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// Copyright 2015 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package lrucache_test
import (
"bytes"
"encoding/gob"
"testing"
. "github.com/jacobsa/oglematchers"
. "github.com/jacobsa/ogletest"
"github.com/jacobsa/util/lrucache"
)
func TestCache(t *testing.T) { RunTests(t) }
////////////////////////////////////////////////////////////////////////
// Invariant-checking cache
////////////////////////////////////////////////////////////////////////
type invariantsCache struct {
Wrapped lrucache.Cache
}
func (c *invariantsCache) Insert(
key string,
value interface{}) {
c.Wrapped.CheckInvariants()
defer c.Wrapped.CheckInvariants()
c.Wrapped.Insert(key, value)
return
}
func (c *invariantsCache) Erase(key string) {
c.Wrapped.CheckInvariants()
defer c.Wrapped.CheckInvariants()
c.Wrapped.Erase(key)
return
}
func (c *invariantsCache) LookUp(key string) (v interface{}) {
c.Wrapped.CheckInvariants()
defer c.Wrapped.CheckInvariants()
v = c.Wrapped.LookUp(key)
return
}
////////////////////////////////////////////////////////////////////////
// Boilerplate
////////////////////////////////////////////////////////////////////////
const capacity = 3
type CacheTest struct {
cache invariantsCache
}
func init() { RegisterTestSuite(&CacheTest{}) }
func (t *CacheTest) SetUp(ti *TestInfo) {
t.cache.Wrapped = lrucache.New(capacity)
}
////////////////////////////////////////////////////////////////////////
// Test functions
////////////////////////////////////////////////////////////////////////
func (t *CacheTest) LookUpInEmptyCache() {
ExpectEq(nil, t.cache.LookUp(""))
ExpectEq(nil, t.cache.LookUp("taco"))
}
func (t *CacheTest) InsertNilValue() {
ExpectThat(
func() { t.cache.Insert("taco", nil) },
Panics(HasSubstr("nil value")),
)
}
func (t *CacheTest) LookUpUnknownKey() {
t.cache.Insert("burrito", 17)
t.cache.Insert("taco", 19)
ExpectEq(nil, t.cache.LookUp(""))
ExpectEq(nil, t.cache.LookUp("enchilada"))
}
func (t *CacheTest) FillUpToCapacity() {
AssertEq(3, capacity)
t.cache.Insert("burrito", 17)
t.cache.Insert("taco", 19)
t.cache.Insert("enchilada", []byte{0x23, 0x29})
ExpectEq(17, t.cache.LookUp("burrito"))
ExpectEq(19, t.cache.LookUp("taco"))
ExpectThat(t.cache.LookUp("enchilada"), DeepEquals([]byte{0x23, 0x29}))
}
func (t *CacheTest) ExpiresLeastRecentlyUsed() {
AssertEq(3, capacity)
t.cache.Insert("burrito", 17)
t.cache.Insert("taco", 19) // Least recent
t.cache.Insert("enchilada", 23) // Second most recent
AssertEq(17, t.cache.LookUp("burrito")) // Most recent
// Insert another.
t.cache.Insert("queso", 29)
// See what's left.
ExpectEq(nil, t.cache.LookUp("taco"))
ExpectEq(17, t.cache.LookUp("burrito"))
ExpectEq(23, t.cache.LookUp("enchilada"))
ExpectEq(29, t.cache.LookUp("queso"))
}
func (t *CacheTest) Overwrite() {
// Write several times
t.cache.Insert("taco", 17)
t.cache.Insert("taco", 19)
t.cache.Insert("taco", 23)
// Look up
ExpectEq(23, t.cache.LookUp("taco"))
// The overwritten entries shouldn't count toward capacity.
AssertEq(3, capacity)
t.cache.Insert("burrito", 29)
t.cache.Insert("enchilada", 31)
ExpectEq(23, t.cache.LookUp("taco"))
ExpectEq(29, t.cache.LookUp("burrito"))
ExpectEq(31, t.cache.LookUp("enchilada"))
}
func (t *CacheTest) Encode_EmptyCache() {
// Encode
buf := new(bytes.Buffer)
encoder := gob.NewEncoder(buf)
AssertEq(nil, encoder.Encode(&t.cache))
// Decode
decoder := gob.NewDecoder(buf)
var decoded invariantsCache
AssertEq(nil, decoder.Decode(&decoded))
ExpectEq(nil, decoded.LookUp(""))
ExpectEq(nil, decoded.LookUp("taco"))
}
func (t *CacheTest) Encode_PreservesLRUOrderAndCapacity() {
// Contents
AssertEq(3, capacity)
t.cache.Insert("burrito", 17)
t.cache.Insert("taco", 19) // Least recent
t.cache.Insert("enchilada", []byte{0x23, 0x29}) // Second most recent
AssertEq(17, t.cache.LookUp("burrito")) // Most recent
// Encode
buf := new(bytes.Buffer)
encoder := gob.NewEncoder(buf)
AssertEq(nil, encoder.Encode(&t.cache))
// Decode
decoder := gob.NewDecoder(buf)
var decoded invariantsCache
AssertEq(nil, decoder.Decode(&decoded))
// Insert another.
decoded.Insert("queso", 29)
// See what's left.
ExpectEq(nil, decoded.LookUp("taco"))
ExpectEq(17, decoded.LookUp("burrito"))
ExpectThat(t.cache.LookUp("enchilada"), DeepEquals([]byte{0x23, 0x29}))
ExpectEq(29, decoded.LookUp("queso"))
}
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