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jobdb.go
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jobdb.go
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package jobdb
import (
"sync"
"github.com/benbjohnson/immutable"
"github.com/google/uuid"
"github.com/pkg/errors"
"golang.org/x/exp/maps"
)
var emptyList = immutable.NewSortedSet[*Job](JobPriorityComparer{})
type JobDb struct {
jobsById map[string]*Job
jobsByRunId map[uuid.UUID]string
jobsByQueue map[string]immutable.SortedSet[*Job]
copyMutex sync.Mutex
writerMutex sync.Mutex
}
func NewJobDb() *JobDb {
return &JobDb{
jobsById: map[string]*Job{},
jobsByRunId: map[uuid.UUID]string{},
jobsByQueue: map[string]immutable.SortedSet[*Job]{},
copyMutex: sync.Mutex{},
}
}
// Upsert will insert the given jobs if they don't already exist or update the if they do
func (jobDb *JobDb) Upsert(txn *Txn, jobs []*Job) error {
if err := jobDb.checkWritableTransaction(txn); err != nil {
return err
}
for _, job := range jobs {
existingJob := txn.jobsById[job.id]
if existingJob != nil {
existingQueue, ok := txn.jobsByQueue[existingJob.queue]
if ok {
txn.jobsByQueue[existingJob.queue] = existingQueue.Delete(existingJob)
}
}
txn.jobsById[job.id] = job
for _, run := range job.runsById {
txn.jobsByRunId[run.id] = job.id
}
if job.Queued() {
newQueue, ok := txn.jobsByQueue[job.queue]
if !ok {
q := emptyList
newQueue = q
}
newQueue = newQueue.Add(job)
txn.jobsByQueue[job.queue] = newQueue
}
}
return nil
}
// GetById returns the job with the given Id or nil if no such job exists
// The Job returned by this function *must not* be subsequently modified
func (jobDb *JobDb) GetById(txn *Txn, id string) *Job {
return txn.jobsById[id]
}
// GetByRunId returns the job with the given run id or nil if no such job exists
// The Job returned by this function *must not* be subsequently modified
func (jobDb *JobDb) GetByRunId(txn *Txn, runId uuid.UUID) *Job {
jobId := txn.jobsByRunId[runId]
return jobDb.GetById(txn, jobId)
}
// HasQueuedJobs returns true if the queue has any jobs in the running state or false otherwise
func (jobDb *JobDb) HasQueuedJobs(txn *Txn, queue string) bool {
queuedJobs, ok := txn.jobsByQueue[queue]
if !ok {
return false
}
return queuedJobs.Len() > 0
}
// QueuedJobs returns true if the queue has any jobs in the running state or false otherwise
func (jobDb *JobDb) QueuedJobs(txn *Txn, queue string) *immutable.SortedSetIterator[*Job] {
jobQueue, ok := txn.jobsByQueue[queue]
if ok {
return jobQueue.Iterator()
} else {
return emptyList.Iterator()
}
}
// GetAll returns all jobs in the database.
// The Jobs returned by this function *must not* be subsequently modified
func (jobDb *JobDb) GetAll(txn *Txn) []*Job {
return maps.Values(txn.jobsById)
}
// BatchDelete removes the jobs with the given ids from the database. Any ids that are not in the database will be
// ignored
func (jobDb *JobDb) BatchDelete(txn *Txn, ids []string) error {
if err := jobDb.checkWritableTransaction(txn); err != nil {
return err
}
for _, id := range ids {
job, present := txn.jobsById[id]
if present {
delete(txn.jobsById, id)
for _, run := range job.runsById {
delete(txn.jobsByRunId, run.id)
}
queue, ok := txn.jobsByQueue[job.queue]
if ok {
newQueue := queue.Delete(job)
txn.jobsByQueue[job.queue] = newQueue
}
}
}
return nil
}
func (jobDb *JobDb) checkWritableTransaction(txn *Txn) error {
if txn.readOnly {
return errors.New("Cannot write using a read only transaction")
}
if !txn.active {
return errors.New("Cannot write using an inactive transaction")
}
return nil
}
// ReadTxn returns a read-only transaction.
// Multiple read-only transactions can access the db concurrently
func (jobDb *JobDb) ReadTxn() *Txn {
jobDb.copyMutex.Lock()
defer jobDb.copyMutex.Unlock()
return &Txn{
readOnly: true,
jobsById: jobDb.jobsById,
jobsByRunId: jobDb.jobsByRunId,
jobsByQueue: jobDb.jobsByQueue,
active: true,
jobDb: jobDb,
}
}
// WriteTxn returns a writeable transaction.
// Only a single write transaction may access the db at any given time so note that this function will block until
// any outstanding write transactions have been committed or aborted
func (jobDb *JobDb) WriteTxn() *Txn {
jobDb.writerMutex.Lock()
jobDb.copyMutex.Lock()
defer jobDb.copyMutex.Unlock()
return &Txn{
readOnly: false,
jobsById: maps.Clone(jobDb.jobsById),
jobsByRunId: maps.Clone(jobDb.jobsByRunId),
jobsByQueue: maps.Clone(jobDb.jobsByQueue),
active: true,
jobDb: jobDb,
}
}
// Txn is a JobDb Transaction. Transactions provide a consistent view of the database, allowing readers to
// perform multiple actions without the database changing from underneath them.
// Write transactions also allow callers to perform write operations that will not be visible to other users
// until the transaction is committed.
type Txn struct {
readOnly bool
jobsById map[string]*Job
jobsByRunId map[uuid.UUID]string
jobsByQueue map[string]immutable.SortedSet[*Job]
jobDb *JobDb
active bool
}
func (txn *Txn) Commit() {
if txn.readOnly || !txn.active {
return
}
txn.jobDb.copyMutex.Lock()
defer txn.jobDb.copyMutex.Unlock()
defer txn.jobDb.writerMutex.Unlock()
txn.jobDb.jobsById = txn.jobsById
txn.jobDb.jobsByRunId = txn.jobsByRunId
txn.jobDb.jobsByQueue = txn.jobsByQueue
txn.active = false
}
func (txn *Txn) Abort() {
if txn.readOnly || !txn.active {
return
}
txn.active = false
txn.jobDb.writerMutex.Unlock()
}