refactor: improve fallback latest when no version found (#13)

Author: julienrbrt

abci/multiplexer.go

@@ -2,7 +2,9 @@ package abci
 
 import (
 	"context"
+	"errors"
 	"fmt"
+	"log"
 	"os"
 	"path/filepath"
 	"sync"
@@ -39,22 +41,30 @@ func NewMultiplexer(latestApp servertypes.ABCI, versions Versions, v *viper.Vipe
 		versions:  versions,
 	}
 
-	// check height from disk
-	wrapper.lastHeight, _ = wrapper.getLatestHeight(home, v) // if error assume genesis
-
-	// prepare correct version
 	var (
 		currentVersion Version
-		name           string
+		err            error
 	)
 
+	// check height from disk
+	wrapper.lastHeight, err = wrapper.getLatestHeight(home, v) // if error assume genesis
+	if err != nil {
+		log.Printf("failed to get latest height from disk, assuming genesis: %v\n", err)
+	}
+
+	// prepare correct version
 	if wrapper.lastHeight == 0 {
-		currentVersion = versions.GenesisVersion()
+		currentVersion, err = versions.GenesisVersion()
 	} else {
-		name, currentVersion = versions.GetForHeight(wrapper.lastHeight)
+		currentVersion, err = versions.GetForHeight(wrapper.lastHeight)
+	}
+	if err != nil && errors.Is(err, ErrNoVersionFound) {
+		return wrapper, nil // no version found, assume latest
+	} else if err != nil {
+		return nil, fmt.Errorf("failed to get app for height %d: %w", wrapper.lastHeight, err)
 	}
 
-	// prepare client
+	// prepare remote app
 	grpcAddress := v.GetString(flagGRPCAddress)
 	if grpcAddress == "" {
 		grpcAddress = "localhost:9090"
@@ -74,11 +84,11 @@ func NewMultiplexer(latestApp servertypes.ABCI, versions Versions, v *viper.Vipe
 		}
 
 		if err := currentVersion.Appd.Run(append(programArgs, currentVersion.StartArgs...)...); err != nil {
-			return nil, fmt.Errorf("failed to start %s app: %w", name, err)
+			return nil, fmt.Errorf("failed to start app: %w", err)
 		}
 
 		if currentVersion.Appd.Pid() == appd.AppdStopped { // should never happen
-			panic(fmt.Sprintf("%s app has not started", name))
+			panic("app has not started")
 		}
 	}
 
@@ -97,7 +107,7 @@ func (m *multiplexer) getLatestHeight(rootDir string, v *viper.Viper) (int64, er
 	return height, db.Close()
 }
 
-// Helper to get the appropriate app based on height
+// getAppForHeight gets the appropriate app based on height
 func (m *multiplexer) getAppForHeight(height int64) servertypes.ABCI {
 	m.mu.Lock()
 	defer m.mu.Unlock()

abci/versions.go

@@ -1,6 +1,14 @@
 package abci
 
-import "github.com/01builders/nova/appd"
+import (
+	"errors"
+	"fmt"
+
+	"github.com/01builders/nova/appd"
+)
+
+// ErrNoVersionFound is returned when no remote version is found for a given height.
+var ErrNoVersionFound = errors.New("no version found")
 
 // Version defines the configuration for remote apps.
 type Version struct {
@@ -12,7 +20,7 @@ type Version struct {
 type Versions map[string]Version
 
 // GenesisVersion returns the genesis version.
-func (v Versions) GenesisVersion() Version {
+func (v Versions) GenesisVersion() (Version, error) {
 	var genesis Version
 	var minHeight int64 = -1
 
@@ -23,23 +31,27 @@ func (v Versions) GenesisVersion() Version {
 		}
 	}
 
-	return genesis
+	if minHeight == -1 {
+		return Version{}, fmt.Errorf("%w: no genesis version found", ErrNoVersionFound)
+	}
+
+	return genesis, nil
 }
 
 // GetForHeight returns the version for a given height.
-func (v Versions) GetForHeight(height int64) (string, Version) {
+func (v Versions) GetForHeight(height int64) (Version, error) {
 	var selectedVersion Version
-	var name string
-
-	for n, version := range v {
+	for _, version := range v {
 		if version.UntilHeight >= height {
 			selectedVersion = version
-			name = n
-			break
 		}
 	}
 
-	return name, selectedVersion
+	if selectedVersion.UntilHeight < height {
+		return Version{}, fmt.Errorf("%w: %d", ErrNoVersionFound, height)
+	}
+
+	return selectedVersion, nil
 }
 
 // ShouldLatestApp returns true if the given height is higher than all version's UntilHeight.

passthrough.go

@@ -60,7 +60,10 @@ Use --version to specify a named version or --height to execute on the version a
 					return fmt.Errorf("height %d requires the latest app, use the command directly without passthrough", height)
 				}
 
-				versionName, appVersion = versions.GetForHeight(height)
+				appVersion, err = versions.GetForHeight(height)
+				if err != nil {
+					return fmt.Errorf("no version found for height %d: %w", height, err)
+				}
 			} else {
 				return errors.New("either --version or --height must be specified")
 			}