Commit Graph

17 Commits

Author SHA1 Message Date
R.B. Boyer a01936442c
cache: refactor agent cache fetching to prevent unnecessary fetches on error (#14956)
This continues the work done in #14908 where a crude solution to prevent a
goroutine leak was implemented. The former code would launch a perpetual
goroutine family every iteration (+1 +1) and the fixed code simply caused a
new goroutine family to first cancel the prior one to prevent the
leak (-1 +1 == 0).

This PR refactors this code completely to:

- make it more understandable
- remove the recursion-via-goroutine strangeness
- prevent unnecessary RPC fetches when the prior one has errored.

The core issue arose from a conflation of the entry.Fetching field to mean:

- there is an RPC (blocking query) in flight right now
- there is a goroutine running to manage the RPC fetch retry loop

The problem is that the goroutine-leak-avoidance check would treat
Fetching like (2), but within the body of a goroutine it would flip that
boolean back to false before the retry sleep. This would cause a new
chain of goroutines to launch which #14908 would correct crudely.

The refactored code uses a plain for-loop and changes the semantics
to track state for "is there a goroutine associated with this cache entry"
instead of the former.

We use a uint64 unique identity per goroutine instead of a boolean so
that any orphaned goroutines can tell when they've been replaced when
the expiry loop deletes a cache entry while the goroutine is still running
and is later replaced.
2022-10-25 10:27:26 -05:00
Daniel Nephin 9d5b738cdb lib/ttlcache: extract package from agent/cache 2020-10-20 19:10:20 -04:00
Daniel Nephin 909b8e674e cache: export ExpiryHeap
and hide internal methods on an unexported type, so that when it is extrated those methods are not exported.
2020-10-20 19:10:20 -04:00
Daniel Nephin b6f24c6554 cache: extract cache eviction heap
Start creating an interface that doesn't require using heap and hides more of the
entry internals.
2020-10-20 19:10:19 -04:00
Pierre Souchay 947d8eb039
Added ratelimit to handle throtling cache (#8226)
This implements a solution for #7863

It does:

    Add a new config cache.entry_fetch_rate to limit the number of calls/s for a given cache entry, default value = rate.Inf
    Add cache.entry_fetch_max_burst size of rate limit (default value = 2)

The new configuration now supports the following syntax for instance to allow 1 query every 3s:

    command line HCL: -hcl 'cache = { entry_fetch_rate = 0.333}'
    in JSON

{
  "cache": {
    "entry_fetch_rate": 0.333
  }
}
2020-07-27 23:11:11 +02:00
Daniel Nephin fb31212de7 Remove TTL from cacheEntryExpiry
This should very slightly reduce the amount of memory required to store each item in
the cache.

It will also enable setting different TTLs based on the type of result. For example
we may want to use a shorter TTL when the result indicates the resource does not exist,
as storing these types of records could easily lead to a DOS caused by
OOM.
2020-04-13 13:10:38 -04:00
Anthony Scalisi 4b92c2deee fix spelling errors (#7135) 2020-01-27 07:00:33 -06:00
Paul Banks c4fa66b4c9
connect: agent leaf cert caching improvements (#5091)
* Add State storage and LastResult argument into Cache so that cache.Types can safely store additional data that is eventually expired.

* New Leaf cache type working and basic tests passing. TODO: more extensive testing for the Root change jitter across blocking requests, test concurrent fetches for different leaves interact nicely with rootsWatcher.

* Add multi-client and delayed rotation tests.

* Typos and cleanup error handling in roots watch

* Add comment about how the FetchResult can be used and change ca leaf state to use a non-pointer state.

* Plumb test override of root CA jitter through TestAgent so that tests are deterministic again!

* Fix failing config test
2019-01-10 12:46:11 +00:00
Paul Banks 5b0d4db6bc Support Agent Caching for Service Discovery Results (#4541)
* Add cache types for catalog/services and health/services and basic test that caching works

* Support non-blocking cache types with Cache-Control semantics.

* Update API docs to include caching info for every endpoint.

* Comment updates per PR feedback.

* Add note on caching to the 10,000 foot view on the architecture page to make the new data path more clear.

* Document prepared query staleness quirk and force all background requests to AllowStale so we can spread service discovery load across servers.
2018-10-10 16:55:34 +01:00
Mitchell Hashimoto 6cf2e1ef1a
agent/cache: string through attempt rather than storing on the entry 2018-06-14 09:42:15 -07:00
Mitchell Hashimoto c42510e1ec
agent/cache: implement refresh backoff 2018-06-14 09:42:14 -07:00
Mitchell Hashimoto 07d878a157
agent/cache: address feedback, clarify comments 2018-06-14 09:42:03 -07:00
Mitchell Hashimoto ad3928b6bd
agent/cache: don't every block on NotifyCh 2018-06-14 09:42:03 -07:00
Mitchell Hashimoto 3f80a9f330
agent/cache: unit tests for ExpiryHeap, found a bug! 2018-06-14 09:42:03 -07:00
Mitchell Hashimoto ec559d77bd
agent/cache: make edge case with prev/next idx == 0 handled better 2018-06-14 09:42:03 -07:00
Mitchell Hashimoto b319d06276
agent/cache: rework how expiry data is stored to be more efficient 2018-06-14 09:42:03 -07:00
Mitchell Hashimoto 449bbd817d
agent/cache: initial TTL work 2018-06-14 09:42:02 -07:00