Access ballast size from Ballast extension via Host.GetExtensions int…

…erface (open-telemetry#3634)

* Remove the global ballast size variable in ballast extension
* Access Ballast extension in Memory Limiter processor via Host.GetExtensions 

**Link to tracking Issue:** 
open-telemetry#2516

extension/ballastextension/memory_ballast.go

@@ -24,51 +24,50 @@ import (
 
 const megaBytes = 1024 * 1024
 
-var ballastSizeBytes uint64
-
-type memoryBallast struct {
-	cfg         *Config
-	logger      *zap.Logger
-	ballast     []byte
-	getTotalMem func() (uint64, error)
+type MemoryBallast struct {
+	cfg              *Config
+	logger           *zap.Logger
+	ballast          []byte
+	ballastSizeBytes uint64
+	getTotalMem      func() (uint64, error)
 }
 
-func (m *memoryBallast) Start(_ context.Context, _ component.Host) error {
+func (m *MemoryBallast) Start(_ context.Context, _ component.Host) error {
 	// absolute value supersedes percentage setting
 	if m.cfg.SizeMiB > 0 {
-		ballastSizeBytes = m.cfg.SizeMiB * megaBytes
+		m.ballastSizeBytes = m.cfg.SizeMiB * megaBytes
 	} else {
 		totalMemory, err := m.getTotalMem()
 		if err != nil {
 			return err
 		}
 		ballastPercentage := m.cfg.SizeInPercentage
-		ballastSizeBytes = ballastPercentage * totalMemory / 100
+		m.ballastSizeBytes = ballastPercentage * totalMemory / 100
 	}
 
-	if ballastSizeBytes > 0 {
-		m.ballast = make([]byte, ballastSizeBytes)
+	if m.ballastSizeBytes > 0 {
+		m.ballast = make([]byte, m.ballastSizeBytes)
 	}
 
-	m.logger.Info("Setting memory ballast", zap.Uint32("MiBs", uint32(ballastSizeBytes/megaBytes)))
+	m.logger.Info("Setting memory ballast", zap.Uint32("MiBs", uint32(m.ballastSizeBytes/megaBytes)))
 
 	return nil
 }
 
-func (m *memoryBallast) Shutdown(_ context.Context) error {
+func (m *MemoryBallast) Shutdown(_ context.Context) error {
 	m.ballast = nil
 	return nil
 }
 
-func newMemoryBallast(cfg *Config, logger *zap.Logger, getTotalMem func() (uint64, error)) *memoryBallast {
-	return &memoryBallast{
+func newMemoryBallast(cfg *Config, logger *zap.Logger, getTotalMem func() (uint64, error)) *MemoryBallast {
+	return &MemoryBallast{
 		cfg:         cfg,
 		logger:      logger,
 		getTotalMem: getTotalMem,
 	}
 }
 
 // GetBallastSize returns the current ballast memory setting in bytes
-func GetBallastSize() uint64 {
-	return ballastSizeBytes
+func (m *MemoryBallast) GetBallastSize() uint64 {
+	return m.ballastSizeBytes
 }

processor/memorylimiter/factory.go

@@ -63,6 +63,7 @@ func createTracesProcessor(
 		nextConsumer,
 		ml.processTraces,
 		processorhelper.WithCapabilities(processorCapabilities),
+		processorhelper.WithStart(ml.start),
 		processorhelper.WithShutdown(ml.shutdown))
 }
 

processor/memorylimiter/memorylimiter.go

@@ -24,6 +24,7 @@ import (
 
 	"go.uber.org/zap"
 
+	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config/configtelemetry"
 	"go.opentelemetry.io/collector/extension/ballastextension"
 	"go.opentelemetry.io/collector/internal/iruntime"
@@ -89,9 +90,6 @@ const minGCIntervalWhenSoftLimited = 10 * time.Second
 
 // newMemoryLimiter returns a new memorylimiter processor.
 func newMemoryLimiter(logger *zap.Logger, cfg *Config) (*memoryLimiter, error) {
-	// Get ballast size in bytes from ballastextension
-	ballastSize := ballastextension.GetBallastSize()
-
 	if cfg.CheckInterval <= 0 {
 		return nil, errCheckIntervalOutOfRange
 	}
@@ -105,14 +103,13 @@ func newMemoryLimiter(logger *zap.Logger, cfg *Config) (*memoryLimiter, error) {
 	}
 
 	logger.Info("Memory limiter configured",
-		zap.Uint64("limit_mib", usageChecker.memAllocLimit),
-		zap.Uint64("spike_limit_mib", usageChecker.memSpikeLimit),
+		zap.Uint64("limit_mib", usageChecker.memAllocLimit/mibBytes),
+		zap.Uint64("spike_limit_mib", usageChecker.memSpikeLimit/mibBytes),
 		zap.Duration("check_interval", cfg.CheckInterval))
 
 	ml := &memoryLimiter{
 		usageChecker:   *usageChecker,
 		memCheckWait:   cfg.CheckInterval,
-		ballastSize:    ballastSize,
 		ticker:         time.NewTicker(cfg.CheckInterval),
 		readMemStatsFn: runtime.ReadMemStats,
 		logger:         logger,
@@ -122,8 +119,6 @@ func newMemoryLimiter(logger *zap.Logger, cfg *Config) (*memoryLimiter, error) {
 		}),
 	}
 
-	ml.startMonitoring()
-
 	return ml, nil
 }
 
@@ -138,12 +133,25 @@ func getMemUsageChecker(cfg *Config, logger *zap.Logger) (*memUsageChecker, erro
 		return nil, fmt.Errorf("failed to get total memory, use fixed memory settings (limit_mib): %w", err)
 	}
 	logger.Info("Using percentage memory limiter",
-		zap.Uint64("total_memory", totalMemory),
+		zap.Uint64("total_memory_mib", totalMemory/mibBytes),
 		zap.Uint32("limit_percentage", cfg.MemoryLimitPercentage),
 		zap.Uint32("spike_limit_percentage", cfg.MemorySpikePercentage))
 	return newPercentageMemUsageChecker(totalMemory, uint64(cfg.MemoryLimitPercentage), uint64(cfg.MemorySpikePercentage))
 }
 
+func (ml *memoryLimiter) start(_ context.Context, host component.Host) error {
+	extensions := host.GetExtensions()
+	for _, extension := range extensions {
+		if ext, ok := extension.(*ballastextension.MemoryBallast); ok {
+			ml.ballastSize = ext.GetBallastSize()
+			break
+		}
+	}
+
+	ml.startMonitoring()
+	return nil
+}
+
 func (ml *memoryLimiter) shutdown(context.Context) error {
 	ml.ticker.Stop()
 	return nil
@@ -245,7 +253,7 @@ func (ml *memoryLimiter) setForcingDrop(b bool) {
 }
 
 func memstatToZapField(ms *runtime.MemStats) zap.Field {
-	return zap.Uint64("cur_mem_mib", ms.Alloc/1024/1024)
+	return zap.Uint64("cur_mem_mib", ms.Alloc/mibBytes)
 }
 
 func (ml *memoryLimiter) doGCandReadMemStats() *runtime.MemStats {

processor/memorylimiter/memorylimiter_test.go

@@ -444,7 +444,7 @@ func TestBallastSizeMiB(t *testing.T) {
 			ballastExtCfg.SizeMiB = tt.ballastExtBallastSizeSetting
 			ballastExt, _ := ballastExtFactory.CreateExtension(ctx, extCreateSet, ballastExtCfg)
 			ballastExt.Start(ctx, nil)
-			assert.Equal(t, tt.expectResult, tt.expectedMemLimiterBallastSize*mibBytes == ballastextension.GetBallastSize())
+			assert.Equal(t, tt.expectResult, tt.expectedMemLimiterBallastSize*mibBytes == ballastExt.(*ballastextension.MemoryBallast).GetBallastSize())
 		})
 	}
 }