103 lines
2 KiB
Go
103 lines
2 KiB
Go
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// Copyright 2014 Quoc-Viet Nguyen. All rights reserved.
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// This software may be modified and distributed under the terms
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// of the BSD license. See the LICENSE file for details.
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package modbus
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import (
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"io"
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"log"
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"sync"
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"time"
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"github.com/goburrow/serial"
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)
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const (
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// Default timeout
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serialTimeout = 5 * time.Second
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serialIdleTimeout = 60 * time.Second
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)
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// serialPort has configuration and I/O controller.
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type serialPort struct {
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// Serial port configuration.
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serial.Config
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Logger *log.Logger
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IdleTimeout time.Duration
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mu sync.Mutex
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// port is platform-dependent data structure for serial port.
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port io.ReadWriteCloser
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lastActivity time.Time
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closeTimer *time.Timer
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}
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func (mb *serialPort) Connect() (err error) {
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mb.mu.Lock()
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defer mb.mu.Unlock()
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return mb.connect()
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}
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// connect connects to the serial port if it is not connected. Caller must hold the mutex.
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func (mb *serialPort) connect() error {
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if mb.port == nil {
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port, err := serial.Open(&mb.Config)
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if err != nil {
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return err
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}
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mb.port = port
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}
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return nil
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}
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func (mb *serialPort) Close() (err error) {
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mb.mu.Lock()
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defer mb.mu.Unlock()
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return mb.close()
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}
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// close closes the serial port if it is connected. Caller must hold the mutex.
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func (mb *serialPort) close() (err error) {
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if mb.port != nil {
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err = mb.port.Close()
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mb.port = nil
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}
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return
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}
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func (mb *serialPort) logf(format string, v ...interface{}) {
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if mb.Logger != nil {
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mb.Logger.Printf(format, v...)
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}
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}
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func (mb *serialPort) startCloseTimer() {
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if mb.IdleTimeout <= 0 {
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return
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}
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if mb.closeTimer == nil {
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mb.closeTimer = time.AfterFunc(mb.IdleTimeout, mb.closeIdle)
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} else {
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mb.closeTimer.Reset(mb.IdleTimeout)
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}
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}
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// closeIdle closes the connection if last activity is passed behind IdleTimeout.
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func (mb *serialPort) closeIdle() {
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mb.mu.Lock()
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defer mb.mu.Unlock()
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if mb.IdleTimeout <= 0 {
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return
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}
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idle := time.Now().Sub(mb.lastActivity)
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if idle >= mb.IdleTimeout {
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mb.logf("modbus: closing connection due to idle timeout: %v", idle)
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mb.close()
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}
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}
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