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package doozer

import (
"code.google.com/p/goprotobuf/proto"
"encoding/binary"
"errors"
"github.com/kr/pretty.go"

"io"
"log"
"math/rand"
"net"
"net/url"
"strings"
)

var (
uriPrefix = "doozer:?"
)

var (
ErrInvalidUri = errors.New("invalid uri")
)

type txn struct {
req request
resp *response
err error
done chan bool
}

type Conn struct {
addr string
conn net.Conn
send chan *txn
msg chan []byte
err error
stop chan bool
stopped chan bool
}

// Dial connects to a single doozer server.
func Dial(addr string) (*Conn, error) {
var c Conn
var err error
c.addr = addr
c.conn, err = net.Dial("tcp", addr)
if err != nil {
return nil, err
}

c.send = make(chan *txn)
c.msg = make(chan []byte)
c.stop = make(chan bool, 1)
c.stopped = make(chan bool)
errch := make(chan error, 1)
go c.mux(errch)
go c.readAll(errch)
return &c, nil
}

// DialUri connects to one of the doozer servers given in `uri`. If `uri`
// contains a cluster name, it will lookup addrs to try in `buri`. If `uri`
// contains a secret key, then DialUri will call `Access` with the secret.
func DialUri(uri, buri string) (*Conn, error) {
if !strings.HasPrefix(uri, uriPrefix) {
return nil, ErrInvalidUri
}

q := uri[len(uriPrefix):]
p, err := url.ParseQuery(q)
if err != nil {
return nil, err
}

addrs := make([]string, 0)

name, ok := p["cn"]
if ok && buri != "" {
c, err := DialUri(buri, "")
if err != nil {
return nil, err
}

addrs, err = lookup(c, name[0])
if err != nil {
return nil, err
}
} else {
var ok bool
addrs, ok = p["ca"]
if !ok {
return nil, ErrInvalidUri
}
}

c, err := Dial(addrs[rand.Int()%len(addrs)])
if err != nil {
return nil, err
}

secret, ok := p["sk"]
if ok {
err = c.Access(secret[0])
if err != nil {
c.Close()
return nil, err
}
}

return c, nil
}

// Find possible addresses for cluster named name.
func lookup(b *Conn, name string) (as []string, err error) {
rev, err := b.Rev()
if err != nil {
return nil, err
}

path := "/ctl/ns/" + name
names, err := b.Getdir(path, rev, 0, -1)
if err, ok := err.(*Error); ok && err.Err == ErrNoEnt {
return nil, nil
} else if err != nil {
return nil, err
}

path += "/"
for _, name := range names {
body, _, err := b.Get(path+name, &rev)
if err != nil {
return nil, err
}
as = append(as, string(body))
}
return as, nil
}

func (c *Conn) call(t *txn) error {
t.done = make(chan bool)
select {
case <-c.stopped:
return c.err
case c.send <- t:
<-t.done
if t.err != nil {
return t.err
}
if t.resp.ErrCode != nil {
return newError(t)
}
}
return nil
}

// After Close is called, operations on c will return ErrClosed.
func (c *Conn) Close() {
select {
case c.stop <- true:
default:
}
}

func (c *Conn) mux(errch chan error) {
txns := make(map[int32]*txn)
var n int32 // next tag
var err error

for {
select {
case t := <-c.send:
// find an unused tag
for t := txns[n]; t != nil; t = txns[n] {
n++
}
txns[n] = t

// don't take n's address; it will change
tag := n
t.req.Tag = &tag

var buf []byte
buf, err = proto.Marshal(&t.req)
if err != nil {
txns[n] = nil
t.err = err
t.done <- true
continue
}

err = c.write(buf)
if err != nil {
goto error
}
case buf := <-c.msg:
var r response
err = proto.Unmarshal(buf, &r)
if err != nil {
log.Print(err)
continue
}

if r.Tag == nil {
log.Printf("nil tag: %# v", pretty.Formatter(r))
continue
}
t := txns[*r.Tag]
if t == nil {
log.Printf("unexpected: %# v", pretty.Formatter(r))
continue
}

delete(txns, *r.Tag)
t.resp = &r
t.done <- true
case err = <-errch:
goto error
case <-c.stop:
err = ErrClosed
goto error
}
}

error:
c.err = err
for _, t := range txns {
t.err = err
t.done <- true
}
c.conn.Close()
close(c.stopped)
}

func (c *Conn) readAll(errch chan error) {
for {
buf, err := c.read()
if err != nil {
errch <- err
return
}

c.msg <- buf
}
}

func (c *Conn) read() ([]byte, error) {
var size int32
err := binary.Read(c.conn, binary.BigEndian, &size)
if err != nil {
return nil, err
}

buf := make([]byte, size)
_, err = io.ReadFull(c.conn, buf)
if err != nil {
return nil, err
}

return buf, nil
}

func (c *Conn) write(buf []byte) error {
err := binary.Write(c.conn, binary.BigEndian, int32(len(buf)))
if err != nil {
return err
}

_, err = c.conn.Write(buf)
return err
}

// Attempts access to the store
func (c *Conn) Access(token string) error {
var t txn
t.req.Verb = newRequest_Verb(request_ACCESS)
t.req.Value = []byte(token)
return c.call(&t)
}

// Sets the contents of file to body, if it hasn't been modified since oldRev.
func (c *Conn) Set(file string, oldRev int64, body []byte) (newRev int64, err error) {
var t txn
t.req.Verb = newRequest_Verb(request_SET)
t.req.Path = &file
t.req.Value = body
t.req.Rev = &oldRev

err = c.call(&t)
if err != nil {
return
}

return proto.GetInt64(t.resp.Rev), nil
}

// Deletes file, if it hasn't been modified since rev.
func (c *Conn) Del(file string, rev int64) error {
var t txn
t.req.Verb = newRequest_Verb(request_DEL)
t.req.Path = &file
t.req.Rev = &rev
return c.call(&t)
}

func (c *Conn) Nop() error {
var t txn
t.req.Verb = newRequest_Verb(request_NOP)
return c.call(&t)
}

// Returns the body and revision of the file at path,
// as of store revision *rev.
// If rev is nil, uses the current state.
func (c *Conn) Get(file string, rev *int64) ([]byte, int64, error) {
var t txn
t.req.Verb = newRequest_Verb(request_GET)
t.req.Path = &file
t.req.Rev = rev

err := c.call(&t)
if err != nil {
return nil, 0, err
}

return t.resp.Value, proto.GetInt64(t.resp.Rev), nil
}

// Getdir reads up to lim names from dir, at revision rev, into an array.
// Names are read in lexicographical order, starting at position off.
// A negative lim means to read until the end.
func (c *Conn) Getdir(dir string, rev int64, off, lim int) (names []string, err error) {
for lim != 0 {
var t txn
t.req.Verb = newRequest_Verb(request_GETDIR)
t.req.Rev = &rev
t.req.Path = &dir
t.req.Offset = proto.Int32(int32(off))
err = c.call(&t)
if err, ok := err.(*Error); ok && err.Err == ErrRange {
return names, nil
}
if err != nil {
return nil, err
}
names = append(names, *t.resp.Path)
off++
lim--
}
return
}

// Getdirinfo reads metadata for up to lim files from dir, at revision rev,
// into an array.
// Files are read in lexicographical order, starting at position off.
// A negative lim means to read until the end.
// Getdirinfo returns the array and an error, if any.
func (c *Conn) Getdirinfo(dir string, rev int64, off, lim int) (a []FileInfo, err error) {
names, err := c.Getdir(dir, rev, off, lim)
if err != nil {
return nil, err
}

if dir != "/" {
dir += "/"
}
a = make([]FileInfo, len(names))
for i, name := range names {
var fp *FileInfo
fp, err = c.Statinfo(rev, dir+name)
if err != nil {
a[i].Name = name
} else {
a[i] = *fp
}
}
return
}

// Statinfo returns metadata about the file or directory at path,
// in revision *storeRev. If storeRev is nil, uses the current
// revision.
func (c *Conn) Statinfo(rev int64, path string) (f *FileInfo, err error) {
f = new(FileInfo)
f.Len, f.Rev, err = c.Stat(path, &rev)
if err != nil {
return nil, err
}
if f.Rev == missing {
return nil, ErrNoEnt
}
f.Name = basename(path)
f.IsSet = true
f.IsDir = f.Rev == dir
return f, nil
}

// Stat returns metadata about the file or directory at path,
// in revision *storeRev. If storeRev is nil, uses the current
// revision.
func (c *Conn) Stat(path string, storeRev *int64) (len int, fileRev int64, err error) {
var t txn
t.req.Verb = newRequest_Verb(request_STAT)
t.req.Path = &path
t.req.Rev = storeRev

err = c.call(&t)
if err != nil {
return 0, 0, err
}

return int(proto.GetInt32(t.resp.Len)), proto.GetInt64(t.resp.Rev), nil
}

// Walk reads up to lim entries matching glob, in revision rev, into an array.
// Entries are read in lexicographical order, starting at position off.
// A negative lim means to read until the end.
// Conn.Walk will be removed in a future release. Use Walk instead.
func (c *Conn) Walk(glob string, rev int64, off, lim int) (info []Event, err error) {
for lim != 0 {
var t txn
t.req.Verb = newRequest_Verb(request_WALK)
t.req.Rev = &rev
t.req.Path = &glob
t.req.Offset = proto.Int32(int32(off))
err = c.call(&t)
if err, ok := err.(*Error); ok && err.Err == ErrRange {
return info, nil
}
if err != nil {
return nil, err
}
info = append(info, Event{
*t.resp.Rev,
*t.resp.Path,
t.resp.Value,
*t.resp.Flags,
})
off++
lim--
}
return
}

// Waits for the first change, on or after rev, to any file matching glob.
func (c *Conn) Wait(glob string, rev int64) (ev Event, err error) {
var t txn
t.req.Verb = newRequest_Verb(request_WAIT)
t.req.Path = &glob
t.req.Rev = &rev

err = c.call(&t)
if err != nil {
return
}

ev.Rev = *t.resp.Rev
ev.Path = *t.resp.Path
ev.Body = t.resp.Value
ev.Flag = *t.resp.Flags & (set | del)
return
}

// Rev returns the current revision of the store.
func (c *Conn) Rev() (int64, error) {
var t txn
t.req.Verb = newRequest_Verb(request_REV)

err := c.call(&t)
if err != nil {
return 0, err
}

return *t.resp.Rev, nil
}
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