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package tanja
import (
"blicky.net/asyncwr"
"bufio"
"errors"
"io"
"strings"
)
type Link struct {
Sync bool
Ready bool
ReadyCh <-chan bool
readyWr chan<- bool
Closed bool
node *Node
io io.ReadWriteCloser
wr *asyncwr.Writer
err chan<- error
regs map[int32]*Registration
paths map[int32]*ReturnPath
lastId int32
lastTup *Tuple
}
func (n *Node) Link(io io.ReadWriteCloser) (l *Link) {
l = &Link{}
l.Sync = true
ready := make(chan bool, 1)
l.ReadyCh = ready
l.readyWr = ready
l.io = io
l.wr = asyncwr.New(io, 1024*1024) // TODO: make configurable
l.node = n
l.regs = make(map[int32]*Registration)
l.paths = make(map[int32]*ReturnPath)
l.lastId = 1
return l
}
func (l *Link) handleHandshake(buf []byte) (err error) {
strl := strings.Split(string(buf), " ")
hasver := false
hasseri := false
hassero := false
for _, arg := range strl {
if strings.HasPrefix(arg, "ver,") && strings.Contains(arg, ",1.") {
hasver = true
}
// TODO: These checks aren't too good, would also match "json-whatever"
if strings.HasPrefix(arg, "seri,") && strings.Contains(arg, ",json") {
hasseri = true
}
if strings.HasPrefix(arg, "sero,") && strings.Contains(arg, ",json") {
hassero = true
}
}
if !hasver || !hasseri || !hassero {
err = errors.New("Invalid handshake message.")
} else {
if l.Sync {
linkMsgWrite(l.wr, linkMsgPatternsync(true))
} else {
l.node.lock.Lock()
r := &Registration{pat: Tup(), active: true, willReply: true, recv: l}
l.node.reg(r)
l.regs[0] = r
l.node.lock.Unlock()
l.Ready = true
l.readyWr <- true
close(l.readyWr)
}
}
return
}
// Called while the node lock is held
func (l *Link) nodeUnreg(id int32) {
if !l.Closed {
linkMsgWrite(l.wr, linkMsgUnregister(id))
}
}
// Called while the node lock is held.
func (l *Link) nodeReg(r *Registration) {
if !l.Closed && r.recv != l {
linkMsgWrite(l.wr, &linkMsgRegister{r.id, r.pat})
}
}
// Called while the node lock is held.
func (l *Link) nodeSend(t *Tuple, p *ReturnPath) {
if !l.Closed && l.lastTup != t {
m := &linkMsgTuple{0, *t}
if p != nil {
old := l.lastId
for old == l.lastId || l.paths[l.lastId] != nil {
l.lastId++
if l.lastId < 0 {
l.lastId = 1
}
}
m.tid = l.lastId
l.paths[m.tid] = p
}
linkMsgWrite(l.wr, m)
l.lastTup = t
} else {
p.unref()
}
}
// Node lock may or may not be held when this function is called
func (l *Link) pathReply(r *ReturnPath, t Tuple) {
if !l.Closed {
linkMsgWrite(l.wr, &linkMsgReply{r.id, t})
}
}
// Node lock is held when this is called.
func (l *Link) pathClose(r *ReturnPath) {
if !l.Closed {
linkMsgWrite(l.wr, linkMsgClose(r.id))
}
}
func (l *Link) handleMessage(msg interface{}) error {
switch m := msg.(type) {
case linkMsgPatternsync:
l.node.lock.Lock()
if bool(m) && !l.Closed {
l.node.links[l] = true
for k, v := range l.node.regs {
linkMsgWrite(l.wr, &linkMsgRegister{k, v.pat})
}
linkMsgWrite(l.wr, linkMsgRegdone{})
} else {
delete(l.node.links, l)
}
l.node.lock.Unlock()
case *linkMsgRegister:
l.node.lock.Lock()
if l.Sync && !l.Closed {
if r := l.regs[m.pid]; r != nil {
l.node.unregOne(r)
}
r := &Registration{pat: m.pat, active: true, willReply: true, recv: l}
l.node.reg(r)
l.regs[m.pid] = r
}
l.node.lock.Unlock()
case linkMsgRegdone:
if !l.Ready {
l.Ready = true
l.readyWr <- true
close(l.readyWr)
}
case linkMsgUnregister:
l.node.lock.Lock()
if l.Sync && !l.Closed {
if r := l.regs[int32(m)]; r != nil {
l.node.unregOne(r)
delete(l.regs, int32(m))
}
}
l.node.lock.Unlock()
case *linkMsgTuple:
l.node.lock.Lock()
var r *ReturnPath
if m.tid != 0 {
r = &ReturnPath{obj: l, id: m.tid}
}
l.node.send(m.tup, r, l)
l.node.lock.Unlock()
case *linkMsgReply:
// l.paths is protected by the node lock. (This lock does protect a lot...)
l.node.lock.Lock()
if r := l.paths[m.tid]; r != nil {
r.reply(m.tup)
}
l.node.lock.Unlock()
case linkMsgClose:
l.node.lock.Lock()
if r := l.paths[int32(m)]; r != nil {
r.unref()
}
l.node.lock.Unlock()
}
return nil
}
// TODO: There should be a timeout on the handshake (+ remote pattern syncing)
func (l *Link) reader() {
// Make sure we've got a buffered reader with a large enough buffer to fit
// any message. This isn't the most elegant approach, but should do the
// trick.
rd := bufio.NewReaderSize(l.io, 1*1024*1024)
// Handshake
line, prefix, err := rd.ReadLine()
if prefix && err == nil {
err = errors.New("Read buffer overflow.")
} else if err == nil {
err = l.handleHandshake(line)
}
// Message loop
for err == nil {
var m interface{}
if m, err = linkMsgRead(rd); err == nil {
err = l.handleMessage(m)
}
}
if err != nil {
l.err <- err
return
}
}
// The returned channel will get exactly a single message when the link is
// closed. Either nil after a normal Close() or an error otherwise.
func (l *Link) Start() <-chan error {
err := make(chan error, 5) // Must be buffered to allow some extra errors (which will be ignored)
uerr := make(chan error)
l.err = err
go l.reader()
// A control goroutine to shut things down. This allows multiple writes to
// l.err, but only the first is handled.
go func() {
var e error
select {
case e = <-err:
case e = <-l.wr.ErrorCh():
}
l.node.lock.Lock()
delete(l.node.links, l)
for _, r := range l.regs {
l.node.unregOne(r)
}
for _, r := range l.paths {
r.unref()
}
l.Closed = true
l.node.lock.Unlock()
l.io.Close() // should wake up the reader (with an error)
uerr <- e
}()
// Send handshake
l.wr.Write([]byte("ver,1.0 seri,json sero,json\n"))
return uerr
}
func (l *Link) Close() {
l.err <- nil
}
|