[feature] support canceling scheduled tasks, some federation API performance improvements (#2329)

internal/scheduler/scheduler.go

@@ -0,0 +1,131 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package scheduler
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"codeberg.org/gruf/go-runners"
+	"codeberg.org/gruf/go-sched"
+)
+
+// Scheduler wraps an underlying task scheduler
+// to provide concurrency safe tracking by 'id'
+// strings in order to provide easy cancellation.
+type Scheduler struct {
+	sch sched.Scheduler
+	ts  map[string]*task
+	mu  sync.Mutex
+}
+
+// Start will start the Scheduler background routine, returning success.
+// Note that this creates a new internal task map, stopping and dropping
+// all previously known running tasks.
+func (sch *Scheduler) Start() bool {
+	if sch.sch.Start(nil) {
+		sch.ts = make(map[string]*task)
+		return true
+	}
+	return false
+}
+
+// Stop will stop the Scheduler background routine, returning success.
+// Note that this nils-out the internal task map, stopping and dropping
+// all previously known running tasks.
+func (sch *Scheduler) Stop() bool {
+	if sch.sch.Stop() {
+		sch.ts = nil
+		return true
+	}
+	return false
+}
+
+// AddOnce adds a run-once job with given id, function and timing parameters, returning success.
+func (sch *Scheduler) AddOnce(id string, start time.Time, fn func(context.Context, time.Time)) bool {
+	return sch.schedule(id, fn, (*sched.Once)(&start))
+}
+
+// AddRecurring adds a new recurring job with given id, function and timing parameters, returning success.
+func (sch *Scheduler) AddRecurring(id string, start time.Time, freq time.Duration, fn func(context.Context, time.Time)) bool {
+	return sch.schedule(id, fn, &sched.PeriodicAt{Once: sched.Once(start), Period: sched.Periodic(freq)})
+}
+
+// Cancel will attempt to cancel job with given id,
+// dropping it from internal scheduler and task map.
+func (sch *Scheduler) Cancel(id string) bool {
+	// Attempt to acquire and
+	// delete task with iD.
+	sch.mu.Lock()
+	task, ok := sch.ts[id]
+	delete(sch.ts, id)
+	sch.mu.Unlock()
+
+	if !ok {
+		// none found.
+		return false
+	}
+
+	// Cancel the queued
+	// job from Scheduler.
+	task.cncl()
+	return true
+}
+
+func (sch *Scheduler) schedule(id string, fn func(context.Context, time.Time), t sched.Timing) bool {
+	if fn == nil {
+		panic("nil function")
+	}
+
+	// Perform within lock.
+	sch.mu.Lock()
+	defer sch.mu.Unlock()
+
+	if _, ok := sch.ts[id]; ok {
+		// existing task already
+		// exists under this ID.
+		return false
+	}
+
+	// Extract current sched context.
+	doneCh := sch.sch.Done()
+	ctx := runners.CancelCtx(doneCh)
+
+	// Create a new job to hold task function with
+	// timing, passing in the current sched context.
+	job := sched.NewJob(func(now time.Time) {
+		fn(ctx, now)
+	})
+	job.With(t)
+
+	// Queue job with the scheduler,
+	// and store a new encompassing task.
+	cncl := sch.sch.Schedule(job)
+	sch.ts[id] = &task{
+		job:  job,
+		cncl: cncl,
+	}
+
+	return true
+}
+
+type task struct {
+	job  *sched.Job
+	cncl func()
+}