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Update README.md (#1381)

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Minor textual cleanup.
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cricketliu
2018-01-11 10:19:16 -08:00
committed by Miek Gieben
parent f1b280de53
commit a952c07453
1 changed files with 7 additions and 7 deletions
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plugin/cache/README.md vendored
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@@ -6,7 +6,7 @@
## Description ## Description
With *cache* enabled all records except zone transfers and metadata records will be cached for up to With *cache* enabled, all records except zone transfers and metadata records will be cached for up to
3600s. Caching is mostly useful in a scenario when fetching data from the backend (upstream, 3600s. Caching is mostly useful in a scenario when fetching data from the backend (upstream,
database, etc.) is expensive. database, etc.) is expensive.
@@ -16,9 +16,9 @@ database, etc.) is expensive.
cache [TTL] [ZONES...] cache [TTL] [ZONES...]
~~~ ~~~
* **TTL** max TTL in seconds. If not specified, the maximum TTL will be used which is 3600 for * **TTL** max TTL in seconds. If not specified, the maximum TTL will be used, which is 3600 for
noerror responses and 1800 for denial of existence ones. noerror responses and 1800 for denial of existence ones.
Setting a TTL of 300: `cache 300` would cache the record up to 300 seconds. Setting a TTL of 300: `cache 300` would cache records up to 300 seconds.
* **ZONES** zones it should cache for. If empty, the zones from the configuration block are used. * **ZONES** zones it should cache for. If empty, the zones from the configuration block are used.
Each element in the cache is cached according to its TTL (with **TTL** as the max). Each element in the cache is cached according to its TTL (with **TTL** as the max).
@@ -36,13 +36,13 @@ cache [TTL] [ZONES...] {
~~~ ~~~
* **TTL** and **ZONES** as above. * **TTL** and **ZONES** as above.
* `success`, override the settings for caching successful responses, **CAPACITY** indicates the maximum * `success`, override the settings for caching successful responses. **CAPACITY** indicates the maximum
number of packets we cache before we start evicting (*randomly*). **TTL** overrides the cache maximum TTL. number of packets we cache before we start evicting (*randomly*). **TTL** overrides the cache maximum TTL.
* `denial`, override the settings for caching denial of existence responses, **CAPACITY** indicates the maximum * `denial`, override the settings for caching denial of existence responses. **CAPACITY** indicates the maximum
number of packets we cache before we start evicting (LRU). **TTL** overrides the cache maximum TTL. number of packets we cache before we start evicting (LRU). **TTL** overrides the cache maximum TTL.
There is a third category (`error`) but those responses are never cached. There is a third category (`error`) but those responses are never cached.
* `prefetch`, will prefetch popular items when they are about to be expunged from the cache. * `prefetch` will prefetch popular items when they are about to be expunged from the cache.
Popular means **AMOUNT** queries have been seen no gaps of **DURATION** or more between them. Popular means **AMOUNT** queries have been seen with no gaps of **DURATION** or more between them.
**DURATION** defaults to 1m. Prefetching will happen when the TTL drops below **PERCENTAGE**, **DURATION** defaults to 1m. Prefetching will happen when the TTL drops below **PERCENTAGE**,
which defaults to `10%`. Values should be in the range `[10%, 90%]`. Note the percent sign is which defaults to `10%`. Values should be in the range `[10%, 90%]`. Note the percent sign is
mandatory. **PERCENTAGE** is treated as an `int`. mandatory. **PERCENTAGE** is treated as an `int`.