Incrementer

[DEPRECATED DOCUMENTATION] I will update the docs in the next few days. Until you can check the usage in incrementer_test.go

Distributed counter based on Couchbase.

Recommendation: Always try to use the AddSafe, it's ensure the 100% the key will gets incremented.

Benchmarks

• Add: Simple add plus one to the specified key, if the key has been locked it will return an gocb.ErrTmpFail
• AddSafe: Solve the issue occured in the Add which cause the gocb.ErrTmpFail

Parameter list of non-persistent functions

• conn string: connection string to couchbase's cluster
• auth gocb.PasswordAuthenticator: password auth for cocuhbase's cluster
• bucketName string: name of the bucket
• bucketPassword string: password of the bucket
• key string: key to increment
• rollover uint64: rollover of the key
• initial int64: initial value of the key
• inc uin64: amount of increment

err := incrmntr.Add(
	"couchbase://localhost",
	gocb.PasswordAuthenticator{
		Username: "Administrator",
		Password: "password",
	},
	"increment",
	"",
	"test2",
	999,
	1,
	1,
)
// handle error

#### Persistent connection

New

New(bucket *gocb.Bucket, rollover uint64, initial int64, inc uint64) (Incrmntr, error)

• cluster waits a previously setted up couchbase cluster connection.
• bucketName waits the name of the bucket
• bucketPassword waits the password of the bucket
• rollover is the rollover limit
• initial is the initial value if the rollover happens put it back to that number
• inc amount of increment

Methods

Interface returned by the incrmntr.New

type Incrmntr interface {
	Get(key string) (int64, error)
	Add(key string) error
	AddSafe(key string) error
	AddWithRollover(key string, rollover uint64) error
	AddSafeWithRollover(key string, rollover uint64) error
	Close() error
}

• Get: Returns the current value of the key
• Add: Simple add plus one to the specified key, if the key has been locked it will return an gocb.ErrTmpFail
• AddSafe: Solve the issue occured in the Add which cause the gocb.ErrTmpFail
• AddWithRollover: Same as the Add with custom rollover
• AddSafeWithRollover: Same as the AddSafe with custom rollover
• Close: Close the bucket

cluster, err := gocb.Connect("couchbase://localhost")
// handle error

cluster.Authenticate(gocb.PasswordAuthenticator{
	Username: "Administrator",
	Password: "password",
})

bucket, err := cluster.OpenBucket("increment", "")
if err != nil {
	t.Error(err)
}

inc, err := incrmntr.New(bucket, 999, 1, 1)
// handle error

err := inc.Add("test")
// handle error

err := inc.AddSafe("test")
// handle error

There is a docker/docker-compose-single.yml which represents a single couchbase server

The docker-compose.yml has a cluster what the developer have to set up manually. The api server waits a req like that to trigger the test case:

curl -X GET \
  'http://localhost:8890/trigger?amount=100&bucket=increment&conn=couchbase://cb2' \
  -H 'content-type: application/x-www-form-urlencoded'