英文:
Read input every n seconds from device sending every m seconds using Go
问题
使用Go语言，我想从连接到串口的设备中每秒读取一次日志，该设备每300毫秒发送一个以换行符结尾的日志。我认为通过串口连接这一点应该是无关紧要的。我应该如何每秒读取一条新的日志条目，并丢弃其他条目，因为设备每300毫秒写入一条日志？
英文:
Using Go, I want to read every 1 second from a device connected to the serial port that sends a log terminated with a newline character every 300 ms. The fact that this is via the serial port should be immaterial, I believe. How can I read a new log entry every 1 second and dropping the other entries, since the device is writing log entries every 300 ms?
答案1
得分: 1
记住上次处理日志条目的时间。循环读取日志条目。如果距离上次日志的时间大于所需的频率，则处理日志并更新上次日志时间。
freq := time.Second
prev := time.Time{}
for {
log := readLog()
if time.Since(prev) > freq {
prev = time.Now()
// 对日志进行处理
}
}
英文:
Remember the last time a log entry was processed. Read log entries in a loop. If time since log is greater than the desired frequency, process log and update last log time.
freq := time.Second
prev := time.Time{}
for {
log := readLog()
if time.Since(prev) > freq {
prev = time.Now()
// do something with log
}
}
答案2
得分: 1
你可以使用Go通道来进行速率限制和节流 - 如果你想要丢弃事件，可以使用带有select和case default:的缓冲通道来实现非阻塞的通道写入。
所以，一个简单的轮询实现（类似于@BurakSerdar建议的方式 - 但是消息会被丢弃直到有一个被读取 - 但是产生相同的结果）：
ch := make(chan string, 1) // 1 - 所以我们至少保留一个消息
go func() {
for {
msg := getLog()
// 非阻塞写入，即消息可能会被丢弃
select {
case ch <- msg:
default:
}
}
}()
// 读取：
for msg := range ch {
Info.Printf("throttled: %s", msg)
time.Sleep(1000 * time.Millisecond) // 每秒节流1条消息
}
工作示例：
https://play.golang.org/p/_QIBGal4_jJ
英文:
You can use Go channels to rate-limit and throttle - and if you want to drop events, a buffered channel with select combined with case default: allows for non-blocking channel writes.
So, a simple polling implementation (similar to what @BurakSerdar suggested - but instead messages are dropped until one is read - but yields the same result):
ch := make(chan string, 1) // 1 - so we keep at least one message
go func() {
for {
msg := getLog()
// non-blocking write i.e. messages may be dropped
select {
case ch <- msg:
default:
}
}
}()
and to read:
for msg := range ch {
Info.Printf("throttled: %s", msg)
time.Sleep(1000 * time.Millisecond) // throttle 1 message/s
}
Working example:
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