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Add an atomic.Bool to singleflight prefetching (#7963)

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Also updated plugin to document single-flighting

Signed-off-by: Ryan Brewster <rpb@anthropic.com>
This commit is contained in:
rpb-ant
2026-03-30 16:18:24 -04:00
committed by GitHub
parent 0ba8e3c850
commit 20626a7464
4 changed files with 113 additions and 4 deletions
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plugin/cache/README.md vendored
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@@ -60,6 +60,9 @@ cache [TTL] [ZONES...] {
**DURATION** defaults to 1m. Prefetching will happen when the TTL drops below **PERCENTAGE**,
which defaults to `10%`, or latest 1 second before TTL expiration. Values should be in the range `[10%, 90%]`.
Note the percent sign is mandatory. **PERCENTAGE** is treated as an `int`.
Concurrent requests that trigger a prefetch for the same cache entry dispatch at most one
background fetch, so prefetch load scales with the number of distinct eligible entries rather
than request rate.
* `serve_stale`, when serve\_stale is set, cache will always serve an expired entry to a client if there is one
available as long as it has not been expired for longer than **DURATION** (default 1 hour). By default, the _cache_ plugin will
attempt to refresh the cache entry after sending the expired cache entry to the client. The
@@ -69,6 +72,8 @@ cache [TTL] [ZONES...] {
checking to see if the entry is available from the source. **REFRESH_MODE** defaults to `immediate`. Setting this
value to `verify` can lead to increased latency when serving stale responses, but will prevent stale entries
from ever being served if an updated response can be retrieved from the source.
In `immediate` mode, concurrent requests for the same expired entry dispatch at most one
background refresh.
* `servfail` cache SERVFAIL responses for **DURATION**. Setting **DURATION** to 0 will disable caching of SERVFAIL
responses. If this option is not set, SERVFAIL responses will be cached for 5 seconds. **DURATION** may not be
greater than 5 minutes.