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.
There is a bug in the error handling code for the Agent cache subsystem discovered:
1. NotifyCallback calls notifyBlockingQuery which calls getWithIndex in
a loop (which backs off on-error up to 1 minute)
2. getWithIndex calls fetch if there’s no valid entry in the cache
3. fetch starts a goroutine which calls Fetch on the cache-type, waits
for a while (again with backoff up to 1 minute for errors) and then
calls fetch to trigger a refresh
The end result being that every 1 minute notifyBlockingQuery spawns an
ancestry of goroutines that essentially lives forever.
This PR ensures that the goroutine started by `fetch` cancels any prior
goroutine spawned by the same line for the same key.
In isolated testing where a cache type was tweaked to indefinitely
error, this patch prevented goroutine counts from skyrocketing.
OSS portion of enterprise PR 1857.
This removes (most) references to the `cache.UpdateEvent` type in the
`proxycfg` package.
As we're going to be direct usage of the agent cache with interfaces that
can be satisfied by alternative server-local datasources, it doesn't make
sense to depend on this type everywhere anymore (particularly on the
`state.ch` channel).
We also plan to extract `proxycfg` out of Consul into a shared library in
the future, which would require removing this dependency.
Aside from a fairly rote find-and-replace, the main change is that the
`cache.Cache` and `health.Client` types now accept a callback function
parameter, rather than a `chan<- cache.UpdateEvents`. This allows us to
do the type conversion without running another goroutine.
Fixes#12048Fixes#12319
Regression introduced in #11693
Local reproduction steps:
1. `consul agent -dev`
2. `curl -sLiv 'localhost:8500/v1/agent/connect/ca/leaf/web'`
3. make note of the `X-Consul-Index` header returned
4. `curl -sLi 'localhost:8500/v1/agent/connect/ca/leaf/web?index=<VALUE_FROM_STEP_3>'`
5. Kill the above curl when it hangs with Ctrl-C
6. Repeat (2) and it should not hang.
set -euo pipefail
unset CDPATH
cd "$(dirname "$0")"
for f in $(git grep '\brequire := require\.New(' | cut -d':' -f1 | sort -u); do
echo "=== require: $f ==="
sed -i '/require := require.New(t)/d' $f
# require.XXX(blah) but not require.XXX(tblah) or require.XXX(rblah)
sed -i 's/\brequire\.\([a-zA-Z0-9_]*\)(\([^tr]\)/require.\1(t,\2/g' $f
# require.XXX(tblah) but not require.XXX(t, blah)
sed -i 's/\brequire\.\([a-zA-Z0-9_]*\)(\(t[^,]\)/require.\1(t,\2/g' $f
# require.XXX(rblah) but not require.XXX(r, blah)
sed -i 's/\brequire\.\([a-zA-Z0-9_]*\)(\(r[^,]\)/require.\1(t,\2/g' $f
gofmt -s -w $f
done
for f in $(git grep '\bassert := assert\.New(' | cut -d':' -f1 | sort -u); do
echo "=== assert: $f ==="
sed -i '/assert := assert.New(t)/d' $f
# assert.XXX(blah) but not assert.XXX(tblah) or assert.XXX(rblah)
sed -i 's/\bassert\.\([a-zA-Z0-9_]*\)(\([^tr]\)/assert.\1(t,\2/g' $f
# assert.XXX(tblah) but not assert.XXX(t, blah)
sed -i 's/\bassert\.\([a-zA-Z0-9_]*\)(\(t[^,]\)/assert.\1(t,\2/g' $f
# assert.XXX(rblah) but not assert.XXX(r, blah)
sed -i 's/\bassert\.\([a-zA-Z0-9_]*\)(\(r[^,]\)/assert.\1(t,\2/g' $f
gofmt -s -w $f
done
* Fix bug in cache where TTLs are effectively ignored
This mostly affects streaming since streaming will immediately return from Fetch calls when the state is Closed on eviction which causes the race condition every time.
However this also affects all other cache types if the fetch call happens to return between the eviction and then next time around the Get loop by any client.
There is a separate bug that allows cache items to be evicted even when there are active clients which is the trigger here.
* Add changelog entry
* Update .changelog/9978.txt
Add a skip condition to all tests slower than 100ms.
This change was made using `gotestsum tool slowest` with data from the
last 3 CI runs of master.
See https://github.com/gotestyourself/gotestsum#finding-and-skipping-slow-tests
With this change:
```
$ time go test -count=1 -short ./agent
ok github.com/hashicorp/consul/agent 0.743s
real 0m4.791s
$ time go test -count=1 -short ./agent/consul
ok github.com/hashicorp/consul/agent/consul 4.229s
real 0m8.769s
```
Prepopulate was setting entry.Expiry.HeapIndex to 0. Previously this would result in a call to heap.Fix(0)
which wasn't correct, but was also not really a problem because at worse it would re-notify.
With the recent change to extract cachettl it was changed to call Update(idx), which would have updated
the wrong entry.
A previous commit removed the setting of entry.Expiry so that the HeapIndex would be reported
as -1, and this commit adds a test and handles the -1 heap index.
And remove duplicate notifications.
Instead of performing the check in the heap implementation, check the
index in the higher level interface (Add,Remove,Update) and notify if one
of the relevant indexes is 0.
This will apply cache throttling parameters are properly applied:
* cache.EntryFetchMaxBurst
* cache.EntryFetchRate
When values are updated, a log is displayed in info.
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
}
}
The rationale behind removing them is that all of our own code (xDS, builtin connect proxy) use the cache notification mechanism. This ensures that the blocking fetch behind the scenes is always executing. Therefore the only way you might go to get a certificate and have to wait is when 1) the request has never been made for that cert before or 2) you are using the v1/agent/connect/ca/leaf API for retrieving the cert yourself.
In the first case, the refresh change doesn’t alter the behavior. In the second case, it can be mitigated by using blocking queries with that API which just like normal cache notification mechanism will cause the blocking fetch to be initiated and to get leaf certs as soon as needed.
If you are not using blocking queries, or Envoy/xDS, or the builtin connect proxy but are retrieving the certs yourself then the HTTP endpoint might take a little longer to respond.
This also renames the RefreshTimeout field on the register options to QueryTimeout to more accurately reflect that it is used for any type that supports blocking queries.
Blocking queries issues will still be uncancellable (that cannot be helped until we get rid of net/rpc). However this makes it so that if calling getWithIndex (like during a cache Notify go routine) we can cancell the outer routine. Previously it would keep issuing more blocking queries until the result state actually changed.
A few of the unexported functions in agent/cache took a large number of
arguments. These arguments were effectively overrides for values that
were provided in RequestInfo.
By using a struct we can not only reduce the number of arguments, but
also simplify the logic by removing the need for overrides.
Previously the SupportsBlocking option was specified by a method on the
type, and all the other options were specified from RegisterOptions.
This change moves RegisterOptions to a method on the type, and moves
SupportsBlocking into the options struct.
Currently there are only 2 cache-types. So all cache-types can implement
this method by embedding a struct with those predefined values. In the
future if a cache type needs to be registered more than once with different
options it can remove the embedded type and implement the method in a way
that allows for paramaterization.
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.
These two notify functions are very similar. There appear to be just
enough differences that trying to parameterize the differences may not
improve things.
For now, reduce some of the cosmetic differences so that the material
differences are more obvious.
Use named returned so that the caller has a better idea of what these
bools mean.
Return early to reduce the scope, and make it more obvious what values
are returned in which cases. Also reduces the number of conditional
expressions in each case.
This change moves all the typeEntry lookups to the first step in the exported methods,
and makes unexporter internals accept the typeEntry struct.
This change is primarily intended to make it easier to extract the container of caches
from the Cache type.
It may incidentally reduce locking in fetch, but that was not a goal.
R.B. Boyer