From b3d4ff7ee2321720c3e13598d8fcb38338462f22 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Mon, 10 Aug 2020 13:17:12 +0300
Subject: [PATCH] app/vmstorage: improve error logging when the request times
 out

---
 app/vmstorage/transport/server.go | 11 +++++++++++
 lib/storage/search.go             |  2 +-
 lib/storage/storage.go            |  3 ++-
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/app/vmstorage/transport/server.go b/app/vmstorage/transport/server.go
index 8df77c557..ae2497b51 100644
--- a/app/vmstorage/transport/server.go
+++ b/app/vmstorage/transport/server.go
@@ -1,6 +1,7 @@
 package transport
 
 import (
+	"errors"
 	"flag"
 	"fmt"
 	"io"
@@ -381,6 +382,9 @@ func (s *Server) processVMSelectConn(bc *handshake.BufferedConn) error {
 				// Remote client gracefully closed the connection.
 				return nil
 			}
+			if errors.Is(err, storage.ErrDeadlineExceeded) {
+				return fmt.Errorf("cannot process vmselect request in %d seconds: %w", ctx.timeout, err)
+			}
 			return fmt.Errorf("cannot process vmselect request: %w", err)
 		}
 		if err := bc.Flush(); err != nil {
@@ -399,6 +403,9 @@ type vmselectRequestCtx struct {
 	sr   storage.Search
 	mb   storage.MetricBlock
 
+	// timeout in seconds for the current request
+	timeout uint64
+
 	// deadline in unix timestamp seconds for the current request.
 	deadline uint64
 }
@@ -466,6 +473,9 @@ func (ctx *vmselectRequestCtx) writeDataBufBytes() error {
 const maxErrorMessageSize = 64 * 1024
 
 func (ctx *vmselectRequestCtx) writeErrorMessage(err error) error {
+	if errors.Is(err, storage.ErrDeadlineExceeded) {
+		err = fmt.Errorf("cannot execute request in %d seconds: %w", ctx.timeout, err)
+	}
 	errMsg := err.Error()
 	if len(errMsg) > maxErrorMessageSize {
 		// Trim too long error message.
@@ -520,6 +530,7 @@ func (s *Server) processVMSelectRequest(ctx *vmselectRequestCtx) error {
 	if err != nil {
 		return fmt.Errorf("cannot read timeout for the request %q: %w", rpcName, err)
 	}
+	ctx.timeout = uint64(timeout)
 	ctx.deadline = fasttime.UnixTimestamp() + uint64(timeout)
 
 	switch rpcName {
diff --git a/lib/storage/search.go b/lib/storage/search.go
index 6736da583..ffe8c7ba6 100644
--- a/lib/storage/search.go
+++ b/lib/storage/search.go
@@ -416,7 +416,7 @@ func (sq *SearchQuery) Unmarshal(src []byte) ([]byte, error) {
 
 func checkSearchDeadlineAndPace(deadline uint64) error {
 	if fasttime.UnixTimestamp() > deadline {
-		return errDeadlineExceeded
+		return ErrDeadlineExceeded
 	}
 	storagepacelimiter.Search.WaitIfNeeded()
 	return nil
diff --git a/lib/storage/storage.go b/lib/storage/storage.go
index acac917bc..a219dffd6 100644
--- a/lib/storage/storage.go
+++ b/lib/storage/storage.go
@@ -957,7 +957,8 @@ func (s *Storage) prefetchMetricNames(tsids []TSID, deadline uint64) error {
 	return nil
 }
 
-var errDeadlineExceeded = fmt.Errorf("deadline exceeded")
+// ErrDeadlineExceeded is returned when the request times out.
+var ErrDeadlineExceeded = fmt.Errorf("deadline exceeded")
 
 // DeleteMetrics deletes all the metrics matching the given tfss.
 //