update

plugins/base_capability.go

@@ -0,0 +1,159 @@
+package plugins
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/navidrome/navidrome/core/metrics"
+	"github.com/navidrome/navidrome/log"
+	"github.com/navidrome/navidrome/model/id"
+	"github.com/navidrome/navidrome/plugins/api"
+)
+
+// newBaseCapability creates a new instance of baseCapability with the required parameters.
+func newBaseCapability[S any, P any](wasmPath, id, capability string, m metrics.Metrics, loader P, loadFunc loaderFunc[S, P]) *baseCapability[S, P] {
+	return &baseCapability[S, P]{
+		wasmPath:   wasmPath,
+		id:         id,
+		capability: capability,
+		loader:     loader,
+		loadFunc:   loadFunc,
+		metrics:    m,
+	}
+}
+
+// LoaderFunc is a generic function type that loads a plugin instance.
+type loaderFunc[S any, P any] func(ctx context.Context, loader P, path string) (S, error)
+
+// baseCapability is a generic base implementation for WASM plugins.
+// S is the capability interface type and P is the plugin loader type.
+type baseCapability[S any, P any] struct {
+	wasmPath   string
+	id         string
+	capability string
+	loader     P
+	loadFunc   loaderFunc[S, P]
+	metrics    metrics.Metrics
+}
+
+func (w *baseCapability[S, P]) PluginID() string {
+	return w.id
+}
+
+func (w *baseCapability[S, P]) serviceName() string {
+	return w.id + "_" + w.capability
+}
+
+func (w *baseCapability[S, P]) getMetrics() metrics.Metrics {
+	return w.metrics
+}
+
+// getInstance loads a new plugin instance and returns a cleanup function.
+func (w *baseCapability[S, P]) getInstance(ctx context.Context, methodName string) (S, func(), error) {
+	start := time.Now()
+	// Add context metadata for tracing
+	ctx = log.NewContext(ctx, "capability", w.serviceName(), "method", methodName)
+
+	inst, err := w.loadFunc(ctx, w.loader, w.wasmPath)
+	if err != nil {
+		var zero S
+		return zero, func() {}, fmt.Errorf("baseCapability: failed to load instance for %s: %w", w.serviceName(), err)
+	}
+	// Add context metadata for tracing
+	ctx = log.NewContext(ctx, "instanceID", getInstanceID(inst))
+	log.Trace(ctx, "baseCapability: loaded instance", "elapsed", time.Since(start))
+	return inst, func() {
+		log.Trace(ctx, "baseCapability: finished using instance", "elapsed", time.Since(start))
+		if closer, ok := any(inst).(interface{ Close(context.Context) error }); ok {
+			_ = closer.Close(ctx)
+		}
+	}, nil
+}
+
+type wasmPlugin[S any] interface {
+	PluginID() string
+	getInstance(ctx context.Context, methodName string) (S, func(), error)
+	getMetrics() metrics.Metrics
+}
+
+func callMethod[S any, R any](ctx context.Context, wp WasmPlugin, methodName string, fn func(inst S) (R, error)) (R, error) {
+	// Add a unique call ID to the context for tracing
+	ctx = log.NewContext(ctx, "callID", id.NewRandom())
+	var r R
+
+	p, ok := wp.(wasmPlugin[S])
+	if !ok {
+		log.Error(ctx, "callMethod: not a wasm plugin", "method", methodName, "pluginID", wp.PluginID())
+		return r, fmt.Errorf("wasm plugin: not a wasm plugin: %s", wp.PluginID())
+	}
+
+	inst, done, err := p.getInstance(ctx, methodName)
+	if err != nil {
+		return r, err
+	}
+	start := time.Now()
+	defer done()
+	r, err = checkErr(fn(inst))
+	elapsed := time.Since(start)
+
+	if !errors.Is(err, api.ErrNotImplemented) {
+		id := p.PluginID()
+		isOk := err == nil
+		metrics := p.getMetrics()
+		if metrics != nil {
+			metrics.RecordPluginRequest(ctx, id, methodName, isOk, elapsed.Milliseconds())
+			log.Trace(ctx, "callMethod: sending metrics", "plugin", id, "method", methodName, "ok", isOk, "elapsed", elapsed)
+		}
+	}
+
+	return r, err
+}
+
+// errorResponse is an interface that defines a method to retrieve an error message.
+// It is automatically implemented (generated) by all plugin responses that have an Error field
+type errorResponse interface {
+	GetError() string
+}
+
+// checkErr returns an updated error if the response implements errorResponse and contains an error message.
+// If the response is nil, it returns the original error. Otherwise, it wraps or creates an error as needed.
+// It also maps error strings to their corresponding api.Err* constants.
+func checkErr[T any](resp T, err error) (T, error) {
+	if any(resp) == nil {
+		return resp, mapAPIError(err)
+	}
+	respErr, ok := any(resp).(errorResponse)
+	if ok && respErr.GetError() != "" {
+		respErrMsg := respErr.GetError()
+		respErrErr := errors.New(respErrMsg)
+		mappedErr := mapAPIError(respErrErr)
+		// Check if the error was mapped to an API error (different from the temp error)
+		if errors.Is(mappedErr, api.ErrNotImplemented) || errors.Is(mappedErr, api.ErrNotFound) {
+			// Return the mapped API error instead of wrapping
+			return resp, mappedErr
+		}
+		// For non-API errors, use wrap the original error if it is not nil
+		return resp, errors.Join(respErrErr, err)
+	}
+	return resp, mapAPIError(err)
+}
+
+// mapAPIError maps error strings to their corresponding api.Err* constants.
+// This is needed as errors from plugins may not be of type api.Error, due to serialization/deserialization.
+func mapAPIError(err error) error {
+	if err == nil {
+		return nil
+	}
+
+	errStr := err.Error()
+	switch errStr {
+	case api.ErrNotImplemented.Error():
+		return api.ErrNotImplemented
+	case api.ErrNotFound.Error():
+		return api.ErrNotFound
+	default:
+		return err
+	}
+}