github.com/codysnider/go-ethereum@v1.10.18-0.20220420071915-14f4ae99222a/accounts/keystore/watch.go (about)

     1  // Copyright 2016 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum 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-ethereum 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-ethereum 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/ethereum/go-ethereum/log"
    26  	"github.com/rjeczalik/notify"
    27  )
    28  
    29  type watcher struct {
    30  	ac       *accountCache
    31  	starting bool
    32  	running  bool
    33  	ev       chan notify.EventInfo
    34  	quit     chan struct{}
    35  }
    36  
    37  func newWatcher(ac *accountCache) *watcher {
    38  	return &watcher{
    39  		ac:   ac,
    40  		ev:   make(chan notify.EventInfo, 10),
    41  		quit: make(chan struct{}),
    42  	}
    43  }
    44  
    45  // starts the watcher loop in the background.
    46  // Start a watcher in the background if that's not already in progress.
    47  // The caller must hold w.ac.mu.
    48  func (w *watcher) start() {
    49  	if w.starting || w.running {
    50  		return
    51  	}
    52  	w.starting = true
    53  	go w.loop()
    54  }
    55  
    56  func (w *watcher) close() {
    57  	close(w.quit)
    58  }
    59  
    60  func (w *watcher) loop() {
    61  	defer func() {
    62  		w.ac.mu.Lock()
    63  		w.running = false
    64  		w.starting = false
    65  		w.ac.mu.Unlock()
    66  	}()
    67  	logger := log.New("path", w.ac.keydir)
    68  
    69  	if err := notify.Watch(w.ac.keydir, w.ev, notify.All); err != nil {
    70  		logger.Trace("Failed to watch keystore folder", "err", err)
    71  		return
    72  	}
    73  	defer notify.Stop(w.ev)
    74  	logger.Trace("Started watching keystore folder")
    75  	defer logger.Trace("Stopped watching keystore folder")
    76  
    77  	w.ac.mu.Lock()
    78  	w.running = true
    79  	w.ac.mu.Unlock()
    80  
    81  	// Wait for file system events and reload.
    82  	// When an event occurs, the reload call is delayed a bit so that
    83  	// multiple events arriving quickly only cause a single reload.
    84  	var (
    85  		debounceDuration = 500 * time.Millisecond
    86  		rescanTriggered  = false
    87  		debounce         = time.NewTimer(0)
    88  	)
    89  	// Ignore initial trigger
    90  	if !debounce.Stop() {
    91  		<-debounce.C
    92  	}
    93  	defer debounce.Stop()
    94  	for {
    95  		select {
    96  		case <-w.quit:
    97  			return
    98  		case <-w.ev:
    99  			// Trigger the scan (with delay), if not already triggered
   100  			if !rescanTriggered {
   101  				debounce.Reset(debounceDuration)
   102  				rescanTriggered = true
   103  			}
   104  		case <-debounce.C:
   105  			w.ac.scanAccounts()
   106  			rescanTriggered = false
   107  		}
   108  	}
   109  }