From 598741382bf6bab9903a96472836eaf18847a884 Mon Sep 17 00:00:00 2001
From: Antoine Toulme <antoine@lunar-ocean.com>
Date: Tue, 19 Dec 2023 22:15:59 -0800
Subject: [PATCH 1/6] [chore] polish sharedcomponent API

---
 internal/sharedcomponent/sharedcomponent.go   | 53 ++++++------
 .../sharedcomponent/sharedcomponent_test.go   | 82 ++++++++++++++-----
 receiver/otlpreceiver/factory.go              |  8 +-
 3 files changed, 92 insertions(+), 51 deletions(-)

diff --git a/internal/sharedcomponent/sharedcomponent.go b/internal/sharedcomponent/sharedcomponent.go
index 23d7d08c79e..4f4041e2308 100644
--- a/internal/sharedcomponent/sharedcomponent.go
+++ b/internal/sharedcomponent/sharedcomponent.go
@@ -1,34 +1,26 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
-// Package sharedcomponent exposes util functionality for receivers and exporters
-// that need to share state between different signal types instances such as net.Listener or os.File.
+// Package sharedcomponent exposes functionality for components
+// to register against a shared key, such as a configuration object, in order to be reused across signal types.
+// This is particularly useful when the component relies on a shared resource such as os.File or http.Server.
 package sharedcomponent // import "go.opentelemetry.io/collector/internal/sharedcomponent"
 
 import (
 	"context"
 	"sync"
+	"sync/atomic"
 
 	"go.opentelemetry.io/collector/component"
 )
 
-// SharedComponents a map that keeps reference of all created instances for a given configuration,
-// and ensures that the shared state is started and stopped only once.
-type SharedComponents[K comparable, V component.Component] struct {
-	comps map[K]*SharedComponent[V]
-}
-
-// NewSharedComponents returns a new empty SharedComponents.
-func NewSharedComponents[K comparable, V component.Component]() *SharedComponents[K, V] {
-	return &SharedComponents[K, V]{
-		comps: make(map[K]*SharedComponent[V]),
-	}
-}
+// Map keeps reference of all created instances for a given shared key such as a component configuration.
+type Map[K comparable, V component.Component] map[K]*SharedComponent[V]
 
-// GetOrAdd returns the already created instance if exists, otherwise creates a new instance
+// LoadOrStore returns the already created instance if exists, otherwise creates a new instance
 // and adds it to the map of references.
-func (scs *SharedComponents[K, V]) GetOrAdd(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*SharedComponent[V], error) {
-	if c, ok := scs.comps[key]; ok {
+func (scs Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*SharedComponent[V], error) {
+	if c, ok := scs[key]; ok {
 		// If we haven't already seen this telemetry settings, this shared component represents
 		// another instance. Wrap ReportComponentStatus to report for all instances this shared
 		// component represents.
@@ -53,25 +45,27 @@ func (scs *SharedComponents[K, V]) GetOrAdd(key K, create func() (V, error), tel
 	newComp := &SharedComponent[V]{
 		component: comp,
 		removeFunc: func() {
-			delete(scs.comps, key)
+			delete(scs, key)
 		},
 		telemetry: telemetrySettings,
 		seenSettings: map[*component.TelemetrySettings]struct{}{
 			telemetrySettings: {},
 		},
+		activeCount: &atomic.Int32{},
 	}
-	scs.comps[key] = newComp
+	scs[key] = newComp
 	return newComp, nil
 }
 
 // SharedComponent ensures that the wrapped component is started and stopped only once.
-// When stopped it is removed from the SharedComponents map.
+// When stopped it is removed from the Map.
 type SharedComponent[V component.Component] struct {
 	component V
 
-	startOnce  sync.Once
-	stopOnce   sync.Once
-	removeFunc func()
+	activeCount *atomic.Int32 // a counter keeping track of the number of active uses of the component
+	startOnce   sync.Once
+	stopOnce    sync.Once
+	removeFunc  func()
 
 	telemetry    *component.TelemetrySettings
 	seenSettings map[*component.TelemetrySettings]struct{}
@@ -82,7 +76,8 @@ func (r *SharedComponent[V]) Unwrap() V {
 	return r.component
 }
 
-// Start implements component.Component.
+// Start starts the underlying component if it never started before. Each call to Start is counted as an active usage.
+// Shutdown will shut down the underlying component if called as many times as Start is called.
 func (r *SharedComponent[V]) Start(ctx context.Context, host component.Host) error {
 	var err error
 	r.startOnce.Do(func() {
@@ -95,17 +90,23 @@ func (r *SharedComponent[V]) Start(ctx context.Context, host component.Host) err
 			_ = r.telemetry.ReportComponentStatus(component.NewPermanentErrorEvent(err))
 		}
 	})
+	r.activeCount.Add(1)
 	return err
 }
 
-// Shutdown implements component.Component.
+// Shutdown shuts down the underlying component if all known usages, measured by the number of times
+// Start was called, are accounted for.
 func (r *SharedComponent[V]) Shutdown(ctx context.Context) error {
+	if r.activeCount.Add(-1) > 0 {
+		return nil
+	}
+
 	var err error
 	r.stopOnce.Do(func() {
 		// It's important that status for a sharedcomponent is reported through its
 		// telemetrysettings to keep status in sync and avoid race conditions. This logic duplicates
 		// and takes priority over the automated status reporting that happens in graph, making the
-		// the status reporting in graph a no-op.
+		// status reporting in graph a no-op.
 		_ = r.telemetry.ReportComponentStatus(component.NewStatusEvent(component.StatusStopping))
 		err = r.component.Shutdown(ctx)
 		if err != nil {
diff --git a/internal/sharedcomponent/sharedcomponent_test.go b/internal/sharedcomponent/sharedcomponent_test.go
index 5ce081fa752..bf6803a253a 100644
--- a/internal/sharedcomponent/sharedcomponent_test.go
+++ b/internal/sharedcomponent/sharedcomponent_test.go
@@ -24,36 +24,36 @@ type baseComponent struct {
 }
 
 func TestNewSharedComponents(t *testing.T) {
-	comps := NewSharedComponents[component.ID, *baseComponent]()
-	assert.Len(t, comps.comps, 0)
+	comps := Map[component.ID, *baseComponent]{}
+	assert.Len(t, comps, 0)
 }
 
 func TestNewSharedComponentsCreateError(t *testing.T) {
-	comps := NewSharedComponents[component.ID, *baseComponent]()
-	assert.Len(t, comps.comps, 0)
+	comps := Map[component.ID, *baseComponent]{}
+	assert.Len(t, comps, 0)
 	myErr := errors.New("my error")
-	_, err := comps.GetOrAdd(
+	_, err := comps.LoadOrStore(
 		id,
 		func() (*baseComponent, error) { return nil, myErr },
 		newNopTelemetrySettings(),
 	)
 	assert.ErrorIs(t, err, myErr)
-	assert.Len(t, comps.comps, 0)
+	assert.Len(t, comps, 0)
 }
 
 func TestSharedComponentsGetOrAdd(t *testing.T) {
 	nop := &baseComponent{}
 
-	comps := NewSharedComponents[component.ID, *baseComponent]()
-	got, err := comps.GetOrAdd(
+	comps := Map[component.ID, *baseComponent]{}
+	got, err := comps.LoadOrStore(
 		id,
 		func() (*baseComponent, error) { return nop, nil },
 		newNopTelemetrySettings(),
 	)
 	require.NoError(t, err)
-	assert.Len(t, comps.comps, 1)
+	assert.Len(t, comps, 1)
 	assert.Same(t, nop, got.Unwrap())
-	gotSecond, err := comps.GetOrAdd(
+	gotSecond, err := comps.LoadOrStore(
 		id,
 		func() (*baseComponent, error) { panic("should not be called") },
 		newNopTelemetrySettings(),
@@ -64,8 +64,8 @@ func TestSharedComponentsGetOrAdd(t *testing.T) {
 
 	// Shutdown nop will remove
 	assert.NoError(t, got.Shutdown(context.Background()))
-	assert.Len(t, comps.comps, 0)
-	gotThird, err := comps.GetOrAdd(
+	assert.Len(t, comps, 0)
+	gotThird, err := comps.LoadOrStore(
 		id,
 		func() (*baseComponent, error) { return nop, nil },
 		newNopTelemetrySettings(),
@@ -88,8 +88,8 @@ func TestSharedComponent(t *testing.T) {
 			return wantErr
 		}}
 
-	comps := NewSharedComponents[component.ID, *baseComponent]()
-	got, err := comps.GetOrAdd(
+	comps := Map[component.ID, *baseComponent]{}
+	got, err := comps.LoadOrStore(
 		id,
 		func() (*baseComponent, error) { return comp, nil },
 		newNopTelemetrySettings(),
@@ -100,9 +100,49 @@ func TestSharedComponent(t *testing.T) {
 	// Second time is not called anymore.
 	assert.NoError(t, got.Start(context.Background(), componenttest.NewNopHost()))
 	assert.Equal(t, 1, calledStart)
+	// first time, shutdown is not called.
+	assert.NoError(t, got.Shutdown(context.Background()))
+	assert.Equal(t, 0, calledStop)
+	// Second time is not called anymore.
 	assert.Equal(t, wantErr, got.Shutdown(context.Background()))
 	assert.Equal(t, 1, calledStop)
+}
+
+func TestSharedComponentLateShutdown(t *testing.T) {
+	calledStart := 0
+	calledStop := 0
+	comp := &baseComponent{
+		StartFunc: func(ctx context.Context, host component.Host) error {
+			calledStart++
+			return nil
+		},
+		ShutdownFunc: func(ctx context.Context) error {
+			calledStop++
+			return nil
+		}}
+
+	comps := Map[component.ID, *baseComponent]{}
+	got, err := comps.LoadOrStore(
+		id,
+		func() (*baseComponent, error) { return comp, nil },
+		newNopTelemetrySettings(),
+	)
+	require.NoError(t, err)
+	assert.NoError(t, got.Start(context.Background(), componenttest.NewNopHost()))
+	assert.Equal(t, 1, calledStart)
 	// Second time is not called anymore.
+	assert.NoError(t, got.Start(context.Background(), componenttest.NewNopHost()))
+	assert.Equal(t, 1, calledStart)
+	// there is still one use, so stop is not called.
+	assert.NoError(t, got.Shutdown(context.Background()))
+	assert.Equal(t, 0, calledStop)
+	// start one more time:
+	assert.NoError(t, got.Start(context.Background(), componenttest.NewNopHost()))
+	assert.Equal(t, 1, calledStart)
+	// there is still one use, so stop is not called.
+	assert.NoError(t, got.Shutdown(context.Background()))
+	assert.Equal(t, 0, calledStop)
+	// finally close all active uses
 	assert.NoError(t, got.Shutdown(context.Background()))
 	assert.Equal(t, 1, calledStop)
 }
@@ -122,7 +162,7 @@ func TestSharedComponentsReportStatus(t *testing.T) {
 	}
 
 	comp := &baseComponent{}
-	comps := NewSharedComponents[component.ID, *baseComponent]()
+	comps := Map[component.ID, *baseComponent]{}
 	var telemetrySettings *component.TelemetrySettings
 
 	// make a shared component that represents three instances
@@ -130,23 +170,23 @@ func TestSharedComponentsReportStatus(t *testing.T) {
 		telemetrySettings = newNopTelemetrySettings()
 		telemetrySettings.ReportComponentStatus = newStatusFunc()
 		// The initial settings for the shared component need to match the ones passed to the first
-		// invocation of GetOrAdd so that underlying telemetry settings reference can be used to
+		// invocation of LoadOrStore so that underlying telemetry settings reference can be used to
 		// wrap ReportComponentStatus for subsequently added "instances".
 		if i == 0 {
 			comp.telemetry = telemetrySettings
 		}
-		got, err := comps.GetOrAdd(
+		got, err := comps.LoadOrStore(
 			id,
 			func() (*baseComponent, error) { return comp, nil },
 			telemetrySettings,
 		)
 		require.NoError(t, err)
-		assert.Len(t, comps.comps, 1)
+		assert.Len(t, comps, 1)
 		assert.Same(t, comp, got.Unwrap())
 	}
 
 	// make sure we don't try to represent a fourth instance if we reuse a telemetrySettings
-	_, _ = comps.GetOrAdd(
+	_, _ = comps.LoadOrStore(
 		id,
 		func() (*baseComponent, error) { return comp, nil },
 		telemetrySettings,
@@ -245,7 +285,7 @@ func TestReportStatusOnStartShutdown(t *testing.T) {
 					return tc.shutdownErr
 				}
 			}
-			comps := NewSharedComponents[component.ID, *baseComponent]()
+			comps := Map[component.ID, *baseComponent]{}
 			var comp *SharedComponent[*baseComponent]
 			var err error
 			for i := 0; i < 3; i++ {
@@ -254,7 +294,7 @@ func TestReportStatusOnStartShutdown(t *testing.T) {
 				if i == 0 {
 					base.telemetry = telemetrySettings
 				}
-				comp, err = comps.GetOrAdd(
+				comp, err = comps.LoadOrStore(
 					id,
 					func() (*baseComponent, error) { return base, nil },
 					telemetrySettings,
diff --git a/receiver/otlpreceiver/factory.go b/receiver/otlpreceiver/factory.go
index cce8b363cd4..ef20d592c13 100644
--- a/receiver/otlpreceiver/factory.go
+++ b/receiver/otlpreceiver/factory.go
@@ -68,7 +68,7 @@ func createTraces(
 	nextConsumer consumer.Traces,
 ) (receiver.Traces, error) {
 	oCfg := cfg.(*Config)
-	r, err := receivers.GetOrAdd(
+	r, err := receivers.LoadOrStore(
 		oCfg,
 		func() (*otlpReceiver, error) {
 			return newOtlpReceiver(oCfg, &set)
@@ -93,7 +93,7 @@ func createMetrics(
 	consumer consumer.Metrics,
 ) (receiver.Metrics, error) {
 	oCfg := cfg.(*Config)
-	r, err := receivers.GetOrAdd(
+	r, err := receivers.LoadOrStore(
 		oCfg,
 		func() (*otlpReceiver, error) {
 			return newOtlpReceiver(oCfg, &set)
@@ -118,7 +118,7 @@ func createLog(
 	consumer consumer.Logs,
 ) (receiver.Logs, error) {
 	oCfg := cfg.(*Config)
-	r, err := receivers.GetOrAdd(
+	r, err := receivers.LoadOrStore(
 		oCfg,
 		func() (*otlpReceiver, error) {
 			return newOtlpReceiver(oCfg, &set)
@@ -141,4 +141,4 @@ func createLog(
 // create separate objects, they must use one otlpReceiver object per configuration.
 // When the receiver is shutdown it should be removed from this map so the same configuration
 // can be recreated successfully.
-var receivers = sharedcomponent.NewSharedComponents[*Config, *otlpReceiver]()
+var receivers = sharedcomponent.Map[*Config, *otlpReceiver]{}

From 38e2d7e659bd812048dad3ef63f58fbd3a049d3f Mon Sep 17 00:00:00 2001
From: Antoine Toulme <antoine@lunar-ocean.com>
Date: Wed, 20 Dec 2023 10:50:33 -0800
Subject: [PATCH 2/6] SharedComponent -> Component

---
 internal/sharedcomponent/sharedcomponent.go   | 24 +++++++++----------
 .../sharedcomponent/sharedcomponent_test.go   |  2 +-
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/internal/sharedcomponent/sharedcomponent.go b/internal/sharedcomponent/sharedcomponent.go
index 4f4041e2308..f9a607e57b5 100644
--- a/internal/sharedcomponent/sharedcomponent.go
+++ b/internal/sharedcomponent/sharedcomponent.go
@@ -15,11 +15,11 @@ import (
 )
 
 // Map keeps reference of all created instances for a given shared key such as a component configuration.
-type Map[K comparable, V component.Component] map[K]*SharedComponent[V]
+type Map[K comparable, V component.Component] map[K]*Component[V]
 
 // LoadOrStore returns the already created instance if exists, otherwise creates a new instance
 // and adds it to the map of references.
-func (scs Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*SharedComponent[V], error) {
+func (scs Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*Component[V], error) {
 	if c, ok := scs[key]; ok {
 		// If we haven't already seen this telemetry settings, this shared component represents
 		// another instance. Wrap ReportComponentStatus to report for all instances this shared
@@ -42,7 +42,7 @@ func (scs Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySetti
 		return nil, err
 	}
 
-	newComp := &SharedComponent[V]{
+	newComp := &Component[V]{
 		component: comp,
 		removeFunc: func() {
 			delete(scs, key)
@@ -57,9 +57,9 @@ func (scs Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySetti
 	return newComp, nil
 }
 
-// SharedComponent ensures that the wrapped component is started and stopped only once.
+// Component ensures that the wrapped component is started and stopped only once.
 // When stopped it is removed from the Map.
-type SharedComponent[V component.Component] struct {
+type Component[V component.Component] struct {
 	component V
 
 	activeCount *atomic.Int32 // a counter keeping track of the number of active uses of the component
@@ -72,17 +72,17 @@ type SharedComponent[V component.Component] struct {
 }
 
 // Unwrap returns the original component.
-func (r *SharedComponent[V]) Unwrap() V {
+func (r *Component[V]) Unwrap() V {
 	return r.component
 }
 
 // Start starts the underlying component if it never started before. Each call to Start is counted as an active usage.
 // Shutdown will shut down the underlying component if called as many times as Start is called.
-func (r *SharedComponent[V]) Start(ctx context.Context, host component.Host) error {
+func (r *Component[V]) Start(ctx context.Context, host component.Host) error {
 	var err error
 	r.startOnce.Do(func() {
-		// It's important that status for a sharedcomponent is reported through its
-		// telemetrysettings to keep status in sync and avoid race conditions. This logic duplicates
+		// It's important that status for a shared component is reported through its
+		// telemetry settings to keep status in sync and avoid race conditions. This logic duplicates
 		// and takes priority over the automated status reporting that happens in graph, making the
 		// status reporting in graph a no-op.
 		_ = r.telemetry.ReportComponentStatus(component.NewStatusEvent(component.StatusStarting))
@@ -96,15 +96,15 @@ func (r *SharedComponent[V]) Start(ctx context.Context, host component.Host) err
 
 // Shutdown shuts down the underlying component if all known usages, measured by the number of times
 // Start was called, are accounted for.
-func (r *SharedComponent[V]) Shutdown(ctx context.Context) error {
+func (r *Component[V]) Shutdown(ctx context.Context) error {
 	if r.activeCount.Add(-1) > 0 {
 		return nil
 	}
 
 	var err error
 	r.stopOnce.Do(func() {
-		// It's important that status for a sharedcomponent is reported through its
-		// telemetrysettings to keep status in sync and avoid race conditions. This logic duplicates
+		// It's important that status for a shared component is reported through its
+		// telemetry settings to keep status in sync and avoid race conditions. This logic duplicates
 		// and takes priority over the automated status reporting that happens in graph, making the
 		// status reporting in graph a no-op.
 		_ = r.telemetry.ReportComponentStatus(component.NewStatusEvent(component.StatusStopping))
diff --git a/internal/sharedcomponent/sharedcomponent_test.go b/internal/sharedcomponent/sharedcomponent_test.go
index bf6803a253a..35e2964df5c 100644
--- a/internal/sharedcomponent/sharedcomponent_test.go
+++ b/internal/sharedcomponent/sharedcomponent_test.go
@@ -286,7 +286,7 @@ func TestReportStatusOnStartShutdown(t *testing.T) {
 				}
 			}
 			comps := Map[component.ID, *baseComponent]{}
-			var comp *SharedComponent[*baseComponent]
+			var comp *Component[*baseComponent]
 			var err error
 			for i := 0; i < 3; i++ {
 				telemetrySettings := newNopTelemetrySettings()

From 78c7fc2dceda193670b6921c90ac2c2b90f38cd9 Mon Sep 17 00:00:00 2001
From: Antoine Toulme <antoine@lunar-ocean.com>
Date: Wed, 20 Dec 2023 11:47:19 -0800
Subject: [PATCH 3/6] reduce scope of changes

---
 internal/sharedcomponent/sharedcomponent.go   | 20 +++------
 .../sharedcomponent/sharedcomponent_test.go   | 44 +------------------
 2 files changed, 7 insertions(+), 57 deletions(-)

diff --git a/internal/sharedcomponent/sharedcomponent.go b/internal/sharedcomponent/sharedcomponent.go
index f9a607e57b5..187e7cd1f55 100644
--- a/internal/sharedcomponent/sharedcomponent.go
+++ b/internal/sharedcomponent/sharedcomponent.go
@@ -9,7 +9,6 @@ package sharedcomponent // import "go.opentelemetry.io/collector/internal/shared
 import (
 	"context"
 	"sync"
-	"sync/atomic"
 
 	"go.opentelemetry.io/collector/component"
 )
@@ -51,7 +50,6 @@ func (scs Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySetti
 		seenSettings: map[*component.TelemetrySettings]struct{}{
 			telemetrySettings: {},
 		},
-		activeCount: &atomic.Int32{},
 	}
 	scs[key] = newComp
 	return newComp, nil
@@ -62,10 +60,9 @@ func (scs Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySetti
 type Component[V component.Component] struct {
 	component V
 
-	activeCount *atomic.Int32 // a counter keeping track of the number of active uses of the component
-	startOnce   sync.Once
-	stopOnce    sync.Once
-	removeFunc  func()
+	startOnce  sync.Once
+	stopOnce   sync.Once
+	removeFunc func()
 
 	telemetry    *component.TelemetrySettings
 	seenSettings map[*component.TelemetrySettings]struct{}
@@ -76,8 +73,7 @@ func (r *Component[V]) Unwrap() V {
 	return r.component
 }
 
-// Start starts the underlying component if it never started before. Each call to Start is counted as an active usage.
-// Shutdown will shut down the underlying component if called as many times as Start is called.
+// Start starts the underlying component if it never started before.
 func (r *Component[V]) Start(ctx context.Context, host component.Host) error {
 	var err error
 	r.startOnce.Do(func() {
@@ -90,17 +86,11 @@ func (r *Component[V]) Start(ctx context.Context, host component.Host) error {
 			_ = r.telemetry.ReportComponentStatus(component.NewPermanentErrorEvent(err))
 		}
 	})
-	r.activeCount.Add(1)
 	return err
 }
 
-// Shutdown shuts down the underlying component if all known usages, measured by the number of times
-// Start was called, are accounted for.
+// Shutdown shuts down the underlying component.
 func (r *Component[V]) Shutdown(ctx context.Context) error {
-	if r.activeCount.Add(-1) > 0 {
-		return nil
-	}
-
 	var err error
 	r.stopOnce.Do(func() {
 		// It's important that status for a shared component is reported through its
diff --git a/internal/sharedcomponent/sharedcomponent_test.go b/internal/sharedcomponent/sharedcomponent_test.go
index 35e2964df5c..78cc614652b 100644
--- a/internal/sharedcomponent/sharedcomponent_test.go
+++ b/internal/sharedcomponent/sharedcomponent_test.go
@@ -41,7 +41,7 @@ func TestNewSharedComponentsCreateError(t *testing.T) {
 	assert.Len(t, comps, 0)
 }
 
-func TestSharedComponentsGetOrAdd(t *testing.T) {
+func TestSharedComponentsLoadOrStore(t *testing.T) {
 	nop := &baseComponent{}
 
 	comps := Map[component.ID, *baseComponent]{}
@@ -100,53 +100,13 @@ func TestSharedComponent(t *testing.T) {
 	// Second time is not called anymore.
 	assert.NoError(t, got.Start(context.Background(), componenttest.NewNopHost()))
 	assert.Equal(t, 1, calledStart)
-	// first time, shutdown is not called.
-	assert.NoError(t, got.Shutdown(context.Background()))
-	assert.Equal(t, 0, calledStop)
-	// Second time is not called anymore.
+	// first time, shutdown is called.
 	assert.Equal(t, wantErr, got.Shutdown(context.Background()))
 	assert.Equal(t, 1, calledStop)
-}
-
-func TestSharedComponentLateShutdown(t *testing.T) {
-	calledStart := 0
-	calledStop := 0
-	comp := &baseComponent{
-		StartFunc: func(ctx context.Context, host component.Host) error {
-			calledStart++
-			return nil
-		},
-		ShutdownFunc: func(ctx context.Context) error {
-			calledStop++
-			return nil
-		}}
-
-	comps := Map[component.ID, *baseComponent]{}
-	got, err := comps.LoadOrStore(
-		id,
-		func() (*baseComponent, error) { return comp, nil },
-		newNopTelemetrySettings(),
-	)
-	require.NoError(t, err)
-	assert.NoError(t, got.Start(context.Background(), componenttest.NewNopHost()))
-	assert.Equal(t, 1, calledStart)
 	// Second time is not called anymore.
-	assert.NoError(t, got.Start(context.Background(), componenttest.NewNopHost()))
-	assert.Equal(t, 1, calledStart)
-	// there is still one use, so stop is not called.
-	assert.NoError(t, got.Shutdown(context.Background()))
-	assert.Equal(t, 0, calledStop)
-	// start one more time:
-	assert.NoError(t, got.Start(context.Background(), componenttest.NewNopHost()))
-	assert.Equal(t, 1, calledStart)
-	// there is still one use, so stop is not called.
-	assert.NoError(t, got.Shutdown(context.Background()))
-	assert.Equal(t, 0, calledStop)
-	// finally close all active uses
 	assert.NoError(t, got.Shutdown(context.Background()))
 	assert.Equal(t, 1, calledStop)
 }
-
 func TestSharedComponentsReportStatus(t *testing.T) {
 	reportedStatuses := make(map[*component.InstanceID][]component.Status)
 	newStatusFunc := func() func(*component.StatusEvent) error {

From 1d6718b6c7c9bc9b4a7df67c116d13fe43a27d05 Mon Sep 17 00:00:00 2001
From: Antoine Toulme <antoine@lunar-ocean.com>
Date: Wed, 20 Dec 2023 12:00:37 -0800
Subject: [PATCH 4/6] rename receivers

---
 internal/sharedcomponent/sharedcomponent.go | 36 ++++++++++-----------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/internal/sharedcomponent/sharedcomponent.go b/internal/sharedcomponent/sharedcomponent.go
index 187e7cd1f55..3a48a14075d 100644
--- a/internal/sharedcomponent/sharedcomponent.go
+++ b/internal/sharedcomponent/sharedcomponent.go
@@ -18,8 +18,8 @@ type Map[K comparable, V component.Component] map[K]*Component[V]
 
 // LoadOrStore returns the already created instance if exists, otherwise creates a new instance
 // and adds it to the map of references.
-func (scs Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*Component[V], error) {
-	if c, ok := scs[key]; ok {
+func (m Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*Component[V], error) {
+	if c, ok := m[key]; ok {
 		// If we haven't already seen this telemetry settings, this shared component represents
 		// another instance. Wrap ReportComponentStatus to report for all instances this shared
 		// component represents.
@@ -44,14 +44,14 @@ func (scs Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySetti
 	newComp := &Component[V]{
 		component: comp,
 		removeFunc: func() {
-			delete(scs, key)
+			delete(m, key)
 		},
 		telemetry: telemetrySettings,
 		seenSettings: map[*component.TelemetrySettings]struct{}{
 			telemetrySettings: {},
 		},
 	}
-	scs[key] = newComp
+	m[key] = newComp
 	return newComp, nil
 }
 
@@ -69,42 +69,42 @@ type Component[V component.Component] struct {
 }
 
 // Unwrap returns the original component.
-func (r *Component[V]) Unwrap() V {
-	return r.component
+func (c *Component[V]) Unwrap() V {
+	return c.component
 }
 
 // Start starts the underlying component if it never started before.
-func (r *Component[V]) Start(ctx context.Context, host component.Host) error {
+func (c *Component[V]) Start(ctx context.Context, host component.Host) error {
 	var err error
-	r.startOnce.Do(func() {
+	c.startOnce.Do(func() {
 		// It's important that status for a shared component is reported through its
 		// telemetry settings to keep status in sync and avoid race conditions. This logic duplicates
 		// and takes priority over the automated status reporting that happens in graph, making the
 		// status reporting in graph a no-op.
-		_ = r.telemetry.ReportComponentStatus(component.NewStatusEvent(component.StatusStarting))
-		if err = r.component.Start(ctx, host); err != nil {
-			_ = r.telemetry.ReportComponentStatus(component.NewPermanentErrorEvent(err))
+		_ = c.telemetry.ReportComponentStatus(component.NewStatusEvent(component.StatusStarting))
+		if err = c.component.Start(ctx, host); err != nil {
+			_ = c.telemetry.ReportComponentStatus(component.NewPermanentErrorEvent(err))
 		}
 	})
 	return err
 }
 
 // Shutdown shuts down the underlying component.
-func (r *Component[V]) Shutdown(ctx context.Context) error {
+func (c *Component[V]) Shutdown(ctx context.Context) error {
 	var err error
-	r.stopOnce.Do(func() {
+	c.stopOnce.Do(func() {
 		// It's important that status for a shared component is reported through its
 		// telemetry settings to keep status in sync and avoid race conditions. This logic duplicates
 		// and takes priority over the automated status reporting that happens in graph, making the
 		// status reporting in graph a no-op.
-		_ = r.telemetry.ReportComponentStatus(component.NewStatusEvent(component.StatusStopping))
-		err = r.component.Shutdown(ctx)
+		_ = c.telemetry.ReportComponentStatus(component.NewStatusEvent(component.StatusStopping))
+		err = c.component.Shutdown(ctx)
 		if err != nil {
-			_ = r.telemetry.ReportComponentStatus(component.NewPermanentErrorEvent(err))
+			_ = c.telemetry.ReportComponentStatus(component.NewPermanentErrorEvent(err))
 		} else {
-			_ = r.telemetry.ReportComponentStatus(component.NewStatusEvent(component.StatusStopped))
+			_ = c.telemetry.ReportComponentStatus(component.NewStatusEvent(component.StatusStopped))
 		}
-		r.removeFunc()
+		c.removeFunc()
 	})
 	return err
 }

From eb539b5f206f8224144ca9020f2ba38bb14ae9f4 Mon Sep 17 00:00:00 2001
From: Antoine Toulme <antoine@lunar-ocean.com>
Date: Wed, 20 Dec 2023 16:51:17 -0800
Subject: [PATCH 5/6] move from builtin map to struct

---
 internal/sharedcomponent/sharedcomponent.go   | 26 ++++++++++++++-----
 .../sharedcomponent/sharedcomponent_test.go   | 26 +++++++++----------
 receiver/otlpreceiver/factory.go              |  2 +-
 3 files changed, 33 insertions(+), 21 deletions(-)

diff --git a/internal/sharedcomponent/sharedcomponent.go b/internal/sharedcomponent/sharedcomponent.go
index 3a48a14075d..098de1f5b70 100644
--- a/internal/sharedcomponent/sharedcomponent.go
+++ b/internal/sharedcomponent/sharedcomponent.go
@@ -14,12 +14,24 @@ import (
 )
 
 // Map keeps reference of all created instances for a given shared key such as a component configuration.
-type Map[K comparable, V component.Component] map[K]*Component[V]
+type Map[K comparable, V component.Component] interface {
+	// LoadOrStore returns the already created instance if exists, otherwise creates a new instance
+	// and adds it to the map of references.
+	LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*Component[V], error)
+}
+
+func NewMap[K comparable, V component.Component]() Map[K, V] {
+	return &mapImpl[K, V]{
+		components: map[K]*Component[V]{},
+	}
+}
+
+type mapImpl[K comparable, V component.Component] struct {
+	components map[K]*Component[V]
+}
 
-// LoadOrStore returns the already created instance if exists, otherwise creates a new instance
-// and adds it to the map of references.
-func (m Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*Component[V], error) {
-	if c, ok := m[key]; ok {
+func (m *mapImpl[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*Component[V], error) {
+	if c, ok := m.components[key]; ok {
 		// If we haven't already seen this telemetry settings, this shared component represents
 		// another instance. Wrap ReportComponentStatus to report for all instances this shared
 		// component represents.
@@ -44,14 +56,14 @@ func (m Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySetting
 	newComp := &Component[V]{
 		component: comp,
 		removeFunc: func() {
-			delete(m, key)
+			delete(m.components, key)
 		},
 		telemetry: telemetrySettings,
 		seenSettings: map[*component.TelemetrySettings]struct{}{
 			telemetrySettings: {},
 		},
 	}
-	m[key] = newComp
+	m.components[key] = newComp
 	return newComp, nil
 }
 
diff --git a/internal/sharedcomponent/sharedcomponent_test.go b/internal/sharedcomponent/sharedcomponent_test.go
index 78cc614652b..767c7fa02c2 100644
--- a/internal/sharedcomponent/sharedcomponent_test.go
+++ b/internal/sharedcomponent/sharedcomponent_test.go
@@ -23,14 +23,14 @@ type baseComponent struct {
 	telemetry *component.TelemetrySettings
 }
 
-func TestNewSharedComponents(t *testing.T) {
-	comps := Map[component.ID, *baseComponent]{}
-	assert.Len(t, comps, 0)
+func TestNewMap(t *testing.T) {
+	comps := NewMap[component.ID, *baseComponent]()
+	assert.Len(t, comps.(*mapImpl[component.ID, *baseComponent]).components, 0)
 }
 
 func TestNewSharedComponentsCreateError(t *testing.T) {
-	comps := Map[component.ID, *baseComponent]{}
-	assert.Len(t, comps, 0)
+	comps := NewMap[component.ID, *baseComponent]().(*mapImpl[component.ID, *baseComponent])
+	assert.Len(t, comps.components, 0)
 	myErr := errors.New("my error")
 	_, err := comps.LoadOrStore(
 		id,
@@ -38,20 +38,20 @@ func TestNewSharedComponentsCreateError(t *testing.T) {
 		newNopTelemetrySettings(),
 	)
 	assert.ErrorIs(t, err, myErr)
-	assert.Len(t, comps, 0)
+	assert.Len(t, comps.components, 0)
 }
 
 func TestSharedComponentsLoadOrStore(t *testing.T) {
 	nop := &baseComponent{}
 
-	comps := Map[component.ID, *baseComponent]{}
+	comps := NewMap[component.ID, *baseComponent]()
 	got, err := comps.LoadOrStore(
 		id,
 		func() (*baseComponent, error) { return nop, nil },
 		newNopTelemetrySettings(),
 	)
 	require.NoError(t, err)
-	assert.Len(t, comps, 1)
+	assert.Len(t, comps.(*mapImpl[component.ID, *baseComponent]).components, 1)
 	assert.Same(t, nop, got.Unwrap())
 	gotSecond, err := comps.LoadOrStore(
 		id,
@@ -64,7 +64,7 @@ func TestSharedComponentsLoadOrStore(t *testing.T) {
 
 	// Shutdown nop will remove
 	assert.NoError(t, got.Shutdown(context.Background()))
-	assert.Len(t, comps, 0)
+	assert.Len(t, comps.(*mapImpl[component.ID, *baseComponent]).components, 0)
 	gotThird, err := comps.LoadOrStore(
 		id,
 		func() (*baseComponent, error) { return nop, nil },
@@ -88,7 +88,7 @@ func TestSharedComponent(t *testing.T) {
 			return wantErr
 		}}
 
-	comps := Map[component.ID, *baseComponent]{}
+	comps := NewMap[component.ID, *baseComponent]()
 	got, err := comps.LoadOrStore(
 		id,
 		func() (*baseComponent, error) { return comp, nil },
@@ -122,7 +122,7 @@ func TestSharedComponentsReportStatus(t *testing.T) {
 	}
 
 	comp := &baseComponent{}
-	comps := Map[component.ID, *baseComponent]{}
+	comps := NewMap[component.ID, *baseComponent]()
 	var telemetrySettings *component.TelemetrySettings
 
 	// make a shared component that represents three instances
@@ -141,7 +141,7 @@ func TestSharedComponentsReportStatus(t *testing.T) {
 			telemetrySettings,
 		)
 		require.NoError(t, err)
-		assert.Len(t, comps, 1)
+		assert.Len(t, comps.(*mapImpl[component.ID, *baseComponent]).components, 1)
 		assert.Same(t, comp, got.Unwrap())
 	}
 
@@ -245,7 +245,7 @@ func TestReportStatusOnStartShutdown(t *testing.T) {
 					return tc.shutdownErr
 				}
 			}
-			comps := Map[component.ID, *baseComponent]{}
+			comps := NewMap[component.ID, *baseComponent]()
 			var comp *Component[*baseComponent]
 			var err error
 			for i := 0; i < 3; i++ {
diff --git a/receiver/otlpreceiver/factory.go b/receiver/otlpreceiver/factory.go
index ef20d592c13..125c7c9f296 100644
--- a/receiver/otlpreceiver/factory.go
+++ b/receiver/otlpreceiver/factory.go
@@ -141,4 +141,4 @@ func createLog(
 // create separate objects, they must use one otlpReceiver object per configuration.
 // When the receiver is shutdown it should be removed from this map so the same configuration
 // can be recreated successfully.
-var receivers = sharedcomponent.Map[*Config, *otlpReceiver]{}
+var receivers = sharedcomponent.NewMap[*Config, *otlpReceiver]()

From 32fdc29bd91cdb40903fc7da2570c60503e74718 Mon Sep 17 00:00:00 2001
From: Antoine Toulme <antoine@lunar-ocean.com>
Date: Wed, 20 Dec 2023 21:40:58 -0800
Subject: [PATCH 6/6] remove interface

---
 internal/sharedcomponent/sharedcomponent.go    | 18 +++++++-----------
 .../sharedcomponent/sharedcomponent_test.go    | 10 +++++-----
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/internal/sharedcomponent/sharedcomponent.go b/internal/sharedcomponent/sharedcomponent.go
index 098de1f5b70..417137a8919 100644
--- a/internal/sharedcomponent/sharedcomponent.go
+++ b/internal/sharedcomponent/sharedcomponent.go
@@ -13,24 +13,20 @@ import (
 	"go.opentelemetry.io/collector/component"
 )
 
-// Map keeps reference of all created instances for a given shared key such as a component configuration.
-type Map[K comparable, V component.Component] interface {
-	// LoadOrStore returns the already created instance if exists, otherwise creates a new instance
-	// and adds it to the map of references.
-	LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*Component[V], error)
-}
-
-func NewMap[K comparable, V component.Component]() Map[K, V] {
-	return &mapImpl[K, V]{
+func NewMap[K comparable, V component.Component]() *Map[K, V] {
+	return &Map[K, V]{
 		components: map[K]*Component[V]{},
 	}
 }
 
-type mapImpl[K comparable, V component.Component] struct {
+// Map keeps reference of all created instances for a given shared key such as a component configuration.
+type Map[K comparable, V component.Component] struct {
 	components map[K]*Component[V]
 }
 
-func (m *mapImpl[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*Component[V], error) {
+// LoadOrStore returns the already created instance if exists, otherwise creates a new instance
+// and adds it to the map of references.
+func (m *Map[K, V]) LoadOrStore(key K, create func() (V, error), telemetrySettings *component.TelemetrySettings) (*Component[V], error) {
 	if c, ok := m.components[key]; ok {
 		// If we haven't already seen this telemetry settings, this shared component represents
 		// another instance. Wrap ReportComponentStatus to report for all instances this shared
diff --git a/internal/sharedcomponent/sharedcomponent_test.go b/internal/sharedcomponent/sharedcomponent_test.go
index 767c7fa02c2..7254bcfcbf3 100644
--- a/internal/sharedcomponent/sharedcomponent_test.go
+++ b/internal/sharedcomponent/sharedcomponent_test.go
@@ -25,11 +25,11 @@ type baseComponent struct {
 
 func TestNewMap(t *testing.T) {
 	comps := NewMap[component.ID, *baseComponent]()
-	assert.Len(t, comps.(*mapImpl[component.ID, *baseComponent]).components, 0)
+	assert.Len(t, comps.components, 0)
 }
 
 func TestNewSharedComponentsCreateError(t *testing.T) {
-	comps := NewMap[component.ID, *baseComponent]().(*mapImpl[component.ID, *baseComponent])
+	comps := NewMap[component.ID, *baseComponent]()
 	assert.Len(t, comps.components, 0)
 	myErr := errors.New("my error")
 	_, err := comps.LoadOrStore(
@@ -51,7 +51,7 @@ func TestSharedComponentsLoadOrStore(t *testing.T) {
 		newNopTelemetrySettings(),
 	)
 	require.NoError(t, err)
-	assert.Len(t, comps.(*mapImpl[component.ID, *baseComponent]).components, 1)
+	assert.Len(t, comps.components, 1)
 	assert.Same(t, nop, got.Unwrap())
 	gotSecond, err := comps.LoadOrStore(
 		id,
@@ -64,7 +64,7 @@ func TestSharedComponentsLoadOrStore(t *testing.T) {
 
 	// Shutdown nop will remove
 	assert.NoError(t, got.Shutdown(context.Background()))
-	assert.Len(t, comps.(*mapImpl[component.ID, *baseComponent]).components, 0)
+	assert.Len(t, comps.components, 0)
 	gotThird, err := comps.LoadOrStore(
 		id,
 		func() (*baseComponent, error) { return nop, nil },
@@ -141,7 +141,7 @@ func TestSharedComponentsReportStatus(t *testing.T) {
 			telemetrySettings,
 		)
 		require.NoError(t, err)
-		assert.Len(t, comps.(*mapImpl[component.ID, *baseComponent]).components, 1)
+		assert.Len(t, comps.components, 1)
 		assert.Same(t, comp, got.Unwrap())
 	}