1 files changed, 75 insertions, 0 deletions
diff --git a/internal/media/ffmpeg/pool.go b/internal/media/ffmpeg/pool.go
new file mode 100644
index 000000000..9f6446be3
--- /dev/null
+++ b/internal/media/ffmpeg/pool.go
@@ -0,0 +1,75 @@
+// 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 ffmpeg
+
+import (
+	"context"
+
+	"codeberg.org/gruf/go-ffmpreg/wasm"
+)
+
+// wasmInstancePool wraps a wasm.Instantiator{} and a
+// channel of wasm.Instance{}s to provide a concurrency
+// safe pool of WebAssembly module instances capable of
+// compiling new instances on-the-fly, with a predetermined
+// maximum number of concurrent instances at any one time.
+type wasmInstancePool struct {
+	inst wasm.Instantiator
+	pool chan *wasm.Instance
+}
+
+func (p *wasmInstancePool) Init(ctx context.Context, sz int) error {
+	p.pool = make(chan *wasm.Instance, sz)
+	for i := 0; i < sz; i++ {
+		inst, err := p.inst.New(ctx)
+		if err != nil {
+			return err
+		}
+		p.pool <- inst
+	}
+	return nil
+}
+
+func (p *wasmInstancePool) Run(ctx context.Context, args wasm.Args) (uint32, error) {
+	var inst *wasm.Instance
+
+	select {
+	// Context canceled.
+	case <-ctx.Done():
+		return 0, ctx.Err()
+
+	// Acquire instance.
+	case inst = <-p.pool:
+
+		// Ensure instance is
+		// ready for running.
+		if inst.IsClosed() {
+			var err error
+			inst, err = p.inst.New(ctx)
+			if err != nil {
+				return 0, err
+			}
+		}
+	}
+
+	// Release instance to pool on end.
+	defer func() { p.pool <- inst }()
+
+	// Pass args to instance.
+	return inst.Run(ctx, args)
+}