1 /*
2 * Copyright (C) 2020 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 "host/frontend/webrtc/kernel_log_events_handler.h"
18
19 #include <android-base/logging.h>
20
21 #include <common/libs/fs/shared_select.h>
22 #include <host/commands/kernel_log_monitor/kernel_log_server.h>
23 #include <host/commands/kernel_log_monitor/utils.h>
24 #include <host/libs/config/cuttlefish_config.h>
25
26 using namespace android;
27
28 namespace cuttlefish {
29
KernelLogEventsHandler(SharedFD kernel_log_fd)30 KernelLogEventsHandler::KernelLogEventsHandler(
31 SharedFD kernel_log_fd)
32 : kernel_log_fd_(kernel_log_fd),
33 eventfd_(SharedFD::Event()),
34 running_(true),
35 read_thread_([this]() { ReadLoop(); }) {}
36
~KernelLogEventsHandler()37 KernelLogEventsHandler::~KernelLogEventsHandler() {
38 running_ = false;
39 eventfd_->EventfdWrite(1);
40 read_thread_.join();
41 }
42
ReadLoop()43 void KernelLogEventsHandler::ReadLoop() {
44 CHECK(eventfd_->IsOpen()) << "Failed to create event fd: "
45 << eventfd_->StrError();
46 while (running_) {
47 SharedFDSet read_set;
48 read_set.Set(eventfd_);
49 read_set.Set(kernel_log_fd_);
50 auto select_ret = Select(&read_set, nullptr, nullptr, nullptr);
51 if (select_ret < 0) {
52 LOG(ERROR) << "Error on select call";
53 break;
54 }
55 if (read_set.IsSet(eventfd_)) {
56 eventfd_t evt;
57 (void)eventfd_->EventfdRead(&evt);
58 if (!running_) {
59 // There won't be anyone listening for kernel log events if the thread
60 // was asked to stop, so break out of the loop without reading.
61 break;
62 }
63 }
64 if (read_set.IsSet(kernel_log_fd_)) {
65 std::optional<monitor::ReadEventResult> read_result =
66 monitor::ReadEvent(kernel_log_fd_);
67 if (!read_result) {
68 LOG(ERROR) << "Failed to read kernel log event: "
69 << kernel_log_fd_->StrError();
70 break;
71 }
72
73 if (read_result->event == monitor::Event::BootStarted) {
74 Json::Value message;
75 message["event"] = kBootStartedMessage;
76 DeliverEvent(message);
77 }
78 if (read_result->event == monitor::Event::BootCompleted) {
79 Json::Value message;
80 message["event"] = kBootCompletedMessage;
81 DeliverEvent(message);
82 }
83 if (read_result->event == monitor::Event::ScreenChanged) {
84 Json::Value message;
85 message["event"] = kScreenChangedMessage;
86 message["metadata"] = read_result->metadata;
87 DeliverEvent(message);
88 }
89 }
90 }
91 }
92
AddSubscriber(std::function<void (const Json::Value &)> subscriber)93 int KernelLogEventsHandler::AddSubscriber(
94 std::function<void(const Json::Value&)> subscriber) {
95 std::lock_guard<std::mutex> lock(subscribers_mtx_);
96 subscribers_[++last_subscriber_id_] = subscriber;
97 return last_subscriber_id_;
98 }
99
Unsubscribe(int subscriber_id)100 void KernelLogEventsHandler::Unsubscribe(int subscriber_id) {
101 std::lock_guard<std::mutex> lock(subscribers_mtx_);
102 subscribers_.erase(subscriber_id);
103 }
104
DeliverEvent(const Json::Value & event)105 void KernelLogEventsHandler::DeliverEvent(const Json::Value& event) {
106 std::lock_guard<std::mutex> lock(subscribers_mtx_);
107 for (const auto& entry : subscribers_) {
108 entry.second(event);
109 }
110 }
111
112 } // namespace cuttlefish
113