Ensure that Cache options are reloaded when consul reload is performed

agent/agent.go

@@ -3748,6 +3748,12 @@ func (a *Agent) reloadConfigInternal(newCfg *config.RuntimeConfig) error {
 		return err
 	}
 
+	if a.cache.ReloadOptions(newCfg.Cache) {
+		a.logger.Info("Cache options have been updated")
+	} else {
+		a.logger.Debug("Cache options have not been modified")
+	}
+
 	// Update filtered metrics
 	metrics.UpdateFilter(newCfg.Telemetry.AllowedPrefixes,
 		newCfg.Telemetry.BlockedPrefixes)

agent/agent_test.go

@@ -43,6 +43,7 @@ import (
 	"github.com/hashicorp/serf/serf"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"golang.org/x/time/rate"
 	"gopkg.in/square/go-jose.v2/jwt"
 )
 
@@ -765,10 +766,18 @@ func TestCacheRateLimit(test *testing.T) {
 		test.Run(fmt.Sprintf("rate_limit_at_%v", currentTest.rateLimit), func(t *testing.T) {
 			tt := currentTest
 			t.Parallel()
-			a := NewTestAgent(t, fmt.Sprintf("cache = { entry_fetch_rate = %v, entry_fetch_max_burst = 1 }", tt.rateLimit))
+			a := NewTestAgent(t, "cache = { entry_fetch_rate = 1, entry_fetch_max_burst = 100 }")
 			defer a.Shutdown()
 			testrpc.WaitForTestAgent(t, a.RPC, "dc1")
 
+			cfg := a.config
+			require.Equal(t, rate.Limit(1), a.config.Cache.EntryFetchRate)
+			require.Equal(t, 100, a.config.Cache.EntryFetchMaxBurst)
+			cfg.Cache.EntryFetchRate = rate.Limit(tt.rateLimit)
+			cfg.Cache.EntryFetchMaxBurst = 1
+			a.reloadConfigInternal(cfg)
+			require.Equal(t, rate.Limit(tt.rateLimit), a.config.Cache.EntryFetchRate)
+			require.Equal(t, 1, a.config.Cache.EntryFetchMaxBurst)
 			var wg sync.WaitGroup
 			stillProcessing := true
 

agent/cache/cache.go

@@ -144,16 +144,26 @@ type Options struct {
 	EntryFetchRate rate.Limit
 }
 
-// New creates a new cache with the given RPC client and reasonable defaults.
-// Further settings can be tweaked on the returned value.
-func New(options Options) *Cache {
+// Equal return true if both options are equivalent
+func (o Options) Equal(other Options) bool {
+	return o.EntryFetchMaxBurst == other.EntryFetchMaxBurst && o.EntryFetchRate == other.EntryFetchRate
+}
+
+// applyDefaultValuesOnOptions set default values on options and returned updated value
+func applyDefaultValuesOnOptions(options Options) Options {
 	if options.EntryFetchRate == 0.0 {
 		options.EntryFetchRate = DefaultEntryFetchRate
 	}
 	if options.EntryFetchMaxBurst == 0 {
 		options.EntryFetchMaxBurst = DefaultEntryFetchMaxBurst
 	}
+	return options
+}
 
+// New creates a new cache with the given RPC client and reasonable defaults.
+// Further settings can be tweaked on the returned value.
+func New(options Options) *Cache {
+	options = applyDefaultValuesOnOptions(options)
 	// Initialize the heap. The buffer of 1 is really important because
 	// its possible for the expiry loop to trigger the heap to update
 	// itself and it'd block forever otherwise.
@@ -234,6 +244,28 @@ func (c *Cache) RegisterType(n string, typ Type) {
 	c.types[n] = typeEntry{Name: n, Type: typ, Opts: &opts}
 }
 
+// ReloadOptions updates the cache with the new options
+// return true if Cache is updated, false if already up to date
+func (c *Cache) ReloadOptions(options Options) bool {
+	options = applyDefaultValuesOnOptions(options)
+	modified := !options.Equal(c.options)
+	if modified {
+		c.entriesLock.RLock()
+		defer c.entriesLock.RUnlock()
+		for _, entry := range c.entries {
+			if c.options.EntryFetchRate != options.EntryFetchRate {
+				entry.FetchRateLimiter.SetLimit(options.EntryFetchRate)
+			}
+			if c.options.EntryFetchMaxBurst != options.EntryFetchMaxBurst {
+				entry.FetchRateLimiter.SetBurst(options.EntryFetchMaxBurst)
+			}
+		}
+		c.options.EntryFetchRate = options.EntryFetchRate
+		c.options.EntryFetchMaxBurst = options.EntryFetchMaxBurst
+	}
+	return modified
+}
+
 // Get loads the data for the given type and request. If data satisfying the
 // minimum index is present in the cache, it is returned immediately. Otherwise,
 // this will block until the data is available or the request timeout is

agent/cache/cache_test.go

@@ -14,6 +14,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
+	"golang.org/x/time/rate"
 )
 
 // Test a basic Get with no indexes (and therefore no blocking queries).
@@ -1220,6 +1221,64 @@ func TestCacheGet_nonBlockingType(t *testing.T) {
 	typ.AssertExpectations(t)
 }
 
+// Test a get with an index set will wait until an index that is higher
+// is set in the cache.
+func TestCacheReload(t *testing.T) {
+	t.Parallel()
+
+	typ1 := TestType(t)
+	defer typ1.AssertExpectations(t)
+
+	c := New(Options{EntryFetchRate: rate.Limit(1), EntryFetchMaxBurst: 1})
+	c.RegisterType("t1", typ1)
+	typ1.Mock.On("Fetch", mock.Anything, mock.Anything).Return(FetchResult{Value: 42, Index: 42}, nil).Maybe()
+
+	require.False(t, c.ReloadOptions(Options{EntryFetchRate: rate.Limit(1), EntryFetchMaxBurst: 1}), "Value should not be reloaded")
+
+	_, meta, err := c.Get(context.Background(), "t1", TestRequest(t, RequestInfo{Key: "hello1", MinIndex: uint64(1)}))
+	require.NoError(t, err)
+	require.Equal(t, meta.Index, uint64(42))
+
+	testEntry := func(t *testing.T, doTest func(t *testing.T, entry cacheEntry)) {
+		c.entriesLock.Lock()
+		tEntry, ok := c.types["t1"]
+		require.True(t, ok)
+		keyName := makeEntryKey("t1", "", "", "hello1")
+		ok, entryValid, entry := c.getEntryLocked(tEntry, keyName, RequestInfo{})
+		require.True(t, ok)
+		require.True(t, entryValid)
+		doTest(t, entry)
+		c.entriesLock.Unlock()
+
+	}
+	testEntry(t, func(t *testing.T, entry cacheEntry) {
+		require.Equal(t, entry.FetchRateLimiter.Limit(), rate.Limit(1))
+		require.Equal(t, entry.FetchRateLimiter.Burst(), 1)
+	})
+
+	// Modify only rateLimit
+	require.True(t, c.ReloadOptions(Options{EntryFetchRate: rate.Limit(100), EntryFetchMaxBurst: 1}))
+	testEntry(t, func(t *testing.T, entry cacheEntry) {
+		require.Equal(t, entry.FetchRateLimiter.Limit(), rate.Limit(100))
+		require.Equal(t, entry.FetchRateLimiter.Burst(), 1)
+	})
+
+	// Modify only Burst
+	require.True(t, c.ReloadOptions(Options{EntryFetchRate: rate.Limit(100), EntryFetchMaxBurst: 5}))
+	testEntry(t, func(t *testing.T, entry cacheEntry) {
+		require.Equal(t, entry.FetchRateLimiter.Limit(), rate.Limit(100))
+		require.Equal(t, entry.FetchRateLimiter.Burst(), 5)
+	})
+
+	// Modify only Burst and Limit at the same time
+	require.True(t, c.ReloadOptions(Options{EntryFetchRate: rate.Limit(1000), EntryFetchMaxBurst: 42}))
+
+	testEntry(t, func(t *testing.T, entry cacheEntry) {
+		require.Equal(t, entry.FetchRateLimiter.Limit(), rate.Limit(1000))
+		require.Equal(t, entry.FetchRateLimiter.Burst(), 42)
+	})
+}
+
 // TestCacheThrottle checks the assumptions for the cache throttling. It sets
 // up a cache with Options{EntryFetchRate: 10.0, EntryFetchMaxBurst: 1}, which
 // allows for 10req/s, or one request every 100ms.