134 lines
3.1 KiB
Go
134 lines
3.1 KiB
Go
// Copyright (c) 2017 Shivaram Lingamneni <slingamn@cs.stanford.edu>
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// released under the MIT license
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package irc
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import (
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"time"
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)
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// BrbTimer is a timer on the client as a whole (not an individual session) for implementing
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// the BRB command and related functionality (where a client can remain online without
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// having any connected sessions).
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type BrbState uint
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const (
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// BrbDisabled is the default state; the client will be disconnected if it has no sessions
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BrbDisabled BrbState = iota
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// BrbEnabled allows the client to remain online without sessions; if a timeout is
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// reached, it will be removed
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BrbEnabled
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// BrbDead is the state of a client after its timeout has expired; it will be removed
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// and therefore new sessions cannot be attached to it
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BrbDead
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)
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type BrbTimer struct {
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// XXX we use client.stateMutex for synchronization, so we can atomically test
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// conditions that use both brbTimer.state and client.sessions. This code
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// is tightly coupled with the rest of Client.
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client *Client
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state BrbState
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brbAt time.Time
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duration time.Duration
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timer *time.Timer
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}
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func (bt *BrbTimer) Initialize(client *Client) {
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bt.client = client
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}
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// attempts to enable BRB for a client, returns whether it succeeded
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func (bt *BrbTimer) Enable() (success bool, duration time.Duration) {
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// TODO make this configurable
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duration = ResumeableTotalTimeout
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bt.client.stateMutex.Lock()
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defer bt.client.stateMutex.Unlock()
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if !bt.client.registered || bt.client.alwaysOn || bt.client.resumeID == "" {
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return
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}
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switch bt.state {
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case BrbDisabled, BrbEnabled:
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bt.state = BrbEnabled
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bt.duration = duration
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bt.resetTimeout()
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// only track the earliest BRB, if multiple sessions are BRB'ing at once
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// TODO(#524) this is inaccurate in case of an auto-BRB
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if bt.brbAt.IsZero() {
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bt.brbAt = time.Now().UTC()
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}
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success = true
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default:
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// BrbDead
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success = false
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}
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return
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}
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// turns off BRB for a client and stops the timer; used on resume and during
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// client teardown
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func (bt *BrbTimer) Disable() (brbAt time.Time) {
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bt.client.stateMutex.Lock()
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defer bt.client.stateMutex.Unlock()
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if bt.state == BrbEnabled {
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bt.state = BrbDisabled
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brbAt = bt.brbAt
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bt.brbAt = time.Time{}
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}
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bt.resetTimeout()
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return
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}
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func (bt *BrbTimer) resetTimeout() {
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if bt.timer != nil {
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bt.timer.Stop()
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}
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if bt.state != BrbEnabled {
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return
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}
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if bt.timer == nil {
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bt.timer = time.AfterFunc(bt.duration, bt.processTimeout)
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} else {
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bt.timer.Reset(bt.duration)
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}
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}
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func (bt *BrbTimer) processTimeout() {
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dead := false
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defer func() {
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if dead {
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bt.client.Quit(bt.client.AwayMessage(), nil)
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bt.client.destroy(nil)
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}
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}()
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bt.client.stateMutex.Lock()
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defer bt.client.stateMutex.Unlock()
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if bt.client.alwaysOn {
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return
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}
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switch bt.state {
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case BrbDisabled, BrbEnabled:
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if len(bt.client.sessions) == 0 {
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// client never returned, quit them
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bt.state = BrbDead
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dead = true
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} else {
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// client resumed, reattached, or has another active session
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bt.state = BrbDisabled
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bt.brbAt = time.Time{}
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}
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case BrbDead:
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dead = true // shouldn't be possible but whatever
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}
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bt.resetTimeout()
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}
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