etcd3locker: Update formatting of docs; timeout -> ttl substitution (#216)

* Update formatting of docs; timeout -> ttl substitution

* Add link to etcd3 locker in main README.md

README.md

@@ -219,6 +219,7 @@ useful tools:
 * [**gcsstore**](https://godoc.org/github.com/tus/tusd/gcsstore): A storage backend using Google cloud storage
 * [**memorylocker**](https://godoc.org/github.com/tus/tusd/memorylocker): An in-memory locker for handling concurrent uploads
 * [**consullocker**](https://godoc.org/github.com/tus/tusd/consullocker): A locker using the distributed Consul service
+* [**etcd3locker**](https://godoc.org/github.com/tus/tusd/etcd3locker): A locker using the distributed KV etcd3 store
 * [**limitedstore**](https://godoc.org/github.com/tus/tusd/limitedstore): A storage wrapper limiting the total used space for uploads
 
 ## Running the testsuite

etcd3locker/lock.go

@@ -1,4 +1,5 @@
-// Tested on etcd 3.1+
+// Package etcd3locker provides a locking mechanism using an etcd3 cluster.
+// Tested on etcd 3.1/3.2./3.3
 package etcd3locker
 
 import (
@@ -22,6 +23,7 @@ func newEtcd3Lock(session *concurrency.Session, id string) *etcd3Lock {
 	}
 }
 
+// Acquires a lock from etcd3
 func (lock *etcd3Lock) Acquire() error {
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
@@ -38,10 +40,12 @@ func (lock *etcd3Lock) Acquire() error {
 	return nil
 }
 
+// Releases a lock from etcd3
 func (lock *etcd3Lock) Release() error {
 	return lock.Mutex.Unlock(context.Background())
 }
 
+// Closes etcd3 session
 func (lock *etcd3Lock) CloseSession() error {
 	return lock.Session.Close()
 }

etcd3locker/locker.go

@@ -67,7 +67,7 @@ type Etcd3Locker struct {
 	locks      map[string]*etcd3Lock
 	mutex      sync.Mutex
 	prefix     string
-	sessionTimeout int
+	sessionTtl int
 }
 
 // New constructs a new locker using the provided client.
@@ -85,7 +85,7 @@ func NewWithPrefix(client *etcd3.Client, prefix string) (*Etcd3Locker, error) {
 // This method may be used if we want control over both prefix/session TTLs. This is used for testing in particular.
 func NewWithLockerOptions(client *etcd3.Client, opts LockerOptions) (*Etcd3Locker, error) {
 	locksMap := map[string]*etcd3Lock{}
-	return &Etcd3Locker{Client: client, prefix: opts.Prefix(), sessionTimeout: opts.Timeout(), locks: locksMap, mutex: sync.Mutex{}}, nil
+	return &Etcd3Locker{Client: client, prefix: opts.Prefix(), sessionTtl: opts.Ttl(), locks: locksMap, mutex: sync.Mutex{}}, nil
 }
 
 // UseIn adds this locker to the passed composer.
@@ -137,7 +137,7 @@ func (locker *Etcd3Locker) UnlockUpload(id string) error {
 }
 
 func (locker *Etcd3Locker) createSession() (*concurrency.Session, error) {
-	return concurrency.NewSession(locker.Client, concurrency.WithTTL(locker.sessionTimeout))
+	return concurrency.NewSession(locker.Client, concurrency.WithTTL(locker.sessionTtl))
 }
 
 func (locker *Etcd3Locker) getId(id string) string {

etcd3locker/locker_options.go

@@ -10,32 +10,38 @@ var (
 )
 
 type LockerOptions struct {
-	timeoutSeconds int
+	ttl    int
 	prefix string
 }
 
+// DefaultLockerOptions() instantiates an instance of LockerOptions
+// with default 60 second time to live and an etcd3 prefix of "/tusd"
 func DefaultLockerOptions() LockerOptions {
 	return LockerOptions{
-		timeoutSeconds: 60,
+		ttl:    60,
 		prefix: "/tusd",
 	}
 }
 
-func NewLockerOptions(timeout int, prefix string) LockerOptions {
+// NewLockerOptions instantiates an instance of LockerOptions with a
+// provided TTL (time to live) and string prefix for keys to be stored in etcd3
+func NewLockerOptions(ttl int, prefix string) LockerOptions {
 	return LockerOptions{
-		timeoutSeconds: timeout,
+		ttl:    ttl,
 		prefix: prefix,
 	}
 }
 
-func (l *LockerOptions) Timeout() int {
-	if l.timeoutSeconds == 0 {
+// Returns the TTL (time to live) of sessions in etcd3
+func (l *LockerOptions) Ttl() int {
+	if l.ttl == 0 {
 		return DefaultTtl
 	} else {
-		return l.timeoutSeconds
+		return l.ttl
 	}
 }
 
+// Returns the string prefix used to store keys in etcd3
 func (l *LockerOptions) Prefix() string {
 	prefix := l.prefix
 	if !strings.HasPrefix(prefix, "/") {
@@ -49,10 +55,12 @@ func (l *LockerOptions) Prefix() string {
 	}
 }
 
-func (l *LockerOptions) SetTimeout(timeout int) {
-	l.timeoutSeconds = timeout
+// Set etcd3 session TTL (time to live)
+func (l *LockerOptions) SetTtl(ttl int) {
+	l.ttl = ttl
 }
 
+// Set string prefix to be used in keys stored into etcd3 by the locker
 func (l *LockerOptions) SetPrefix(prefix string) {
 	l.prefix = prefix
 }