refactor(generator): generators use context.Context instead of stopflag

In process of removing the `stopFlag` from gemini's codebase,
first step is to migrate the `Value Generators` for patitions.
Using context with generators make a lot more sense then the custom
built, `stopFlag`. `context` is built-in package in Go, and
this is it's usecase - cancelation propagation to background task.

Signed-off-by: Dusan Malusev <[email protected]>

cmd/gemini/root.go

@@ -269,12 +269,14 @@ func run(_ *cobra.Command, _ []string) error {
 	stop.StartOsSignalsTransmitter(logger, stopFlag, warmupStopFlag)
 	pump := jobs.NewPump(stopFlag, logger)
 
-	gens, err := createGenerators(schema, schemaConfig, intSeed, partitionCount, logger)
+	distFunc, err := createDistributionFunc(partitionKeyDistribution, partitionCount, intSeed, stdDistMean, oneStdDev)
 	if err != nil {
-		return err
+		return errors.Wrapf(err, "Faile to create distribution function: %s", partitionKeyDistribution)
 	}
-	gens.StartAll(stopFlag)
 
+	gens := generators.New(ctx, schema, distFunc, schemaConfig.GetPartitionRangeConfig(), intSeed, partitionCount, pkBufferReuseSize, logger)
+	defer utils.IgnoreError(gens.Close)
+
 	if !nonInteractive {
 		sp := createSpinner(interactive())
 		ticker := time.NewTicker(time.Second)

pkg/generators/generator.go

@@ -15,12 +15,12 @@
 package generators
 
 import (
+	"context"
 	"github.com/pkg/errors"
 	"go.uber.org/zap"
 	"golang.org/x/exp/rand"
 
 	"github.com/scylladb/gemini/pkg/routingkey"
-	"github.com/scylladb/gemini/pkg/stop"
 	"github.com/scylladb/gemini/pkg/typedef"
 )
 
@@ -37,7 +37,7 @@ type TokenIndex uint64
 
 type DistributionFunc func() TokenIndex
 
-type GeneratorInterface interface {
+type Interface interface {
 	Get() *typedef.ValueWithToken
 	GetOld() *typedef.ValueWithToken
 	GiveOld(_ *typedef.ValueWithToken)
@@ -64,14 +64,6 @@ func (g *Generator) PartitionCount() uint64 {
 	return g.partitionCount
 }
 
-type Generators []*Generator
-
-func (g Generators) StartAll(stopFlag *stop.Flag) {
-	for _, gen := range g {
-		gen.Start(stopFlag)
-	}
-}
-
 type Config struct {
 	PartitionsDistributionFunc DistributionFunc
 	PartitionsRangeConfig      typedef.PartitionRangeConfig
@@ -80,9 +72,9 @@ type Config struct {
 	PkUsedBufferSize           uint64
 }
 
-func NewGenerator(table *typedef.Table, config *Config, logger *zap.Logger) *Generator {
+func NewGenerator(table *typedef.Table, config Config, logger *zap.Logger) Generator {
 	wakeUpSignal := make(chan struct{})
-	return &Generator{
+	return Generator{
 		partitions:        NewPartitions(int(config.PartitionsCount), int(config.PkUsedBufferSize), wakeUpSignal),
 		partitionCount:    config.PartitionsCount,
 		table:             table,
@@ -135,47 +127,41 @@ func (g *Generator) ReleaseToken(token uint64) {
 	g.GetPartitionForToken(TokenIndex(token)).releaseToken(token)
 }
 
-func (g *Generator) Start(stopFlag *stop.Flag) {
-	go func() {
-		g.logger.Info("starting partition key generation loop")
-		defer g.partitions.CloseAll()
-		for {
-			g.fillAllPartitions(stopFlag)
-			select {
-			case <-stopFlag.SignalChannel():
-				g.logger.Debug("stopping partition key generation loop",
-					zap.Uint64("keys_created", g.cntCreated),
-					zap.Uint64("keys_emitted", g.cntEmitted))
-				return
-			case <-g.wakeUpSignal:
-			}
+func (g *Generator) Start(ctx context.Context) {
+	defer g.partitions.Close()
+	g.logger.Info("starting partition key generation loop")
+	for {
+		g.fillAllPartitions(ctx)
+		select {
+		case <-ctx.Done():
+			g.logger.Debug("stopping partition key generation loop",
+				zap.Uint64("keys_created", g.cntCreated),
+				zap.Uint64("keys_emitted", g.cntEmitted))
+			return
+		case <-g.wakeUpSignal:
 		}
-	}()
+	}
 }
 
 func (g *Generator) FindAndMarkStalePartitions() {
 	r := rand.New(rand.NewSource(10))
-	nonStale := make([]bool, g.partitionCount)
-	for n := uint64(0); n < g.partitionCount*100; n++ {
-		values := CreatePartitionKeyValues(g.table, r, &g.partitionsConfig)
-		token, err := g.routingKeyCreator.GetHash(g.table, values)
+
+	for range g.partitionCount * 100 {
+		token, _, err := g.createPartitionKeyValues(r)
 		if err != nil {
-			g.logger.Panic(errors.Wrap(err, "failed to get primary key hash").Error())
+			g.logger.Panic("failed to get primary key hash", zap.Error(err))
 		}
-		nonStale[g.shardOf(token)] = true
-	}
 
-	for idx, val := range nonStale {
-		if !val {
-			g.partitions[idx].MarkStale()
+		if err = g.partition(token).MarkStale(); err != nil {
+			g.logger.Panic("failed to mark partition as stale", zap.Error(err))
 		}
 	}
 }
 
 // fillAllPartitions guarantees that each partition was tested to be full
 // at least once since the function started and before it ended.
 // In other words no partition will be starved.
-func (g *Generator) fillAllPartitions(stopFlag *stop.Flag) {
+func (g *Generator) fillAllPartitions(ctx context.Context) {
 	pFilled := make([]bool, len(g.partitions))
 	allFilled := func() bool {
 		for idx, filled := range pFilled {
@@ -188,22 +174,30 @@ func (g *Generator) fillAllPartitions(stopFlag *stop.Flag) {
 		}
 		return true
 	}
-	for !stopFlag.IsHardOrSoft() {
-		values := CreatePartitionKeyValues(g.table, g.r, &g.partitionsConfig)
-		token, err := g.routingKeyCreator.GetHash(g.table, values)
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
+
+		token, values, err := g.createPartitionKeyValues()
 		if err != nil {
-			g.logger.Panic(errors.Wrap(err, "failed to get primary key hash").Error())
+			g.logger.Panic("failed to get primary key hash", zap.Error(err))
 		}
 		g.cntCreated++
-		idx := token % g.partitionCount
-		partition := g.partitions[idx]
+
+		partition := g.partition(token)
 		if partition.Stale() || partition.inFlight.Has(token) {
 			continue
 		}
+
 		select {
 		case partition.values <- &typedef.ValueWithToken{Token: token, Value: values}:
 			g.cntEmitted++
 		default:
+			idx := g.shardOf(token)
 			if !pFilled[idx] {
 				pFilled[idx] = true
 				if allFilled() {
@@ -217,3 +211,28 @@ func (g *Generator) fillAllPartitions(stopFlag *stop.Flag) {
 func (g *Generator) shardOf(token uint64) int {
 	return int(token % g.partitionCount)
 }
+
+func (g *Generator) partition(token uint64) *Partition {
+	return g.partitions[g.shardOf(token)]
+}
+
+func (g *Generator) createPartitionKeyValues(r ...*rand.Rand) (uint64, []any, error) {
+	rnd := g.r
+
+	if len(r) > 0 && r[0] != nil {
+		rnd = r[0]
+	}
+
+	values := make([]any, 0, g.table.PartitionKeysLenValues())
+
+	for _, pk := range g.table.PartitionKeys {
+		values = append(values, pk.Type.GenValue(rnd, &g.partitionsConfig)...)
+	}
+
+	token, err := g.routingKeyCreator.GetHash(g.table, values)
+	if err != nil {
+		return 0, nil, errors.Wrap(err, "failed to get primary key hash")
+	}
+
+	return token, values, nil
+}

pkg/generators/generators.go

@@ -0,0 +1,84 @@
+// Copyright 2019 ScyllaDB
+//
+// 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 generators
+
+import (
+	"context"
+	"math"
+	"sync"
+
+	"go.uber.org/zap"
+
+	"github.com/scylladb/gemini/pkg/typedef"
+)
+
+type Generators struct {
+	Generators []Generator
+	wg         *sync.WaitGroup
+	cancel     context.CancelFunc
+}
+
+func New(
+	ctx context.Context,
+	schema *typedef.Schema,
+	distFunc DistributionFunc,
+	partitionRangeConfig typedef.PartitionRangeConfig,
+	seed, distributionSize, pkBufferReuseSize uint64,
+	logger *zap.Logger,
+) *Generators {
+	gs := make([]Generator, 0, len(schema.Tables))
+
+	cfg := Config{
+		PartitionsRangeConfig:      partitionRangeConfig,
+		PartitionsCount:            distributionSize,
+		PartitionsDistributionFunc: distFunc,
+		Seed:                       seed,
+		PkUsedBufferSize:           pkBufferReuseSize,
+	}
+
+	wg := new(sync.WaitGroup)
+	wg.Add(len(schema.Tables))
+
+	ctx, cancel := context.WithCancel(ctx)
+
+	for _, table := range schema.Tables {
+		g := NewGenerator(table, cfg, logger.Named("generators-"+table.Name))
+		go func() {
+			defer wg.Done()
+			g.Start(ctx)
+		}()
+
+		if table.PartitionKeys.ValueVariationsNumber(&partitionRangeConfig) < math.MaxUint32 {
+			// Low partition key variation can lead to having staled partitions
+			// Let's detect and mark them before running test
+			g.FindAndMarkStalePartitions()
+		}
+
+		gs = append(gs, g)
+	}
+
+	return &Generators{
+		Generators: gs,
+		wg:         wg,
+		cancel:     cancel,
+	}
+}
+
+func (g *Generators) Close() error {
+	g.cancel()
+	g.wg.Wait()
+
+	return nil
+}