address review feedback

cmd/otel-allocator/allocation/consistent_hashing.go

@@ -25,7 +25,6 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 
 	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/diff"
-	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/prehook"
 	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/target"
 )
 
@@ -53,10 +52,10 @@ type consistentHashingAllocator struct {
 
 	log logr.Logger
 
-	filterFunction Filter
+	filter Filter
 }
 
-func newConsistentHashingAllocator(log logr.Logger, opts ...AllocOption) Allocator {
+func newConsistentHashingAllocator(log logr.Logger, opts ...AllocationOption) Allocator {
 	config := consistent.Config{
 		PartitionCount:    1061,
 		ReplicationFactor: 5,
@@ -77,9 +76,9 @@ func newConsistentHashingAllocator(log logr.Logger, opts ...AllocOption) Allocat
 	return chAllocator
 }
 
-// SetHook sets the filtering hook to use.
-func (c *consistentHashingAllocator) SetFilter(filterFunction Filter) {
-	c.filterFunction = filterFunction
+// SetFilter sets the filtering hook to use.
+func (c *consistentHashingAllocator) SetFilter(filter Filter) {
+	c.filter = filter
 }
 
 // addTargetToTargetItems assigns a target to the collector based on its hash and adds it to the allocator's targetItems
@@ -161,10 +160,10 @@ func (c *consistentHashingAllocator) SetTargets(targets map[string]*target.Targe
 	timer := prometheus.NewTimer(TimeToAssign.WithLabelValues("SetTargets", consistentHashingStrategyName))
 	defer timer.ObserveDuration()
 
-	if c.filterFunction != nil {
-		targets = c.filterFunction.Apply(targets)
+	if c.filter != nil {
+		targets = c.filter.Apply(targets)
 	}
-	prehook.RecordTargetsKeptPerJob(targets)
+	RecordTargetsKeptPerJob(targets)
 
 	c.m.Lock()
 	defer c.m.Unlock()

cmd/otel-allocator/allocation/least_weighted.go

@@ -20,7 +20,6 @@ import (
 	"sync"
 
 	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/diff"
-	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/prehook"
 	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/target"
 
 	"github.com/go-logr/logr"
@@ -52,12 +51,12 @@ type leastWeightedAllocator struct {
 
 	log logr.Logger
 
-	filterFunction Filter
+	filter Filter
 }
 
-// SetHook sets the filtering hook to use.
-func (allocator *leastWeightedAllocator) SetFilter(filterFunction Filter) {
-	allocator.filterFunction = filterFunction
+// SetFilter sets the filtering hook to use.
+func (allocator *leastWeightedAllocator) SetFilter(filter Filter) {
+	allocator.filter = filter
 }
 
 // TargetItems returns a shallow copy of the targetItems map.
@@ -173,10 +172,10 @@ func (allocator *leastWeightedAllocator) SetTargets(targets map[string]*target.T
 	timer := prometheus.NewTimer(TimeToAssign.WithLabelValues("SetTargets", leastWeightedStrategyName))
 	defer timer.ObserveDuration()
 
-	if allocator.filterFunction != nil {
-		targets = allocator.filterFunction.Apply(targets)
+	if allocator.filter != nil {
+		targets = allocator.filter.Apply(targets)
 	}
-	prehook.RecordTargetsKeptPerJob(targets)
+	RecordTargetsKeptPerJob(targets)
 
 	allocator.m.Lock()
 	defer allocator.m.Unlock()
@@ -216,7 +215,7 @@ func (allocator *leastWeightedAllocator) SetCollectors(collectors map[string]*Co
 	}
 }
 
-func newLeastWeightedAllocator(log logr.Logger, opts ...AllocOption) Allocator {
+func newLeastWeightedAllocator(log logr.Logger, opts ...AllocationOption) Allocator {
 	lwAllocator := &leastWeightedAllocator{
 		log:         log,
 		collectors:  make(map[string]*Collector),

cmd/otel-allocator/allocation/strategy.go

@@ -26,7 +26,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/target"
 )
 
-type AllocatorProvider func(log logr.Logger, opts ...AllocOption) Allocator
+type AllocatorProvider func(log logr.Logger, opts ...AllocationOption) Allocator
 
 var (
 	registry = map[string]AllocatorProvider{}
@@ -45,21 +45,39 @@ var (
 		Name: "opentelemetry_allocator_time_to_allocate",
 		Help: "The time it takes to allocate",
 	}, []string{"method", "strategy"})
+	targetsKeptPerJob = promauto.NewGaugeVec(prometheus.GaugeOpts{
+		Name: "opentelemetry_allocator_targets_kept",
+		Help: "Number of targets kept after filtering.",
+	}, []string{"job_name"})
 )
 
-type AllocOption func(Allocator)
+type AllocationOption func(Allocator)
 
 type Filter interface {
 	Apply(map[string]*target.TargetItem) map[string]*target.TargetItem
 }
 
-func WithFilter(filterFunction Filter) AllocOption {
+func WithFilter(filter Filter) AllocationOption {
 	return func(allocator Allocator) {
-		allocator.SetFilter(filterFunction)
+		allocator.SetFilter(filter)
 	}
 }
 
-func New(name string, log logr.Logger, opts ...AllocOption) (Allocator, error) {
+func RecordTargetsKeptPerJob(targets map[string]*target.TargetItem) map[string]float64 {
+	targetsPerJob := make(map[string]float64)
+
+	for _, tItem := range targets {
+		targetsPerJob[tItem.JobName] += 1
+	}
+
+	for jName, numTargets := range targetsPerJob {
+		targetsKeptPerJob.WithLabelValues(jName).Set(numTargets)
+	}
+
+	return targetsPerJob
+}
+
+func New(name string, log logr.Logger, opts ...AllocationOption) (Allocator, error) {
 	if p, ok := registry[name]; ok {
 		return p(log, opts...), nil
 	}
@@ -79,7 +97,7 @@ type Allocator interface {
 	SetTargets(targets map[string]*target.TargetItem)
 	TargetItems() map[string]*target.TargetItem
 	Collectors() map[string]*Collector
-	SetFilter(filterFunction Filter)
+	SetFilter(filter Filter)
 }
 
 var _ consistent.Member = Collector{}

cmd/otel-allocator/main.go

@@ -74,11 +74,8 @@ func main() {
 	log := ctrl.Log.WithName("allocator")
 
 	// allocatorPrehook will be nil if filterStrategy is not set or
-	// unrecognized. This means no filtering will be used.
-	allocatorPrehook, err := prehook.New(cfg.GetTargetsFilterStrategy(), log)
-	if err != nil {
-		log.Info("Unrecognized filter strategy; filtering disabled")
-	}
+	// unrecognized. No filtering will be used in this case.
+	allocatorPrehook := prehook.New(cfg.GetTargetsFilterStrategy(), log)
 
 	allocator, err := allocation.New(cfg.GetAllocationStrategy(), log, allocation.WithFilter(allocatorPrehook))
 	if err != nil {

cmd/otel-allocator/prehook/prehook.go

@@ -16,11 +16,8 @@ package prehook
 
 import (
 	"errors"
-	"fmt"
 
 	"github.com/go-logr/logr"
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/prometheus/prometheus/model/relabel"
 
 	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/target"
@@ -30,13 +27,6 @@ const (
 	relabelConfigTargetFilterName = "relabel-config"
 )
 
-var (
-	TargetsKept = promauto.NewGaugeVec(prometheus.GaugeOpts{
-		Name: "opentelemetry_allocator_targets_kept",
-		Help: "Number of targets kept after filtering.",
-	}, []string{"job_name"})
-)
-
 type Hook interface {
 	Apply(map[string]*target.TargetItem) map[string]*target.TargetItem
 	SetConfig(map[string][]*relabel.Config)
@@ -49,25 +39,13 @@ var (
 	registry = map[string]HookProvider{}
 )
 
-func RecordTargetsKeptPerJob(targets map[string]*target.TargetItem) map[string]float64 {
-	targetsPerJob := make(map[string]float64)
-
-	for _, tItem := range targets {
-		targetsPerJob[tItem.JobName] += 1
-	}
-
-	for jName, numTargets := range targetsPerJob {
-		TargetsKept.WithLabelValues(jName).Set(numTargets)
-	}
-
-	return targetsPerJob
-}
-
-func New(name string, log logr.Logger) (Hook, error) {
+func New(name string, log logr.Logger) Hook {
 	if p, ok := registry[name]; ok {
-		return p(log.WithName("Prehook").WithName(name)), nil
+		return p(log.WithName("Prehook").WithName(name))
 	}
-	return nil, fmt.Errorf("unregistered filtering strategy: %s", name)
+
+	log.Info("Unrecognized filter strategy; filtering disabled")
+	return nil
 }
 
 func Register(name string, provider HookProvider) error {

cmd/otel-allocator/prehook/relabel_test.go

@@ -156,8 +156,8 @@ func makeNNewTargets(n int, numCollectors int, startingIndex int) (map[string]*t
 }
 
 func TestApply(t *testing.T) {
-	allocatorPrehook, err := New("relabel-config", logger)
-	assert.Nil(t, err)
+	allocatorPrehook := New("relabel-config", logger)
+	assert.NotNil(t, allocatorPrehook)
 
 	targets, numRemaining, expectedTargetMap, relabelCfg := makeNNewTargets(numTargets, 3, 0)
 	allocatorPrehook.SetConfig(relabelCfg)
@@ -180,8 +180,8 @@ func TestApply(t *testing.T) {
 
 func TestApplyEmptyRelabelCfg(t *testing.T) {
 
-	allocatorPrehook, err := New("relabel-config", logger)
-	assert.Nil(t, err)
+	allocatorPrehook := New("relabel-config", logger)
+	assert.NotNil(t, allocatorPrehook)
 
 	targets, _, _, _ := makeNNewTargets(numTargets, 3, 0)
 
@@ -194,8 +194,8 @@ func TestApplyEmptyRelabelCfg(t *testing.T) {
 }
 
 func TestSetConfig(t *testing.T) {
-	allocatorPrehook, err := New("relabel-config", logger)
-	assert.Nil(t, err)
+	allocatorPrehook := New("relabel-config", logger)
+	assert.NotNil(t, allocatorPrehook)
 
 	_, _, _, relabelCfg := makeNNewTargets(numTargets, 3, 0)
 	allocatorPrehook.SetConfig(relabelCfg)