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lib/promscrape: use HostClient.DoDeadline instead of HostClient.Do in order to guarantee strict deadline across multiple scrape attempts

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This commit is contained in:
Aliaksandr Valialkin 2020-07-03 21:33:17 +03:00
parent ee03b4ccbd
commit 6f1d926698
1 changed files with 7 additions and 11 deletions
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18
lib/promscrape/client.go
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@ -7,7 +7,6 @@ import (
"strings"
"time"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
"github.com/VictoriaMetrics/fasthttp"
"github.com/VictoriaMetrics/metrics"
)
@ -77,6 +76,7 @@ func newClient(sw *ScrapeWork) *client {
}
func (c *client) ReadData(dst []byte) ([]byte, error) {
deadline := time.Now().Add(c.hc.ReadTimeout)
req := fasthttp.AcquireRequest()
req.SetRequestURI(c.requestURI)
req.SetHost(c.host)
@ -90,7 +90,7 @@ func (c *client) ReadData(dst []byte) ([]byte, error) {
req.Header.Set("Authorization", c.authHeader)
}
resp := fasthttp.AcquireResponse()
err := doRequestWithPossibleRetry(c.hc, req, resp, c.hc.ReadTimeout)
err := doRequestWithPossibleRetry(c.hc, req, resp, deadline)
statusCode := resp.StatusCode()
if err == nil && (statusCode == fasthttp.StatusMovedPermanently || statusCode == fasthttp.StatusFound) {
// Allow a single redirect.
@ -98,7 +98,7 @@ func (c *client) ReadData(dst []byte) ([]byte, error) {
// Otherwise it won't work.
if location := resp.Header.Peek("Location"); len(location) > 0 {
req.URI().UpdateBytes(location)
err = c.hc.Do(req, resp)
err = c.hc.DoDeadline(req, resp, deadline)
statusCode = resp.StatusCode()
}
}
@ -145,13 +145,12 @@ var (
scrapesGunzipFailed = metrics.NewCounter(`vm_promscrape_scrapes_gunzip_failed_total`)
)
func doRequestWithPossibleRetry(hc *fasthttp.HostClient, req *fasthttp.Request, resp *fasthttp.Response, timeout time.Duration) error {
// Round deadline to the smallest value in order to protect from too big deadline misses on retry.
deadline := fasttime.UnixTimestamp() + uint64(timeout.Seconds()) - 1
func doRequestWithPossibleRetry(hc *fasthttp.HostClient, req *fasthttp.Request, resp *fasthttp.Response, deadline time.Time) error {
attempts := 0
again:
// There is no need in calling DoTimeout, since the timeout must be already set in hc.ReadTimeout.
err := hc.Do(req, resp)
// Use DoDeadline instead of Do even if hc.ReadTimeout is already set in order to guarantee the given deadline
// across multiple retries.
err := hc.DoDeadline(req, resp, deadline)
if err == nil {
return nil
}
@ -159,9 +158,6 @@ again:
return err
}
// Retry request if the server closes the keep-alive connection unless deadline exceeds.
if fasttime.UnixTimestamp() > deadline {
return fasthttp.ErrTimeout
}
attempts++
if attempts > 3 {
return fmt.Errorf("the server closed 3 subsequent connections: %w", err)