031dfede90
* pkg/cache: fix race in Add() and Evict() This fixes a race in Add() when the shard is at max capacity and the key being added is already stored. Previously, the shard would evict a random value - when all it needed to do was replace an existing value. There was a race in how Evict() picked which key to remove, which would cause concurrent calls to Evict() to remove the same key. Additionally, this commit removes a lot of the lock contention and a race around Add() and Evict() by changing them to immediately hold the write lock. Previously, they would check conditions with the read lock held and not re-check those conditions once the write lock was acquired (this is a race). * pkg/cache: code review comments * pkg/cache: simplify Add() logic
64 lines
1.1 KiB
Go
64 lines
1.1 KiB
Go
package cache
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import "testing"
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func TestCacheAddAndGet(t *testing.T) {
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const N = shardSize * 4
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c := New(N)
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c.Add(1, 1)
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if _, found := c.Get(1); !found {
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t.Fatal("Failed to find inserted record")
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}
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for i := 0; i < N; i++ {
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c.Add(uint64(i), 1)
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}
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for i := 0; i < N; i++ {
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c.Add(uint64(i), 1)
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if c.Len() != N {
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t.Fatal("A item was unnecessarily evicted from the cache")
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}
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}
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}
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func TestCacheLen(t *testing.T) {
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c := New(4)
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c.Add(1, 1)
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if l := c.Len(); l != 1 {
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t.Fatalf("Cache size should %d, got %d", 1, l)
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}
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c.Add(1, 1)
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if l := c.Len(); l != 1 {
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t.Fatalf("Cache size should %d, got %d", 1, l)
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}
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c.Add(2, 2)
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if l := c.Len(); l != 2 {
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t.Fatalf("Cache size should %d, got %d", 2, l)
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}
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}
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func TestCacheSharding(t *testing.T) {
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c := New(shardSize)
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for i := 0; i < shardSize*2; i++ {
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c.Add(uint64(i), 1)
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}
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for i, s := range c.shards {
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if s.Len() == 0 {
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t.Errorf("Failed to populate shard: %d", i)
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}
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}
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}
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func BenchmarkCache(b *testing.B) {
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b.ReportAllocs()
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c := New(4)
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for n := 0; n < b.N; n++ {
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c.Add(1, 1)
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c.Get(1)
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}
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}
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