rls: Some minor updates to the RLS cache. (#3442)
* Add a Resize method which will be invoked by the RLS LB policy when it receives a new cacheSize in its ServiceConfig. * Change the size fields in the cache to int64. This is the type of the cacheSize field in the proto. * Store the BackoffState field in the cache.Entry by value instead of as a pointer because it doesn not buy us much (the backoff state is not shared between the data cache and the pending cache).
This commit is contained in:
Easwar Swaminathan
GitHub
Родитель
dc074d6727
Коммит
6d849d5cd9
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@ -79,7 +79,7 @@ type Entry struct {
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CallStatus error
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// Backoff contains all backoff related state. When an RLS request
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// succeeds, backoff state is reset.
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Backoff *BackoffState
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Backoff BackoffState
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// HeaderData is received in an RLS response and is to be sent in the
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// X-Google-RLS-Data header for matching RPCs.
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HeaderData string
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@ -88,7 +88,7 @@ type Entry struct {
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// size stores the size of this cache entry. Uses only a subset of the
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// fields. See `entrySize` for this is computed.
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size int
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size int64
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// key contains the cache key corresponding to this entry. This is required
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// from methods like `removeElement` which only have a pointer to the
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// list.Element which contains a reference to the cache.Entry. But these
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@ -117,8 +117,8 @@ type BackoffState struct {
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// LRU is a cache with a least recently used eviction policy. It is not safe
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// for concurrent access.
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type LRU struct {
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maxSize int
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usedSize int
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maxSize int64
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usedSize int64
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onEvicted func(Key, *Entry)
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ll *list.List
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@ -141,7 +141,7 @@ type LRU struct {
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// The cache package trusts the RLS policy (its only user) to supply a default
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// minimum non-zero maxSize, in the event that the ServiceConfig does not
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// provide a value for it.
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func NewLRU(maxSize int, onEvicted func(Key, *Entry)) *LRU {
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func NewLRU(maxSize int64, onEvicted func(Key, *Entry)) *LRU {
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return &LRU{
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maxSize: maxSize,
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onEvicted: onEvicted,
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@ -150,14 +150,21 @@ func NewLRU(maxSize int, onEvicted func(Key, *Entry)) *LRU {
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}
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}
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// Resize sets the size limit of the LRU to newMaxSize and removes older
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// entries, if required, to comply with the new limit.
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func (lru *LRU) Resize(newMaxSize int64) {
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lru.maxSize = newMaxSize
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lru.removeToFit(0)
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}
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// TODO(easwars): If required, make this function more sophisticated.
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func entrySize(key Key, value *Entry) int {
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return len(key.Path) + len(key.KeyMap) + len(value.HeaderData)
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func entrySize(key Key, value *Entry) int64 {
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return int64(len(key.Path) + len(key.KeyMap) + len(value.HeaderData))
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}
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// removeToFit removes older entries from the cache to make room for a new
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// entry of size newSize.
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func (lru *LRU) removeToFit(newSize int) {
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func (lru *LRU) removeToFit(newSize int64) {
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now := time.Now()
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for lru.usedSize+newSize > lru.maxSize {
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elem := lru.ll.Back()
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@ -27,7 +27,11 @@ import (
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"github.com/google/go-cmp/cmp/cmpopts"
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)
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const testCacheMaxSize = 1000000
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const (
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defaultTestCacheSize = 5
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defaultTestCacheMaxSize = 1000000
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defaultTestTimeout = 1 * time.Second
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)
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// TestGet verifies the Add and Get methods of cache.LRU.
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func TestGet(t *testing.T) {
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@ -77,7 +81,7 @@ func TestGet(t *testing.T) {
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for _, test := range tests {
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t.Run(test.desc, func(t *testing.T) {
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lru := NewLRU(testCacheMaxSize, nil)
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lru := NewLRU(defaultTestCacheMaxSize, nil)
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for i, key := range test.keysToAdd {
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lru.Add(key, test.valsToAdd[i])
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}
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@ -100,7 +104,7 @@ func TestRemove(t *testing.T) {
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{Path: "/service3/method3", KeyMap: "k1=v1,k2=v2"},
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}
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lru := NewLRU(testCacheMaxSize, nil)
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lru := NewLRU(defaultTestCacheMaxSize, nil)
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for _, k := range keys {
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lru.Add(k, &Entry{})
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}
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@ -115,12 +119,7 @@ func TestRemove(t *testing.T) {
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// TestExceedingSizeCausesEviction verifies the case where adding a new entry
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// to the cache leads to eviction of old entries to make space for the new one.
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func TestExceedingSizeCausesEviction(t *testing.T) {
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const (
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testCacheSize = 5
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testTimeout = 2 * time.Second
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)
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evictCh := make(chan Key, testCacheSize)
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evictCh := make(chan Key, defaultTestCacheSize)
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onEvicted := func(k Key, _ *Entry) {
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t.Logf("evicted key {%+v} from cache", k)
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evictCh <- k
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@ -129,7 +128,7 @@ func TestExceedingSizeCausesEviction(t *testing.T) {
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keysToFill := []Key{{Path: "a"}, {Path: "b"}, {Path: "c"}, {Path: "d"}, {Path: "e"}}
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keysCausingEviction := []Key{{Path: "f"}, {Path: "g"}, {Path: "h"}, {Path: "i"}, {Path: "j"}}
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lru := NewLRU(testCacheSize, onEvicted)
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lru := NewLRU(defaultTestCacheSize, onEvicted)
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for _, key := range keysToFill {
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lru.Add(key, &Entry{})
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}
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@ -137,7 +136,7 @@ func TestExceedingSizeCausesEviction(t *testing.T) {
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for i, key := range keysCausingEviction {
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lru.Add(key, &Entry{})
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timer := time.NewTimer(testTimeout)
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timer := time.NewTimer(defaultTestTimeout)
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select {
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case <-timer.C:
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t.Fatal("Test timeout waiting for eviction")
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@ -153,12 +152,7 @@ func TestExceedingSizeCausesEviction(t *testing.T) {
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// TestAddCausesMultipleEvictions verifies the case where adding one new entry
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// causes the eviction of multiple old entries to make space for the new one.
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func TestAddCausesMultipleEvictions(t *testing.T) {
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const (
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testCacheSize = 5
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testTimeout = 2 * time.Second
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)
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evictCh := make(chan Key, testCacheSize)
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evictCh := make(chan Key, defaultTestCacheSize)
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onEvicted := func(k Key, _ *Entry) {
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evictCh <- k
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}
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@ -166,7 +160,7 @@ func TestAddCausesMultipleEvictions(t *testing.T) {
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keysToFill := []Key{{Path: "a"}, {Path: "b"}, {Path: "c"}, {Path: "d"}, {Path: "e"}}
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keyCausingEviction := Key{Path: "abcde"}
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lru := NewLRU(testCacheSize, onEvicted)
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lru := NewLRU(defaultTestCacheSize, onEvicted)
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for _, key := range keysToFill {
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lru.Add(key, &Entry{})
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}
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@ -174,7 +168,7 @@ func TestAddCausesMultipleEvictions(t *testing.T) {
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lru.Add(keyCausingEviction, &Entry{})
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for i := range keysToFill {
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timer := time.NewTimer(testTimeout)
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timer := time.NewTimer(defaultTestTimeout)
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select {
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case <-timer.C:
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t.Fatal("Test timeout waiting for eviction")
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@ -191,25 +185,20 @@ func TestAddCausesMultipleEvictions(t *testing.T) {
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// existing entry to increase its size leads to the eviction of older entries
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// to make space for the new one.
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func TestModifyCausesMultipleEvictions(t *testing.T) {
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const (
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testCacheSize = 5
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testTimeout = 2 * time.Second
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)
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evictCh := make(chan Key, testCacheSize)
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evictCh := make(chan Key, defaultTestCacheSize)
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onEvicted := func(k Key, _ *Entry) {
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evictCh <- k
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}
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keysToFill := []Key{{Path: "a"}, {Path: "b"}, {Path: "c"}, {Path: "d"}, {Path: "e"}}
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lru := NewLRU(testCacheSize, onEvicted)
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lru := NewLRU(defaultTestCacheSize, onEvicted)
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for _, key := range keysToFill {
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lru.Add(key, &Entry{})
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}
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lru.Add(keysToFill[len(keysToFill)-1], &Entry{HeaderData: "xxxx"})
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for i := range keysToFill[:len(keysToFill)-1] {
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timer := time.NewTimer(testTimeout)
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timer := time.NewTimer(defaultTestTimeout)
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select {
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case <-timer.C:
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t.Fatal("Test timeout waiting for eviction")
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@ -221,3 +210,53 @@ func TestModifyCausesMultipleEvictions(t *testing.T) {
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}
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}
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}
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func TestLRUResize(t *testing.T) {
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tests := []struct {
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desc string
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maxSize int64
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keysToFill []Key
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newMaxSize int64
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wantEvictedKeys []Key
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}{
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{
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desc: "resize causes multiple evictions",
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maxSize: 5,
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keysToFill: []Key{{Path: "a"}, {Path: "b"}, {Path: "c"}, {Path: "d"}, {Path: "e"}},
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newMaxSize: 3,
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wantEvictedKeys: []Key{{Path: "a"}, {Path: "b"}},
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},
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{
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desc: "resize causes no evictions",
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maxSize: 50,
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keysToFill: []Key{{Path: "a"}, {Path: "b"}, {Path: "c"}, {Path: "d"}, {Path: "e"}},
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newMaxSize: 10,
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wantEvictedKeys: []Key{},
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},
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{
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desc: "resize to higher value",
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maxSize: 5,
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keysToFill: []Key{{Path: "a"}, {Path: "b"}, {Path: "c"}, {Path: "d"}, {Path: "e"}},
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newMaxSize: 10,
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wantEvictedKeys: []Key{},
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},
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}
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for _, test := range tests {
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t.Run(test.desc, func(t *testing.T) {
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var evictedKeys []Key
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onEvicted := func(k Key, _ *Entry) {
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evictedKeys = append(evictedKeys, k)
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}
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lru := NewLRU(test.maxSize, onEvicted)
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for _, key := range test.keysToFill {
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lru.Add(key, &Entry{})
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}
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lru.Resize(test.newMaxSize)
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if !cmp.Equal(evictedKeys, test.wantEvictedKeys, cmpopts.EquateEmpty()) {
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t.Fatalf("lru.Resize evicted keys {%v}, should have evicted {%v}", evictedKeys, test.wantEvictedKeys)
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}
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})
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}
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}
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