Cache responses from purple pages when relays are not found

planetary-social · Nov 15, 2023 · 4a5020a · 4a5020a
1 parent f735d3e
commit 4a5020a
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Showing 2 changed files with 40 additions and 23 deletions.
diff --git a/service/adapters/purple_pages.go b/service/adapters/purple_pages.go
@@ -15,13 +15,16 @@ import (
 
 var (
 	ErrRelayListNotFoundInPurplePages = errors.New("relay list not found in purple pages")
-	ErrPurplePagesTimeout             = errors.New("purple pages lookup timed out")
+
+	errLookupFoundNoEvents = errors.New("lookup found no events")
 )
 
 var purplePagesAddress = domain.MustNewRelayAddress("wss://purplepag.es")
 
 const purplePagesLookupTimeout = 10 * time.Second
 
+const numLookups = 2
+
 type PurplePages struct {
 	logger     logging.Logger
 	metrics    app.Metrics
@@ -79,26 +82,34 @@ func (p *PurplePages) GetRelays(ctx context.Context, publicKey domain.PublicKey)
 
 	results := internal.NewEmptySet[domain.RelayAddress]()
 
-	var compoundError error
-	errorsCounter := 0
+	var compoundError *multierror.Error
 
-	for i := 0; i < 2; i++ {
+	for i := 0; i < numLookups; i++ {
 		result := <-ch
-
 		if err := result.Err; err != nil {
-			if errors.Is(err, ErrPurplePagesTimeout) {
-				return nil, errors.Wrap(err, "one of the lookups timed out")
+			if !errors.Is(err, errLookupFoundNoEvents) {
+				return nil, errors.Wrap(err, "one of the lookups failed")
 			}
-
 			compoundError = multierror.Append(compoundError, err)
-			errorsCounter++
 			continue
 		}
 		results.PutMany(result.Addresses)
 	}
 
-	if errorsCounter == 2 {
-		return nil, compoundError
+	// if any of the lookups failed with err != errLookupFoundNoEvents return compoundErr
+	// if all of the lookups failed with err == errLookupFoundNoEvents return ErrRelayListNotFoundInPurplePages
+	if compoundError != nil {
+		errLookupFoundNoEventsCounter := 0
+		for _, componentErr := range compoundError.Errors {
+			if !errors.Is(componentErr, errLookupFoundNoEvents) {
+				return nil, errors.Wrap(compoundError, "some lookups failed")
+			}
+			errLookupFoundNoEventsCounter++
+		}
+
+		if errLookupFoundNoEventsCounter == numLookups {
+			return nil, ErrRelayListNotFoundInPurplePages
+		}
 	}
 
 	return results.List(), nil
@@ -117,7 +128,7 @@ func (p *PurplePages) getRelaysFromRelayMetadata(ctx context.Context, publicKey
 		nil,
 	) {
 		if eventOrEOSE.EOSE() {
-			return nil, ErrRelayListNotFoundInPurplePages
+			return nil, errLookupFoundNoEvents
 		}
 
 		event := eventOrEOSE.Event()
@@ -140,7 +151,7 @@ func (p *PurplePages) getRelaysFromRelayMetadata(ctx context.Context, publicKey
 		}
 	}
 
-	return nil, ErrPurplePagesTimeout
+	return nil, errors.New("timeout")
 }
 
 func (p *PurplePages) getRelaysFromContacts(ctx context.Context, publicKey domain.PublicKey) ([]domain.RelayAddress, error) {
@@ -156,7 +167,7 @@ func (p *PurplePages) getRelaysFromContacts(ctx context.Context, publicKey domai
 		nil,
 	) {
 		if eventOrEOSE.EOSE() {
-			return nil, ErrRelayListNotFoundInPurplePages
+			return nil, errLookupFoundNoEvents
 		}
 
 		event := eventOrEOSE.Event()
@@ -173,7 +184,7 @@ func (p *PurplePages) getRelaysFromContacts(ctx context.Context, publicKey domai
 		}
 	}
 
-	return nil, ErrPurplePagesTimeout
+	return nil, errors.New("timeout")
 }
 
 type relaysOrError struct {

diff --git a/service/adapters/relay_source.go b/service/adapters/relay_source.go
@@ -40,7 +40,7 @@ func (p RelaySource) GetRelays(ctx context.Context, publicKey domain.PublicKey)
 		result.Put(relayAddress)
 	}
 
-	relayAddressesFromPurplePages, err := p.getRelaysFromPurplePages(ctx, publicKey)
+	relayAddressesFromPurplePages, err := p.getRelaysFromPurplePagesOrCache(ctx, publicKey)
 	if err != nil {
 		return nil, errors.Wrap(err, "error getting relays from purple pages")
 	}
@@ -52,7 +52,7 @@ func (p RelaySource) GetRelays(ctx context.Context, publicKey domain.PublicKey)
 	return result.List(), nil
 }
 
-func (p RelaySource) getRelaysFromPurplePages(ctx context.Context, publicKey domain.PublicKey) ([]domain.RelayAddress, error) {
+func (p RelaySource) getRelaysFromPurplePagesOrCache(ctx context.Context, publicKey domain.PublicKey) ([]domain.RelayAddress, error) {
 	var previousEntries []domain.RelayAddress
 
 	entry, ok := p.cache.Get(publicKey)
@@ -63,18 +63,24 @@ func (p RelaySource) getRelaysFromPurplePages(ctx context.Context, publicKey dom
 		}
 	}
 
-	relayAddressesFromPurplePages, err := p.purplePages.GetRelays(ctx, publicKey)
+	relayAddressesFromPurplePages, err := p.getRelaysFromPurplePages(ctx, publicKey)
 	if err != nil {
-		if errors.Is(err, ErrRelayListNotFoundInPurplePages) ||
-			errors.Is(err, ErrPurplePagesTimeout) {
-			p.logger.Debug().WithError(err).Message("known error from purple pages")
-			return previousEntries, nil
-		}
 		return nil, errors.Wrap(err, "error querying purple pages")
 	}
 
 	p.cache.Set(publicKey, relayAddressesFromPurplePages)
+	return relayAddressesFromPurplePages, nil
+}
 
+func (p RelaySource) getRelaysFromPurplePages(ctx context.Context, publicKey domain.PublicKey) ([]domain.RelayAddress, error) {
+	relayAddressesFromPurplePages, err := p.purplePages.GetRelays(ctx, publicKey)
+	if err != nil {
+		if errors.Is(err, ErrRelayListNotFoundInPurplePages) {
+			p.logger.Debug().WithError(err).Message("relay list not found in purple pages")
+			return nil, nil
+		}
+		return nil, errors.Wrap(err, "error querying purple pages")
+	}
 	return relayAddressesFromPurplePages, nil
 }