plugins/forward: Add max_concurrent option (#3640)

* 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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@ -45,4 +45,10 @@ var (
Name: "sockets_open",
Help: "Gauge of open sockets per upstream.",
}, []string{"to"})
MaxConcurrentRejectCount = prometheus.NewCounter(prometheus.CounterOpts{
Namespace: plugin.Namespace,
Subsystem: "forward",
Name: "max_concurrent_reject_count_total",
Help: "Counter of the number of queries rejected because the concurrent queries were at maximum.",
})
)