Pool query objects

session.go

@@ -68,6 +68,8 @@ type Session struct {
 
 	closeMu  sync.RWMutex
 	isClosed bool
+
+	queryPool *sync.Pool
 }
 
 func addrsToHosts(addrs []string, defaultPort int) ([]*HostInfo, error) {
@@ -98,11 +100,12 @@ func NewSession(cfg ClusterConfig) (*Session, error) {
 	}
 
 	s := &Session{
-		cons:     cfg.Consistency,
-		prefetch: 0.25,
-		cfg:      cfg,
-		pageSize: cfg.PageSize,
-		stmtsLRU: &preparedLRU{lru: lru.New(cfg.MaxPreparedStmts)},
+		cons:      cfg.Consistency,
+		prefetch:  0.25,
+		cfg:       cfg,
+		pageSize:  cfg.PageSize,
+		stmtsLRU:  &preparedLRU{lru: lru.New(cfg.MaxPreparedStmts)},
+		queryPool: &sync.Pool{New: func() interface{} { return new(Query) }},
 	}
 
 	connCfg, err := connConfig(s)
@@ -259,11 +262,17 @@ func (s *Session) SetTrace(trace Tracer) {
 // if it has not previously been executed.
 func (s *Session) Query(stmt string, values ...interface{}) *Query {
 	s.mu.RLock()
-	qry := &Query{stmt: stmt, values: values, cons: s.cons,
-		session: s, pageSize: s.pageSize, trace: s.trace,
-		prefetch: s.prefetch, rt: s.cfg.RetryPolicy, serialCons: s.cfg.SerialConsistency,
-		defaultTimestamp: s.cfg.DefaultTimestamp,
-	}
+	qry := s.queryPool.Get().(*Query)
+	qry.stmt = stmt
+	qry.values = values
+	qry.cons = s.cons
+	qry.session = s
+	qry.pageSize = s.pageSize
+	qry.trace = s.trace
+	qry.prefetch = s.prefetch
+	qry.rt = s.cfg.RetryPolicy
+	qry.serialCons = s.cfg.SerialConsistency
+	qry.defaultTimestamp = s.cfg.DefaultTimestamp
 	s.mu.RUnlock()
 	return qry
 }
@@ -947,6 +956,43 @@ func (q *Query) MapScanCAS(dest map[string]interface{}) (applied bool, err error
 	return applied, iter.Close()
 }
 
+// Release releases a query back into a pool of queries. Released Queries
+// cannot be reused.
+//
+// Example:
+// 		qry := session.Query("SELECT * FROM my_table")
+// 		qry.Exec()
+// 		qry.Release()
+func (q *Query) Release() {
+	if q == nil || q.session == nil || q.session.queryPool == nil {
+		return
+	}
+	pool := q.session.queryPool
+	pool.Put(q)
+}
+
+// reset zeroes out all fields of a query so that it can be safely pooled.
+func (q *Query) reset() {
+	q.stmt = ""
+	q.values = nil
+	q.cons = 0
+	q.pageSize = 0
+	q.routingKey = nil
+	q.routingKeyBuffer = nil
+	q.pageState = nil
+	q.prefetch = 0
+	q.trace = nil
+	q.session = nil
+	q.rt = nil
+	q.binding = nil
+	q.attempts = 0
+	q.totalLatency = 0
+	q.serialCons = 0
+	q.defaultTimestamp = false
+	q.disableSkipMetadata = false
+	q.disableAutoPage = false
+}
+
 // Iter represents an iterator that can be used to iterate over all rows that
 // were returned by a query. The iterator might send additional queries to the
 // database during the iteration if paging was enabled.