github.com/core-coin/go-core/v2@v2.1.9/accounts/keystore/watch.go (about)

     1  // Copyright 2016 by the Authors
     2  // This file is part of the go-core library.
     3  //
     4  // The go-core library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-core library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-core library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  //go:build (darwin && !ios && cgo) || freebsd || (linux && !arm64) || netbsd || solaris
    18  // +build darwin,!ios,cgo freebsd linux,!arm64 netbsd solaris
    19  
    20  package keystore
    21  
    22  import (
    23  	"time"
    24  
    25  	"github.com/rjeczalik/notify"
    26  
    27  	"github.com/core-coin/go-core/v2/log"
    28  )
    29  
    30  type watcher struct {
    31  	ac       *accountCache
    32  	starting bool
    33  	running  bool
    34  	ev       chan notify.EventInfo
    35  	quit     chan struct{}
    36  }
    37  
    38  func newWatcher(ac *accountCache) *watcher {
    39  	return &watcher{
    40  		ac:   ac,
    41  		ev:   make(chan notify.EventInfo, 10),
    42  		quit: make(chan struct{}),
    43  	}
    44  }
    45  
    46  // starts the watcher loop in the background.
    47  // Start a watcher in the background if that's not already in progress.
    48  // The caller must hold w.ac.mu.
    49  func (w *watcher) start() {
    50  	if w.starting || w.running {
    51  		return
    52  	}
    53  	w.starting = true
    54  	go w.loop()
    55  }
    56  
    57  func (w *watcher) close() {
    58  	close(w.quit)
    59  }
    60  
    61  func (w *watcher) loop() {
    62  	defer func() {
    63  		w.ac.mu.Lock()
    64  		w.running = false
    65  		w.starting = false
    66  		w.ac.mu.Unlock()
    67  	}()
    68  	logger := log.New("path", w.ac.keydir)
    69  
    70  	if err := notify.Watch(w.ac.keydir, w.ev, notify.All); err != nil {
    71  		logger.Trace("Failed to watch keystore folder", "err", err)
    72  		return
    73  	}
    74  	defer notify.Stop(w.ev)
    75  	logger.Trace("Started watching keystore folder")
    76  	defer logger.Trace("Stopped watching keystore folder")
    77  
    78  	w.ac.mu.Lock()
    79  	w.running = true
    80  	w.ac.mu.Unlock()
    81  
    82  	// Wait for file system events and reload.
    83  	// When an event occurs, the reload call is delayed a bit so that
    84  	// multiple events arriving quickly only cause a single reload.
    85  	var (
    86  		debounceDuration = 500 * time.Millisecond
    87  		rescanTriggered  = false
    88  		debounce         = time.NewTimer(0)
    89  	)
    90  	// Ignore initial trigger
    91  	if !debounce.Stop() {
    92  		<-debounce.C
    93  	}
    94  	defer debounce.Stop()
    95  	for {
    96  		select {
    97  		case <-w.quit:
    98  			return
    99  		case <-w.ev:
   100  			// Trigger the scan (with delay), if not already triggered
   101  			if !rescanTriggered {
   102  				debounce.Reset(debounceDuration)
   103  				rescanTriggered = true
   104  			}
   105  		case <-debounce.C:
   106  			w.ac.scanAccounts()
   107  			rescanTriggered = false
   108  		}
   109  	}
   110  }