query_executor.go

package gocql

import (
	"time"
)

type ExecutableQuery interface {
	execute(conn *Conn) *Iter
	attempt(time.Duration)
	retryPolicy() RetryPolicy
	GetRoutingKey() ([]byte, error)
	RetryableQuery
}

type queryExecutor struct {
	pool   *policyConnPool
	policy HostSelectionPolicy
}

func (q *queryExecutor) executeQuery(qry ExecutableQuery) (*Iter, error) {
	rt := qry.retryPolicy()
	hostIter := q.policy.Pick(qry)

	var iter *Iter
	for hostResponse := hostIter(); hostResponse != nil; hostResponse = hostIter() {
		host := hostResponse.Info()
		if host == nil || !host.IsUp() {
			continue
		}

		pool, ok := q.pool.getPool(host)
		if !ok {
			continue
		}

		conn := pool.Pick()
		if conn == nil {
			continue
		}

		start := time.Now()
		iter = qry.execute(conn)

		qry.attempt(time.Since(start))

		// Update host
		hostResponse.Mark(iter.err)

		// Exit for loop if the query was successful
		if iter.err == nil {
			return iter, nil
		}

		if rt == nil || !rt.Attempt(qry) {
			// What do here? Should we just return an error here?
			break
		}
	}

	if iter == nil {
		return nil, ErrNoConnections
	}

	return iter, nil
}