loki/pkg/querier/querier.go

package querier

import (
	"context"
	"flag"
	"time"

	cortex_client "github.com/weaveworks/cortex/pkg/ingester/client"
	"github.com/weaveworks/cortex/pkg/ring"
	"google.golang.org/grpc/health/grpc_health_v1"

	"github.com/grafana/logish/pkg/ingester/client"
	"github.com/grafana/logish/pkg/logproto"
)

type Config struct {
	RemoteTimeout time.Duration
	ClientConfig  client.Config
}

func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
	f.DurationVar(&cfg.RemoteTimeout, "querier.remote-timeout", 10*time.Second, "")
	cfg.ClientConfig.RegisterFlags(f)
}

type Querier struct {
	cfg  Config
	ring ring.ReadRing
	pool *cortex_client.IngesterPool
}

func New(cfg Config, ring ring.ReadRing) (*Querier, error) {
	factory := func(addr string) (grpc_health_v1.HealthClient, error) {
		return client.New(cfg.ClientConfig, addr)
	}

	return &Querier{
		cfg:  cfg,
		ring: ring,
		pool: cortex_client.NewIngesterPool(factory, cfg.RemoteTimeout),
	}, nil
}

func (q *Querier) Query(req *logproto.QueryRequest, queryServer logproto.Querier_QueryServer) error {

	return q.forAllIngesters(func(client logproto.QuerierClient) error {
		_, err := client.Query(queryServer.Context(), req)
		if err != nil {
			return err
		}

		// TODO: a heap to in-order merge and dedupe results

		return nil
	})
}

// forAllIngesters runs f, in parallel, for all ingesters
// TODO taken from Cortex, see if we can refactor out an usable interface.
func (q *Querier) forAllIngesters(f func(logproto.QuerierClient) error) error {
	replicationSet, err := q.ring.GetAll()
	if err != nil {
		return err
	}

	errs := make(chan error)
	for _, ingester := range replicationSet.Ingesters {
		go func(ingester *ring.IngesterDesc) {
			client, err := q.pool.GetClientFor(ingester.Addr)
			if err != nil {
				errs <- err
				return
			}

			errs <- f(client.(logproto.QuerierClient))
		}(ingester)
	}

	var lastErr error
	numErrs := 0
	for range replicationSet.Ingesters {
		select {
		case err := <-errs:
			if err != nil {
				lastErr = err
				numErrs++
			}
		}
	}

	if numErrs > replicationSet.MaxErrors {
		return lastErr
	}

	return nil
}

// Check implements the grpc healthcheck
func (*Querier) Check(ctx context.Context, req *grpc_health_v1.HealthCheckRequest) (*grpc_health_v1.HealthCheckResponse, error) {
	return &grpc_health_v1.HealthCheckResponse{Status: grpc_health_v1.HealthCheckResponse_SERVING}, nil
}