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gotosocial/internal/media/ffmpeg/wasm.go

119 lines
2.7 KiB
Go

// 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/>.
//go:build !nowasm
package ffmpeg
import (
"context"
"os"
"sync/atomic"
"unsafe"
"codeberg.org/gruf/go-ffmpreg/embed"
"codeberg.org/gruf/go-ffmpreg/wasm"
"github.com/tetratelabs/wazero"
)
// ffmpreg is a concurrency-safe pointer
// to our necessary WebAssembly runtime
// and compiled ffmpreg module instance.
var ffmpreg atomic.Pointer[struct {
run wazero.Runtime
mod wazero.CompiledModule
}]
// initWASM safely prepares new WebAssembly runtime
// and compiles ffmpreg module instance, if the global
// pointer has not been already. else, is a no-op.
func initWASM(ctx context.Context) error {
if ffmpreg.Load() != nil {
return nil
}
// Create new runtime config.
cfg := wazero.NewRuntimeConfig()
if dir := os.Getenv("GTS_WAZERO_COMPILATION_CACHE"); dir != "" {
// Use on-filesystem compilation cache given by env.
cache, err := wazero.NewCompilationCacheWithDir(dir)
if err != nil {
return err
}
// Update runtime config with cache.
cfg = cfg.WithCompilationCache(cache)
}
var (
run wazero.Runtime
mod wazero.CompiledModule
err error
set bool
)
defer func() {
if err == nil && set {
// Drop binary.
embed.B = nil
return
}
// Close module.
if !isNil(mod) {
mod.Close(ctx)
}
// Close runtime.
if !isNil(run) {
run.Close(ctx)
}
}()
// Initialize new runtime from config.
run, err = wasm.NewRuntime(ctx, cfg)
if err != nil {
return err
}
// Compile ffmpreg WebAssembly into memory.
mod, err = run.CompileModule(ctx, embed.B)
if err != nil {
return err
}
// Try set global WASM runtime and module,
// or if beaten to it defer will handle close.
set = ffmpreg.CompareAndSwap(nil, &struct {
run wazero.Runtime
mod wazero.CompiledModule
}{
run: run,
mod: mod,
})
return nil
}
// isNil will safely check if 'v' is nil without
// dealing with weird Go interface nil bullshit.
func isNil(i interface{}) bool {
type eface struct{ Type, Data unsafe.Pointer }
return (*eface)(unsafe.Pointer(&i)).Data == nil
}