README
¶
gue
Gue is Golang queue on top of PostgreSQL that uses transaction-level locks.
Originally this project used to be a fork of bgentry/que-go but because of some backward-compatibility breaking changes and original library author not being very responsive for PRs I turned fork into standalone project. Version 2 breaks internal backward-compatibility with the original project - DB table and all the internal logic (queries, algorithms) is completely rewritten.
The name Gue is yet another silly word transformation: Queue -> Que, Go + Que -> Gue.
Install
go get -u github.com/vgarvardt/gue/v2
Additionally, you need to apply DB migration.
Usage Example
package main
import (
"context"
"encoding/json"
"fmt"
"log"
"os"
"time"
"github.com/jackc/pgx/v4/pgxpool"
"github.com/vgarvardt/gue/v2"
"github.com/vgarvardt/gue/v2/adapter/pgxv4"
)
type printNameArgs struct {
Name string
}
func main() {
printName := func(j *gue.Job) error {
var args printNameArgs
if err := json.Unmarshal(j.Args, &args); err != nil {
return err
}
fmt.Printf("Hello %s!\n", args.Name)
return nil
}
pgxCfg, err := pgxpool.ParseConfig(os.Getenv("DATABASE_URL"))
if err != nil {
log.Fatal(err)
}
pgxPool, err := pgxpool.ConnectConfig(context.Background(), pgxCfg)
if err != nil {
log.Fatal(err)
}
defer pgxPool.Close()
poolAdapter := pgxv4.NewConnPool(pgxPool)
gc := gue.NewClient(poolAdapter)
wm := gue.WorkMap{
"PrintName": printName,
}
// create a pool w/ 2 workers
workers := gue.NewWorkerPool(gc, wm, 2, gue.WithPoolQueue("name_printer"))
ctx, shutdown := context.WithCancel(context.Background())
// work jobs in goroutine
if err := workers.Start(ctx); err != nil {
log.Fatal(err)
}
args, err := json.Marshal(printNameArgs{Name: "vgarvardt"})
if err != nil {
log.Fatal(err)
}
j := &gue.Job{
Type: "PrintName",
Args: args,
}
if err := gc.Enqueue(context.Background(), j); err != nil {
log.Fatal(err)
}
j := &gue.Job{
Type: "PrintName",
RunAt: time.Now().UTC().Add(30 * time.Second), // delay 30 seconds
Args: args,
}
if err := gc.Enqueue(context.Background(), j); err != nil {
log.Fatal(err)
}
time.Sleep(30 * time.Second) // wait for while
// send shutdown signal to worker
shutdown()
}
PostgreSQL drivers
Package supports several PostgreSQL drivers using adapter interface internally. Currently, adapters for the following drivers have been implemented:
pgx/v4
package main
import(
"context"
"log"
"os"
"github.com/jackc/pgx/v4/pgxpool"
"github.com/vgarvardt/gue/v2"
"github.com/vgarvardt/gue/v2/adapter/pgxv4"
)
func main() {
pgxCfg, err := pgxpool.ParseConfig(os.Getenv("DATABASE_URL"))
if err != nil {
log.Fatal(err)
}
pgxPool, err := pgxpool.ConnectConfig(context.Background(), pgxCfg)
if err != nil {
log.Fatal(err)
}
defer pgxPool.Close()
poolAdapter := pgxv4.NewConnPool(pgxPool)
gc := gue.NewClient(poolAdapter)
...
}
pgx/v3
package main
import(
"log"
"os"
"github.com/jackc/pgx"
"github.com/vgarvardt/gue/v2"
"github.com/vgarvardt/gue/v2/adapter/pgxv3"
)
func main() {
pgxCfg, err := pgx.ParseURI(os.Getenv("DATABASE_URL"))
if err != nil {
log.Fatal(err)
}
pgxPool, err := pgx.NewConnPool(pgx.ConnPoolConfig{
ConnConfig: pgxCfg,
})
if err != nil {
log.Fatal(err)
}
defer pgxPool.Close()
poolAdapter := pgxv3.NewConnPool(pgxPool)
gc := gue.NewClient(poolAdapter)
...
}
lib/pq
package main
import(
"database/sql"
"log"
"os"
_ "github.com/lib/pq" // register postgres driver
"github.com/vgarvardt/gue/v2"
"github.com/vgarvardt/gue/v2/adapter/libpq"
)
func main() {
db, err := sql.Open("postgres", os.Getenv("DATABASE_URL"))
if err != nil {
log.Fatal(err)
}
defer db.Close()
poolAdapter := libpq.NewConnPool(db)
gc := gue.NewClient(poolAdapter)
...
}
Logging
Package supports several logging libraries using adapter interface internally. Currently, adapters for the following drivers have been implemented:
- NoOp (
adapter.NoOpLogger) - default adapter that does nothing, so it is basically/dev/nulllogger - Stdlib
log- adapter that usesloglogger for logs output. Instantiate it withadapter.NewStdLogger(...). - Uber
zap- adapter that usesgo.uber.org/zaplogger for logs output. Instantiate it withadapter.zap.New(...).
Testing
Linter and tests are running for every Pull Request, but it is possible to run linter
and tests locally using docker and make.
Run linter: make link. This command runs liner in docker container with the project
source code mounted.
Run tests: make test. This command runs project dependencies in docker containers
if they are not started yet and runs go tests with coverage.
Documentation
¶
Overview ¶
Package gue implements Golang queue on top of PostgreSQL. It uses transaction-level locks for concurrent work.
PostgreSQL drivers ¶
Package supports several PostgreSQL drivers using adapter interface internally. Currently, adapters for the following drivers have been implemented:
- github.com/jackc/pgx v4
- github.com/jackc/pgx v3
- github.com/lib/pq
Usage ¶
Here is a complete example showing worker setup for pgx/v4 and two jobs enqueued, one with a delay:
package main
import (
"context"
"encoding/json"
"fmt"
"log"
"os"
"time"
"github.com/jackc/pgx/v4/pgxpool"
"github.com/vgarvardt/gue/v2"
"github.com/vgarvardt/gue/v2/adapter/pgxv4"
)
type printNameArgs struct {
Name string
}
func main() {
printName := func(j *gue.Job) error {
var args printNameArgs
if err := json.Unmarshal(j.Args, &args); err != nil {
return err
}
fmt.Printf("Hello %s!\n", args.Name)
return nil
}
pgxCfg, err := pgxpool.ParseConfig(os.Getenv("DATABASE_URL"))
if err != nil {
log.Fatal(err)
}
pgxPool, err := pgxpool.ConnectConfig(context.Background(), pgxCfg)
if err != nil {
log.Fatal(err)
}
defer pgxPool.Close()
poolAdapter := pgxv4.NewConnPool(pgxPool)
gc := gue.NewClient(poolAdapter)
wm := gue.WorkMap{
"PrintName": printName,
}
// create a pool w/ 2 workers
workers := gue.NewWorkerPool(gc, wm, 2, gue.WithPoolQueue("name_printer"))
ctx, shutdown := context.WithCancel(context.Background())
// work jobs in goroutine
if err := workers.Start(ctx); err != nil {
log.Fatal(err)
}
args, err := json.Marshal(printNameArgs{Name: "vgarvardt"})
if err != nil {
log.Fatal(err)
}
j := &gue.Job{
Type: "PrintName",
Args: args,
}
if err := gc.Enqueue(context.Background(), j); err != nil {
log.Fatal(err)
}
j := &gue.Job{
Type: "PrintName",
RunAt: time.Now().UTC().Add(30 * time.Second), // delay 30 seconds
Args: args,
}
if err := gc.Enqueue(context.Background(), j); err != nil {
log.Fatal(err)
}
time.Sleep(30 * time.Second) // wait for while
// send shutdown signal to worker
shutdown()
}
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ErrMissingType = errors.New("job type must be specified")
ErrMissingType is returned when you attempt to enqueue a job with no Type specified.
Functions ¶
This section is empty.
Types ¶
type Backoff ¶
Backoff is the interface for backoff implementation that will be used to reschedule errored jobs.
type Client ¶
type Client struct {
// contains filtered or unexported fields
}
Client is a Gue client that can add jobs to the queue and remove jobs from the queue.
func NewClient ¶
func NewClient(pool adapter.ConnPool, options ...ClientOption) *Client
NewClient creates a new Client that uses the pgx pool.
func (*Client) EnqueueTx ¶
EnqueueTx adds a job to the queue within the scope of the transaction. This allows you to guarantee that an enqueued job will either be committed or rolled back atomically with other changes in the course of this transaction.
It is the caller's responsibility to Commit or Rollback the transaction after this function is called.
func (*Client) LockJob ¶
LockJob attempts to retrieve a Job from the database in the specified queue. If a job is found, it will be locked on the transactional level, so other workers will be skipping it. If no job is found, nil will be returned instead of an error.
Because Gue uses transaction-level locks, we have to hold the same transaction throughout the process of getting a job, working it, deleting it, and releasing the lock.
After the Job has been worked, you must call either Done() or Error() on it in order to commit transaction to persist Job changes (remove or update it).
type ClientOption ¶
type ClientOption func(*Client)
ClientOption defines a type that allows to set client properties during the build-time.
func WithClientBackoff ¶
func WithClientBackoff(backoff Backoff) ClientOption
WithClientBackoff sets backoff implementation that will be applied to errored jobs within current client session.
func WithClientID ¶
func WithClientID(id string) ClientOption
WithClientID sets client ID for easier identification in logs
func WithClientLogger ¶
func WithClientLogger(logger adapter.Logger) ClientOption
WithClientLogger sets Logger implementation to client
func WithClientSchema ¶
func WithClientSchema(schema string) ClientOption
WithClientSchema sets database schema name that contains 'gue_jobs' table.
type Job ¶
type Job struct {
// ID is the unique database ID of the Job. It is ignored on job creation.
ID int64
// Queue is the name of the queue. It defaults to the empty queue "".
Queue string
// Priority is the priority of the Job. The default priority is 0, and a
// lower number means a higher priority.
//
// The highest priority is -32768, the lowest one is +32767
Priority int16
// RunAt is the time that this job should be executed. It defaults to now(),
// meaning the job will execute immediately. Set it to a value in the future
// to delay a job's execution.
RunAt time.Time
// Type maps job to a worker func.
Type string
// Args must be the bytes of a valid JSON string
Args []byte
// ErrorCount is the number of times this job has attempted to run, but
// failed with an error. It is ignored on job creation.
ErrorCount int32
// LastError is the error message or stack trace from the last time the job
// failed. It is ignored on job creation.
LastError pgtype.Text
// contains filtered or unexported fields
}
Job is a single unit of work for Gue to perform.
func (*Job) Delete ¶
Delete marks this job as complete by deleting it form the database.
You must also later call Done() to return this job's database connection to the pool.
func (*Job) Error ¶
Error marks the job as failed and schedules it to be reworked. An error message or backtrace can be provided as msg, which will be saved on the job. It will also increase the error count.
This call marks job as done and releases (commits) transaction, so calling Done() is not required, although calling it will not cause any issues.
type WorkFunc ¶
WorkFunc is a function that performs a Job. If an error is returned, the job is re-enqueued with exponential backoff.
type WorkMap ¶
WorkMap is a map of Job names to WorkFuncs that are used to perform Jobs of a given type.
type Worker ¶
type Worker struct {
// contains filtered or unexported fields
}
Worker is a single worker that pulls jobs off the specified queue. If no Job is found, the Worker will sleep for interval seconds.
func NewWorker ¶
func NewWorker(c *Client, wm WorkMap, options ...WorkerOption) *Worker
NewWorker returns a Worker that fetches Jobs from the Client and executes them using WorkMap. If the type of Job is not registered in the WorkMap, it's considered an error and the job is re-enqueued with a backoff.
Worker defaults to a poll interval of 5 seconds, which can be overridden by WithWorkerPollInterval option. The default queue is the nameless queue "", which can be overridden by WithWorkerQueue option.
type WorkerOption ¶
type WorkerOption func(*Worker)
WorkerOption defines a type that allows to set worker properties during the build-time.
func WithWorkerID ¶
func WithWorkerID(id string) WorkerOption
WithWorkerID sets worker ID for easier identification in logs
func WithWorkerLogger ¶
func WithWorkerLogger(logger adapter.Logger) WorkerOption
WithWorkerLogger sets Logger implementation to worker
func WithWorkerPollInterval ¶
func WithWorkerPollInterval(d time.Duration) WorkerOption
WithWorkerPollInterval overrides default poll interval with the given value. Poll interval is the "sleep" duration if there were no jobs found in the DB.
func WithWorkerQueue ¶
func WithWorkerQueue(queue string) WorkerOption
WithWorkerQueue overrides default worker queue name with the given value.
func WithWorkerSchema ¶
func WithWorkerSchema(schema string) WorkerOption
WithWorkerSchema sets database schema name. Default schema name is "public".
type WorkerPool ¶
type WorkerPool struct {
// contains filtered or unexported fields
}
WorkerPool is a pool of Workers, each working jobs from the queue queue at the specified interval using the WorkMap.
func NewWorkerPool ¶
func NewWorkerPool(c *Client, wm WorkMap, poolSize int, options ...WorkerPoolOption) *WorkerPool
NewWorkerPool creates a new WorkerPool with count workers using the Client c.
Each Worker in the pool default to a poll interval of 5 seconds, which can be overridden by WithPoolPollInterval option. The default queue is the nameless queue "", which can be overridden by WithPoolQueue option.
type WorkerPoolOption ¶
type WorkerPoolOption func(pool *WorkerPool)
WorkerPoolOption defines a type that allows to set worker pool properties during the build-time.
func WithPoolID ¶
func WithPoolID(id string) WorkerPoolOption
WithPoolID sets worker pool ID for easier identification in logs
func WithPoolLogger ¶
func WithPoolLogger(logger adapter.Logger) WorkerPoolOption
WithPoolLogger sets Logger implementation to worker pool
func WithPoolPollInterval ¶
func WithPoolPollInterval(d time.Duration) WorkerPoolOption
WithPoolPollInterval overrides default poll interval with the given value. Poll interval is the "sleep" duration if there were no jobs found in the DB.
func WithPoolQueue ¶
func WithPoolQueue(queue string) WorkerPoolOption
WithPoolQueue overrides default worker queue name with the given value.
func WithPoolSchema ¶
func WithPoolSchema(schema string) WorkerPoolOption
WithPoolSchema sets database schema name. Default schema name is "public".
Source Files
Directories