github.com/electroneum/electroneum-sc@v0.0.0-20230105223411-3bc1d078281e/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/electroneum/electroneum-sc/log"
    26  	"github.com/fsnotify/fsnotify"
    27  )
    28  
    29  type watcher struct {
    30  	ac       *accountCache
    31  	starting bool
    32  	running  bool
    33  	quit     chan struct{}
    34  }
    35  
    36  func newWatcher(ac *accountCache) *watcher {
    37  	return &watcher{
    38  		ac:   ac,
    39  		quit: make(chan struct{}),
    40  	}
    41  }
    42  
    43  // starts the watcher loop in the background.
    44  // Start a watcher in the background if that's not already in progress.
    45  // The caller must hold w.ac.mu.
    46  func (w *watcher) start() {
    47  	if w.starting || w.running {
    48  		return
    49  	}
    50  	w.starting = true
    51  	go w.loop()
    52  }
    53  
    54  func (w *watcher) close() {
    55  	close(w.quit)
    56  }
    57  
    58  func (w *watcher) loop() {
    59  	defer func() {
    60  		w.ac.mu.Lock()
    61  		w.running = false
    62  		w.starting = false
    63  		w.ac.mu.Unlock()
    64  	}()
    65  	logger := log.New("path", w.ac.keydir)
    66  
    67  	// Create new watcher.
    68  	watcher, err := fsnotify.NewWatcher()
    69  	if err != nil {
    70  		log.Error("Failed to start filesystem watcher", "err", err)
    71  		return
    72  	}
    73  	defer watcher.Close()
    74  	if err := watcher.Add(w.ac.keydir); err != nil {
    75  		logger.Warn("Failed to watch keystore folder", "err", err)
    76  		return
    77  	}
    78  
    79  	logger.Trace("Started watching keystore folder", "folder", w.ac.keydir)
    80  	defer logger.Trace("Stopped watching keystore folder")
    81  
    82  	w.ac.mu.Lock()
    83  	w.running = true
    84  	w.ac.mu.Unlock()
    85  
    86  	// Wait for file system events and reload.
    87  	// When an event occurs, the reload call is delayed a bit so that
    88  	// multiple events arriving quickly only cause a single reload.
    89  	var (
    90  		debounceDuration = 500 * time.Millisecond
    91  		rescanTriggered  = false
    92  		debounce         = time.NewTimer(0)
    93  	)
    94  	// Ignore initial trigger
    95  	if !debounce.Stop() {
    96  		<-debounce.C
    97  	}
    98  	defer debounce.Stop()
    99  	for {
   100  		select {
   101  		case <-w.quit:
   102  			return
   103  		case _, ok := <-watcher.Events:
   104  			if !ok {
   105  				return
   106  			}
   107  			// Trigger the scan (with delay), if not already triggered
   108  			if !rescanTriggered {
   109  				debounce.Reset(debounceDuration)
   110  				rescanTriggered = true
   111  			}
   112  			// The fsnotify library does provide more granular event-info, it
   113  			// would be possible to refresh individual affected files instead
   114  			// of scheduling a full rescan. For most cases though, the
   115  			// full rescan is quick and obviously simplest.
   116  		case err, ok := <-watcher.Errors:
   117  			if !ok {
   118  				return
   119  			}
   120  			log.Info("Filsystem watcher error", "err", err)
   121  		case <-debounce.C:
   122  			w.ac.scanAccounts()
   123  			rescanTriggered = false
   124  		}
   125  	}
   126  }