gearman-go/worker/worker.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 (
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"encoding/binary"
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"fmt"
"sync"
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"time"
)
const (
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Immediately = 0
)
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/*
Worker side api for gearman
usage:
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w = worker.New()
w.AddFunction("foobar", foobar)
w.AddServer("127.0.0.1:4730")
w.Work() // Enter the worker's main loop
The definition of the callback function 'foobar' should suit for the type 'JobFunction'.
It looks like this:
func foobar(job *Job) (data []byte, err os.Error) {
//sth. here
//plaplapla...
return
}
*/
type Worker struct {
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agents []*agent
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funcs JobFuncs
in chan *inPack
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running bool
Id string
// assign a ErrFunc to handle errors
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ErrorHandler ErrorHandler
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JobHandler JobHandler
mutex sync.Mutex
}
// Get a new worker
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func New() (worker *Worker) {
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worker = &Worker{
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agents: make([]*agent, 0),
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funcs: make(JobFuncs),
in: make(chan *inPack, QUEUE_SIZE),
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}
return
}
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//
func (worker *Worker) err(e error) {
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if worker.ErrorHandler != nil {
worker.ErrorHandler(e)
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}
}
// Add a server. The addr should be 'host:port' format.
// The connection is established at this time.
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func (worker *Worker) AddServer(net, addr string) (err error) {
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// Create a new job server's client as a agent of server
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a, err := newAgent(net, addr, worker)
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if err != nil {
return err
}
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worker.agents = append(worker.agents, a)
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return
}
// Write a job to job server.
// Here, the job's mean is not the oraginal mean.
// Just looks like a network package for job's result or tell job server, there was a fail.
func (worker *Worker) broadcast(outpack *outPack) {
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for _, v := range worker.agents {
v.write(outpack)
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}
}
// Add a function.
// Plz added job servers first, then functions.
// The API will tell every connected job server that 'I can do this'
func (worker *Worker) AddFunc(funcname string,
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f JobFunc, timeout uint32) (err error) {
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worker.mutex.Lock()
defer worker.mutex.Unlock()
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if _, ok := worker.funcs[funcname]; ok {
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return fmt.Errorf("The function already exists: %s", funcname)
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}
worker.funcs[funcname] = &jobFunc{f: f, timeout: timeout}
if worker.running {
worker.addFunc(funcname, timeout)
}
return
}
// inner add function
func (worker *Worker) addFunc(funcname string, timeout uint32) {
outpack := getOutPack()
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if timeout == 0 {
outpack.dataType = CAN_DO
outpack.data = []byte(funcname)
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} else {
outpack.dataType = CAN_DO_TIMEOUT
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l := len(funcname)
outpack.data = getBuffer(l + 5)
copy(outpack.data, []byte(funcname))
outpack.data[l] = '\x00'
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binary.BigEndian.PutUint32(outpack.data[l+1:], timeout)
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}
worker.broadcast(outpack)
}
// Remove a function.
func (worker *Worker) RemoveFunc(funcname string) (err error) {
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worker.mutex.Lock()
defer worker.mutex.Unlock()
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if _, ok := worker.funcs[funcname]; !ok {
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return fmt.Errorf("The function does not exist: %s", funcname)
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}
delete(worker.funcs, funcname)
if worker.running {
worker.removeFunc(funcname)
}
return
}
// inner remove function
func (worker *Worker) removeFunc(funcname string) {
outpack := getOutPack()
outpack.dataType = CANT_DO
outpack.data = []byte(funcname)
worker.broadcast(outpack)
}
func (worker *Worker) handleInPack(inpack *inPack) {
switch inpack.dataType {
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case NO_JOB:
inpack.a.PreSleep()
case NOOP:
inpack.a.Grab()
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case ERROR:
worker.err(GetError(inpack.data))
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case JOB_ASSIGN, JOB_ASSIGN_UNIQ:
if err := worker.exec(inpack); err != nil {
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worker.err(err)
}
default:
worker.customeHandler(inpack)
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}
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}
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func (worker *Worker) Ready() (err error) {
for _, v := range worker.agents {
if err = v.Connect(); err != nil {
return
}
}
for funcname, f := range worker.funcs {
worker.addFunc(funcname, f.timeout)
}
return
}
// Main loop
func (worker *Worker) Work() {
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worker.running = true
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for _, v := range worker.agents {
v.Grab()
}
var inpack *inPack
for inpack = range worker.in {
go worker.handleInPack(inpack)
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}
}
// job handler
func (worker *Worker) customeHandler(inpack *inPack) {
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if worker.JobHandler != nil {
if err := worker.JobHandler(inpack); err != nil {
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worker.err(err)
}
}
}
// Close.
func (worker *Worker) Close() {
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worker.running = false
close(worker.in)
}
// Send a something out, get the samething back.
func (worker *Worker) Echo(data []byte) {
outpack := getOutPack()
outpack.dataType = ECHO_REQ
outpack.data = data
worker.broadcast(outpack)
}
// Remove all of functions.
// Both from the worker or job servers.
func (worker *Worker) Reset() {
outpack := getOutPack()
outpack.dataType = RESET_ABILITIES
worker.broadcast(outpack)
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worker.funcs = make(JobFuncs)
}
// Set the worker's unique id.
func (worker *Worker) SetId(id string) {
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worker.Id = id
outpack := getOutPack()
outpack.dataType = SET_CLIENT_ID
outpack.data = []byte(id)
worker.broadcast(outpack)
}
// Execute the job. And send back the result.
func (worker *Worker) exec(inpack *inPack) (err error) {
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defer func() {
if r := recover(); r != nil {
if e, ok := r.(error); ok {
err = e
} else {
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err = ErrUnknown
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}
}
}()
f, ok := worker.funcs[inpack.fn]
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if !ok {
return fmt.Errorf("The function does not exist: %s", inpack.fn)
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}
var r *result
if f.timeout == 0 {
d, e := f.f(inpack)
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r = &result{data: d, err: e}
} else {
r = execTimeout(f.f, inpack, time.Duration(f.timeout)*time.Second)
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}
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if worker.running {
outpack := getOutPack()
if r.err == nil {
outpack.dataType = WORK_COMPLETE
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} else {
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if len(r.data) == 0 {
outpack.dataType = WORK_FAIL
} else {
outpack.dataType = WORK_EXCEPTION
}
err = r.err
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}
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outpack.handle = inpack.handle
outpack.data = r.data
inpack.a.write(outpack)
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inpack.a.Grab()
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}
return
}
type result struct {
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data []byte
err error
}
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func execTimeout(f JobFunc, job Job, timeout time.Duration) (r *result) {
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rslt := make(chan *result)
defer close(rslt)
go func() {
defer func() { recover() }()
d, e := f(job)
rslt <- &result{data: d, err: e}
}()
select {
case r = <-rslt:
case <-time.After(timeout):
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return &result{err: ErrTimeOut}
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}
return r
}