[VOL-3801] remove unused KV consul code in voltha-lib-go

Change-Id: Iedfd7c24440692d74c8f463d80f3ad259cbf2e6d
diff --git a/pkg/db/backend.go b/pkg/db/backend.go
index d6867a5..418bf8e 100644
--- a/pkg/db/backend.go
+++ b/pkg/db/backend.go
@@ -75,8 +75,6 @@
 
 func (b *Backend) newClient(ctx context.Context, address string, timeout time.Duration) (kvstore.Client, error) {
 	switch b.StoreType {
-	case "consul":
-		return kvstore.NewConsulClient(ctx, address, timeout)
 	case "etcd":
 		return kvstore.NewEtcdClient(ctx, address, timeout, log.WarnLevel)
 	}
@@ -170,9 +168,6 @@
 			case codes.DataLoss:
 				alive = false
 			}
-
-			//} else {
-			// TODO: Implement for consul backend; would it be needed ever?
 		}
 	}
 
diff --git a/pkg/db/backend_test.go b/pkg/db/backend_test.go
index 78e626b..a5659e4 100644
--- a/pkg/db/backend_test.go
+++ b/pkg/db/backend_test.go
@@ -18,15 +18,16 @@
 
 import (
 	"context"
+	"os"
+	"strconv"
+	"testing"
+	"time"
+
 	mocks "github.com/opencord/voltha-lib-go/v4/pkg/mocks/etcd"
 	"github.com/phayes/freeport"
 	"github.com/stretchr/testify/assert"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
-	"os"
-	"strconv"
-	"testing"
-	"time"
 )
 
 const (
@@ -94,16 +95,6 @@
 	assert.Equal(t, backend.LivenessChannelInterval, DefaultLivenessChannelInterval)
 }
 
-// Create instance using Consul Kvstore
-func TestNewBackend_ConsulKvStore(t *testing.T) {
-	backend := NewBackend(context.Background(), "consul", embedEtcdServerHost+":"+strconv.Itoa(embedEtcdServerPort), defaultTimeout, defaultPathPrefix)
-
-	// Verify kvstore type attribute of backend has got set correctly
-	assert.NotNil(t, backend)
-	assert.NotNil(t, backend.Client)
-	assert.Equal(t, backend.StoreType, "consul")
-}
-
 // Create instance using Invalid Kvstore; instance creation should fail
 func TestNewBackend_InvalidKvstore(t *testing.T) {
 	backend := NewBackend(context.Background(), "unknown", embedEtcdServerHost+":"+strconv.Itoa(embedEtcdServerPort), defaultTimeout, defaultPathPrefix)
diff --git a/pkg/db/kvstore/client.go b/pkg/db/kvstore/client.go
index 480d476..2060b06 100644
--- a/pkg/db/kvstore/client.go
+++ b/pkg/db/kvstore/client.go
@@ -21,8 +21,6 @@
 )
 
 const (
-	// Default timeout in seconds when making a kvstore request
-	defaultKVGetTimeout = 5 * time.Second
 	// Maximum channel buffer between publisher/subscriber goroutines
 	maxClientChannelBufferSize = 10
 )
diff --git a/pkg/db/kvstore/consulclient.go b/pkg/db/kvstore/consulclient.go
deleted file mode 100644
index 2593608..0000000
--- a/pkg/db/kvstore/consulclient.go
+++ /dev/null
@@ -1,512 +0,0 @@
-/*
- * Copyright 2018-present Open Networking Foundation
-
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
-
- * http://www.apache.org/licenses/LICENSE-2.0
-
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package kvstore
-
-import (
-	"bytes"
-	"context"
-	"errors"
-	log "github.com/opencord/voltha-lib-go/v4/pkg/log"
-	"sync"
-	"time"
-	//log "ciena.com/coordinator/common"
-	consulapi "github.com/hashicorp/consul/api"
-)
-
-type channelContextMap struct {
-	ctx     context.Context
-	channel chan *Event
-	cancel  context.CancelFunc
-}
-
-// ConsulClient represents the consul KV store client
-type ConsulClient struct {
-	session                *consulapi.Session
-	sessionID              string
-	consul                 *consulapi.Client
-	doneCh                 *chan int
-	keyReservations        map[string]interface{}
-	watchedChannelsContext map[string][]*channelContextMap
-	writeLock              sync.Mutex
-}
-
-// NewConsulClient returns a new client for the Consul KV store
-func NewConsulClient(ctx context.Context, addr string, timeout time.Duration) (*ConsulClient, error) {
-	config := consulapi.DefaultConfig()
-	config.Address = addr
-	config.WaitTime = timeout
-	consul, err := consulapi.NewClient(config)
-	if err != nil {
-		logger.Error(ctx, err)
-		return nil, err
-	}
-
-	doneCh := make(chan int, 1)
-	wChannelsContext := make(map[string][]*channelContextMap)
-	reservations := make(map[string]interface{})
-	return &ConsulClient{consul: consul, doneCh: &doneCh, watchedChannelsContext: wChannelsContext, keyReservations: reservations}, nil
-}
-
-// IsConnectionUp returns whether the connection to the Consul KV store is up
-func (c *ConsulClient) IsConnectionUp(ctx context.Context) bool {
-	logger.Error(ctx, "Unimplemented function")
-	return false
-}
-
-// List returns an array of key-value pairs with key as a prefix.  Timeout defines how long the function will
-// wait for a response
-func (c *ConsulClient) List(ctx context.Context, key string) (map[string]*KVPair, error) {
-
-	deadline, _ := ctx.Deadline()
-	kv := c.consul.KV()
-	var queryOptions consulapi.QueryOptions
-	// Substract current time from deadline to get the waitTime duration
-	queryOptions.WaitTime = time.Until(deadline)
-
-	// For now we ignore meta data
-	kvps, _, err := kv.List(key, &queryOptions)
-	if err != nil {
-		logger.Error(ctx, err)
-		return nil, err
-	}
-	m := make(map[string]*KVPair)
-	for _, kvp := range kvps {
-		m[string(kvp.Key)] = NewKVPair(string(kvp.Key), kvp.Value, string(kvp.Session), 0, -1)
-	}
-	return m, nil
-}
-
-// Get returns a key-value pair for a given key. Timeout defines how long the function will
-// wait for a response
-func (c *ConsulClient) Get(ctx context.Context, key string) (*KVPair, error) {
-
-	deadline, _ := ctx.Deadline()
-	kv := c.consul.KV()
-	var queryOptions consulapi.QueryOptions
-	// Substract current time from deadline to get the waitTime duration
-	queryOptions.WaitTime = time.Until(deadline)
-
-	// For now we ignore meta data
-	kvp, _, err := kv.Get(key, &queryOptions)
-	if err != nil {
-		logger.Error(ctx, err)
-		return nil, err
-	}
-	if kvp != nil {
-		return NewKVPair(string(kvp.Key), kvp.Value, string(kvp.Session), 0, -1), nil
-	}
-
-	return nil, nil
-}
-
-// Put writes a key-value pair to the KV store.  Value can only be a string or []byte since the consul API
-// accepts only a []byte as a value for a put operation. Timeout defines how long the function will
-// wait for a response
-func (c *ConsulClient) Put(ctx context.Context, key string, value interface{}) error {
-
-	// Validate that we can create a byte array from the value as consul API expects a byte array
-	var val []byte
-	var er error
-	if val, er = ToByte(value); er != nil {
-		logger.Error(ctx, er)
-		return er
-	}
-
-	// Create a key value pair
-	kvp := consulapi.KVPair{Key: key, Value: val}
-	kv := c.consul.KV()
-	var writeOptions consulapi.WriteOptions
-	c.writeLock.Lock()
-	defer c.writeLock.Unlock()
-	_, err := kv.Put(&kvp, &writeOptions)
-	if err != nil {
-		logger.Error(ctx, err)
-		return err
-	}
-	return nil
-}
-
-// Delete removes a key from the KV store. Timeout defines how long the function will
-// wait for a response
-func (c *ConsulClient) Delete(ctx context.Context, key string) error {
-	kv := c.consul.KV()
-	var writeOptions consulapi.WriteOptions
-	c.writeLock.Lock()
-	defer c.writeLock.Unlock()
-	_, err := kv.Delete(key, &writeOptions)
-	if err != nil {
-		logger.Error(ctx, err)
-		return err
-	}
-	return nil
-}
-
-func (c *ConsulClient) deleteSession(ctx context.Context) {
-	if c.sessionID != "" {
-		logger.Debug(ctx, "cleaning-up-session")
-		session := c.consul.Session()
-		_, err := session.Destroy(c.sessionID, nil)
-		if err != nil {
-			logger.Errorw(ctx, "error-cleaning-session", log.Fields{"session": c.sessionID, "error": err})
-		}
-	}
-	c.sessionID = ""
-	c.session = nil
-}
-
-func (c *ConsulClient) createSession(ctx context.Context, ttl time.Duration, retries int) (*consulapi.Session, string, error) {
-	session := c.consul.Session()
-	entry := &consulapi.SessionEntry{
-		Behavior: consulapi.SessionBehaviorDelete,
-		TTL:      ttl.String(),
-	}
-
-	for {
-		id, meta, err := session.Create(entry, nil)
-		if err != nil {
-			logger.Errorw(ctx, "create-session-error", log.Fields{"error": err})
-			if retries == 0 {
-				return nil, "", err
-			}
-		} else if meta.RequestTime == 0 {
-			logger.Errorw(ctx, "create-session-bad-meta-data", log.Fields{"meta-data": meta})
-			if retries == 0 {
-				return nil, "", errors.New("bad-meta-data")
-			}
-		} else if id == "" {
-			logger.Error(ctx, "create-session-nil-id")
-			if retries == 0 {
-				return nil, "", errors.New("ID-nil")
-			}
-		} else {
-			return session, id, nil
-		}
-		// If retry param is -1 we will retry indefinitely
-		if retries > 0 {
-			retries--
-		}
-		logger.Debug(ctx, "retrying-session-create-after-a-second-delay")
-		time.Sleep(time.Duration(1) * time.Second)
-	}
-}
-
-// Helper function to verify mostly whether the content of two interface types are the same.  Focus is []byte and
-// string types
-func isEqual(val1 interface{}, val2 interface{}) bool {
-	b1, err := ToByte(val1)
-	b2, er := ToByte(val2)
-	if err == nil && er == nil {
-		return bytes.Equal(b1, b2)
-	}
-	return val1 == val2
-}
-
-// Reserve is invoked to acquire a key and set it to a given value. Value can only be a string or []byte since
-// the consul API accepts only a []byte.  Timeout defines how long the function will wait for a response.  TTL
-// defines how long that reservation is valid.  When TTL expires the key is unreserved by the KV store itself.
-// If the key is acquired then the value returned will be the value passed in.  If the key is already acquired
-// then the value assigned to that key will be returned.
-func (c *ConsulClient) Reserve(ctx context.Context, key string, value interface{}, ttl time.Duration) (interface{}, error) {
-
-	// Validate that we can create a byte array from the value as consul API expects a byte array
-	var val []byte
-	var er error
-	if val, er = ToByte(value); er != nil {
-		logger.Error(ctx, er)
-		return nil, er
-	}
-
-	// Cleanup any existing session and recreate new ones.  A key is reserved against a session
-	if c.sessionID != "" {
-		c.deleteSession(ctx)
-	}
-
-	// Clear session if reservation is not successful
-	reservationSuccessful := false
-	defer func() {
-		if !reservationSuccessful {
-			logger.Debug(ctx, "deleting-session")
-			c.deleteSession(ctx)
-		}
-	}()
-
-	session, sessionID, err := c.createSession(ctx, ttl, -1)
-	if err != nil {
-		logger.Errorw(ctx, "no-session-created", log.Fields{"error": err})
-		return "", errors.New("no-session-created")
-	}
-	logger.Debugw(ctx, "session-created", log.Fields{"session-id": sessionID})
-	c.sessionID = sessionID
-	c.session = session
-
-	// Try to grap the Key using the session
-	kv := c.consul.KV()
-	kvp := consulapi.KVPair{Key: key, Value: val, Session: c.sessionID}
-	result, _, err := kv.Acquire(&kvp, nil)
-	if err != nil {
-		logger.Errorw(ctx, "error-acquiring-keys", log.Fields{"error": err})
-		return nil, err
-	}
-
-	logger.Debugw(ctx, "key-acquired", log.Fields{"key": key, "status": result})
-
-	// Irrespective whether we were successful in acquiring the key, let's read it back and see if it's us.
-	m, err := c.Get(ctx, key)
-	if err != nil {
-		return nil, err
-	}
-	if m != nil {
-		logger.Debugw(ctx, "response-received", log.Fields{"key": m.Key, "m.value": string(m.Value.([]byte)), "value": value})
-		if m.Key == key && isEqual(m.Value, value) {
-			// My reservation is successful - register it.  For now, support is only for 1 reservation per key
-			// per session.
-			reservationSuccessful = true
-			c.writeLock.Lock()
-			c.keyReservations[key] = m.Value
-			c.writeLock.Unlock()
-			return m.Value, nil
-		}
-		// My reservation has failed.  Return the owner of that key
-		return m.Value, nil
-	}
-	return nil, nil
-}
-
-// ReleaseAllReservations releases all key reservations previously made (using Reserve API)
-func (c *ConsulClient) ReleaseAllReservations(ctx context.Context) error {
-	kv := c.consul.KV()
-	var kvp consulapi.KVPair
-	var result bool
-	var err error
-
-	c.writeLock.Lock()
-	defer c.writeLock.Unlock()
-
-	for key, value := range c.keyReservations {
-		kvp = consulapi.KVPair{Key: key, Value: value.([]byte), Session: c.sessionID}
-		result, _, err = kv.Release(&kvp, nil)
-		if err != nil {
-			logger.Errorw(ctx, "cannot-release-reservation", log.Fields{"key": key, "error": err})
-			return err
-		}
-		if !result {
-			logger.Errorw(ctx, "cannot-release-reservation", log.Fields{"key": key})
-		}
-		delete(c.keyReservations, key)
-	}
-	return nil
-}
-
-// ReleaseReservation releases reservation for a specific key.
-func (c *ConsulClient) ReleaseReservation(ctx context.Context, key string) error {
-	var ok bool
-	var reservedValue interface{}
-	c.writeLock.Lock()
-	defer c.writeLock.Unlock()
-	if reservedValue, ok = c.keyReservations[key]; !ok {
-		return errors.New("key-not-reserved:" + key)
-	}
-	// Release the reservation
-	kv := c.consul.KV()
-	kvp := consulapi.KVPair{Key: key, Value: reservedValue.([]byte), Session: c.sessionID}
-
-	result, _, er := kv.Release(&kvp, nil)
-	if er != nil {
-		return er
-	}
-	// Remove that key entry on success
-	if result {
-		delete(c.keyReservations, key)
-		return nil
-	}
-	return errors.New("key-cannot-be-unreserved")
-}
-
-// RenewReservation renews a reservation.  A reservation will go stale after the specified TTL (Time To Live)
-// period specified when reserving the key
-func (c *ConsulClient) RenewReservation(ctx context.Context, key string) error {
-	// In the case of Consul, renew reservation of a reserve key only require renewing the client session.
-
-	c.writeLock.Lock()
-	defer c.writeLock.Unlock()
-
-	// Verify the key was reserved
-	if _, ok := c.keyReservations[key]; !ok {
-		return errors.New("key-not-reserved")
-	}
-
-	if c.session == nil {
-		return errors.New("no-session-exist")
-	}
-
-	var writeOptions consulapi.WriteOptions
-	if _, _, err := c.session.Renew(c.sessionID, &writeOptions); err != nil {
-		return err
-	}
-	return nil
-}
-
-// Watch provides the watch capability on a given key.  It returns a channel onto which the callee needs to
-// listen to receive Events.
-func (c *ConsulClient) Watch(ctx context.Context, key string, withPrefix bool) chan *Event {
-
-	// Create a new channel
-	ch := make(chan *Event, maxClientChannelBufferSize)
-
-	// Create a context to track this request
-	watchContext, cFunc := context.WithCancel(context.Background())
-
-	// Save the channel and context reference for later
-	c.writeLock.Lock()
-	defer c.writeLock.Unlock()
-	ccm := channelContextMap{channel: ch, ctx: watchContext, cancel: cFunc}
-	c.watchedChannelsContext[key] = append(c.watchedChannelsContext[key], &ccm)
-
-	// Launch a go routine to listen for updates
-	go c.listenForKeyChange(watchContext, key, ch)
-
-	return ch
-}
-
-// CloseWatch closes a specific watch. Both the key and the channel are required when closing a watch as there
-// may be multiple listeners on the same key.  The previously created channel serves as a key
-func (c *ConsulClient) CloseWatch(ctx context.Context, key string, ch chan *Event) {
-	// First close the context
-	var ok bool
-	var watchedChannelsContexts []*channelContextMap
-	c.writeLock.Lock()
-	defer c.writeLock.Unlock()
-	if watchedChannelsContexts, ok = c.watchedChannelsContext[key]; !ok {
-		logger.Errorw(ctx, "key-has-no-watched-context-or-channel", log.Fields{"key": key})
-		return
-	}
-	// Look for the channels
-	var pos = -1
-	for i, chCtxMap := range watchedChannelsContexts {
-		if chCtxMap.channel == ch {
-			logger.Debug(ctx, "channel-found")
-			chCtxMap.cancel()
-			//close the channel
-			close(ch)
-			pos = i
-			break
-		}
-	}
-	// Remove that entry if present
-	if pos >= 0 {
-		c.watchedChannelsContext[key] = append(c.watchedChannelsContext[key][:pos], c.watchedChannelsContext[key][pos+1:]...)
-	}
-	logger.Debugw(ctx, "watched-channel-exiting", log.Fields{"key": key, "channel": c.watchedChannelsContext[key]})
-}
-
-func (c *ConsulClient) isKVEqual(kv1 *consulapi.KVPair, kv2 *consulapi.KVPair) bool {
-	if (kv1 == nil) && (kv2 == nil) {
-		return true
-	} else if (kv1 == nil) || (kv2 == nil) {
-		return false
-	}
-	// Both the KV should be non-null here
-	if kv1.Key != kv2.Key ||
-		!bytes.Equal(kv1.Value, kv2.Value) ||
-		kv1.Session != kv2.Session ||
-		kv1.LockIndex != kv2.LockIndex ||
-		kv1.ModifyIndex != kv2.ModifyIndex {
-		return false
-	}
-	return true
-}
-
-func (c *ConsulClient) listenForKeyChange(ctx context.Context, key string, ch chan *Event) {
-	logger.Debugw(ctx, "start-watching-channel", log.Fields{"key": key, "channel": ch})
-
-	defer c.CloseWatch(ctx, key, ch)
-	kv := c.consul.KV()
-	var queryOptions consulapi.QueryOptions
-	queryOptions.WaitTime = defaultKVGetTimeout
-
-	// Get the existing value, if any
-	previousKVPair, meta, err := kv.Get(key, &queryOptions)
-	if err != nil {
-		logger.Debug(ctx, err)
-	}
-	lastIndex := meta.LastIndex
-
-	// Wait for change.  Push any change onto the channel and keep waiting for new update
-	//var waitOptions consulapi.QueryOptions
-	var pair *consulapi.KVPair
-	//watchContext, _ := context.WithCancel(context.Background())
-	waitOptions := queryOptions.WithContext(ctx)
-	for {
-		//waitOptions = consulapi.QueryOptions{WaitIndex: lastIndex}
-		waitOptions.WaitIndex = lastIndex
-		pair, meta, err = kv.Get(key, waitOptions)
-		select {
-		case <-ctx.Done():
-			logger.Debug(ctx, "done-event-received-exiting")
-			return
-		default:
-			if err != nil {
-				logger.Warnw(ctx, "error-from-watch", log.Fields{"error": err})
-				ch <- NewEvent(CONNECTIONDOWN, key, []byte(""), -1)
-			} else {
-				logger.Debugw(ctx, "index-state", log.Fields{"lastindex": lastIndex, "newindex": meta.LastIndex, "key": key})
-			}
-		}
-		if err != nil {
-			logger.Debug(ctx, err)
-			// On error, block for 10 milliseconds to prevent endless loop
-			time.Sleep(10 * time.Millisecond)
-		} else if meta.LastIndex <= lastIndex {
-			logger.Info(ctx, "no-index-change-or-negative")
-		} else {
-			logger.Debugw(ctx, "update-received", log.Fields{"pair": pair})
-			if pair == nil {
-				ch <- NewEvent(DELETE, key, []byte(""), -1)
-			} else if !c.isKVEqual(pair, previousKVPair) {
-				// Push the change onto the channel if the data has changed
-				// For now just assume it's a PUT change
-				logger.Debugw(ctx, "pair-details", log.Fields{"session": pair.Session, "key": pair.Key, "value": pair.Value})
-				ch <- NewEvent(PUT, pair.Key, pair.Value, -1)
-			}
-			previousKVPair = pair
-			lastIndex = meta.LastIndex
-		}
-	}
-}
-
-// Close closes the KV store client
-func (c *ConsulClient) Close(ctx context.Context) {
-	var writeOptions consulapi.WriteOptions
-	// Inform any goroutine it's time to say goodbye.
-	c.writeLock.Lock()
-	defer c.writeLock.Unlock()
-	if c.doneCh != nil {
-		close(*c.doneCh)
-	}
-
-	// Clear the sessionID
-	if _, err := c.consul.Session().Destroy(c.sessionID, &writeOptions); err != nil {
-		logger.Errorw(ctx, "error-closing-client", log.Fields{"error": err})
-	}
-}
-
-func (c *ConsulClient) AcquireLock(ctx context.Context, lockName string, timeout time.Duration) error {
-	return nil
-}
-
-func (c *ConsulClient) ReleaseLock(lockName string) error {
-	return nil
-}
diff --git a/pkg/db/kvstore/kvutils.go b/pkg/db/kvstore/kvutils.go
index 64e7d30..70bd977 100644
--- a/pkg/db/kvstore/kvutils.go
+++ b/pkg/db/kvstore/kvutils.go
@@ -15,7 +15,10 @@
  */
 package kvstore
 
-import "fmt"
+import (
+	"bytes"
+	"fmt"
+)
 
 // ToString converts an interface value to a string.  The interface should either be of
 // a string type or []byte.  Otherwise, an error is returned.
@@ -42,3 +45,14 @@
 		return nil, fmt.Errorf("unexpected-type-%T", t)
 	}
 }
+
+// Helper function to verify mostly whether the content of two interface types are the same.  Focus is []byte and
+// string types
+func isEqual(val1 interface{}, val2 interface{}) bool {
+	b1, err := ToByte(val1)
+	b2, er := ToByte(val2)
+	if err == nil && er == nil {
+		return bytes.Equal(b1, b2)
+	}
+	return val1 == val2
+}