90 lines
1.8 KiB
Go
90 lines
1.8 KiB
Go
package scheduler
|
|
|
|
import (
|
|
"context"
|
|
"errors"
|
|
"fmt"
|
|
"log/slog"
|
|
"math/rand"
|
|
"time"
|
|
|
|
"git.front.kjuulh.io/kjuulh/orbis/internal/executor"
|
|
"github.com/jackc/pgx/v5"
|
|
)
|
|
|
|
type Scheduler struct {
|
|
logger *slog.Logger
|
|
db *pgx.Conn
|
|
executor *executor.Executor
|
|
}
|
|
|
|
func NewScheduler(logger *slog.Logger, db *pgx.Conn, executor *executor.Executor) *Scheduler {
|
|
return &Scheduler{
|
|
logger: logger,
|
|
db: db,
|
|
executor: executor,
|
|
}
|
|
}
|
|
|
|
func (s *Scheduler) Execute(ctx context.Context) error {
|
|
acquiredLeader, err := s.acquireLeader(ctx)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
if !acquiredLeader {
|
|
s.logger.Info("gracefully shutting down non-elected scheduler")
|
|
return nil
|
|
}
|
|
|
|
ticker := time.NewTicker(5 * time.Second)
|
|
defer ticker.Stop()
|
|
for {
|
|
select {
|
|
case <-ctx.Done():
|
|
s.logger.Info("gracefully shutting down elected scheduler")
|
|
return nil
|
|
case <-ticker.C:
|
|
if err := s.process(ctx); err != nil {
|
|
return fmt.Errorf("scheduler failed: %w", err)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
func (s *Scheduler) acquireLeader(ctx context.Context) (bool, error) {
|
|
for {
|
|
select {
|
|
case <-ctx.Done():
|
|
return false, nil
|
|
default:
|
|
var acquiredLock bool
|
|
if err := s.db.QueryRow(ctx, "SELECT pg_try_advisory_lock(1234)").Scan(&acquiredLock); err != nil {
|
|
if errors.Is(err, pgx.ErrNoRows) {
|
|
return false, nil
|
|
}
|
|
}
|
|
|
|
if !acquiredLock {
|
|
wait := time.Second * time.Duration(rand.Float32()*9+1)
|
|
|
|
s.logger.Debug("failed to acquire lock, parking non-elected scheduler", "wait_seconds", wait)
|
|
time.Sleep(wait)
|
|
continue
|
|
}
|
|
|
|
s.logger.Info("acquired lock, electing application to leader")
|
|
return true, nil
|
|
|
|
}
|
|
}
|
|
}
|
|
|
|
func (s *Scheduler) process(ctx context.Context) error {
|
|
if err := s.executor.DispatchEvents(ctx); err != nil {
|
|
return fmt.Errorf("failed to dispatch events: %w", err)
|
|
}
|
|
|
|
return nil
|
|
}
|