[feature] support processing of (many) more media types (#3090)

* initial work replacing our media decoding / encoding pipeline with ffprobe + ffmpeg

* specify the video codec to use when generating static image from emoji

* update go-storage library (fixes incompatibility after updating go-iotools)

* maintain image aspect ratio when generating a thumbnail for it

* update readme to show go-ffmpreg

* fix a bunch of media tests, move filesize checking to callers of media manager for more flexibility

* remove extra debug from error message

* fix up incorrect function signatures

* update PutFile to just use regular file copy, as changes are file is on separate partition

* fix remaining tests, remove some unneeded tests now we're working with ffmpeg/ffprobe

* update more tests, add more code comments

* add utilities to generate processed emoji / media outputs

* fix remaining tests

* add test for opus media file, add license header to utility cmds

* limit the number of concurrently available ffmpeg / ffprobe instances

* reduce number of instances

* further reduce number of instances

* fix envparsing test with configuration variables

* update docs and configuration with new media-{local,remote}-max-size variables

vendor/codeberg.org/gruf/go-ffmpreg/wasm/instance.go

@@ -0,0 +1,181 @@
+package wasm
+
+import (
+	"context"
+	"errors"
+	"io"
+	"sync"
+
+	"github.com/tetratelabs/wazero"
+	"github.com/tetratelabs/wazero/sys"
+)
+
+type Args struct {
+	// Standard FDs.
+	Stdin  io.Reader
+	Stdout io.Writer
+	Stderr io.Writer
+
+	// CLI args.
+	Args []string
+
+	// Optional further module configuration function.
+	// (e.g. to mount filesystem dir, set env vars, etc).
+	Config func(wazero.ModuleConfig) wazero.ModuleConfig
+}
+
+type Instantiator struct {
+	// Module ...
+	Module string
+
+	// Runtime ...
+	Runtime func(context.Context) wazero.Runtime
+
+	// Config ...
+	Config func() wazero.ModuleConfig
+
+	// Source ...
+	Source []byte
+}
+
+func (inst *Instantiator) New(ctx context.Context) (*Instance, error) {
+	switch {
+	case inst.Module == "":
+		panic("missing module name")
+	case inst.Runtime == nil:
+		panic("missing runtime instantiator")
+	case inst.Config == nil:
+		panic("missing module configuration")
+	case len(inst.Source) == 0:
+		panic("missing module source")
+	}
+
+	// Create new host runtime.
+	rt := inst.Runtime(ctx)
+
+	// Compile guest module from WebAssembly source.
+	mod, err := rt.CompileModule(ctx, inst.Source)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Instance{
+		inst: inst,
+		wzrt: rt,
+		cmod: mod,
+	}, nil
+}
+
+type InstancePool struct {
+	Instantiator
+
+	pool []*Instance
+	lock sync.Mutex
+}
+
+func (p *InstancePool) Get(ctx context.Context) (*Instance, error) {
+	for {
+		// Check for cached.
+		inst := p.Cached()
+		if inst == nil {
+			break
+		}
+
+		// Check if closed.
+		if inst.IsClosed() {
+			continue
+		}
+
+		return inst, nil
+	}
+
+	// Must create new instance.
+	return p.Instantiator.New(ctx)
+}
+
+func (p *InstancePool) Put(inst *Instance) {
+	if inst.inst != &p.Instantiator {
+		panic("instance and pool instantiators do not match")
+	}
+	p.lock.Lock()
+	p.pool = append(p.pool, inst)
+	p.lock.Unlock()
+}
+
+func (p *InstancePool) Cached() *Instance {
+	var inst *Instance
+	p.lock.Lock()
+	if len(p.pool) > 0 {
+		inst = p.pool[len(p.pool)-1]
+		p.pool = p.pool[:len(p.pool)-1]
+	}
+	p.lock.Unlock()
+	return inst
+}
+
+// Instance ...
+//
+// NOTE: Instance is NOT concurrency
+// safe. One at a time please!!
+type Instance struct {
+	inst *Instantiator
+	wzrt wazero.Runtime
+	cmod wazero.CompiledModule
+}
+
+func (inst *Instance) Run(ctx context.Context, args Args) (uint32, error) {
+	if inst.inst == nil {
+		panic("not initialized")
+	}
+
+	// Check instance open.
+	if inst.IsClosed() {
+		return 0, errors.New("instance closed")
+	}
+
+	// Prefix binary name as argv0 to args.
+	cargs := make([]string, len(args.Args)+1)
+	copy(cargs[1:], args.Args)
+	cargs[0] = inst.inst.Module
+
+	// Create base module config.
+	modcfg := inst.inst.Config()
+	modcfg = modcfg.WithName(inst.inst.Module)
+	modcfg = modcfg.WithArgs(cargs...)
+	modcfg = modcfg.WithStdin(args.Stdin)
+	modcfg = modcfg.WithStdout(args.Stdout)
+	modcfg = modcfg.WithStderr(args.Stderr)
+
+	if args.Config != nil {
+		// Pass through config fn.
+		modcfg = args.Config(modcfg)
+	}
+
+	// Instantiate the module from precompiled wasm module data.
+	mod, err := inst.wzrt.InstantiateModule(ctx, inst.cmod, modcfg)
+
+	if mod != nil {
+		// Close module.
+		mod.Close(ctx)
+	}
+
+	// Check for a returned exit code error.
+	if err, ok := err.(*sys.ExitError); ok {
+		return err.ExitCode(), nil
+	}
+
+	return 0, err
+}
+
+func (inst *Instance) IsClosed() bool {
+	return (inst.wzrt == nil || inst.cmod == nil)
+}
+
+func (inst *Instance) Close(ctx context.Context) error {
+	if inst.IsClosed() {
+		return nil
+	}
+	err1 := inst.cmod.Close(ctx)
+	err2 := inst.wzrt.Close(ctx)
+	return errors.Join(err1, err2)
+}