yonlu
8fc075c24a
- backend/explore/ratelimiter.go - backend/explore/cache.go - backend/database/sql/schemas/explore_cache.sql - backend/database/database.go
124 lines
2.7 KiB
Go
124 lines
2.7 KiB
Go
package explore
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import (
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"fmt"
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"log/slog"
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"time"
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"yellowjacket/backend/database"
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)
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// Cache provides a SQLite-backed response cache with TTL expiry.
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// It stores raw JSON API responses keyed by URL and supports
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// optional MBID columns for future autotagging lookups.
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//
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// All operations use the shared database.DB connection and its
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// single-writer constraint (SetMaxOpenConns(1)).
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type Cache struct {
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db *database.DB
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logger *slog.Logger
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}
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// NewCache returns a cache backed by the given database connection.
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func NewCache(db *database.DB, logger *slog.Logger) *Cache {
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return &Cache{db: db, logger: logger}
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}
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// Get returns the cached response for the given URL key if it
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// exists and has not expired. Returns (data, true) on a cache hit
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// and (nil, false) on a miss or expired entry.
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func (c *Cache) Get(key string) ([]byte, bool) {
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rows, err := c.db.QueryContext(
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"SELECT response FROM explore_cache WHERE url_key = ? AND expires_at > datetime('now')",
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key,
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)
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if err != nil {
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c.logger.Warn("explore cache get error",
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"key", key,
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"err", err,
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)
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return nil, false
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}
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defer func() { _ = rows.Close() }()
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if !rows.Next() {
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c.logger.Debug("explore cache miss", "key", key)
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return nil, false
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}
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var response string
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if err := rows.Scan(&response); err != nil {
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c.logger.Warn("explore cache scan error",
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"key", key,
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"err", err,
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)
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return nil, false
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}
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c.logger.Debug("explore cache hit", "key", key)
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return []byte(response), true
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}
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// Set stores a response in the cache with the given TTL. If mbid
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// and entityType are non-empty they are stored for future
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// autotagging lookups; otherwise they are stored as NULL.
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func (c *Cache) Set(
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key string,
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data []byte,
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ttl time.Duration,
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mbid string,
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entityType string,
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) {
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seconds := int(ttl.Seconds())
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if seconds < 1 {
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seconds = 1
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}
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expr := fmt.Sprintf("datetime('now', '+%d seconds')", seconds)
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query := fmt.Sprintf(
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`INSERT OR REPLACE INTO explore_cache
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(url_key, response, mbid, entity_type, expires_at)
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VALUES (?, ?, NULLIF(?, ''), NULLIF(?, ''), %s)`,
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expr,
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)
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if _, err := c.db.ExecContext(query, key, string(data), mbid, entityType); err != nil {
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c.logger.Warn("explore cache set error",
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"key", key,
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"err", err,
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)
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} else {
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c.logger.Debug("explore cache set",
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"key", key,
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"ttl", ttl,
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"mbid", mbid,
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"entityType", entityType,
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)
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}
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}
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// Evict removes all expired entries from the cache.
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func (c *Cache) Evict() {
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result, err := c.db.ExecContext(
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"DELETE FROM explore_cache WHERE expires_at < datetime('now')",
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)
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if err != nil {
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c.logger.Warn("explore cache evict error", "err", err)
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return
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}
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if n, _ := result.RowsAffected(); n > 0 {
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c.logger.Info("explore cache evicted expired entries",
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"count", n,
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)
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}
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}
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