components/resolver: Use database instead of file approach

cmd/update_prefix_config.go

@@ -1,19 +1,22 @@
 package cmd
 
 import (
-	"io"
+	"fmt"
 
 	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
+	"github.com/FAU-CDI/wisski-distillery/internal/component/instances"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
-	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
-	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
+	"github.com/FAU-CDI/wisski-distillery/pkg/smartp"
 	"github.com/tkw1536/goprogram/exit"
+	"github.com/tkw1536/goprogram/stream"
 )
 
 // Cron is the 'cron' command
 var UpdatePrefixConfig wisski_distillery.Command = updateprefixconfig{}
 
-type updateprefixconfig struct{}
+type updateprefixconfig struct {
+	Parallel int `short:"p" long:"parallel" description:"run on (at most) this many instances in parallel. 0 for no limit." default:"1"`
+}
 
 func (updateprefixconfig) Description() wisski_distillery.Description {
 	return wisski_distillery.Description{
@@ -26,55 +29,26 @@ func (updateprefixconfig) Description() wisski_distillery.Description {
 }
 
 var errPrefixUpdateFailed = exit.Error{
-	Message:  "Failed to update the prefix configuration: %s",
+	Message:  "Failed to update the prefix configuration",
 	ExitCode: exit.ExitGeneric,
 }
 
 func (upc updateprefixconfig) Run(context wisski_distillery.Context) error {
 	dis := context.Environment
 
-	instances, err := dis.Instances().All()
+	wissKIs, err := dis.Instances().All()
 	if err != nil {
-		return errPrefixUpdateFailed.WithMessageF(err)
+		return errPrefixUpdateFailed.Wrap(err)
 	}
 
-	ddis := dis.Control()
-	target := dis.Resolver().ConfigPath()
-
-	// print the configuration
-	config, err := dis.Core.Environment.Create(target, environment.DefaultFilePerm)
-	if err != nil {
-		return errPrefixUpdateFailed.WithMessageF(err)
-	}
-
-	// iterate over the instances and store the last value of error
-	for _, instance := range instances {
-		if err := logging.LogOperation(func() error {
-			// read the prefix config
-			data, err := instance.PrefixConfig()
-			if err != nil {
-				data = "# error, skipped\n"
-				context.EPrintln(err)
-				err = nil
-			}
-			context.IOStream.Printf("%s", data)
-
-			// and write it out!
-			if _, err := io.WriteString(config, data); err != nil {
-				return err
-			}
-
-			return nil
-		}, context.IOStream, "reading prefix config %s", instance.Slug); err != nil {
-			return errPrefixUpdateFailed.WithMessageF(err)
+	return smartp.Run(context.IOStream, upc.Parallel, func(instance instances.WissKI, io stream.IOStream) error {
+		io.Println("reading prefixes")
+		err := instance.UpdatePrefixes()
+		if err != nil {
+			return errPrefixUpdateFailed.Wrap(err)
 		}
-	}
-
-	// and restart the resolver to apply the config!
-	logging.LogMessage(context.IOStream, "restarting resolver stack")
-	if err := ddis.Stack(ddis.Environment).Restart(context.IOStream); err != nil {
-		return errPrefixUpdateFailed.WithMessageF(err)
-	}
-
-	return err
+		return nil
+	}, wissKIs, smartp.SmartMessage(func(item instances.WissKI) string {
+		return fmt.Sprintf("update_prefix %q", item.Slug)
+	}))
 }

internal/component/control/control.go

@@ -14,8 +14,6 @@ type Control struct {
 	component.ComponentBase
 
 	Servables []component.Servable
-
-	ResolverFile string // TODO: this shouldn't be needed!
 }
 
 func (control Control) Name() string {
@@ -48,7 +46,6 @@ func (control *Control) Stack(env environment.Environment) component.StackWithRe
 			"SELF_RESOLVER_BLOCK_FILE":    control.Config.SelfResolverBlockFile,
 		},
 
-		TouchFiles:       []string{control.ResolverFile},
 		CopyContextFiles: []string{core.Executable},
 	})
 	return stt

internal/component/instances/meta.go

@@ -35,9 +35,9 @@ type MetaStorage interface {
 	// Any other metadata with the same key is deleted.
 	Set(key MetaKey, value any) error
 
-	// Add serializes values and stores each as associated with the provided key.
-	// Already existing metadata is left intact.
-	Add(key MetaKey, values ...any) error
+	// Set serializes values and stores them with the provided key.
+	// Any other metadata with the same key is deleted.
+	SetAll(key MetaKey, values ...any) error
 
 	// Purge removes all metadata, regardless of key.
 	Purge() error
@@ -163,13 +163,19 @@ func (s *storage) Set(key MetaKey, value any) error {
 	})
 }
 
-func (s *storage) Add(key MetaKey, values ...any) error {
+func (s *storage) SetAll(key MetaKey, values ...any) error {
 	table, err := s.SQL.QueryTable(true, models.MetadataTable)
 	if err != nil {
 		return err
 	}
 
 	return table.Transaction(func(tx *gorm.DB) error {
+		// delete the old values
+		status := tx.Where(&models.Metadatum{Slug: s.Slug, Key: string(key)}).Delete(&models.Metadatum{})
+		if err := status.Error; err != nil {
+			return err
+		}
+
 		for _, value := range values {
 			bytes, err := json.Marshal(value)
 			if err != nil {

internal/component/instances/wisski_prefix.go

@@ -82,6 +82,29 @@ func hasAnyPrefix(candidate string, prefixes []string) bool {
 	)
 }
 
+var PrefixConfigKey MetaKey = "prefix"
+
+// Prefixes returns the prefixes for the instance
+func (wisski *WissKI) PrefixesCached() (results []string, err error) {
+	err = wisski.Metadata().GetAll(PrefixConfigKey, func(index, total int) any {
+		if results == nil {
+			results = make([]string, total)
+		}
+		return &results[index]
+	})
+	return
+}
+
+// UpdatePrefixes updates the cached prefixes of this instance
+func (wisski *WissKI) UpdatePrefixes() error {
+	prefixes, err := wisski.Prefixes()
+	if err != nil {
+		return err
+	}
+
+	return wisski.Metadata().SetAll(PrefixConfigKey, slicesx.AsAny(prefixes)...)
+}
+
 // PrefixConfig returns the prefix config belonging to this instance.
 func (wisski *WissKI) PrefixConfig() (config string, err error) {
 	// if the user requested to skip the prefix, then don't do anything with it!

internal/component/pool_meta.go

@@ -8,10 +8,6 @@ import (
 	"github.com/tkw1536/goprogram/lib/reflectx"
 )
 
-//
-// META
-//
-
 var metaCache sync.Map
 
 // getMeta gets the component belonging to a component type
@@ -118,7 +114,7 @@ func filterSubtype(sliceS reflect.Value, iface reflect.Type) reflect.Value {
 	result := reflect.MakeSlice(reflect.SliceOf(iface), 0, len)
 	for i := 0; i < len; i++ {
 		element := sliceS.Index(i)
-		if element.Type().Implements(iface) {
+		if element.Elem().Type().Implements(iface) {
 			result = reflect.Append(result, element.Elem().Convert(iface))
 		}
 	}

internal/component/resolver/resolver.go

@@ -2,15 +2,14 @@ package resolver
 
 import (
 	"fmt"
-	"io/fs"
 	"net/http"
-	"path/filepath"
 	"regexp"
+	"time"
 
 	"github.com/FAU-CDI/wdresolve"
 	"github.com/FAU-CDI/wdresolve/resolvers"
 	"github.com/FAU-CDI/wisski-distillery/internal/component"
-	"github.com/FAU-CDI/wisski-distillery/internal/component/control"
+	"github.com/FAU-CDI/wisski-distillery/internal/component/instances"
 	"github.com/FAU-CDI/wisski-distillery/pkg/lazy"
 	"github.com/tkw1536/goprogram/stream"
 )
@@ -18,13 +17,13 @@ import (
 type Resolver struct {
 	component.ComponentBase
 
-	Control      *control.Control
-	ResolverFile string
+	Instances *instances.Instances
 
-	handler lazy.Lazy[wdresolve.ResolveHandler]
+	prefixes lazy.Lazy[map[string]string]        // cached prefixes (from the server)
+	handler  lazy.Lazy[wdresolve.ResolveHandler] // handler
 }
 
-func (Resolver) Name() string { return "resolver" }
+func (*Resolver) Name() string { return "resolver" }
 
 func (resolver *Resolver) Routes() []string { return []string{"/go/", "/wisski/get/"} }
 
@@ -50,35 +49,48 @@ func (resolver *Resolver) Handler(route string, io stream.IOStream) (http.Handle
 			io.Printf("registering legacy domain %s\n", domain)
 		}
 
-		configPath := resolver.ConfigPath()
-		{
-			// load the prefix path!
-			var fs fs.File
-			fs, err = resolver.Environment.Open(configPath)
-			io.Println("loading prefixes from ", configPath)
-			if err != nil {
-				return
-			}
-			defer fs.Close()
-
-			// read the file
-			var prefixes resolvers.Prefix
-			prefixes, err = resolvers.ReadPrefixes(fs)
-			if err != nil {
-				return
-			}
-
-			// and use that as the resolver!
-			p.Resolver = resolvers.InOrder{
-				prefixes,
-				fallback,
-			}
-
-			return p
+		// resolve the prefixes
+		p.Resolver = resolvers.InOrder{
+			resolver,
+			fallback,
 		}
+		return p
 	}), err
 }
 
-func (resolver *Resolver) ConfigPath() string {
-	return filepath.Join(resolver.Control.Path(), resolver.ResolverFile)
+func (resolver *Resolver) Target(uri string) string {
+	return wdresolve.PrefixTarget(resolver, uri)
+}
+
+// allow reloading prefixes from the server every minute
+const prefixesRefresh = time.Minute
+
+func (resolver *Resolver) Prefixes() (prefixes map[string]string) {
+	// reset the prefixes after a specific time, but only if requested
+	resolver.prefixes.ResetAfter(prefixesRefresh)
+	return resolver.prefixes.Get(resolver.freshPrefixes)
+}
+
+func (resolver *Resolver) freshPrefixes() map[string]string {
+	instances, err := resolver.Instances.All()
+	if err != nil {
+		return nil
+	}
+
+	gPrefixes := make(map[string]string)
+	for _, instance := range instances {
+		url := instance.URL().String()
+
+		// failed to fetch prefixes for this particular instance
+		// => skip it!
+		prefixes, err := instance.PrefixesCached()
+		if err != nil {
+			continue
+		}
+
+		for _, p := range prefixes {
+			gPrefixes[url] = p
+		}
+	}
+	return gPrefixes
 }

internal/core/core.go

@@ -20,6 +20,7 @@ const ConfigFile = ".env"
 const OverridesJSON = "overrides.json"
 
 // DefaultOverridesJSON contains a template for a new 'overrides.json' file
+//
 //go:embed bootstrap/overrides.json
 var DefaultOverridesJSON []byte
 
@@ -28,6 +29,7 @@ var DefaultOverridesJSON []byte
 const ResolverBlockedTXT = "resolver-blocked.txt"
 
 // ResolverBlockTXT contains a template for 'resolver-blocked' file
+//
 //go:embed bootstrap/resolver-blocked.txt
 var DefaultResolverBlockedTXT []byte
 
@@ -35,9 +37,6 @@ var DefaultResolverBlockedTXT []byte
 const AuthorizedKeys = "authorized_keys"
 
 // DefaultAuthorizedKeys contains a template for a new 'global_authorized_keys' file
+//
 //go:embed bootstrap/global_authorized_keys
 var DefaultAuthorizedKeys []byte
-
-// PrefixConfig is the name for the global resolver prefix configuration.
-// It should be found within the prefix component directory.
-const PrefixConfig = "prefix.cfg"

internal/dis/component.go

@@ -12,7 +12,6 @@ import (
 	"github.com/FAU-CDI/wisski-distillery/internal/component/ssh"
 	"github.com/FAU-CDI/wisski-distillery/internal/component/triplestore"
 	"github.com/FAU-CDI/wisski-distillery/internal/component/web"
-	"github.com/FAU-CDI/wisski-distillery/internal/core"
 )
 
 // register returns all components of the distillery
@@ -43,13 +42,9 @@ func (dis *Distillery) register(context *component.PoolContext) []component.Comp
 		ra[*snapshots.Pathbuilders](dis, context),
 
 		// Control server
-		r(dis, context, func(control *control.Control) {
-			control.ResolverFile = core.PrefixConfig
-		}),
+		ra[*control.Control](dis, context),
 		ra[*control.SelfHandler](dis, context),
-		r(dis, context, func(resolver *resolver.Resolver) {
-			resolver.ResolverFile = core.PrefixConfig
-		}),
+		ra[*resolver.Resolver](dis, context),
 		ra[*control.Info](dis, context),
 	}
 }

pkg/lazy/lazy.go

@@ -1,6 +1,9 @@
 package lazy
 
-import "sync"
+import (
+	"sync"
+	"time"
+)
 
 // Lazy is an object that a lazily-initialized value of type T.
 //
@@ -8,6 +11,9 @@ import "sync"
 type Lazy[T any] struct {
 	once  sync.Once
 	value T
+
+	m         sync.RWMutex // m protects resetting this lazy
+	lastReset time.Time    // last time this mutex was reset
 }
 
 // Get returns the value associated with this Lazy.
@@ -20,8 +26,53 @@ type Lazy[T any] struct {
 //
 // Get may safely be called concurrently.
 func (lazy *Lazy[T]) Get(init func() T) T {
+	lazy.m.RLock()
+	defer lazy.m.RUnlock()
+
 	lazy.once.Do(func() {
 		lazy.value = init()
 	})
 	return lazy.value
 }
+
+// Reset resets this Lazy, deleting any previously associated value.
+//
+// May be called concurrently with [Get].
+// Future calls to [Get] will invoke init.
+func (lazy *Lazy[T]) Reset() {
+	lazy.m.Lock()
+	defer lazy.m.Unlock()
+
+	lazy.reset()
+}
+
+// ResetAfter resets this lazy if more than d time has passed since the last reset.
+// If ResetAfter cannot lock, then it does not reset.
+//
+// May be called concurrently with other functions on this lazy.
+func (lazy *Lazy[T]) ResetAfter(d time.Duration) {
+	if !lazy.m.TryLock() {
+		return
+	}
+	defer lazy.m.Unlock()
+
+	if time.Since(lazy.lastReset) < d {
+		return
+	}
+
+	lazy.reset()
+}
+
+// reset implements resetting this lazy.
+// m myst be held for writing.
+func (lazy *Lazy[T]) reset() {
+	// reset the once
+	lazy.once = sync.Once{}
+
+	// reset the value
+	var t T
+	lazy.value = t
+
+	// time of the last reset
+	lazy.lastReset = time.Now()
+}

pkg/slicesx/slicesx.go

@@ -49,6 +49,15 @@ func Filter[T any](values []T, filter func(T) bool) []T {
 	return results
 }
 
+// AsAny returns the same slice as values, but as any
+func AsAny[T any](values []T) []any {
+	results := make([]any, len(values))
+	for i, v := range values {
+		results[i] = v
+	}
+	return results
+}
+
 // Partition partitions values in T by the given functions.
 func Partition[T any, P comparable](values []T, partition func(value T) P) map[P][]T {
 	result := make(map[P][]T)