();
118 }
119
120 #if PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID)
ReadProperty(const std::string & name)121 const std::optional<std::string> AndroidSystemPropertyDataSource::ReadProperty(
122 const std::string& name) {
123 std::string value = base::GetAndroidProp(name.c_str());
124 if (value.empty()) {
125 PERFETTO_LOG("Unable to read %s", name.c_str());
126 return std::nullopt;
127 }
128 return std::make_optional(value);
129 }
130 #else
ReadProperty(const std::string &)131 const std::optional<std::string> AndroidSystemPropertyDataSource::ReadProperty(
132 const std::string&) {
133 PERFETTO_ELOG("Android System Properties only supported on Android.");
134 return std::nullopt;
135 }
136 #endif
137
Flush(FlushRequestID,std::function<void ()> callback)138 void AndroidSystemPropertyDataSource::Flush(FlushRequestID,
139 std::function<void()> callback) {
140 writer_->Flush(callback);
141 }
142
143 } // namespace perfetto
144