consul/agent/proxycfg-sources/catalog/mock_SessionLimiter.go
Derek Menteer 0ac8ae6c3b
Fix xDS deadlock due to syncLoop termination. (#20867)
* Fix xDS deadlock due to syncLoop termination.

This fixes an issue where agentless xDS streams can deadlock permanently until
a server is restarted. When this issue occurs, no new proxies are able to
successfully connect to the server.

Effectively, the trigger for this deadlock stems from the following return
statement:
https://github.com/hashicorp/consul/blob/v1.18.0/agent/proxycfg-sources/catalog/config_source.go#L199-L202

When this happens, the entire `syncLoop()` terminates and stops consuming from
the following channel:
https://github.com/hashicorp/consul/blob/v1.18.0/agent/proxycfg-sources/catalog/config_source.go#L182-L192

Which results in the `ConfigSource.cleanup()` function never receiving a
response and holding a mutex indefinitely:
https://github.com/hashicorp/consul/blob/v1.18.0/agent/proxycfg-sources/catalog/config_source.go#L241-L247

Because this mutex is shared, it effectively deadlocks the server's ability to
process new xDS streams.

----

The fix to this issue involves removing the `chan chan struct{}` used like an
RPC-over-channels pattern and replacing it with two distinct channels:

+ `stopSyncLoopCh` - indicates that the `syncLoop()` should terminate soon.  +
`syncLoopDoneCh` - indicates that the `syncLoop()` has terminated.

Splitting these two concepts out and deferring a `close(syncLoopDoneCh)` in the
`syncLoop()` function ensures that the deadlock above should no longer occur.

We also now evict xDS connections of all proxies for the corresponding
`syncLoop()` whenever it encounters an irrecoverable error. This is done by
hoisting the new `syncLoopDoneCh` upwards so that it's visible to the xDS delta
processing. Prior to this fix, the behavior was to simply orphan them so they
would never receive catalog-registration or service-defaults updates.

* Add changelog.
2024-03-15 13:57:11 -05:00

61 lines
1.4 KiB
Go

// Code generated by mockery v2.37.1. DO NOT EDIT.
package catalog
import (
context "context"
limiter "github.com/hashicorp/consul/agent/grpc-external/limiter"
mock "github.com/stretchr/testify/mock"
)
// MockSessionLimiter is an autogenerated mock type for the SessionLimiter type
type MockSessionLimiter struct {
mock.Mock
}
// BeginSession provides a mock function with given fields:
func (_m *MockSessionLimiter) BeginSession() (limiter.Session, error) {
ret := _m.Called()
var r0 limiter.Session
var r1 error
if rf, ok := ret.Get(0).(func() (limiter.Session, error)); ok {
return rf()
}
if rf, ok := ret.Get(0).(func() limiter.Session); ok {
r0 = rf()
} else {
if ret.Get(0) != nil {
r0 = ret.Get(0).(limiter.Session)
}
}
if rf, ok := ret.Get(1).(func() error); ok {
r1 = rf()
} else {
r1 = ret.Error(1)
}
return r0, r1
}
// Run provides a mock function with given fields: ctx
func (_m *MockSessionLimiter) Run(ctx context.Context) {
_m.Called(ctx)
}
// NewMockSessionLimiter creates a new instance of MockSessionLimiter. It also registers a testing interface on the mock and a cleanup function to assert the mocks expectations.
// The first argument is typically a *testing.T value.
func NewMockSessionLimiter(t interface {
mock.TestingT
Cleanup(func())
}) *MockSessionLimiter {
mock := &MockSessionLimiter{}
mock.Mock.Test(t)
t.Cleanup(func() { mock.AssertExpectations(t) })
return mock
}