goirc/client/dispatch.go

153 lines
3.3 KiB
Go

package client
import (
"github.com/fluffle/golog/logging"
"runtime"
"strings"
"sync"
)
// An IRC Handler looks like this:
type Handler interface {
Handle(*Conn, *Line)
}
// And when they've been added to the client they are removable.
type Remover interface {
Remove()
}
// A HandlerFunc implements Handler.
type HandlerFunc func(*Conn, *Line)
func (hf HandlerFunc) Handle(conn *Conn, line *Line) {
hf(conn, line)
}
// Handlers are organised using a map of linked-lists, with each map
// key representing an IRC verb or numeric, and the linked list values
// being handlers that are executed in parallel when a Line from the
// server with that verb or numeric arrives.
type hSet struct {
set map[string]*hList
sync.RWMutex
}
type hList struct {
start, end *hNode
}
// Storing the forward and backward links in the node allows O(1) removal.
// This probably isn't strictly necessary but I think it's kinda nice.
type hNode struct {
next, prev *hNode
set *hSet
event string
handler Handler
}
// A hNode implements both Handler (with configurable panic recovery)...
func (hn *hNode) Handle(conn *Conn, line *Line) {
defer conn.cfg.Recover(conn, line)
hn.handler.Handle(conn, line)
}
// ... and Remover.
func (hn *hNode) Remove() {
hn.set.remove(hn)
}
func handlerSet() *hSet {
return &hSet{set: make(map[string]*hList)}
}
// When a new Handler is added for an event, it is wrapped in a hNode and
// returned as a Remover so the caller can remove it at a later time.
func (hs *hSet) add(ev string, h Handler) Remover {
hs.Lock()
defer hs.Unlock()
ev = strings.ToLower(ev)
l, ok := hs.set[ev]
if !ok {
l = &hList{}
}
hn := &hNode{
set: hs,
event: ev,
handler: h,
}
if !ok {
l.start = hn
} else {
hn.prev = l.end
l.end.next = hn
}
l.end = hn
hs.set[ev] = l
return hn
}
func (hs *hSet) remove(hn *hNode) {
hs.Lock()
defer hs.Unlock()
l, ok := hs.set[hn.event]
if !ok {
logging.Error("Removing node for unknown event '%s'", hn.event)
return
}
if hn.next == nil {
l.end = hn.prev
} else {
hn.next.prev = hn.prev
}
if hn.prev == nil {
l.start = hn.next
} else {
hn.prev.next = hn.next
}
hn.next = nil
hn.prev = nil
hn.set = nil
if l.start == nil || l.end == nil {
delete(hs.set, hn.event)
}
}
func (hs *hSet) dispatch(conn *Conn, line *Line) {
hs.RLock()
defer hs.RUnlock()
ev := strings.ToLower(line.Cmd)
list, ok := hs.set[ev]
if !ok {
return
}
for hn := list.start; hn != nil; hn = hn.next {
go hn.Handle(conn, line.Copy())
}
}
// Handlers are triggered on incoming Lines from the server, with the handler
// "name" being equivalent to Line.Cmd. Read the RFCs for details on what
// replies could come from the server. They'll generally be things like
// "PRIVMSG", "JOIN", etc. but all the numeric replies are left as ascii
// strings of digits like "332" (mainly because I really didn't feel like
// putting massive constant tables in).
func (conn *Conn) Handle(name string, h Handler) Remover {
return conn.handlers.add(name, h)
}
func (conn *Conn) HandleFunc(name string, hf HandlerFunc) Remover {
return conn.Handle(name, hf)
}
func (conn *Conn) dispatch(line *Line) {
conn.handlers.dispatch(conn, line)
}
func (conn *Conn) LogPanic(line *Line) {
if err := recover(); err != nil {
_, f, l, _ := runtime.Caller(2)
logging.Error("%s:%d: panic: %v", f, l, err)
}
}