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plugins/forward: Add max_concurrent option (#3640)

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* count and limit concurrent queries

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* add option

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* return servfail when limit exceeded

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* docs

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* docs

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* docs

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* review feedback

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* move atomic counter to beginning of struct

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* add comment for ErrLimitExceeded

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* rename option to max_concurrent

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* add metric

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* response REFUSED; incl max in error; add more docs

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* avoid err setup race

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* respond SERVFAIL; doc memory usage

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>
This commit is contained in:
Chris O'Haver 2020-02-04 07:59:08 -05:00 • committed by GitHub
parent 8724a134c4
commit 22cd28a798
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5 changed files with 85 additions and 2 deletions
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15
plugin/forward/setup.go
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@ -1,6 +1,7 @@
package forward
import (
"errors"
"fmt"
"strconv"
"time"
@ -121,6 +122,7 @@ func parseStanza(c *caddy.Controller) (*Forward, error) {
}
f.proxies[i].SetExpire(f.expire)
}
return f, nil
}
@ -211,6 +213,19 @@ func parseBlock(c *caddy.Controller, f *Forward) error {
default:
return c.Errf("unknown policy '%s'", x)
}
case "max_concurrent":
if !c.NextArg() {
return c.ArgErr()
}
n, err := strconv.Atoi(c.Val())
if err != nil {
return err
}
if n < 0 {
return fmt.Errorf("max_concurrent can't be negative: %d", n)
}
f.ErrLimitExceeded = errors.New("concurrent queries exceeded maximum " + c.Val())
f.maxConcurrent = int64(n)
default:
return c.Errf("unknown property '%s'", c.Val())