1 files changed, 142 insertions, 0 deletions
diff --git a/internal/workers/worker_fn.go b/internal/workers/worker_fn.go
new file mode 100644
index 000000000..c41bee2b0
--- /dev/null
+++ b/internal/workers/worker_fn.go
@@ -0,0 +1,142 @@
+// 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 workers
+
+import (
+	"context"
+
+	"codeberg.org/gruf/go-runners"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/queue"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+)
+
+// FnWorkerPool wraps multiple FnWorker{}s in
+// a singular struct for easy multi start / stop.
+type FnWorkerPool struct {
+
+	// Queue is embedded queue.SimpleQueue{}
+	// passed to each of the pool Worker{}s.
+	Queue queue.SimpleQueue[func(context.Context)]
+
+	// internal fields.
+	workers []*FnWorker
+}
+
+// Start will attempt to start 'n' FnWorker{}s.
+func (p *FnWorkerPool) Start(n int) {
+	// Check whether workers are
+	// set (is already running).
+	ok := (len(p.workers) > 0)
+	if ok {
+		return
+	}
+
+	// Allocate new workers slice.
+	p.workers = make([]*FnWorker, n)
+	for i := range p.workers {
+
+		// Allocate new FnWorker{}.
+		p.workers[i] = new(FnWorker)
+		p.workers[i].Queue = &p.Queue
+
+		// Attempt to start worker.
+		// Return bool not useful
+		// here, as true = started,
+		// false = already running.
+		_ = p.workers[i].Start()
+	}
+}
+
+// Stop will attempt to stop contained FnWorker{}s.
+func (p *FnWorkerPool) Stop() {
+	// Check whether workers are
+	// set (is currently running).
+	ok := (len(p.workers) == 0)
+	if ok {
+		return
+	}
+
+	// Stop all running workers.
+	for i := range p.workers {
+
+		// return bool not useful
+		// here, as true = stopped,
+		// false = never running.
+		_ = p.workers[i].Stop()
+	}
+
+	// Unset workers slice.
+	p.workers = p.workers[:0]
+}
+
+// FnWorker wraps a queue.SimpleQueue{} which
+// it feeds from to provide it with function
+// tasks to execute. It does so in a single
+// goroutine with state management utilities.
+type FnWorker struct {
+
+	// Queue is the fn queue that FnWorker
+	// will feed from for upcoming tasks.
+	Queue *queue.SimpleQueue[func(context.Context)]
+
+	// internal fields.
+	service runners.Service
+}
+
+// Start will attempt to start the Worker{}.
+func (w *FnWorker) Start() bool {
+	return w.service.GoRun(w.run)
+}
+
+// Stop will attempt to stop the Worker{}.
+func (w *FnWorker) Stop() bool {
+	return w.service.Stop()
+}
+
+// run wraps process to restart on any panic.
+func (w *FnWorker) run(ctx context.Context) {
+	if w.Queue == nil {
+		panic("not yet initialized")
+	}
+	log.Infof(ctx, "%p: starting worker", w)
+	defer log.Infof(ctx, "%p: stopped worker", w)
+	util.Must(func() { w.process(ctx) })
+}
+
+// process is the main delivery worker processing routine.
+func (w *FnWorker) process(ctx context.Context) {
+	if w.Queue == nil {
+		// we perform this check here just
+		// to ensure the compiler knows these
+		// variables aren't nil in the loop,
+		// even if already checked by caller.
+		panic("not yet initialized")
+	}
+
+	for {
+		// Block until pop next func.
+		fn, ok := w.Queue.PopCtx(ctx)
+		if !ok {
+			return
+		}
+
+		// run!
+		fn(ctx)
+	}
+}