github.com/flashbots/go-ethereum@v1.9.7/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  // +build darwin,!ios,cgo freebsd linux,!arm64 netbsd solaris
    18  
    19  package keystore
    20  
    21  import (
    22  	"time"
    23  
    24  	"github.com/ethereum/go-ethereum/log"
    25  	"github.com/rjeczalik/notify"
    26  )
    27  
    28  type watcher struct {
    29  	ac       *accountCache
    30  	starting bool
    31  	running  bool
    32  	ev       chan notify.EventInfo
    33  	quit     chan struct{}
    34  }
    35  
    36  func newWatcher(ac *accountCache) *watcher {
    37  	return &watcher{
    38  		ac:   ac,
    39  		ev:   make(chan notify.EventInfo, 10),
    40  		quit: make(chan struct{}),
    41  	}
    42  }
    43  
    44  // starts the watcher loop in the background.
    45  // Start a watcher in the background if that's not already in progress.
    46  // The caller must hold w.ac.mu.
    47  func (w *watcher) start() {
    48  	if w.starting || w.running {
    49  		return
    50  	}
    51  	w.starting = true
    52  	go w.loop()
    53  }
    54  
    55  func (w *watcher) close() {
    56  	close(w.quit)
    57  }
    58  
    59  func (w *watcher) loop() {
    60  	defer func() {
    61  		w.ac.mu.Lock()
    62  		w.running = false
    63  		w.starting = false
    64  		w.ac.mu.Unlock()
    65  	}()
    66  	logger := log.New("path", w.ac.keydir)
    67  
    68  	if err := notify.Watch(w.ac.keydir, w.ev, notify.All); err != nil {
    69  		logger.Trace("Failed to watch keystore folder", "err", err)
    70  		return
    71  	}
    72  	defer notify.Stop(w.ev)
    73  	logger.Trace("Started watching keystore folder")
    74  	defer logger.Trace("Stopped watching keystore folder")
    75  
    76  	w.ac.mu.Lock()
    77  	w.running = true
    78  	w.ac.mu.Unlock()
    79  
    80  	// Wait for file system events and reload.
    81  	// When an event occurs, the reload call is delayed a bit so that
    82  	// multiple events arriving quickly only cause a single reload.
    83  	var (
    84  		debounceDuration = 500 * time.Millisecond
    85  		rescanTriggered  = false
    86  		debounce         = time.NewTimer(0)
    87  	)
    88  	// Ignore initial trigger
    89  	if !debounce.Stop() {
    90  		<-debounce.C
    91  	}
    92  	defer debounce.Stop()
    93  	for {
    94  		select {
    95  		case <-w.quit:
    96  			return
    97  		case <-w.ev:
    98  			// Trigger the scan (with delay), if not already triggered
    99  			if !rescanTriggered {
   100  				debounce.Reset(debounceDuration)
   101  				rescanTriggered = true
   102  			}
   103  		case <-debounce.C:
   104  			w.ac.scanAccounts()
   105  			rescanTriggered = false
   106  		}
   107  	}
   108  }