better error handling

rpc-pool.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"fmt"
 	"strings"
 	"sync"
 )
@@ -28,17 +27,17 @@ type RemoteGrain struct {
 	Address string
 }
 
-func NewRemoteGrain(id CartId, address string) *RemoteGrain {
+func NewRemoteGrain(id CartId, address string) (*RemoteGrain, error) {
 	client, err := CartDial(address)
 	if err != nil {
-		return nil
+		return nil, err
 	}
 
 	return &RemoteGrain{
 		Id:         id,
 		Address:    address,
 		CartClient: client,
-	}
+	}, nil
 }
 
 func (g *RemoteGrain) HandleMessage(message *Message, isReplay bool) ([]byte, error) {
@@ -81,16 +80,19 @@ func (p *RemoteGrainPool) findRemoteGrain(id CartId) *RemoteGrain {
 	return grain
 }
 
-func (p *RemoteGrainPool) findOrCreateGrain(id CartId) *RemoteGrain {
+func (p *RemoteGrainPool) findOrCreateGrain(id CartId) (*RemoteGrain, error) {
 	grain := p.findRemoteGrain(id)
-	if grain == nil {
-		grain = NewRemoteGrain(id, p.Host)
 
+	if grain == nil {
+		grain, err := NewRemoteGrain(id, p.Host)
+		if err != nil {
+			return nil, err
+		}
 		p.mu.Lock()
 		p.grains[id] = grain
 		p.mu.Unlock()
 	}
-	return grain
+	return grain, nil
 }
 
 func (p *RemoteGrainPool) Delete(id CartId) {
@@ -101,10 +103,9 @@ func (p *RemoteGrainPool) Delete(id CartId) {
 
 func (p *RemoteGrainPool) Process(id CartId, messages ...Message) ([]byte, error) {
 	var result []byte
-	var err error
-	grain := p.findOrCreateGrain(id)
-	if grain == nil {
-		return nil, fmt.Errorf("grain not found")
+	grain, err := p.findOrCreateGrain(id)
+	if err != nil {
+		return nil, err
 	}
 	for _, message := range messages {
 		result, err = grain.HandleMessage(&message, false)
@@ -113,9 +114,9 @@ func (p *RemoteGrainPool) Process(id CartId, messages ...Message) ([]byte, error
 }
 
 func (p *RemoteGrainPool) Get(id CartId) ([]byte, error) {
-	grain := p.findOrCreateGrain(id)
-	if grain == nil {
-		return nil, fmt.Errorf("grain not found")
+	grain, err := p.findOrCreateGrain(id)
+	if err != nil {
+		return nil, err
 	}
 	return grain.GetCurrentState()
 }