[FAB-3617] Add ChaincodePackageExists function

Currently, we detect a chaincodepackage's existense by trying reading
its content. This is heavy when the package is large (very often).

This patchset add a ChaincodePackageExists function, to saves the effort by
detecting the existence using os.stat().

Change-Id: I99b16eeaee2bb6e80087e08f3ad136d01c044857
Signed-off-by: Baohua Yang <baohyang@cn.ibm.com>

core/common/ccprovider/ccprovider.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/golang/protobuf/proto"
@@ -98,6 +99,17 @@ func GetChaincodePackage(ccname string, ccversion string) ([]byte, error) {
 	return ccbytes, nil
 }
 
+//ChaincodePackageExists returns whether the chaincode package exists in the file system
+func ChaincodePackageExists(ccname string, ccversion string) (bool, error) {
+	path := filepath.Join(chaincodeInstallPath, ccname+"."+ccversion)
+	_, err := os.Stat(path)
+	if err == nil {
+		// chaincodepackage already exists
+		return true, nil
+	}
+	return false, err
+}
+
 // GetChaincodeFromFS this is a wrapper for hiding package implementation.
 func GetChaincodeFromFS(ccname string, ccversion string) (CCPackage, error) {
 	//try raw CDS

peer/chaincode/install.go

@@ -90,9 +90,8 @@ func install(msg proto.Message, cf *ChaincodeCmdFactory) error {
 
 //generateChaincode creates ChaincodeDeploymentSpec as the package to install
 func generateChaincode(cmd *cobra.Command, chaincodeName, chaincodeVersion string) (*pb.ChaincodeDeploymentSpec, error) {
-	tmppkg, _ := ccprovider.GetChaincodePackage(chaincodeName, chaincodeVersion)
-	if tmppkg != nil {
-		return nil, fmt.Errorf("chaincode %s:%s exists", chaincodeName, chaincodeVersion)
+	if existed, _ := ccprovider.ChaincodePackageExists(chaincodeName, chaincodeVersion); existed {
+		return nil, fmt.Errorf("chaincode %s:%s already exists", chaincodeName, chaincodeVersion)
 	}
 
 	spec, err := getChaincodeSpec(cmd)