v0.9.0 restructure for flow architecture, dirty

src/internal/flow/ratelimiter.go

@@ -0,0 +1,115 @@
+// FILE: src/internal/flow/rate.go
+package flow
+
+import (
+	"strings"
+	"sync/atomic"
+
+	"logwisp/src/internal/config"
+	"logwisp/src/internal/core"
+	"logwisp/src/internal/tokenbucket"
+
+	"github.com/lixenwraith/log"
+)
+
+// RateLimiter enforces rate limits on log entries flowing through a pipeline.
+type RateLimiter struct {
+	bucket *tokenbucket.TokenBucket
+	policy config.RateLimitPolicy
+	logger *log.Logger
+
+	// Statistics
+	maxEntrySizeBytes  int64
+	droppedBySizeCount atomic.Uint64
+	droppedCount       atomic.Uint64
+}
+
+// NewRateLimiter creates a new pipeline-level rate limiter from configuration.
+func NewRateLimiter(cfg config.RateLimitConfig, logger *log.Logger) (*RateLimiter, error) {
+	if cfg.Rate <= 0 {
+		return nil, nil // No rate limit
+	}
+
+	burst := cfg.Burst
+	if burst <= 0 {
+		burst = cfg.Rate // Default burst to rate
+	}
+
+	var policy config.RateLimitPolicy
+	switch strings.ToLower(cfg.Policy) {
+	case "drop":
+		policy = config.PolicyDrop
+	default:
+		policy = config.PolicyPass
+	}
+
+	l := &RateLimiter{
+		bucket:            tokenbucket.New(burst, cfg.Rate),
+		policy:            policy,
+		logger:            logger,
+		maxEntrySizeBytes: cfg.MaxEntrySizeBytes,
+	}
+
+	return l, nil
+}
+
+// Allow checks if a log entry is permitted to pass based on the rate limit.
+func (l *RateLimiter) Allow(entry core.LogEntry) bool {
+	if l == nil || l.policy == config.PolicyPass {
+		return true
+	}
+
+	// Check size limit first
+	if l.maxEntrySizeBytes > 0 && entry.RawSize > l.maxEntrySizeBytes {
+		l.droppedBySizeCount.Add(1)
+		return false
+	}
+
+	// Check rate limit if configured
+	if l.bucket != nil {
+		if l.bucket.Allow() {
+			return true
+		}
+		// Not enough tokens, drop the entry
+		l.droppedCount.Add(1)
+		return false
+	}
+
+	// No rate limit configured, size check passed
+	return true
+}
+
+// GetStats returns statistics for the rate limiter.
+func (l *RateLimiter) GetStats() map[string]any {
+	if l == nil {
+		return map[string]any{
+			"enabled": false,
+		}
+	}
+
+	stats := map[string]any{
+		"enabled":               true,
+		"dropped_total":         l.droppedCount.Load(),
+		"dropped_by_size_total": l.droppedBySizeCount.Load(),
+		"policy":                policyString(l.policy),
+		"max_entry_size_bytes":  l.maxEntrySizeBytes,
+	}
+
+	if l.bucket != nil {
+		stats["tokens"] = l.bucket.Tokens()
+	}
+
+	return stats
+}
+
+// policyString returns the string representation of a rate limit policy.
+func policyString(p config.RateLimitPolicy) string {
+	switch p {
+	case config.PolicyDrop:
+		return "drop"
+	case config.PolicyPass:
+		return "pass"
+	default:
+		return "unknown"
+	}
+}