jobs: github.com/albrow/jobs Index | Files | Directories

package jobs

import "github.com/albrow/jobs"

Package jobs is a persistent and flexible background jobs library.

Version: 0.4.2

Jobs is powered by redis and supports the following features:

  - A job can encapsulate any arbitrary functionality. A job can do anything
    which can be done in a go function.
  - A job can be one-off (only executed once) or recurring (scheduled to
    execute at a specific interval).
  - A job can be retried a specified number of times if it fails.
  - A job is persistent, with protections against power loss and other worst
    case scenarios.
  - Jobs can be executed by any number of concurrent workers accross any
    number of machines.
  - Provided it is persisted to disk, every job will be executed *at least* once,
	    and in ideal network conditions will be executed *exactly* once.
  - You can query the database to find out e.g. the number of jobs that are
    currently executing or how long a particular job took to execute.
  - Any job that permanently fails will have its error captured and stored.

Why is it Useful

Jobs is intended to be used in web applications. It is useful for cases where you need to execute some long-running code, but you don't want your users to wait for the code to execute before rendering a response. A good example is sending a welcome email to your users after they sign up. You can use Jobs to schedule the email to be sent asynchronously, and render a response to your user without waiting for the email to be sent. You could use a goroutine to accomplish the same thing, but in the event of a server restart or power loss, the email might never be sent. Jobs guarantees that the email will be sent at some time, and allows you to spread the work between different machines.

More Information

Visit https://github.com/albrow/jobs for a Quickstart Guide, code examples, and more information.

Index

Package Files

config.go doc.go encode.go job.go job_status.go job_type.go pool.go redis_keys.go redis_pool.go scripts.go test_utils.go transaction.go utils.go worker.go

Variables

var Config = configType{
    Db: databaseConfig{

        Address: "localhost:6379",

        Network: "tcp",

        Database: 0,

        Password: "",
    },
}

Config is where all configuration variables are stored. You may modify Config directly in order to change config variables, and should only do so at the start of your program.

var DefaultPoolConfig = &PoolConfig{
    NumWorkers:   runtime.GOMAXPROCS(0),
    BatchSize:    runtime.GOMAXPROCS(0),
    MinWait:      200 * time.Millisecond,
    StaleTimeout: 30 * time.Second,
}

DefaultPoolConfig is the default config for pools. You can override any values by passing in a *PoolConfig to NewPool. Any zero values in PoolConfig will be interpreted as the default.

var Keys = struct {
    // jobsTimeIndex is the key for a sorted set which keeps all outstanding
    // jobs sorted by their time field.
    JobsTimeIndex string
    // jobsTemp is the key for a temporary set which is created and then destroyed
    // during the process of getting the next jobs in the queue.
    JobsTemp string
    // activePools is the key for a set which holds the pool ids for all active
    // pools.
    ActivePools string
}{
    JobsTimeIndex: "jobs:time",
    JobsTemp:      "jobs:temp",
    ActivePools:   "pools:active",
}

keys stores any constant redis keys. By storing them all here, we avoid using string literals which are prone to typos.

var Types = map[string]*Type{}

Types is map of job type names to *Type

type ErrorJobNotFound Uses

type ErrorJobNotFound struct {
    // contains filtered or unexported fields
}

ErrorJobNotFound is returned whenever a specific job is not found, e.g. from the FindById function.

func (ErrorJobNotFound) Error Uses

func (e ErrorJobNotFound) Error() string

type ErrorNameAlreadyRegistered Uses

type ErrorNameAlreadyRegistered struct {
    // contains filtered or unexported fields
}

ErrorNameAlreadyRegistered is returned whenever RegisterType is called with a name that has already been registered.

func (ErrorNameAlreadyRegistered) Error Uses

func (e ErrorNameAlreadyRegistered) Error() string

Error satisfies the error interface.

type HandlerFunc Uses

type HandlerFunc interface{}

A HandlerFunc is a function which accepts ether zero or one arguments and returns an error. The function will be executed by a worker. If the function returns a non-nil error or causes a panic, the worker will capture and log the error, and if applicable the job may be queued for retry.

type Job Uses

type Job struct {
    // contains filtered or unexported fields
}

Job represents a discrete piece of work to be done by a worker.

func FindById Uses

func FindById(id string) (*Job, error)

FindById returns the job with the given id or an error if the job cannot be found (in which case the error will have type ErrorJobNotFound) or there was a problem connecting to the database.

func (*Job) Cancel Uses

func (j *Job) Cancel() error

Cancel cancels the job, but does not remove it from the database. It will be added to a list of cancelled jobs. If you wish to remove it from the database, use the Destroy method. Attempting to cancel a destroyed job will have no effect.

func (*Job) Data Uses

func (j *Job) Data() []byte

Data returns the gob-encoded data of the job

func (*Job) Destroy Uses

func (j *Job) Destroy() error

Destroy removes all traces of the job from the database. If the job is currently being executed by a worker, the worker may still finish the job. Attempting to destroy a job that has already been destroyed will have no effect, so it is safe to call Destroy multiple times.

func (*Job) Duration Uses

func (j *Job) Duration() time.Duration

Duration returns how long the job took to execute with nanosecond precision. I.e. the difference between j.Finished() and j.Started(). It returns a duration of zero if the job has not finished yet.

func (*Job) Error Uses

func (j *Job) Error() error

Error returns the last error that arose during execution of the job. It is only non-nil if the job has failed at some point.

func (*Job) Finished Uses

func (j *Job) Finished() time.Time

Finished returns the time that the job finished executing (in local time with nanosecond precision) or the zero time if the job has not finished executing yet.

func (*Job) Freq Uses

func (j *Job) Freq() int64

Freq returns the frequency at which the job should be executed. Specifically it returns the number of nanoseconds between each scheduled execution.

func (*Job) Id Uses

func (j *Job) Id() string

Id returns the unique identifier used for the job. If the job has not yet been saved to the database, it may return an empty string.

func (*Job) IsRecurring Uses

func (j *Job) IsRecurring() bool

IsRecurring returns true iff the job is recurring

func (*Job) Key Uses

func (j *Job) Key() string

Key returns the key used for the hash in redis which stores all the fields for this job.

func (*Job) NextTime Uses

func (j *Job) NextTime() int64

NextTime returns the time (unix UTC with nanosecond precision) that the job should execute next, if it is a recurring job, and 0 if it is not.

func (*Job) PoolId Uses

func (j *Job) PoolId() string

PoolId returns the pool id of the job if it is currently being executed or has been executed and at some point has been assigned to a specific pool. Otherwise, it returns an empty string.

func (*Job) Priority Uses

func (j *Job) Priority() int

Priority returns the job's priority.

func (*Job) Refresh Uses

func (j *Job) Refresh() error

Refresh mutates the job by setting its fields to the most recent data found in the database. It returns an error if there was a problem connecting to the database or if the job was destroyed.

func (*Job) Reschedule Uses

func (j *Job) Reschedule(time time.Time) error

Reschedule reschedules the job with the given time. It can be used to reschedule cancelled jobs. It may also be used to reschedule finished or failed jobs, however, in most cases if you want to reschedule finished jobs you should use the ScheduleRecurring method and if you want to reschedule failed jobs, you should set the number of retries > 0 when registering the job type. Attempting to reschedule a destroyed job will have no effect. Reschedule returns an error if there was a problem connecting to the database.

func (*Job) Retries Uses

func (j *Job) Retries() uint

Retries returns the number of remaining retries for the job.

func (*Job) Started Uses

func (j *Job) Started() time.Time

Started returns the time that the job started executing (in local time with nanosecond precision) or the zero time if the job has not started executing yet.

func (*Job) Status Uses

func (j *Job) Status() Status

Status returns the status of the job.

func (*Job) Time Uses

func (j *Job) Time() int64

Time returns the time at which the job should be executed in UTC UNIX format with nanosecond precision.

type Pool Uses

type Pool struct {

    // RWMutex is only used during testing when we need to
    // change some of the fields for the pool after it was started.
    // NOTE: currently only used in one test (TestStalePoolsArePurged)
    // and might be removed if we refactor later.
    sync.RWMutex
    // contains filtered or unexported fields
}

Pool is a pool of workers. Pool will query the database for queued jobs and delegate those jobs to some number of workers. It will do this continuously until the main program exits or you call Pool.Close().

func NewPool Uses

func NewPool(config *PoolConfig) (*Pool, error)

NewPool creates and returns a new pool with the given configuration. You can pass in nil to use the default values. Otherwise, any zero values in config will be interpreted as the default value.

func (*Pool) Close Uses

func (p *Pool) Close()

Close closes the worker pool and prevents it from delegating any new jobs. However, any jobs that are currently being executed will still be executed. Close returns immediately. If you want to wait until all workers are done executing their current jobs, use the Wait method.

func (*Pool) SetAfterFunc Uses

func (p *Pool) SetAfterFunc(f func(*Job))

SetAfterFunc will assign a function that will be executed each time a job is finished.

func (*Pool) Start Uses

func (p *Pool) Start() error

Start starts the worker pool. This means the pool will initialize workers, continuously query the database for queued jobs, and delegate those jobs to the workers.

func (*Pool) Wait Uses

func (p *Pool) Wait() error

Wait will return when all workers are done executing their jobs. Wait can only possibly return after you have called Close. To prevent errors due to partially-executed jobs, any go program which starts a worker pool should call Wait (and Close before that if needed) before exiting.

type PoolConfig Uses

type PoolConfig struct {
    // NumWorkers is the number of workers to run
    // Each worker will run inside its own goroutine
    // and execute jobs asynchronously. Default is
    // runtime.GOMAXPROCS.
    NumWorkers int
    // BatchSize is the number of jobs to send through
    // the jobs channel at once. Increasing BatchSize means
    // the worker pool will query the database less frequently,
    // so you would get higher performance. However this comes
    // at the cost that jobs with lower priority may sometimes be
    // executed before jobs with higher priority, because the jobs
    // with higher priority were not ready yet the last time the pool
    // queried the database. Decreasing BatchSize means more
    // frequent queries to the database and lower performance, but
    // greater likelihood of executing jobs in perfect order with regards
    // to priority. Setting BatchSize to 1 gaurantees that higher priority
    // jobs are always executed first as soon as they are ready. Default is
    // runtime.GOMAXPROCS.
    BatchSize int
    // MinWait is the minimum amount of time the pool will wait before checking
    // the database for queued jobs. The pool may take longer to query the database
    // if the jobs channel is blocking (i.e. if no workers are ready to execute new
    // jobs). Default is 200ms.
    MinWait time.Duration
    // StaleTimeout is the amount of time to wait for a pool to reply to a ping request
    // before considering it stale. Stale pools will be purged and if they have any
    // corresponding jobs in the executing set, those jobs will be requeued. Default
    // is 30 seconds.
    StaleTimeout time.Duration
}

PoolConfig is a set of configuration options for pools. Setting any value to the zero value will be interpretted as the default.

type Status Uses

type Status string

Status represents the different statuses a job can have.

const (
    // StatusSaved is the status of any job that has been saved into the database but not yet queued
    StatusSaved Status = "saved"
    // StatusQueued is the status of any job that has been queued for execution but not yet selected
    StatusQueued Status = "queued"
    // StatusExecuting is the status of any job that has been selected for execution and is being delegated
    // to some worker and any job that is currently being executed by some worker.
    StatusExecuting Status = "executing"
    // StatusFinished is the status of any job that has been successfully executed.
    StatusFinished Status = "finished"
    // StatusFailed is the status of any job that failed to execute and for which there are no remaining retries.
    StatusFailed Status = "failed"
    // StatusCancelled is the status of any job that was manually cancelled.
    StatusCancelled Status = "cancelled"
    // StatusDestroyed is the status of any job that has been destroyed, i.e. completely removed
    // from the database.
    StatusDestroyed Status = "destroyed"
)

func (Status) Count Uses

func (status Status) Count() (int, error)

Count returns the number of jobs that currently have the given status or an error if there was a problem connecting to the database.

func (Status) JobIds Uses

func (status Status) JobIds() ([]string, error)

JobIds returns the ids of all jobs that have the given status, ordered by priority or an error if there was a problem connecting to the database.

func (Status) Jobs Uses

func (status Status) Jobs() ([]*Job, error)

Jobs returns all jobs that have the given status, ordered by priority or an error if there was a problem connecting to the database.

func (Status) Key Uses

func (status Status) Key() string

key returns the key used for the sorted set in redis which will hold all jobs with this status.

type Type Uses

type Type struct {
    // contains filtered or unexported fields
}

Type represents a type of job that can be executed by workers

func RegisterType Uses

func RegisterType(name string, retries uint, handler HandlerFunc) (*Type, error)

RegisterType registers a new type of job that can be executed by workers. name should be a unique string identifier for the job. retries is the number of times this type of job should be retried if it fails. handler is a function that a worker will call in order to execute the job. handler should be a function which accepts either 0 or 1 arguments of any type, corresponding to the data for a job of this type. All jobs of this type must have data with the same type as the first argument to handler, or nil if the handler accepts no arguments.

func (*Type) Schedule Uses

func (jt *Type) Schedule(priority int, time time.Time, data interface{}) (*Job, error)

Schedule schedules a on-off job of the given type with the given parameters. Jobs with a higher priority will be executed first. The job will not be executed until after time. data is the data associated with this particular job and should have the same type as the first argument to the handler for this Type.

func (*Type) ScheduleRecurring Uses

func (jt *Type) ScheduleRecurring(priority int, time time.Time, freq time.Duration, data interface{}) (*Job, error)

ScheduleRecurring schedules a recurring job of the given type with the given parameters. Jobs with a higher priority will be executed first. The job will not be executed until after time. After time, the job will be executed with a frequency specified by freq. data is the data associated with this particular job and should have the same type as the first argument to the handler for this Type. Every recurring execution of the job will use the same data.

func (*Type) String Uses

func (jt *Type) String() string

String satisfies the Stringer interface and returns the name of the Type.

Directories

PathSynopsis
scripts

Package jobs imports 12 packages (graph) and is imported by 6 packages. Updated 2017-12-14. Refresh now. Tools for package owners.