CRT-P0001 · Multiple `append` can be combined into a single call

Multiple append can be combined into a single call CRT-P0001

Performance

Major

2 years ago — 2 years old

can combine chain of 6 appends into one

pkg/blockchain/hyperledger/fabric/controller/docker/orderer.go

41		Tty:        true,
42	}
43	if tls {
44		service.Environment = append(service.Environment, fmt.Sprintf("ORDERER_GENERAL_TLS_PRIVATEKEY=/var/hyperledger/orderer/tls/server.key"))45		service.Environment = append(service.Environment, fmt.Sprintf("ORDERER_GENERAL_TLS_CERTIFICATE=/var/hyperledger/orderer/tls/server.crt"))
46		service.Environment = append(service.Environment, fmt.Sprintf("ORDERER_GENERAL_TLS_ROOTCAS=[/var/hyperledger/orderer/tls/ca.crt]"))
47		service.Environment = append(service.Environment, fmt.Sprintf("ORDERER_GENERAL_CLUSTER_CLIENTCERTIFICATE=/var/hyperledger/orderer/tls/server.crt"))

can combine chain of 4 appends into one

pkg/container/docker/ssh.go

 5// StartSshServerInDockerCommand Connect with `ssh -p port user@ip`
 6func StartSshServerInDockerCommand(newPwd, user string) []string {
 7	var cmds []string
 8	cmds = append(cmds, fmt.Sprintf("apt-get install -y openssh-server openssh-clients")) 9	cmds = append(cmds, fmt.Sprintf("echo \"%s\" | passwd --stdin %s", newPwd, user))
10	cmds = append(cmds, fmt.Sprintf("echo \"PermitRootLogin yes\" >> /etc/ssh/sshd_config"))
11	cmds = append(cmds, fmt.Sprintf("/etc/init.d/sshd restart"))

can combine chain of 2 appends into one

pkg/blockchain/hyperledger/fabric/controller/fabric/channel.go

38	cmds = append(cmds, fmt.Sprintf("FABRIC_CFG_PATH=%sconfigtx", getBaseFolderPath()))
39	ordererDomain := fmt.Sprintf("%s.%s.%s", ordererPeerName, ordererOrgName, ordererDomainRoot)
40	blockFile := fmt.Sprintf("BLOCKFILE=\"%schannel-artifacts/%s.block\"", getBaseFolderPath(), channelName)
41	cmds = append(cmds, fmt.Sprintf("BLOCKFILE=%s", blockFile))42	cmds = append(cmds, fmt.Sprintf("peer channel create -o %s:%d -c %s --ordererTLSHostnameOverride %s -f .%schannel-artifacts/%s.tx --outputBlock %s --tls --cafile %sorganizations/ordererOrganizations/%s/orderers/%s/msp/tlscacerts/tlsca.%s-cert.pem", ordererDomain, ordererPort, channelName, ordererDomain, getBaseFolderPath(), channelName, blockFile, getBaseFolderPath(), ordererDomain, ordererDomain, ordererDomainRoot))
43
44	// TODO Check tlscacert file: "tlsca.orderer.examle.com" name.

can combine chain of 5 appends into one

pkg/blockchain/hyperledger/fabric/controller/fabric/channel.go

79	ordererDomain := fmt.Sprintf("%s.%s.%s", ordererPeerName, ordererOrgName, ordererDomainRoot)
80
81	blockFile := fmt.Sprintf("BLOCKFILE=\"%schannel-artifacts/%s.block\"", getBaseFolderPath(), channelName)
82	cmds = append(cmds, fmt.Sprintf("BLOCKFILE=%s", blockFile))83
84	cmds = append(cmds, fmt.Sprintf("peer channel create -o %s:%d -c %s --ordererTLSHostnameOverride %s -f %schannel-artifacts/%s.tx --outputBlock %s --tls --cafile %s", ordererDomain, ordererPort, channelName, ordererDomain, getBaseFolderPath(), channelName, blockFile, ordererCaPath))
85

can combine chain of 3 appends into one

pkg/blockchain/hyperledger/fabric/controller/fabric/organization.go

 57	orgGroup := getOrgSubPathByOrderer(orderer)
 58	var cmds []string
 59
 60	cmds = append(cmds, fmt.Sprintf("  mkdir -p \"%sorganizations/%s/%s/msp/tlscacerts\"\n && cp \"%sorganizations/fabric-ca/%s/ca-cert.pem\" \"%sorganizations/%s/%s/msp/tlscacerts/ca.crt\"", getBaseFolderPath(), orgGroup, domain, getBaseFolderPath(), caOrg, getBaseFolderPath(), orgGroup, domain)) 61
 62	cmds = append(cmds, fmt.Sprintf("  mkdir -p \"%sorganizations/%s/%s/tlsca\"\n && cp \"%sorganizations/fabric-ca/%s/ca-cert.pem\" \"%sorganizations/%s/%s/tlsca/tlsca.%s-cert.pem\"", getBaseFolderPath(), orgGroup, domain, getBaseFolderPath(), caOrg, getBaseFolderPath(), orgGroup, domain, domain))
 63

Description

Multiple calls for append could be combined into a single call for append.

The append built-in function appends elements to the end of a slice. If it has sufficient capacity, the destination is resliced to accommodate the new elements, but if capacity is not enough, then append will allocate a new underlying array and return the updated slice. Therefore, it is necessary to store the result of append, often in the variable holding the slice itself. Appending calls in a single call of append allocates memory just once to accommodate all the elements to be appended. Whereas multiple calls to append introduce many overheads, most notably being the possibility of more calls for memory allocation because the total number of elements to be appended over multiple calls of append is unknown beforehand, resulting in inaccurate preallocation.

Read more about a similar implementation for append. Hence, a single call to append is recommended.

Bad practice

xs = append(xs, 1)
xs = append(xs, 2)
xs = append(xs, 3)
xs = append(xs, 4)
xs = append(xs, 5)

EternallyAscend / GoToolkits

Bad practice

Recommended