syncthing/lib/events/events.go

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// Copyright (C) 2014 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.
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// Package events provides event subscription and polling functionality.
package events
import (
"errors"
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stdsync "sync"
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"time"
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"github.com/syncthing/syncthing/lib/sync"
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)
type EventType int
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const (
Ping EventType = 1 << iota
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Starting
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StartupComplete
DeviceDiscovered
DeviceConnected
DeviceDisconnected
DeviceRejected
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DevicePaused
DeviceResumed
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LocalIndexUpdated
RemoteIndexUpdated
ItemStarted
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ItemFinished
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StateChanged
FolderRejected
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ConfigSaved
DownloadProgress
FolderSummary
FolderCompletion
FolderErrors
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FolderScanProgress
ListenAddressesChanged
LoginAttempt
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AllEvents = (1 << iota) - 1
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)
func (t EventType) String() string {
switch t {
case Ping:
return "Ping"
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case Starting:
return "Starting"
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case StartupComplete:
return "StartupComplete"
case DeviceDiscovered:
return "DeviceDiscovered"
case DeviceConnected:
return "DeviceConnected"
case DeviceDisconnected:
return "DeviceDisconnected"
case DeviceRejected:
return "DeviceRejected"
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case LocalIndexUpdated:
return "LocalIndexUpdated"
case RemoteIndexUpdated:
return "RemoteIndexUpdated"
case ItemStarted:
return "ItemStarted"
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case ItemFinished:
return "ItemFinished"
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case StateChanged:
return "StateChanged"
case FolderRejected:
return "FolderRejected"
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case ConfigSaved:
return "ConfigSaved"
case DownloadProgress:
return "DownloadProgress"
case FolderSummary:
return "FolderSummary"
case FolderCompletion:
return "FolderCompletion"
case FolderErrors:
return "FolderErrors"
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case DevicePaused:
return "DevicePaused"
case DeviceResumed:
return "DeviceResumed"
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case FolderScanProgress:
return "FolderScanProgress"
case ListenAddressesChanged:
return "ListenAddressesChanged"
case LoginAttempt:
return "LoginAttempt"
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default:
return "Unknown"
}
}
func (t EventType) MarshalText() ([]byte, error) {
return []byte(t.String()), nil
}
const BufferSize = 64
type Logger struct {
subs []*Subscription
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nextID int
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mutex sync.Mutex
}
type Event struct {
ID int `json:"id"`
Time time.Time `json:"time"`
Type EventType `json:"type"`
Data interface{} `json:"data"`
}
type Subscription struct {
mask EventType
events chan Event
timeout *time.Timer
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}
var Default = NewLogger()
var (
ErrTimeout = errors.New("timeout")
ErrClosed = errors.New("closed")
)
func NewLogger() *Logger {
return &Logger{
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mutex: sync.NewMutex(),
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}
}
func (l *Logger) Log(t EventType, data interface{}) {
l.mutex.Lock()
Implement facility based logger, debugging via REST API This implements a new debug/trace infrastructure based on a slightly hacked up logger. Instead of the traditional "if debug { ... }" I've rewritten the logger to have no-op Debugln and Debugf, unless debugging has been enabled for a given "facility". The "facility" is just a string, typically a package name. This will be slightly slower than before; but not that much as it's mostly a function call that returns immediately. For the cases where it matters (the Debugln takes a hex.Dump() of something for example, and it's not in a very occasional "if err != nil" branch) there is an l.ShouldDebug(facility) that is fast enough to be used like the old "if debug". The point of all this is that we can now toggle debugging for the various packages on and off at runtime. There's a new method /rest/system/debug that can be POSTed a set of facilities to enable and disable debug for, or GET from to get a list of facilities with descriptions and their current debug status. Similarly a /rest/system/log?since=... can grab the latest log entries, up to 250 of them (hardcoded constant in main.go) plus the initial few. Not implemented in this commit (but planned) is a simple debug GUI available on /debug that shows the current log in an easily pasteable format and has checkboxes to enable the various debug facilities. The debug instructions to a user then becomes "visit this URL, check these boxes, reproduce your problem, copy and paste the log". The actual log viewer on the hypothetical /debug URL can poll regularly for new log entries and this bypass the 250 line limit. The existing STTRACE=foo variable is still obeyed and just sets the start state of the system.
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dl.Debugln("log", l.nextID, t, data)
l.nextID++
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e := Event{
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ID: l.nextID,
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Time: time.Now(),
Type: t,
Data: data,
}
for _, s := range l.subs {
if s.mask&t != 0 {
select {
case s.events <- e:
default:
// if s.events is not ready, drop the event
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}
}
}
l.mutex.Unlock()
}
func (l *Logger) Subscribe(mask EventType) *Subscription {
l.mutex.Lock()
Implement facility based logger, debugging via REST API This implements a new debug/trace infrastructure based on a slightly hacked up logger. Instead of the traditional "if debug { ... }" I've rewritten the logger to have no-op Debugln and Debugf, unless debugging has been enabled for a given "facility". The "facility" is just a string, typically a package name. This will be slightly slower than before; but not that much as it's mostly a function call that returns immediately. For the cases where it matters (the Debugln takes a hex.Dump() of something for example, and it's not in a very occasional "if err != nil" branch) there is an l.ShouldDebug(facility) that is fast enough to be used like the old "if debug". The point of all this is that we can now toggle debugging for the various packages on and off at runtime. There's a new method /rest/system/debug that can be POSTed a set of facilities to enable and disable debug for, or GET from to get a list of facilities with descriptions and their current debug status. Similarly a /rest/system/log?since=... can grab the latest log entries, up to 250 of them (hardcoded constant in main.go) plus the initial few. Not implemented in this commit (but planned) is a simple debug GUI available on /debug that shows the current log in an easily pasteable format and has checkboxes to enable the various debug facilities. The debug instructions to a user then becomes "visit this URL, check these boxes, reproduce your problem, copy and paste the log". The actual log viewer on the hypothetical /debug URL can poll regularly for new log entries and this bypass the 250 line limit. The existing STTRACE=foo variable is still obeyed and just sets the start state of the system.
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dl.Debugln("subscribe", mask)
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s := &Subscription{
mask: mask,
events: make(chan Event, BufferSize),
timeout: time.NewTimer(0),
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}
// We need to create the timeout timer in the stopped, non-fired state so
// that Subscription.Poll() can safely reset it and select on the timeout
// channel. This ensures the timer is stopped and the channel drained.
if !s.timeout.Stop() {
<-s.timeout.C
}
l.subs = append(l.subs, s)
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l.mutex.Unlock()
return s
}
func (l *Logger) Unsubscribe(s *Subscription) {
l.mutex.Lock()
Implement facility based logger, debugging via REST API This implements a new debug/trace infrastructure based on a slightly hacked up logger. Instead of the traditional "if debug { ... }" I've rewritten the logger to have no-op Debugln and Debugf, unless debugging has been enabled for a given "facility". The "facility" is just a string, typically a package name. This will be slightly slower than before; but not that much as it's mostly a function call that returns immediately. For the cases where it matters (the Debugln takes a hex.Dump() of something for example, and it's not in a very occasional "if err != nil" branch) there is an l.ShouldDebug(facility) that is fast enough to be used like the old "if debug". The point of all this is that we can now toggle debugging for the various packages on and off at runtime. There's a new method /rest/system/debug that can be POSTed a set of facilities to enable and disable debug for, or GET from to get a list of facilities with descriptions and their current debug status. Similarly a /rest/system/log?since=... can grab the latest log entries, up to 250 of them (hardcoded constant in main.go) plus the initial few. Not implemented in this commit (but planned) is a simple debug GUI available on /debug that shows the current log in an easily pasteable format and has checkboxes to enable the various debug facilities. The debug instructions to a user then becomes "visit this URL, check these boxes, reproduce your problem, copy and paste the log". The actual log viewer on the hypothetical /debug URL can poll regularly for new log entries and this bypass the 250 line limit. The existing STTRACE=foo variable is still obeyed and just sets the start state of the system.
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dl.Debugln("unsubscribe")
for i, ss := range l.subs {
if s == ss {
last := len(l.subs) - 1
l.subs[i] = l.subs[last]
l.subs[last] = nil
l.subs = l.subs[:last]
break
}
}
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close(s.events)
l.mutex.Unlock()
}
// Poll returns an event from the subscription or an error if the poll times
// out of the event channel is closed. Poll should not be called concurrently
// from multiple goroutines for a single subscription.
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func (s *Subscription) Poll(timeout time.Duration) (Event, error) {
Implement facility based logger, debugging via REST API This implements a new debug/trace infrastructure based on a slightly hacked up logger. Instead of the traditional "if debug { ... }" I've rewritten the logger to have no-op Debugln and Debugf, unless debugging has been enabled for a given "facility". The "facility" is just a string, typically a package name. This will be slightly slower than before; but not that much as it's mostly a function call that returns immediately. For the cases where it matters (the Debugln takes a hex.Dump() of something for example, and it's not in a very occasional "if err != nil" branch) there is an l.ShouldDebug(facility) that is fast enough to be used like the old "if debug". The point of all this is that we can now toggle debugging for the various packages on and off at runtime. There's a new method /rest/system/debug that can be POSTed a set of facilities to enable and disable debug for, or GET from to get a list of facilities with descriptions and their current debug status. Similarly a /rest/system/log?since=... can grab the latest log entries, up to 250 of them (hardcoded constant in main.go) plus the initial few. Not implemented in this commit (but planned) is a simple debug GUI available on /debug that shows the current log in an easily pasteable format and has checkboxes to enable the various debug facilities. The debug instructions to a user then becomes "visit this URL, check these boxes, reproduce your problem, copy and paste the log". The actual log viewer on the hypothetical /debug URL can poll regularly for new log entries and this bypass the 250 line limit. The existing STTRACE=foo variable is still obeyed and just sets the start state of the system.
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dl.Debugln("poll", timeout)
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s.timeout.Reset(timeout)
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select {
case e, ok := <-s.events:
if !ok {
return e, ErrClosed
}
if !s.timeout.Stop() {
// The timeout must be stopped and possibly drained to be ready
// for reuse in the next call.
<-s.timeout.C
}
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return e, nil
case <-s.timeout.C:
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return Event{}, ErrTimeout
}
}
func (s *Subscription) C() <-chan Event {
return s.events
}
type bufferedSubscription struct {
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sub *Subscription
buf []Event
next int
cur int
mut sync.Mutex
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cond *stdsync.Cond
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}
type BufferedSubscription interface {
Since(id int, into []Event) []Event
}
func NewBufferedSubscription(s *Subscription, size int) BufferedSubscription {
bs := &bufferedSubscription{
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sub: s,
buf: make([]Event, size),
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mut: sync.NewMutex(),
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}
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bs.cond = stdsync.NewCond(bs.mut)
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go bs.pollingLoop()
return bs
}
func (s *bufferedSubscription) pollingLoop() {
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for {
ev, err := s.sub.Poll(60 * time.Second)
if err == ErrTimeout {
continue
}
if err == ErrClosed {
return
}
if err != nil {
panic("unexpected error: " + err.Error())
}
s.mut.Lock()
s.buf[s.next] = ev
s.next = (s.next + 1) % len(s.buf)
s.cur = ev.ID
s.cond.Broadcast()
s.mut.Unlock()
}
}
func (s *bufferedSubscription) Since(id int, into []Event) []Event {
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s.mut.Lock()
defer s.mut.Unlock()
for id >= s.cur {
s.cond.Wait()
}
for i := s.next; i < len(s.buf); i++ {
if s.buf[i].ID > id {
into = append(into, s.buf[i])
}
}
for i := 0; i < s.next; i++ {
if s.buf[i].ID > id {
into = append(into, s.buf[i])
}
}
return into
}
// Error returns a string pointer suitable for JSON marshalling errors. It
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// retains the "null on success" semantics, but ensures the error result is a
// string regardless of the underlying concrete error type.
func Error(err error) *string {
if err == nil {
return nil
}
str := err.Error()
return &str
}