forked from cortexproject/cortex
/
worker_frontend_manager.go
172 lines (145 loc) · 4.37 KB
/
worker_frontend_manager.go
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package frontend
import (
"context"
"fmt"
"io"
"net/http"
"sync"
"time"
"github.com/go-kit/kit/log"
"github.com/go-kit/kit/log/level"
"github.com/weaveworks/common/httpgrpc"
"github.com/weaveworks/common/httpgrpc/server"
"go.uber.org/atomic"
"github.com/cortexproject/cortex/pkg/util"
"github.com/cortexproject/cortex/pkg/util/grpcclient"
)
var (
backoffConfig = util.BackoffConfig{
MinBackoff: 50 * time.Millisecond,
MaxBackoff: 1 * time.Second,
}
)
type frontendManager struct {
server *server.Server
connection io.Closer
client FrontendClient
clientCfg grpcclient.ConfigWithTLS
querierID string
log log.Logger
workerCancels []context.CancelFunc
serverCtx context.Context
wg sync.WaitGroup
currentProcessors *atomic.Int32
}
func newFrontendManager(serverCtx context.Context, log log.Logger, server *server.Server, connection io.Closer, client FrontendClient, clientCfg grpcclient.ConfigWithTLS, querierID string) *frontendManager {
f := &frontendManager{
log: log,
connection: connection,
client: client,
clientCfg: clientCfg,
server: server,
serverCtx: serverCtx,
currentProcessors: atomic.NewInt32(0),
querierID: querierID,
}
return f
}
func (f *frontendManager) stop() {
f.concurrentRequests(0)
f.wg.Wait()
_ = f.connection.Close()
}
func (f *frontendManager) concurrentRequests(n int) {
if n < 0 {
n = 0
}
for len(f.workerCancels) < n {
ctx, cancel := context.WithCancel(f.serverCtx)
f.workerCancels = append(f.workerCancels, cancel)
go f.runOne(ctx)
}
for len(f.workerCancels) > n {
var cancel context.CancelFunc
cancel, f.workerCancels = f.workerCancels[0], f.workerCancels[1:]
cancel()
}
}
// runOne loops, trying to establish a stream to the frontend to begin
// request processing.
func (f *frontendManager) runOne(ctx context.Context) {
f.wg.Add(1)
defer f.wg.Done()
f.currentProcessors.Inc()
defer f.currentProcessors.Dec()
backoff := util.NewBackoff(ctx, backoffConfig)
for backoff.Ongoing() {
c, err := f.client.Process(ctx)
if err != nil {
level.Error(f.log).Log("msg", "error contacting frontend", "err", err)
backoff.Wait()
continue
}
if err := f.process(c); err != nil {
level.Error(f.log).Log("msg", "error processing requests", "err", err)
backoff.Wait()
continue
}
backoff.Reset()
}
}
// process loops processing requests on an established stream.
func (f *frontendManager) process(c Frontend_ProcessClient) error {
// Build a child context so we can cancel a query when the stream is closed.
ctx, cancel := context.WithCancel(c.Context())
defer cancel()
for {
request, err := c.Recv()
if err != nil {
return err
}
switch request.Type {
case HTTP_REQUEST:
// Handle the request on a "background" goroutine, so we go back to
// blocking on c.Recv(). This allows us to detect the stream closing
// and cancel the query. We don't actually handle queries in parallel
// here, as we're running in lock step with the server - each Recv is
// paired with a Send.
go f.runRequest(ctx, request.HttpRequest, func(response *httpgrpc.HTTPResponse) error {
return c.Send(&ClientToFrontend{HttpResponse: response})
})
case GET_ID:
err := c.Send(&ClientToFrontend{ClientID: f.querierID})
if err != nil {
return err
}
default:
return fmt.Errorf("unknown request type: %v", request.Type)
}
}
}
func (f *frontendManager) runRequest(ctx context.Context, request *httpgrpc.HTTPRequest, sendHTTPResponse func(response *httpgrpc.HTTPResponse) error) {
response, err := f.server.Handle(ctx, request)
if err != nil {
var ok bool
response, ok = httpgrpc.HTTPResponseFromError(err)
if !ok {
response = &httpgrpc.HTTPResponse{
Code: http.StatusInternalServerError,
Body: []byte(err.Error()),
}
}
}
// Ensure responses that are too big are not retried.
if len(response.Body) >= f.clientCfg.GRPC.MaxSendMsgSize {
errMsg := fmt.Sprintf("response larger than the max (%d vs %d)", len(response.Body), f.clientCfg.GRPC.MaxSendMsgSize)
response = &httpgrpc.HTTPResponse{
Code: http.StatusRequestEntityTooLarge,
Body: []byte(errMsg),
}
level.Error(f.log).Log("msg", "error processing query", "err", errMsg)
}
if err := sendHTTPResponse(response); err != nil {
level.Error(f.log).Log("msg", "error processing requests", "err", err)
}
}