perf(api): bound reverse geocode requests

vehicle-data-platform/apps/api/internal/app/server.go

@@ -2,6 +2,7 @@ package app
 
 import (
 	"bytes"
+	"container/list"
 	"context"
 	"database/sql"
 	"encoding/json"
@@ -238,6 +239,112 @@ type mapReverseGeocodeResponse struct {
 	Adcode           string  `json:"adcode,omitempty"`
 }
 
+const (
+	reverseGeocodeCacheTTL        = time.Hour
+	reverseGeocodeCacheMaxEntries = 4096
+)
+
+type reverseGeocodeCacheEntry struct {
+	key       string
+	value     mapReverseGeocodeResponse
+	expiresAt time.Time
+}
+
+type reverseGeocodeKeyLock struct {
+	mu   sync.Mutex
+	refs int
+}
+
+type reverseGeocodeCache struct {
+	mu         sync.Mutex
+	entries    map[string]*list.Element
+	recency    *list.List
+	keyLocks   map[string]*reverseGeocodeKeyLock
+	maxEntries int
+	ttl        time.Duration
+	now        func() time.Time
+}
+
+func newReverseGeocodeCache(maxEntries int, ttl time.Duration) *reverseGeocodeCache {
+	return &reverseGeocodeCache{
+		entries:    make(map[string]*list.Element),
+		recency:    list.New(),
+		keyLocks:   make(map[string]*reverseGeocodeKeyLock),
+		maxEntries: maxEntries,
+		ttl:        ttl,
+		now:        time.Now,
+	}
+}
+
+func reverseGeocodeCacheKey(longitude, latitude float64) string {
+	return fmt.Sprintf("%.5f,%.5f", longitude, latitude)
+}
+
+func (cache *reverseGeocodeCache) get(key string) (mapReverseGeocodeResponse, bool) {
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+	element, ok := cache.entries[key]
+	if !ok {
+		return mapReverseGeocodeResponse{}, false
+	}
+	entry := element.Value.(*reverseGeocodeCacheEntry)
+	if !entry.expiresAt.After(cache.now()) {
+		cache.remove(element)
+		return mapReverseGeocodeResponse{}, false
+	}
+	cache.recency.MoveToFront(element)
+	return entry.value, true
+}
+
+func (cache *reverseGeocodeCache) put(key string, value mapReverseGeocodeResponse) {
+	if cache.maxEntries <= 0 || cache.ttl <= 0 {
+		return
+	}
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+	if element, ok := cache.entries[key]; ok {
+		entry := element.Value.(*reverseGeocodeCacheEntry)
+		entry.value = value
+		entry.expiresAt = cache.now().Add(cache.ttl)
+		cache.recency.MoveToFront(element)
+		return
+	}
+	for len(cache.entries) >= cache.maxEntries {
+		cache.remove(cache.recency.Back())
+	}
+	entry := &reverseGeocodeCacheEntry{key: key, value: value, expiresAt: cache.now().Add(cache.ttl)}
+	cache.entries[key] = cache.recency.PushFront(entry)
+}
+
+func (cache *reverseGeocodeCache) remove(element *list.Element) {
+	if element == nil {
+		return
+	}
+	delete(cache.entries, element.Value.(*reverseGeocodeCacheEntry).key)
+	cache.recency.Remove(element)
+}
+
+func (cache *reverseGeocodeCache) lockKey(key string) func() {
+	cache.mu.Lock()
+	keyLock := cache.keyLocks[key]
+	if keyLock == nil {
+		keyLock = &reverseGeocodeKeyLock{}
+		cache.keyLocks[key] = keyLock
+	}
+	keyLock.refs++
+	cache.mu.Unlock()
+	keyLock.mu.Lock()
+	return func() {
+		keyLock.mu.Unlock()
+		cache.mu.Lock()
+		keyLock.refs--
+		if keyLock.refs == 0 {
+			delete(cache.keyLocks, key)
+		}
+		cache.mu.Unlock()
+	}
+}
+
 func withAMapReverseGeocodeAPI(next http.Handler, cfg config.Config, upstream string, client *http.Client) http.Handler {
 	apiKey := strings.TrimSpace(cfg.AMapAPIKey)
 	if client == nil {
@@ -247,6 +354,7 @@ func withAMapReverseGeocodeAPI(next http.Handler, cfg config.Config, upstream st
 	if upstream == "" {
 		upstream = "https://restapi.amap.com"
 	}
+	cache := newReverseGeocodeCache(reverseGeocodeCacheMaxEntries, reverseGeocodeCacheTTL)
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.URL.Path != "/api/map/reverse-geocode" {
 			next.ServeHTTP(w, r)
@@ -265,6 +373,17 @@ func withAMapReverseGeocodeAPI(next http.Handler, cfg config.Config, upstream st
 			httpx.WriteError(w, http.StatusBadRequest, "BAD_COORDINATE", "经纬度参数无效", err.Error(), requestTraceID(r))
 			return
 		}
+		cacheKey := reverseGeocodeCacheKey(longitude, latitude)
+		unlock := cache.lockKey(cacheKey)
+		defer unlock()
+		if cached, ok := cache.get(cacheKey); ok {
+			cached.Longitude = longitude
+			cached.Latitude = latitude
+			w.Header().Set("X-Reverse-Geocode-Cache", "HIT")
+			httpx.WriteOK(w, requestTraceID(r), cached)
+			return
+		}
+		w.Header().Set("X-Reverse-Geocode-Cache", "MISS")
 		target, err := url.Parse(upstream + "/v3/geocode/regeo")
 		if err != nil {
 			httpx.WriteError(w, http.StatusBadGateway, "AMAP_REVERSE_GEOCODE_URL_INVALID", "高德逆地理编码地址无效", err.Error(), requestTraceID(r))
@@ -331,6 +450,7 @@ func withAMapReverseGeocodeAPI(next http.Handler, cfg config.Config, upstream st
 			Township:         amapJSONText(body.Regeocode.AddressComponent.Township),
 			Adcode:           amapJSONText(body.Regeocode.AddressComponent.Adcode),
 		}
+		cache.put(cacheKey, result)
 		httpx.WriteOK(w, requestTraceID(r), result)
 	})
 }