gearman-go/worker/agent.go

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// Copyright 2011 Xing Xing <mikespook@gmail.com> All rights reserved.
// Use of this source code is governed by a MIT
// license that can be found in the LICENSE file.
package worker
import (
"io"
"net"
"bitbucket.org/mikespook/gearman-go/common"
)
// The agent of job server.
type agent struct {
conn net.Conn
worker *Worker
in chan []byte
out chan *Job
}
// Create the agent of job server.
func newAgent(addr string, worker *Worker) (a *agent, err error) {
conn, err := net.Dial(common.NETWORK, addr)
if err != nil {
return
}
a = &agent{
conn: conn,
worker: worker,
in: make(chan []byte, common.QUEUE_SIZE),
out: make(chan *Job, common.QUEUE_SIZE),
}
return
}
// outputing loop
func (a *agent) outLoop() {
ok := true
for ok {
if job, ok := <-a.out; ok {
if err := a.write(job.Encode()); err != nil {
a.worker.err(err)
}
}
}
}
// inputing loop
func (a *agent) inLoop() {
defer func() {
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recover()
close(a.in)
close(a.out)
a.worker.removeAgent(a)
}()
noop := true
for a.worker.running {
// got noop msg and in queue is zero, grab job
if noop && len(a.in) == 0 {
a.WriteJob(newJob(common.REQ, common.GRAB_JOB, nil))
}
rel, err := a.read()
if err != nil {
if err == common.ErrEmptyReading {
break
}
a.worker.err(err)
continue
}
job, err := decodeJob(rel)
if err != nil {
a.worker.err(err)
continue
}
switch job.DataType {
case common.NOOP:
noop = true
case common.NO_JOB:
noop = false
a.WriteJob(newJob(common.REQ, common.PRE_SLEEP, nil))
case common.ERROR, common.ECHO_RES, common.JOB_ASSIGN_UNIQ, common.JOB_ASSIGN:
job.agent = a
a.worker.in <- job
}
}
}
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func (a *agent) Close() {
a.conn.Close()
}
func (a *agent) Work() {
go a.outLoop()
go a.inLoop()
}
// Internal read
func (a *agent) read() (data []byte, err error) {
if len(a.in) > 0 {
// in queue is not empty
data = <-a.in
} else {
for {
buf := make([]byte, common.BUFFER_SIZE)
var n int
if n, err = a.conn.Read(buf); err != nil {
if err == io.EOF && n == 0 {
if data == nil {
err = common.ErrEmptyReading
return
}
break
}
return
}
data = append(data, buf[0:n]...)
if n < common.BUFFER_SIZE {
break
}
}
}
// split package
tl := len(data)
start := 0
for i := 0; i < tl; i++ {
if string(data[start:start+4]) == common.RES_STR {
l := int(common.BytesToUint32([4]byte{data[start+8],
data[start+9], data[start+10], data[start+11]}))
total := l + 12
if total == tl {
return
} else {
a.in <- data[total:]
data = data[:total]
return
}
} else {
start++
}
}
return nil, common.Errorf("Invalid data: %V", data)
}
// Send a job to the job server.
func (a *agent) WriteJob(job *Job) {
a.out <- job
}
// Internal write the encoded job.
func (a *agent) write(buf []byte) (err error) {
var n int
for i := 0; i < len(buf); i += n {
n, err = a.conn.Write(buf[i:])
if err != nil {
return err
}
}
return
}