routewatch/internal/streamer/streamer.go
sneak e14c89e4f1 Implement backpressure mechanism to prevent memory exhaustion
- Add semaphore to limit concurrent message handlers to 100
- Drop messages when at capacity instead of creating unbounded goroutines
- Track and log dropped messages (every 1000 drops)
- Remove nested goroutine spawning in handler loop
- Add metrics for dropped messages and active handlers

This prevents the memory usage from growing unboundedly when the
database can't keep up with the incoming BGP message stream. Messages
are dropped gracefully rather than causing OOM errors.
2025-07-27 22:51:02 +02:00

323 lines
8.4 KiB
Go

// Package streamer implements an HTTP client that connects to the RIPE RIS Live streaming API,
// parses BGP UPDATE messages from the JSON stream, and dispatches them to registered handlers.
package streamer
import (
"bufio"
"context"
"encoding/json"
"fmt"
"log/slog"
"net/http"
"os"
"sync"
"sync/atomic"
"time"
"git.eeqj.de/sneak/routewatch/internal/metrics"
"git.eeqj.de/sneak/routewatch/internal/ristypes"
)
const (
risLiveURL = "https://ris-live.ripe.net/v1/stream/?format=json"
metricsWindowSize = 60 // seconds for rolling average
metricsUpdateRate = time.Second
metricsLogInterval = 10 * time.Second
bytesPerKB = 1024
bytesPerMB = 1024 * 1024
maxConcurrentHandlers = 100 // Maximum number of concurrent message handlers
)
// MessageHandler is an interface for handling RIS messages
type MessageHandler interface {
// WantsMessage returns true if this handler wants to process messages of the given type
WantsMessage(messageType string) bool
// HandleMessage processes a RIS message
HandleMessage(msg *ristypes.RISMessage)
}
// RawMessageHandler is a callback for handling raw JSON lines from the stream
type RawMessageHandler func(line string)
// Streamer handles streaming BGP updates from RIS Live
type Streamer struct {
logger *slog.Logger
client *http.Client
handlers []MessageHandler
rawHandler RawMessageHandler
mu sync.RWMutex
cancel context.CancelFunc
running bool
metrics *metrics.Tracker
semaphore chan struct{} // Limits concurrent message processing
droppedMessages uint64 // Atomic counter for dropped messages
}
// New creates a new RIS streamer
func New(logger *slog.Logger, metrics *metrics.Tracker) *Streamer {
return &Streamer{
logger: logger,
client: &http.Client{
Timeout: 0, // No timeout for streaming
},
handlers: make([]MessageHandler, 0),
metrics: metrics,
semaphore: make(chan struct{}, maxConcurrentHandlers),
}
}
// RegisterHandler adds a callback for message processing
func (s *Streamer) RegisterHandler(handler MessageHandler) {
s.mu.Lock()
defer s.mu.Unlock()
s.handlers = append(s.handlers, handler)
}
// RegisterRawHandler sets a callback for raw message lines
func (s *Streamer) RegisterRawHandler(handler RawMessageHandler) {
s.mu.Lock()
defer s.mu.Unlock()
s.rawHandler = handler
}
// Start begins streaming in a goroutine
func (s *Streamer) Start() error {
s.mu.Lock()
defer s.mu.Unlock()
if s.running {
return fmt.Errorf("streamer already running")
}
ctx, cancel := context.WithCancel(context.Background())
s.cancel = cancel
s.running = true
go func() {
if err := s.stream(ctx); err != nil {
s.logger.Error("Streaming error", "error", err)
}
s.mu.Lock()
s.running = false
s.mu.Unlock()
}()
return nil
}
// Stop halts the streaming
func (s *Streamer) Stop() {
s.mu.Lock()
if s.cancel != nil {
s.cancel()
}
s.mu.Unlock()
s.metrics.SetConnected(false)
}
// IsRunning returns whether the streamer is currently active
func (s *Streamer) IsRunning() bool {
s.mu.RLock()
defer s.mu.RUnlock()
return s.running
}
// GetMetrics returns current streaming metrics
func (s *Streamer) GetMetrics() metrics.StreamMetrics {
return s.metrics.GetStreamMetrics()
}
// GetDroppedMessages returns the total number of dropped messages
func (s *Streamer) GetDroppedMessages() uint64 {
return atomic.LoadUint64(&s.droppedMessages)
}
// logMetrics logs the current streaming statistics
func (s *Streamer) logMetrics() {
metrics := s.metrics.GetStreamMetrics()
uptime := time.Since(metrics.ConnectedSince)
const bitsPerMegabit = 1000000
droppedMessages := atomic.LoadUint64(&s.droppedMessages)
s.logger.Info("Stream statistics",
"uptime", uptime,
"total_messages", metrics.TotalMessages,
"total_bytes", metrics.TotalBytes,
"total_mb", fmt.Sprintf("%.2f", float64(metrics.TotalBytes)/bytesPerMB),
"messages_per_sec", fmt.Sprintf("%.2f", metrics.MessagesPerSec),
"bits_per_sec", fmt.Sprintf("%.0f", metrics.BitsPerSec),
"mbps", fmt.Sprintf("%.2f", metrics.BitsPerSec/bitsPerMegabit),
"dropped_messages", droppedMessages,
"active_handlers", len(s.semaphore),
)
}
// updateMetrics updates the metrics counters and rates
func (s *Streamer) updateMetrics(messageBytes int) {
s.metrics.RecordMessage(int64(messageBytes))
}
func (s *Streamer) stream(ctx context.Context) error {
req, err := http.NewRequestWithContext(ctx, "GET", risLiveURL, nil)
if err != nil {
return fmt.Errorf("failed to create request: %w", err)
}
resp, err := s.client.Do(req)
if err != nil {
return fmt.Errorf("failed to connect to RIS Live: %w", err)
}
defer func() {
if err := resp.Body.Close(); err != nil {
s.logger.Error("Failed to close response body", "error", err)
}
}()
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("unexpected status code: %d", resp.StatusCode)
}
s.logger.Info("Connected to RIS Live stream")
s.metrics.SetConnected(true)
// Start metrics logging goroutine
metricsTicker := time.NewTicker(metricsLogInterval)
defer metricsTicker.Stop()
go func() {
for {
select {
case <-metricsTicker.C:
s.logMetrics()
case <-ctx.Done():
return
}
}
}()
scanner := bufio.NewScanner(resp.Body)
for scanner.Scan() {
select {
case <-ctx.Done():
s.logger.Info("Stream stopped by context")
return ctx.Err()
default:
}
line := scanner.Bytes()
if len(line) == 0 {
continue
}
// Update metrics with message size
s.updateMetrics(len(line))
// Call raw handler if registered
s.mu.RLock()
rawHandler := s.rawHandler
s.mu.RUnlock()
if rawHandler != nil {
// Call raw handler synchronously to preserve order
rawHandler(string(line))
}
// Get current handlers
s.mu.RLock()
handlers := make([]MessageHandler, len(s.handlers))
copy(handlers, s.handlers)
s.mu.RUnlock()
// Try to acquire semaphore, drop message if at capacity
select {
case s.semaphore <- struct{}{}:
// Successfully acquired semaphore, process message
go func(rawLine []byte, messageHandlers []MessageHandler) {
defer func() { <-s.semaphore }() // Release semaphore when done
// Parse the outer wrapper first
var wrapper ristypes.RISLiveMessage
if err := json.Unmarshal(rawLine, &wrapper); err != nil {
// Output the raw line and panic on parse failure
fmt.Fprintf(os.Stderr, "Failed to parse JSON: %v\n", err)
fmt.Fprintf(os.Stderr, "Raw line: %s\n", string(rawLine))
panic(fmt.Sprintf("JSON parse error: %v", err))
}
// Check if it's a ris_message wrapper
if wrapper.Type != "ris_message" {
s.logger.Error("Unexpected wrapper type",
"type", wrapper.Type,
"line", string(rawLine),
)
return
}
// Get the actual message
msg := wrapper.Data
// Parse the timestamp
msg.ParsedTimestamp = time.Unix(int64(msg.Timestamp), 0).UTC()
// Process based on message type
switch msg.Type {
case "UPDATE":
// Process BGP UPDATE messages
// Will be handled by registered handlers
case "RIS_PEER_STATE":
// RIS peer state messages - silently ignore
case "KEEPALIVE":
// BGP keepalive messages - silently process
case "OPEN":
// BGP open messages
s.logger.Info("BGP session opened",
"peer", msg.Peer,
"peer_asn", msg.PeerASN,
)
case "NOTIFICATION":
// BGP notification messages (errors)
s.logger.Warn("BGP notification",
"peer", msg.Peer,
"peer_asn", msg.PeerASN,
)
case "STATE":
// Peer state changes - silently ignore
default:
fmt.Fprintf(
os.Stderr,
"UNKNOWN MESSAGE TYPE: %s\nRAW MESSAGE: %s\n",
msg.Type,
string(rawLine),
)
panic(fmt.Sprintf("Unknown RIS message type: %s", msg.Type))
}
// Call handlers synchronously within this goroutine
// This prevents unbounded goroutine growth at the handler level
for _, handler := range messageHandlers {
if handler.WantsMessage(msg.Type) {
handler.HandleMessage(&msg)
}
}
}(append([]byte(nil), line...), handlers) // Copy the line to avoid data races
default:
// Semaphore is full, drop the message
dropped := atomic.AddUint64(&s.droppedMessages, 1)
if dropped%1000 == 0 { // Log every 1000 dropped messages
s.logger.Warn("Dropping messages due to overload", "total_dropped", dropped, "max_handlers", maxConcurrentHandlers)
}
}
}
if err := scanner.Err(); err != nil {
return fmt.Errorf("scanner error: %w", err)
}
return nil
}