Initial commit: Open sourcing all of the Maple Open Technologies code.

cloud/maplefile-backend/pkg/cache/cassandra.go

@@ -0,0 +1,109 @@
+package cache
+
+import (
+	"context"
+	"time"
+
+	"github.com/gocql/gocql"
+	"go.uber.org/zap"
+)
+
+// CassandraCacher defines the interface for Cassandra cache operations
+type CassandraCacher interface {
+	Shutdown(ctx context.Context)
+	Get(ctx context.Context, key string) ([]byte, error)
+	Set(ctx context.Context, key string, val []byte) error
+	SetWithExpiry(ctx context.Context, key string, val []byte, expiry time.Duration) error
+	Delete(ctx context.Context, key string) error
+	PurgeExpired(ctx context.Context) error
+}
+
+type cassandraCache struct {
+	session *gocql.Session
+	logger  *zap.Logger
+}
+
+// NewCassandraCache creates a new Cassandra cache instance
+func NewCassandraCache(session *gocql.Session, logger *zap.Logger) CassandraCacher {
+	logger = logger.Named("cassandra-cache")
+	logger.Info("✓ Cassandra cache layer initialized")
+	return &cassandraCache{
+		session: session,
+		logger:  logger,
+	}
+}
+
+func (c *cassandraCache) Shutdown(ctx context.Context) {
+	c.logger.Info("shutting down Cassandra cache")
+	// Note: Don't close the session here as it's managed by the database layer
+}
+
+func (c *cassandraCache) Get(ctx context.Context, key string) ([]byte, error) {
+	var value []byte
+	var expiresAt time.Time
+
+	query := `SELECT value, expires_at FROM cache WHERE key = ?`
+	err := c.session.Query(query, key).WithContext(ctx).Consistency(gocql.LocalQuorum).Scan(&value, &expiresAt)
+
+	if err == gocql.ErrNotFound {
+		// Key doesn't exist - this is not an error
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	// Check if expired in application code
+	if time.Now().After(expiresAt) {
+		// Entry is expired, delete it and return nil
+		_ = c.Delete(ctx, key) // Clean up expired entry
+		return nil, nil
+	}
+
+	return value, nil
+}
+
+func (c *cassandraCache) Set(ctx context.Context, key string, val []byte) error {
+	expiresAt := time.Now().Add(24 * time.Hour) // Default 24 hour expiry
+	query := `INSERT INTO cache (key, expires_at, value) VALUES (?, ?, ?)`
+	return c.session.Query(query, key, expiresAt, val).WithContext(ctx).Consistency(gocql.LocalQuorum).Exec()
+}
+
+func (c *cassandraCache) SetWithExpiry(ctx context.Context, key string, val []byte, expiry time.Duration) error {
+	expiresAt := time.Now().Add(expiry)
+	query := `INSERT INTO cache (key, expires_at, value) VALUES (?, ?, ?)`
+	return c.session.Query(query, key, expiresAt, val).WithContext(ctx).Consistency(gocql.LocalQuorum).Exec()
+}
+
+func (c *cassandraCache) Delete(ctx context.Context, key string) error {
+	query := `DELETE FROM cache WHERE key = ?`
+	return c.session.Query(query, key).WithContext(ctx).Consistency(gocql.LocalQuorum).Exec()
+}
+
+func (c *cassandraCache) PurgeExpired(ctx context.Context) error {
+	now := time.Now()
+
+	// Thanks to the index on expires_at, this query is efficient
+	iter := c.session.Query(`SELECT key FROM cache WHERE expires_at < ? ALLOW FILTERING`, now).WithContext(ctx).Iter()
+
+	var expiredKeys []string
+	var key string
+	for iter.Scan(&key) {
+		expiredKeys = append(expiredKeys, key)
+	}
+
+	if err := iter.Close(); err != nil {
+		return err
+	}
+
+	// Delete expired keys in batch
+	if len(expiredKeys) > 0 {
+		batch := c.session.NewBatch(gocql.LoggedBatch).WithContext(ctx)
+		for _, expiredKey := range expiredKeys {
+			batch.Query(`DELETE FROM cache WHERE key = ?`, expiredKey)
+		}
+		return c.session.ExecuteBatch(batch)
+	}
+
+	return nil
+}