Lock free and single event loop

Author: Ashesh Vidyut

datastructures/hnsw/graph.go

@@ -5,7 +5,6 @@ import (
 	"math"
 	"math/rand"
 	"sort"
-	"sync"
 	"time"
 
 	"github.com/absolutelightning/gods/queues/priorityqueue"
@@ -24,7 +23,6 @@ type HNSW struct {
 	LayerFactor   float64      // Probability factor, but we won't use it with the current randomLevel
 	EfSearch      int          // number of candidates during search
 	DistFunc      DistanceFunc // distance function
-	lock          sync.Mutex   // lock for thread-safe operations
 	EntryPoint    *Node        // top entry point into the graph
 	Rand          *rand.Rand   // random number generator
 }
@@ -96,9 +94,6 @@ func (h *HNSW) randomLevel() int {
 
 // Insert adds a new element `vector` into the HNSW graph.
 func (h *HNSW) Insert(vector Vector) string {
-	h.lock.Lock()
-	defer h.lock.Unlock()
-
 	level := h.randomLevel()
 
 	// Create the new node
@@ -440,9 +435,6 @@ func min(a, b int) int {
 }
 
 func (h *HNSW) Delete(nodeID string) bool {
-	h.lock.Lock()
-	defer h.lock.Unlock()
-
 	if len(h.Layers) == 0 {
 		return false
 	}

main.go

@@ -92,7 +92,8 @@ func main() {
 	log.Fatal(gnet.Run(
 		tredsServer,
 		"tcp://0.0.0.0:"+strconv.Itoa(tredsServer.Port),
-		gnet.WithMulticore(true),
+		// Single Event loop
+		gnet.WithMulticore(false),
 		gnet.WithReusePort(false),
 		gnet.WithTCPKeepAlive(300*time.Second),
 	))

server/discard.go

@@ -35,8 +35,6 @@ func executeDiscard() ExecutionHook {
 			return gnet.None
 		}
 
-		ts.LockClientTransaction()
-		defer ts.UnlockClientTransaction()
 		delete(ts.GetClientTransaction(), c.RemoteAddr().String())
 
 		res := "OK"

server/exec.go

@@ -36,9 +36,6 @@ func executeExec() ExecutionHook {
 			return gnet.None
 		}
 
-		ts.LockClientTransaction()
-		defer ts.UnlockClientTransaction()
-
 		clientTransaction, ok := ts.GetClientTransaction()[c.RemoteAddr().String()]
 		if !ok {
 			ts.RespondErr(c, fmt.Errorf("no transaction started"))

server/multi.go

@@ -44,9 +44,6 @@ func executeMulti() ExecutionHook {
 			return gnet.None
 		}
 
-		ts.LockClientTransaction()
-		defer ts.UnlockClientTransaction()
-
 		ts.GetClientTransaction()[c.RemoteAddr().String()] = make([]string, 0)
 
 		res := "OK"

server/psubscribe.go

@@ -66,9 +66,6 @@ func executePSubscribeCommand() ExecutionHook {
 			allChannels[channelPrefix] = struct{}{}
 		}
 
-		ts.LockChannelSubs()
-		defer ts.UnlockChannelSubs()
-
 		for channel := range allChannels {
 			prevData, ok := subscriptionData.Get([]byte(channel))
 			if !ok {

server/punsubscribe.go

@@ -66,8 +66,6 @@ func executePUnsubscribeCommand() ExecutionHook {
 			allChannels[channelPrefix] = struct{}{}
 		}
 
-		ts.LockChannelSubs()
-		defer ts.UnlockChannelSubs()
 		for channel := range allChannels {
 			prevData, ok := subscriptionData.Get([]byte(channel))
 			if !ok {

server/server.go

@@ -11,7 +11,6 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 
 	wal "github.com/hashicorp/raft-wal"
@@ -39,10 +38,8 @@ type Server struct {
 	tredsCommandRegistry       commands.CommandRegistry
 	tredsServerCommandRegistry ServerCommandRegistry
 	clientTransaction          map[string][]string
-	clientTransactionLock      *sync.Mutex
 
 	channelSubscriptionData *radix.Tree
-	channelSubscriptionLock *sync.Mutex
 	connectionSubscription  map[string]map[string]struct{}
 
 	connectionMap map[string]gnet.Conn
@@ -206,10 +203,8 @@ func New(port, segmentSize int, bindAddr, advertiseAddr, serverId string, applyT
 		id:                         config.LocalID,
 		raftApplyTimeout:           applyTimeout,
 		clientTransaction:          make(map[string][]string),
-		clientTransactionLock:      &sync.Mutex{},
 		connP:                      connPool.NewConnPool(time.Second * 5),
 		channelSubscriptionData:    radix.New(),
-		channelSubscriptionLock:    &sync.Mutex{},
 		connectionSubscription:     make(map[string]map[string]struct{}),
 		connectionMap:              make(map[string]gnet.Conn),
 	}, nil
@@ -276,22 +271,6 @@ func (ts *Server) GetRaftApplyTimeout() time.Duration {
 	return ts.raftApplyTimeout
 }
 
-func (ts *Server) LockClientTransaction() {
-	ts.clientTransactionLock.Lock()
-}
-
-func (ts *Server) UnlockClientTransaction() {
-	ts.clientTransactionLock.Unlock()
-}
-
-func (ts *Server) LockChannelSubs() {
-	ts.channelSubscriptionLock.Lock()
-}
-
-func (ts *Server) UnlockChannelSubs() {
-	ts.channelSubscriptionLock.Unlock()
-}
-
 func (ts *Server) SetChannelSubscriptionData(data *radix.Tree) {
 	ts.channelSubscriptionData = data
 }
@@ -323,8 +302,6 @@ func (ts *Server) OnTraffic(c gnet.Conn) gnet.Action {
 
 	// Check for transaction first, if transaction just enqueue the command
 	if _, ok := ts.clientTransaction[c.RemoteAddr().String()]; ok {
-		ts.clientTransactionLock.Lock()
-		defer ts.clientTransactionLock.Unlock()
 		ts.clientTransaction[c.RemoteAddr().String()] = append(ts.clientTransaction[c.RemoteAddr().String()], inp)
 		res := "QUEUED"
 		_, errConn := c.Write([]byte(resp.EncodeSimpleString(res)))
@@ -428,14 +405,10 @@ func (ts *Server) OnClose(c gnet.Conn, _ error) gnet.Action {
 }
 
 func (ts *Server) CleanUpClientTransaction(c gnet.Conn) {
-	ts.clientTransactionLock.Lock()
-	defer ts.clientTransactionLock.Unlock()
 	delete(ts.clientTransaction, c.RemoteAddr().String())
 }
 
 func (ts *Server) CleanUpChannelSubscriptions(c gnet.Conn) {
-	ts.channelSubscriptionLock.Lock()
-	defer ts.channelSubscriptionLock.Unlock()
 	// use connectionSubscription map to delete all subscriptions for this connection
 	if _, ok := ts.connectionSubscription[c.RemoteAddr().String()]; ok {
 		for channel := range ts.connectionSubscription[c.RemoteAddr().String()] {

server/subscribe.go

@@ -57,8 +57,6 @@ func executeSubscribeCommandName() ExecutionHook {
 			allChannels[channel] = struct{}{}
 		}
 
-		ts.LockChannelSubs()
-		defer ts.UnlockChannelSubs()
 		for channel := range allChannels {
 			prevData, ok := subscriptionData.Get([]byte(channel))
 			if !ok {

server/treds_fsm.go

@@ -5,7 +5,6 @@ import (
 	"io"
 	"log"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/hashicorp/raft"
@@ -22,7 +21,6 @@ type TredsFsm struct {
 	cmdRegistry commands.CommandRegistry
 	tredsStore  store.Store
 	conn        gnet.Conn
-	storeLock   *sync.Mutex
 }
 
 func (t *TredsFsm) Apply(log *raft.Log) interface{} {
@@ -35,10 +33,6 @@ func (t *TredsFsm) Apply(log *raft.Log) interface{} {
 	if err != nil {
 		return err
 	}
-	if commandReg.IsWrite {
-		t.storeLock.Lock()
-		defer t.storeLock.Unlock()
-	}
 	currentStore := t.tredsStore
 	if currentStore != nil {
 		return commandReg.Execute(args, currentStore)
@@ -85,8 +79,6 @@ func (t *TredsFsm) Restore(old io.ReadCloser) error {
 		return err
 	}
 	ts := store.NewTredsStore()
-	t.storeLock.Lock()
-	defer t.storeLock.Unlock()
 	err = ts.Restore(data)
 	t.tredsStore = ts
 	if err != nil {
@@ -96,5 +88,5 @@ func (t *TredsFsm) Restore(old io.ReadCloser) error {
 }
 
 func NewTredsFsm(registry commands.CommandRegistry, store store.Store) *TredsFsm {
-	return &TredsFsm{cmdRegistry: registry, tredsStore: store, storeLock: &sync.Mutex{}}
+	return &TredsFsm{cmdRegistry: registry, tredsStore: store}
 }