open-consul/agent/cache/watch_test.go

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package cache
import (
"context"
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"errors"
"fmt"
"sync/atomic"
"testing"
"time"
"github.com/stretchr/testify/mock"
"github.com/stretchr/testify/require"
)
// Test that a type registered with a periodic refresh can be watched.
func TestCacheNotify(t *testing.T) {
t.Parallel()
typ := TestType(t)
typ.On("RegisterOptions").Return(RegisterOptions{})
defer typ.AssertExpectations(t)
c := New(Options{})
c.RegisterType("t", typ)
// Setup triggers to control when "updates" should be delivered
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trigger := make([]chan time.Time, 5)
for i := range trigger {
trigger[i] = make(chan time.Time)
}
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// Send an error to fake a situation where the servers aren't reachable
// initially.
typ.Static(FetchResult{Value: nil, Index: 0}, errors.New("no servers available")).Once()
// Configure the type. The first time we use the fake index of "1" to verify we
// don't regress on https://github.com/hashicorp/consul/issues/6521 .
typ.Static(FetchResult{Value: 1, Index: 1}, nil).Once().Run(func(args mock.Arguments) {
// Assert the right request type - all real Fetch implementations do this so
// it keeps us honest that Watch doesn't require type mangling which will
// break in real life (hint: it did on the first attempt)
_, ok := args.Get(1).(*MockRequest)
require.True(t, ok)
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}).WaitUntil(trigger[0])
typ.Static(FetchResult{Value: 12, Index: 5}, nil).Once().WaitUntil(trigger[1])
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typ.Static(FetchResult{Value: 12, Index: 5}, nil).Once().WaitUntil(trigger[2])
typ.Static(FetchResult{Value: 42, Index: 7}, nil).Once().WaitUntil(trigger[3])
// It's timing dependent whether the blocking loop manages to make another
// call before we cancel so don't require it. We need to have a higher index
// here because if the index is the same then the cache Get will not return
// until the full 10 min timeout expires. This causes the last fetch to return
// after cancellation as if it had timed out.
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typ.Static(FetchResult{Value: 42, Index: 8}, nil).WaitUntil(trigger[4])
require := require.New(t)
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
ch := make(chan UpdateEvent)
err := c.Notify(ctx, "t", TestRequest(t, RequestInfo{Key: "hello"}), "test", ch)
require.NoError(err)
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// Should receive the error with index == 0 first.
TestCacheNotifyChResult(t, ch, UpdateEvent{
CorrelationID: "test",
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Result: nil,
Meta: ResultMeta{Hit: false, Index: 0},
Err: errors.New("no servers available"),
})
// There should be no more updates delivered yet
require.Len(ch, 0)
// Trigger blocking query to return a "change"
close(trigger[0])
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// Should receive the first real update next.
TestCacheNotifyChResult(t, ch, UpdateEvent{
CorrelationID: "test",
Result: 1,
Meta: ResultMeta{Hit: false, Index: 1},
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Err: nil,
})
// Trigger blocking query to return a "change"
close(trigger[1])
// Should receive the next result pretty soon
TestCacheNotifyChResult(t, ch, UpdateEvent{
CorrelationID: "test",
Result: 12,
// Note these are never cache "hits" because blocking will wait until there
// is a new value at which point it's not considered a hit.
Meta: ResultMeta{Hit: false, Index: 5},
Err: nil,
})
// Register a second observer using same chan and request. Note that this is
// testing a few things implicitly:
// - that multiple watchers on the same cache entity are de-duped in their
// requests to the "backend"
// - that multiple watchers can distinguish their results using correlationID
err = c.Notify(ctx, "t", TestRequest(t, RequestInfo{Key: "hello"}), "test2", ch)
require.NoError(err)
// Should get test2 notify immediately, and it should be a cache hit
TestCacheNotifyChResult(t, ch, UpdateEvent{
CorrelationID: "test2",
Result: 12,
Meta: ResultMeta{Hit: true, Index: 5},
Err: nil,
})
// We could wait for a full timeout but we can't directly observe it so
// simulate the behavior by triggering a response with the same value and
// index as the last one.
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close(trigger[2])
// We should NOT be notified about that. Note this is timing dependent but
// it's only a sanity check, if we somehow _do_ get the change delivered later
// than 10ms the next value assertion will fail anyway.
time.Sleep(10 * time.Millisecond)
require.Len(ch, 0)
// Trigger final update
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close(trigger[3])
TestCacheNotifyChResult(t, ch, UpdateEvent{
CorrelationID: "test",
Result: 42,
Meta: ResultMeta{Hit: false, Index: 7},
Err: nil,
}, UpdateEvent{
CorrelationID: "test2",
Result: 42,
Meta: ResultMeta{Hit: false, Index: 7},
Err: nil,
})
// Sanity check closing chan before context is canceled doesn't panic
//close(ch)
// Close context
cancel()
// It's likely but not certain that at least one of the watchers was blocked
// on the next cache Get so trigger that to timeout so we can observe the
// watch goroutines being cleaned up. This is necessary since currently we
// have no way to interrupt a blocking query. In practice it's fine to know
// that after 10 mins max the blocking query will return and the resources
// will be cleaned.
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close(trigger[4])
// I want to test that canceling the context cleans up goroutines (which it
// does from manual verification with debugger etc). I had a check based on a
// similar approach to https://golang.org/src/net/http/main_test.go#L60 but it
// was just too flaky because it relies on the timing of the error backoff
// timer goroutines and similar so I've given up for now as I have more
// important things to get working.
}
func TestCacheNotifyPolling(t *testing.T) {
t.Parallel()
typ := TestTypeNonBlocking(t)
defer typ.AssertExpectations(t)
c := New(Options{})
c.RegisterType("t", typ)
// Configure the type
typ.Static(FetchResult{Value: 1, Index: 1}, nil).Once().Run(func(args mock.Arguments) {
// Assert the right request type - all real Fetch implementations do this so
// it keeps us honest that Watch doesn't require type mangling which will
// break in real life (hint: it did on the first attempt)
_, ok := args.Get(1).(*MockRequest)
require.True(t, ok)
})
typ.Static(FetchResult{Value: 12, Index: 1}, nil).Once()
typ.Static(FetchResult{Value: 42, Index: 1}, nil).Once()
require := require.New(t)
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
ch := make(chan UpdateEvent)
err := c.Notify(ctx, "t", TestRequest(t, RequestInfo{Key: "hello", MaxAge: 100 * time.Millisecond}), "test", ch)
require.NoError(err)
// Should receive the first result pretty soon
TestCacheNotifyChResult(t, ch, UpdateEvent{
CorrelationID: "test",
Result: 1,
Meta: ResultMeta{Hit: false, Index: 1},
Err: nil,
})
// There should be no more updates delivered yet
require.Len(ch, 0)
// make sure the updates do not come too quickly
select {
case <-time.After(50 * time.Millisecond):
case <-ch:
require.Fail("Received update too early")
}
// make sure we get the update not too far out.
select {
case <-time.After(100 * time.Millisecond):
require.Fail("Didn't receive the notification")
case result := <-ch:
require.Equal(result.Result, 12)
require.Equal(result.CorrelationID, "test")
require.Equal(result.Meta.Hit, false)
require.Equal(result.Meta.Index, uint64(1))
// pretty conservative check it should be even newer because without a second
// notifier each value returned will have been executed just then and not served
// from the cache.
require.True(result.Meta.Age < 50*time.Millisecond)
require.NoError(result.Err)
}
require.Len(ch, 0)
// Register a second observer using same chan and request. Note that this is
// testing a few things implicitly:
// - that multiple watchers on the same cache entity are de-duped in their
// requests to the "backend"
// - that multiple watchers can distinguish their results using correlationID
err = c.Notify(ctx, "t", TestRequest(t, RequestInfo{Key: "hello", MaxAge: 100 * time.Millisecond}), "test2", ch)
require.NoError(err)
// Should get test2 notify immediately, and it should be a cache hit
TestCacheNotifyChResult(t, ch, UpdateEvent{
CorrelationID: "test2",
Result: 12,
Meta: ResultMeta{Hit: true, Index: 1},
Err: nil,
})
require.Len(ch, 0)
// wait for the next batch of responses
events := make([]UpdateEvent, 0)
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// At least 110ms is needed to allow for the jitter
timeout := time.After(220 * time.Millisecond)
for i := 0; i < 2; i++ {
select {
case <-timeout:
require.Fail("UpdateEvent not received in time")
case eve := <-ch:
events = append(events, eve)
}
}
require.Equal(events[0].Result, 42)
require.Equal(events[0].Meta.Hit, false)
require.Equal(events[0].Meta.Index, uint64(1))
require.True(events[0].Meta.Age < 50*time.Millisecond)
require.NoError(events[0].Err)
require.Equal(events[1].Result, 42)
// Sometimes this would be a hit and others not. It all depends on when the various getWithIndex calls got fired.
// If both are done concurrently then it will not be a cache hit but the request gets single flighted and both
// get notified at the same time.
// require.Equal(events[1].Meta.Hit, true)
require.Equal(events[1].Meta.Index, uint64(1))
require.True(events[1].Meta.Age < 100*time.Millisecond)
require.NoError(events[1].Err)
}
// Test that a refresh performs a backoff.
func TestCacheWatch_ErrorBackoff(t *testing.T) {
t.Parallel()
typ := TestType(t)
typ.On("RegisterOptions").Return(RegisterOptions{})
defer typ.AssertExpectations(t)
c := New(Options{})
c.RegisterType("t", typ)
// Configure the type
var retries uint32
fetchErr := fmt.Errorf("test fetch error")
typ.Static(FetchResult{Value: 1, Index: 4}, nil).Once()
typ.Static(FetchResult{Value: nil, Index: 5}, fetchErr).Run(func(args mock.Arguments) {
atomic.AddUint32(&retries, 1)
})
require := require.New(t)
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
ch := make(chan UpdateEvent)
err := c.Notify(ctx, "t", TestRequest(t, RequestInfo{Key: "hello"}), "test", ch)
require.NoError(err)
// Should receive the first result pretty soon
TestCacheNotifyChResult(t, ch, UpdateEvent{
CorrelationID: "test",
Result: 1,
Meta: ResultMeta{Hit: false, Index: 4},
Err: nil,
})
numErrors := 0
// Loop for a little while and count how many errors we see reported. If this
// was running as fast as it could go we'd expect this to be huge. We have to
// be a little careful here because the watch chan ch doesn't have a large
// buffer so we could be artificially slowing down the loop without the
// backoff actually taking effect. We can validate that by ensuring this test
// fails without the backoff code reliably.
timeoutC := time.After(500 * time.Millisecond)
OUT:
for {
select {
case <-timeoutC:
break OUT
case u := <-ch:
numErrors++
require.Error(u.Err)
}
}
// Must be fewer than 10 failures in that time
require.True(numErrors < 10, fmt.Sprintf("numErrors: %d", numErrors))
// Check the number of RPCs as a sanity check too
actual := atomic.LoadUint32(&retries)
require.True(actual < 10, fmt.Sprintf("actual: %d", actual))
}
// Test that a refresh performs a backoff.
func TestCacheWatch_ErrorBackoffNonBlocking(t *testing.T) {
t.Parallel()
typ := TestTypeNonBlocking(t)
defer typ.AssertExpectations(t)
c := New(Options{})
c.RegisterType("t", typ)
// Configure the type
var retries uint32
fetchErr := fmt.Errorf("test fetch error")
typ.Static(FetchResult{Value: 1, Index: 4}, nil).Once()
typ.Static(FetchResult{Value: nil, Index: 5}, fetchErr).Run(func(args mock.Arguments) {
atomic.AddUint32(&retries, 1)
})
require := require.New(t)
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
ch := make(chan UpdateEvent)
err := c.Notify(ctx, "t", TestRequest(t, RequestInfo{Key: "hello", MaxAge: 100 * time.Millisecond}), "test", ch)
require.NoError(err)
// Should receive the first result pretty soon
TestCacheNotifyChResult(t, ch, UpdateEvent{
CorrelationID: "test",
Result: 1,
Meta: ResultMeta{Hit: false, Index: 4},
Err: nil,
})
numErrors := 0
// Loop for a little while and count how many errors we see reported. If this
// was running as fast as it could go we'd expect this to be huge. We have to
// be a little careful here because the watch chan ch doesn't have a large
// buffer so we could be artificially slowing down the loop without the
// backoff actually taking effect. We can validate that by ensuring this test
// fails without the backoff code reliably.
//
// 100 + 500 milliseconds. 100 because the first retry will not happen until
// the 100 + jitter milliseconds have elapsed.
timeoutC := time.After(600 * time.Millisecond)
OUT:
for {
select {
case <-timeoutC:
break OUT
case u := <-ch:
numErrors++
require.Error(u.Err)
}
}
// Must be fewer than 10 failures in that time
require.True(numErrors < 10, fmt.Sprintf("numErrors: %d", numErrors))
// Check the number of RPCs as a sanity check too
actual := atomic.LoadUint32(&retries)
require.True(actual < 10, fmt.Sprintf("actual: %d", actual))
}