You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
105 lines
3.0 KiB
105 lines
3.0 KiB
/*
|
|
* Copyright (C) 2020 The Android Open Source Project
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#include "property_monitor.h"
|
|
|
|
#include <atomic>
|
|
#include <functional>
|
|
#include <optional>
|
|
#include <string>
|
|
#include <thread>
|
|
#include <utility>
|
|
#include <vector>
|
|
|
|
#include <android-base/logging.h>
|
|
|
|
static uint32_t WaitForSerialChange(uint32_t current_serial) {
|
|
uint32_t result;
|
|
__system_property_wait(nullptr, current_serial, &result, nullptr);
|
|
return result;
|
|
}
|
|
|
|
static bool FindProperty(const std::string& property_name, PropertyMonitorData* data) {
|
|
const prop_info* p = __system_property_find(property_name.c_str());
|
|
if (!p) {
|
|
return false;
|
|
}
|
|
|
|
data->prop_info = p;
|
|
return true;
|
|
}
|
|
|
|
// Read a property and return its value if it's been changed, while updating our cached serial.
|
|
static std::optional<std::string> ReadProperty(PropertyMonitorData* data) {
|
|
struct ReadData {
|
|
std::string value;
|
|
uint32_t serial;
|
|
};
|
|
|
|
ReadData result;
|
|
__system_property_read_callback(
|
|
data->prop_info,
|
|
[](void* cookie, const char* name, const char* value, uint32_t serial) {
|
|
ReadData* result = static_cast<ReadData*>(cookie);
|
|
result->value = value;
|
|
result->serial = serial;
|
|
},
|
|
&result);
|
|
|
|
if (result.serial <= data->serial) {
|
|
return {};
|
|
}
|
|
|
|
data->serial = result.serial;
|
|
return result.value;
|
|
}
|
|
|
|
void PropertyMonitor::Add(std::string property, std::function<PropertyMonitorCallback> callback) {
|
|
PropertyMonitorData data = {
|
|
.callback = std::move(callback),
|
|
.prop_info = nullptr,
|
|
.serial = 0,
|
|
};
|
|
|
|
if (FindProperty(property, &data)) {
|
|
data.callback(ReadProperty(&data).value());
|
|
} else {
|
|
data.callback(std::string());
|
|
}
|
|
|
|
properties_.emplace(std::move(property), std::move(data));
|
|
}
|
|
|
|
void PropertyMonitor::Run() {
|
|
bool result = true;
|
|
while (result) {
|
|
uint32_t current_serial = WaitForSerialChange(last_serial_);
|
|
for (auto& [property_name, data] : properties_) {
|
|
if (!data.prop_info) {
|
|
if (FindProperty(property_name, &data)) {
|
|
result &= data.callback(ReadProperty(&data).value());
|
|
}
|
|
} else {
|
|
if (auto value = ReadProperty(&data); value) {
|
|
result &= data.callback(value.value());
|
|
}
|
|
}
|
|
}
|
|
|
|
last_serial_ = current_serial;
|
|
}
|
|
}
|