diff --git a/2q.go b/2q.go deleted file mode 100644 index 15fcad0..0000000 --- a/2q.go +++ /dev/null @@ -1,222 +0,0 @@ -package lru - -import ( - "fmt" - "sync" - - "github.com/hashicorp/golang-lru/simplelru" -) - -const ( - // Default2QRecentRatio is the ratio of the 2Q cache dedicated - // to recently added entries that have only been accessed once. - Default2QRecentRatio = 0.25 - - // Default2QGhostEntries is the default ratio of ghost - // entries kept to track entries recently evicted - Default2QGhostEntries = 0.50 -) - -// TwoQueueCache is a thread-safe fixed size 2Q cache. -// 2Q is an enhancement over the standard LRU cache -// in that it tracks both frequently and recently used -// entries separately. This avoids a burst in access to new -// entries from evicting frequently used entries. It adds some -// additional tracking overhead to the standard LRU cache, and is -// computationally about 2x the cost, and adds some metadata over -// head. The ARCCache is similar, but does not require setting any -// parameters. -type TwoQueueCache struct { - size int - recentSize int - - recent simplelru.LRUCache - frequent simplelru.LRUCache - recentEvict simplelru.LRUCache - lock sync.RWMutex -} - -// New2Q creates a new TwoQueueCache using the default -// values for the parameters. -func New2Q(size int) (*TwoQueueCache, error) { - return New2QParams(size, Default2QRecentRatio, Default2QGhostEntries) -} - -// New2QParams creates a new TwoQueueCache using the provided -// parameter values. -func New2QParams(size int, recentRatio, ghostRatio float64) (*TwoQueueCache, error) { - if size <= 0 { - return nil, fmt.Errorf("invalid size") - } - if recentRatio < 0.0 || recentRatio > 1.0 { - return nil, fmt.Errorf("invalid recent ratio") - } - if ghostRatio < 0.0 || ghostRatio > 1.0 { - return nil, fmt.Errorf("invalid ghost ratio") - } - - // Determine the sub-sizes - recentSize := int(float64(size) * recentRatio) - evictSize := int(float64(size) * ghostRatio) - - // Allocate the LRUs - recent, err := simplelru.NewLRU(size, nil) - if err != nil { - return nil, err - } - frequent, err := simplelru.NewLRU(size, nil) - if err != nil { - return nil, err - } - recentEvict, err := simplelru.NewLRU(evictSize, nil) - if err != nil { - return nil, err - } - - // Initialize the cache - c := &TwoQueueCache{ - size: size, - recentSize: recentSize, - recent: recent, - frequent: frequent, - recentEvict: recentEvict, - } - return c, nil -} - -// Get looks up a key's value from the cache. -func (c *TwoQueueCache) Get(key interface{}) (value interface{}, ok bool) { - c.lock.Lock() - defer c.lock.Unlock() - - // Check if this is a frequent value - if val, ok := c.frequent.Get(key); ok { - return val, ok - } - - // If the value is contained in recent, then we - // promote it to frequent - if val, ok := c.recent.Peek(key); ok { - c.recent.Remove(key) - c.frequent.Add(key, val) - return val, ok - } - - // No hit - return nil, false -} - -// Add adds a value to the cache. -func (c *TwoQueueCache) Add(key, value interface{}) { - c.lock.Lock() - defer c.lock.Unlock() - - // Check if the value is frequently used already, - // and just update the value - if c.frequent.Contains(key) { - c.frequent.Add(key, value) - return - } - - // Check if the value is recently used, and promote - // the value into the frequent list - if c.recent.Contains(key) { - c.recent.Remove(key) - c.frequent.Add(key, value) - return - } - - // If the value was recently evicted, add it to the - // frequently used list - if c.recentEvict.Contains(key) { - c.ensureSpace(true) - c.recentEvict.Remove(key) - c.frequent.Add(key, value) - return - } - - // Add to the recently seen list - c.ensureSpace(false) - c.recent.Add(key, value) -} - -// ensureSpace is used to ensure we have space in the cache -func (c *TwoQueueCache) ensureSpace(recentEvict bool) { - // If we have space, nothing to do - recentLen := c.recent.Len() - freqLen := c.frequent.Len() - if recentLen+freqLen < c.size { - return - } - - // If the recent buffer is larger than - // the target, evict from there - if recentLen > 0 && (recentLen > c.recentSize || (recentLen == c.recentSize && !recentEvict)) { - k, _, _ := c.recent.RemoveOldest() - c.recentEvict.Add(k, nil) - return - } - - // Remove from the frequent list otherwise - c.frequent.RemoveOldest() -} - -// Len returns the number of items in the cache. -func (c *TwoQueueCache) Len() int { - c.lock.RLock() - defer c.lock.RUnlock() - return c.recent.Len() + c.frequent.Len() -} - -// Keys returns a slice of the keys in the cache. -// The frequently used keys are first in the returned slice. -func (c *TwoQueueCache) Keys() []interface{} { - c.lock.RLock() - defer c.lock.RUnlock() - k1 := c.frequent.Keys() - k2 := c.recent.Keys() - return append(k1, k2...) -} - -// Remove removes the provided key from the cache. -func (c *TwoQueueCache) Remove(key interface{}) { - c.lock.Lock() - defer c.lock.Unlock() - if c.frequent.Remove(key) { - return - } - if c.recent.Remove(key) { - return - } - if c.recentEvict.Remove(key) { - return - } -} - -// Purge is used to completely clear the cache. -func (c *TwoQueueCache) Purge() { - c.lock.Lock() - defer c.lock.Unlock() - c.recent.Purge() - c.frequent.Purge() - c.recentEvict.Purge() -} - -// Contains is used to check if the cache contains a key -// without updating recency or frequency. -func (c *TwoQueueCache) Contains(key interface{}) bool { - c.lock.RLock() - defer c.lock.RUnlock() - return c.frequent.Contains(key) || c.recent.Contains(key) -} - -// Peek is used to inspect the cache value of a key -// without updating recency or frequency. -func (c *TwoQueueCache) Peek(key interface{}) (value interface{}, ok bool) { - c.lock.RLock() - defer c.lock.RUnlock() - if val, ok := c.frequent.Peek(key); ok { - return val, ok - } - return c.recent.Peek(key) -} diff --git a/2q_test.go b/2q_test.go deleted file mode 100644 index 606384d..0000000 --- a/2q_test.go +++ /dev/null @@ -1,305 +0,0 @@ -package lru - -import ( - "testing" -) - -func Benchmark2Q_Rand(b *testing.B) { - l, err := New2Q(8192) - if err != nil { - b.Fatalf("err: %v", err) - } - - trace := make([]int64, b.N*2) - for i := 0; i < b.N*2; i++ { - trace[i] = getRand(b) % 32768 - } - - b.ResetTimer() - - var hit, miss int - for i := 0; i < 2*b.N; i++ { - if i%2 == 0 { - l.Add(trace[i], trace[i]) - } else { - _, ok := l.Get(trace[i]) - if ok { - hit++ - } else { - miss++ - } - } - } - b.Logf("hit: %d miss: %d ratio: %f", hit, miss, float64(hit)/float64(miss)) -} - -func Benchmark2Q_Freq(b *testing.B) { - l, err := New2Q(8192) - if err != nil { - b.Fatalf("err: %v", err) - } - - trace := make([]int64, b.N*2) - for i := 0; i < b.N*2; i++ { - if i%2 == 0 { - trace[i] = getRand(b) % 16384 - } else { - trace[i] = getRand(b) % 32768 - } - } - - b.ResetTimer() - - for i := 0; i < b.N; i++ { - l.Add(trace[i], trace[i]) - } - var hit, miss int - for i := 0; i < b.N; i++ { - _, ok := l.Get(trace[i]) - if ok { - hit++ - } else { - miss++ - } - } - b.Logf("hit: %d miss: %d ratio: %f", hit, miss, float64(hit)/float64(miss)) -} - -func Test2Q_RandomOps(t *testing.T) { - size := 128 - l, err := New2Q(128) - if err != nil { - t.Fatalf("err: %v", err) - } - - n := 200000 - for i := 0; i < n; i++ { - key := getRand(t) % 512 - r := getRand(t) - switch r % 3 { - case 0: - l.Add(key, key) - case 1: - l.Get(key) - case 2: - l.Remove(key) - } - - if l.recent.Len()+l.frequent.Len() > size { - t.Fatalf("bad: recent: %d freq: %d", - l.recent.Len(), l.frequent.Len()) - } - } -} - -func Test2Q_Get_RecentToFrequent(t *testing.T) { - l, err := New2Q(128) - if err != nil { - t.Fatalf("err: %v", err) - } - - // Touch all the entries, should be in t1 - for i := 0; i < 128; i++ { - l.Add(i, i) - } - if n := l.recent.Len(); n != 128 { - t.Fatalf("bad: %d", n) - } - if n := l.frequent.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - - // Get should upgrade to t2 - for i := 0; i < 128; i++ { - _, ok := l.Get(i) - if !ok { - t.Fatalf("missing: %d", i) - } - } - if n := l.recent.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if n := l.frequent.Len(); n != 128 { - t.Fatalf("bad: %d", n) - } - - // Get be from t2 - for i := 0; i < 128; i++ { - _, ok := l.Get(i) - if !ok { - t.Fatalf("missing: %d", i) - } - } - if n := l.recent.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if n := l.frequent.Len(); n != 128 { - t.Fatalf("bad: %d", n) - } -} - -func Test2Q_Add_RecentToFrequent(t *testing.T) { - l, err := New2Q(128) - if err != nil { - t.Fatalf("err: %v", err) - } - - // Add initially to recent - l.Add(1, 1) - if n := l.recent.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - if n := l.frequent.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - - // Add should upgrade to frequent - l.Add(1, 1) - if n := l.recent.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if n := l.frequent.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - - // Add should remain in frequent - l.Add(1, 1) - if n := l.recent.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if n := l.frequent.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } -} - -func Test2Q_Add_RecentEvict(t *testing.T) { - l, err := New2Q(4) - if err != nil { - t.Fatalf("err: %v", err) - } - - // Add 1,2,3,4,5 -> Evict 1 - l.Add(1, 1) - l.Add(2, 2) - l.Add(3, 3) - l.Add(4, 4) - l.Add(5, 5) - if n := l.recent.Len(); n != 4 { - t.Fatalf("bad: %d", n) - } - if n := l.recentEvict.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - if n := l.frequent.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - - // Pull in the recently evicted - l.Add(1, 1) - if n := l.recent.Len(); n != 3 { - t.Fatalf("bad: %d", n) - } - if n := l.recentEvict.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - if n := l.frequent.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - - // Add 6, should cause another recent evict - l.Add(6, 6) - if n := l.recent.Len(); n != 3 { - t.Fatalf("bad: %d", n) - } - if n := l.recentEvict.Len(); n != 2 { - t.Fatalf("bad: %d", n) - } - if n := l.frequent.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } -} - -func Test2Q(t *testing.T) { - l, err := New2Q(128) - if err != nil { - t.Fatalf("err: %v", err) - } - - for i := 0; i < 256; i++ { - l.Add(i, i) - } - if l.Len() != 128 { - t.Fatalf("bad len: %v", l.Len()) - } - - for i, k := range l.Keys() { - if v, ok := l.Get(k); !ok || v != k || v != i+128 { - t.Fatalf("bad key: %v", k) - } - } - for i := 0; i < 128; i++ { - _, ok := l.Get(i) - if ok { - t.Fatalf("should be evicted") - } - } - for i := 128; i < 256; i++ { - _, ok := l.Get(i) - if !ok { - t.Fatalf("should not be evicted") - } - } - for i := 128; i < 192; i++ { - l.Remove(i) - _, ok := l.Get(i) - if ok { - t.Fatalf("should be deleted") - } - } - - l.Purge() - if l.Len() != 0 { - t.Fatalf("bad len: %v", l.Len()) - } - if _, ok := l.Get(200); ok { - t.Fatalf("should contain nothing") - } -} - -// Test that Contains doesn't update recent-ness -func Test2Q_Contains(t *testing.T) { - l, err := New2Q(2) - if err != nil { - t.Fatalf("err: %v", err) - } - - l.Add(1, 1) - l.Add(2, 2) - if !l.Contains(1) { - t.Errorf("1 should be contained") - } - - l.Add(3, 3) - if l.Contains(1) { - t.Errorf("Contains should not have updated recent-ness of 1") - } -} - -// Test that Peek doesn't update recent-ness -func Test2Q_Peek(t *testing.T) { - l, err := New2Q(2) - if err != nil { - t.Fatalf("err: %v", err) - } - - l.Add(1, 1) - l.Add(2, 2) - if v, ok := l.Peek(1); !ok || v != 1 { - t.Errorf("1 should be set to 1: %v, %v", v, ok) - } - - l.Add(3, 3) - if l.Contains(1) { - t.Errorf("should not have updated recent-ness of 1") - } -} diff --git a/LICENSE b/LICENSE deleted file mode 100644 index 0e5d580..0000000 --- a/LICENSE +++ /dev/null @@ -1,364 +0,0 @@ -Copyright (c) 2014 HashiCorp, Inc. - -Mozilla Public License, version 2.0 - -1. Definitions - -1.1. "Contributor" - - means each individual or legal entity that creates, contributes to the - creation of, or owns Covered Software. - -1.2. "Contributor Version" - - means the combination of the Contributions of others (if any) used by a - Contributor and that particular Contributor's Contribution. - -1.3. "Contribution" - - means Covered Software of a particular Contributor. - -1.4. "Covered Software" - - means Source Code Form to which the initial Contributor has attached the - notice in Exhibit A, the Executable Form of such Source Code Form, and - Modifications of such Source Code Form, in each case including portions - thereof. - -1.5. "Incompatible With Secondary Licenses" - means - - a. that the initial Contributor has attached the notice described in - Exhibit B to the Covered Software; or - - b. that the Covered Software was made available under the terms of - version 1.1 or earlier of the License, but not also under the terms of - a Secondary License. - -1.6. "Executable Form" - - means any form of the work other than Source Code Form. - -1.7. "Larger Work" - - means a work that combines Covered Software with other material, in a - separate file or files, that is not Covered Software. - -1.8. "License" - - means this document. - -1.9. "Licensable" - - means having the right to grant, to the maximum extent possible, whether - at the time of the initial grant or subsequently, any and all of the - rights conveyed by this License. - -1.10. "Modifications" - - means any of the following: - - a. any file in Source Code Form that results from an addition to, - deletion from, or modification of the contents of Covered Software; or - - b. any new file in Source Code Form that contains any Covered Software. - -1.11. "Patent Claims" of a Contributor - - means any patent claim(s), including without limitation, method, - process, and apparatus claims, in any patent Licensable by such - Contributor that would be infringed, but for the grant of the License, - by the making, using, selling, offering for sale, having made, import, - or transfer of either its Contributions or its Contributor Version. - -1.12. "Secondary License" - - means either the GNU General Public License, Version 2.0, the GNU Lesser - General Public License, Version 2.1, the GNU Affero General Public - License, Version 3.0, or any later versions of those licenses. - -1.13. "Source Code Form" - - means the form of the work preferred for making modifications. - -1.14. "You" (or "Your") - - means an individual or a legal entity exercising rights under this - License. For legal entities, "You" includes any entity that controls, is - controlled by, or is under common control with You. For purposes of this - definition, "control" means (a) the power, direct or indirect, to cause - the direction or management of such entity, whether by contract or - otherwise, or (b) ownership of more than fifty percent (50%) of the - outstanding shares or beneficial ownership of such entity. - - -2. License Grants and Conditions - -2.1. Grants - - Each Contributor hereby grants You a world-wide, royalty-free, - non-exclusive license: - - a. under intellectual property rights (other than patent or trademark) - Licensable by such Contributor to use, reproduce, make available, - modify, display, perform, distribute, and otherwise exploit its - Contributions, either on an unmodified basis, with Modifications, or - as part of a Larger Work; and - - b. under Patent Claims of such Contributor to make, use, sell, offer for - sale, have made, import, and otherwise transfer either its - Contributions or its Contributor Version. - -2.2. Effective Date - - The licenses granted in Section 2.1 with respect to any Contribution - become effective for each Contribution on the date the Contributor first - distributes such Contribution. - -2.3. Limitations on Grant Scope - - The licenses granted in this Section 2 are the only rights granted under - this License. No additional rights or licenses will be implied from the - distribution or licensing of Covered Software under this License. - Notwithstanding Section 2.1(b) above, no patent license is granted by a - Contributor: - - a. for any code that a Contributor has removed from Covered Software; or - - b. for infringements caused by: (i) Your and any other third party's - modifications of Covered Software, or (ii) the combination of its - Contributions with other software (except as part of its Contributor - Version); or - - c. under Patent Claims infringed by Covered Software in the absence of - its Contributions. - - This License does not grant any rights in the trademarks, service marks, - or logos of any Contributor (except as may be necessary to comply with - the notice requirements in Section 3.4). - -2.4. Subsequent Licenses - - No Contributor makes additional grants as a result of Your choice to - distribute the Covered Software under a subsequent version of this - License (see Section 10.2) or under the terms of a Secondary License (if - permitted under the terms of Section 3.3). - -2.5. Representation - - Each Contributor represents that the Contributor believes its - Contributions are its original creation(s) or it has sufficient rights to - grant the rights to its Contributions conveyed by this License. - -2.6. Fair Use - - This License is not intended to limit any rights You have under - applicable copyright doctrines of fair use, fair dealing, or other - equivalents. - -2.7. Conditions - - Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted in - Section 2.1. - - -3. Responsibilities - -3.1. Distribution of Source Form - - All distribution of Covered Software in Source Code Form, including any - Modifications that You create or to which You contribute, must be under - the terms of this License. You must inform recipients that the Source - Code Form of the Covered Software is governed by the terms of this - License, and how they can obtain a copy of this License. You may not - attempt to alter or restrict the recipients' rights in the Source Code - Form. - -3.2. Distribution of Executable Form - - If You distribute Covered Software in Executable Form then: - - a. such Covered Software must also be made available in Source Code Form, - as described in Section 3.1, and You must inform recipients of the - Executable Form how they can obtain a copy of such Source Code Form by - reasonable means in a timely manner, at a charge no more than the cost - of distribution to the recipient; and - - b. You may distribute such Executable Form under the terms of this - License, or sublicense it under different terms, provided that the - license for the Executable Form does not attempt to limit or alter the - recipients' rights in the Source Code Form under this License. - -3.3. Distribution of a Larger Work - - You may create and distribute a Larger Work under terms of Your choice, - provided that You also comply with the requirements of this License for - the Covered Software. If the Larger Work is a combination of Covered - Software with a work governed by one or more Secondary Licenses, and the - Covered Software is not Incompatible With Secondary Licenses, this - License permits You to additionally distribute such Covered Software - under the terms of such Secondary License(s), so that the recipient of - the Larger Work may, at their option, further distribute the Covered - Software under the terms of either this License or such Secondary - License(s). - -3.4. Notices - - You may not remove or alter the substance of any license notices - (including copyright notices, patent notices, disclaimers of warranty, or - limitations of liability) contained within the Source Code Form of the - Covered Software, except that You may alter any license notices to the - extent required to remedy known factual inaccuracies. - -3.5. Application of Additional Terms - - You may choose to offer, and to charge a fee for, warranty, support, - indemnity or liability obligations to one or more recipients of Covered - Software. However, You may do so only on Your own behalf, and not on - behalf of any Contributor. You must make it absolutely clear that any - such warranty, support, indemnity, or liability obligation is offered by - You alone, and You hereby agree to indemnify every Contributor for any - liability incurred by such Contributor as a result of warranty, support, - indemnity or liability terms You offer. You may include additional - disclaimers of warranty and limitations of liability specific to any - jurisdiction. - -4. Inability to Comply Due to Statute or Regulation - - If it is impossible for You to comply with any of the terms of this License - with respect to some or all of the Covered Software due to statute, - judicial order, or regulation then You must: (a) comply with the terms of - this License to the maximum extent possible; and (b) describe the - limitations and the code they affect. Such description must be placed in a - text file included with all distributions of the Covered Software under - this License. Except to the extent prohibited by statute or regulation, - such description must be sufficiently detailed for a recipient of ordinary - skill to be able to understand it. - -5. Termination - -5.1. The rights granted under this License will terminate automatically if You - fail to comply with any of its terms. However, if You become compliant, - then the rights granted under this License from a particular Contributor - are reinstated (a) provisionally, unless and until such Contributor - explicitly and finally terminates Your grants, and (b) on an ongoing - basis, if such Contributor fails to notify You of the non-compliance by - some reasonable means prior to 60 days after You have come back into - compliance. Moreover, Your grants from a particular Contributor are - reinstated on an ongoing basis if such Contributor notifies You of the - non-compliance by some reasonable means, this is the first time You have - received notice of non-compliance with this License from such - Contributor, and You become compliant prior to 30 days after Your receipt - of the notice. - -5.2. If You initiate litigation against any entity by asserting a patent - infringement claim (excluding declaratory judgment actions, - counter-claims, and cross-claims) alleging that a Contributor Version - directly or indirectly infringes any patent, then the rights granted to - You by any and all Contributors for the Covered Software under Section - 2.1 of this License shall terminate. - -5.3. In the event of termination under Sections 5.1 or 5.2 above, all end user - license agreements (excluding distributors and resellers) which have been - validly granted by You or Your distributors under this License prior to - termination shall survive termination. - -6. Disclaimer of Warranty - - Covered Software is provided under this License on an "as is" basis, - without warranty of any kind, either expressed, implied, or statutory, - including, without limitation, warranties that the Covered Software is free - of defects, merchantable, fit for a particular purpose or non-infringing. - The entire risk as to the quality and performance of the Covered Software - is with You. Should any Covered Software prove defective in any respect, - You (not any Contributor) assume the cost of any necessary servicing, - repair, or correction. This disclaimer of warranty constitutes an essential - part of this License. No use of any Covered Software is authorized under - this License except under this disclaimer. - -7. Limitation of Liability - - Under no circumstances and under no legal theory, whether tort (including - negligence), contract, or otherwise, shall any Contributor, or anyone who - distributes Covered Software as permitted above, be liable to You for any - direct, indirect, special, incidental, or consequential damages of any - character including, without limitation, damages for lost profits, loss of - goodwill, work stoppage, computer failure or malfunction, or any and all - other commercial damages or losses, even if such party shall have been - informed of the possibility of such damages. This limitation of liability - shall not apply to liability for death or personal injury resulting from - such party's negligence to the extent applicable law prohibits such - limitation. Some jurisdictions do not allow the exclusion or limitation of - incidental or consequential damages, so this exclusion and limitation may - not apply to You. - -8. Litigation - - Any litigation relating to this License may be brought only in the courts - of a jurisdiction where the defendant maintains its principal place of - business and such litigation shall be governed by laws of that - jurisdiction, without reference to its conflict-of-law provisions. Nothing - in this Section shall prevent a party's ability to bring cross-claims or - counter-claims. - -9. Miscellaneous - - This License represents the complete agreement concerning the subject - matter hereof. If any provision of this License is held to be - unenforceable, such provision shall be reformed only to the extent - necessary to make it enforceable. Any law or regulation which provides that - the language of a contract shall be construed against the drafter shall not - be used to construe this License against a Contributor. - - -10. Versions of the License - -10.1. New Versions - - Mozilla Foundation is the license steward. Except as provided in Section - 10.3, no one other than the license steward has the right to modify or - publish new versions of this License. Each version will be given a - distinguishing version number. - -10.2. Effect of New Versions - - You may distribute the Covered Software under the terms of the version - of the License under which You originally received the Covered Software, - or under the terms of any subsequent version published by the license - steward. - -10.3. Modified Versions - - If you create software not governed by this License, and you want to - create a new license for such software, you may create and use a - modified version of this License if you rename the license and remove - any references to the name of the license steward (except to note that - such modified license differs from this License). - -10.4. Distributing Source Code Form that is Incompatible With Secondary - Licenses If You choose to distribute Source Code Form that is - Incompatible With Secondary Licenses under the terms of this version of - the License, the notice described in Exhibit B of this License must be - attached. - -Exhibit A - Source Code Form License Notice - - This Source Code Form is subject to the - terms of the Mozilla Public License, v. - 2.0. If a copy of the MPL was not - distributed with this file, You can - obtain one at - http://mozilla.org/MPL/2.0/. - -If it is not possible or desirable to put the notice in a particular file, -then You may include the notice in a location (such as a LICENSE file in a -relevant directory) where a recipient would be likely to look for such a -notice. - -You may add additional accurate notices of copyright ownership. - -Exhibit B - "Incompatible With Secondary Licenses" Notice - - This Source Code Form is "Incompatible - With Secondary Licenses", as defined by - the Mozilla Public License, v. 2.0. diff --git a/README.md b/README.md index 063bb16..591a0b8 100644 --- a/README.md +++ b/README.md @@ -1,25 +1,6 @@ golang-lru ========== -This provides the `lru` package which implements a fixed-size -thread safe LRU cache. It is based on the cache in Groupcache. - -Documentation -============= - -Full docs are available on [Godoc](https://pkg.go.dev/github.com/hashicorp/golang-lru) - -Example -======= - -Using the LRU is very simple: - -```go -l, _ := New(128) -for i := 0; i < 256; i++ { - l.Add(i, nil) -} -if l.Len() != 128 { - panic(fmt.Sprintf("bad len: %v", l.Len())) -} -``` +Please use `github.com/hashicorp/golang-lru/v2` for all new code as this +version supports generics and is faster; old code can specify a specific tag, +e.g. `github.com/hashicorp/golang-lru/v0.6.0` for backwards compatibility. diff --git a/arc.go b/arc.go deleted file mode 100644 index e396f84..0000000 --- a/arc.go +++ /dev/null @@ -1,256 +0,0 @@ -package lru - -import ( - "sync" - - "github.com/hashicorp/golang-lru/simplelru" -) - -// ARCCache is a thread-safe fixed size Adaptive Replacement Cache (ARC). -// ARC is an enhancement over the standard LRU cache in that tracks both -// frequency and recency of use. This avoids a burst in access to new -// entries from evicting the frequently used older entries. It adds some -// additional tracking overhead to a standard LRU cache, computationally -// it is roughly 2x the cost, and the extra memory overhead is linear -// with the size of the cache. ARC has been patented by IBM, but is -// similar to the TwoQueueCache (2Q) which requires setting parameters. -type ARCCache struct { - size int // Size is the total capacity of the cache - p int // P is the dynamic preference towards T1 or T2 - - t1 simplelru.LRUCache // T1 is the LRU for recently accessed items - b1 simplelru.LRUCache // B1 is the LRU for evictions from t1 - - t2 simplelru.LRUCache // T2 is the LRU for frequently accessed items - b2 simplelru.LRUCache // B2 is the LRU for evictions from t2 - - lock sync.RWMutex -} - -// NewARC creates an ARC of the given size -func NewARC(size int) (*ARCCache, error) { - // Create the sub LRUs - b1, err := simplelru.NewLRU(size, nil) - if err != nil { - return nil, err - } - b2, err := simplelru.NewLRU(size, nil) - if err != nil { - return nil, err - } - t1, err := simplelru.NewLRU(size, nil) - if err != nil { - return nil, err - } - t2, err := simplelru.NewLRU(size, nil) - if err != nil { - return nil, err - } - - // Initialize the ARC - c := &ARCCache{ - size: size, - p: 0, - t1: t1, - b1: b1, - t2: t2, - b2: b2, - } - return c, nil -} - -// Get looks up a key's value from the cache. -func (c *ARCCache) Get(key interface{}) (value interface{}, ok bool) { - c.lock.Lock() - defer c.lock.Unlock() - - // If the value is contained in T1 (recent), then - // promote it to T2 (frequent) - if val, ok := c.t1.Peek(key); ok { - c.t1.Remove(key) - c.t2.Add(key, val) - return val, ok - } - - // Check if the value is contained in T2 (frequent) - if val, ok := c.t2.Get(key); ok { - return val, ok - } - - // No hit - return nil, false -} - -// Add adds a value to the cache. -func (c *ARCCache) Add(key, value interface{}) { - c.lock.Lock() - defer c.lock.Unlock() - - // Check if the value is contained in T1 (recent), and potentially - // promote it to frequent T2 - if c.t1.Contains(key) { - c.t1.Remove(key) - c.t2.Add(key, value) - return - } - - // Check if the value is already in T2 (frequent) and update it - if c.t2.Contains(key) { - c.t2.Add(key, value) - return - } - - // Check if this value was recently evicted as part of the - // recently used list - if c.b1.Contains(key) { - // T1 set is too small, increase P appropriately - delta := 1 - b1Len := c.b1.Len() - b2Len := c.b2.Len() - if b2Len > b1Len { - delta = b2Len / b1Len - } - if c.p+delta >= c.size { - c.p = c.size - } else { - c.p += delta - } - - // Potentially need to make room in the cache - if c.t1.Len()+c.t2.Len() >= c.size { - c.replace(false) - } - - // Remove from B1 - c.b1.Remove(key) - - // Add the key to the frequently used list - c.t2.Add(key, value) - return - } - - // Check if this value was recently evicted as part of the - // frequently used list - if c.b2.Contains(key) { - // T2 set is too small, decrease P appropriately - delta := 1 - b1Len := c.b1.Len() - b2Len := c.b2.Len() - if b1Len > b2Len { - delta = b1Len / b2Len - } - if delta >= c.p { - c.p = 0 - } else { - c.p -= delta - } - - // Potentially need to make room in the cache - if c.t1.Len()+c.t2.Len() >= c.size { - c.replace(true) - } - - // Remove from B2 - c.b2.Remove(key) - - // Add the key to the frequently used list - c.t2.Add(key, value) - return - } - - // Potentially need to make room in the cache - if c.t1.Len()+c.t2.Len() >= c.size { - c.replace(false) - } - - // Keep the size of the ghost buffers trim - if c.b1.Len() > c.size-c.p { - c.b1.RemoveOldest() - } - if c.b2.Len() > c.p { - c.b2.RemoveOldest() - } - - // Add to the recently seen list - c.t1.Add(key, value) -} - -// replace is used to adaptively evict from either T1 or T2 -// based on the current learned value of P -func (c *ARCCache) replace(b2ContainsKey bool) { - t1Len := c.t1.Len() - if t1Len > 0 && (t1Len > c.p || (t1Len == c.p && b2ContainsKey)) { - k, _, ok := c.t1.RemoveOldest() - if ok { - c.b1.Add(k, nil) - } - } else { - k, _, ok := c.t2.RemoveOldest() - if ok { - c.b2.Add(k, nil) - } - } -} - -// Len returns the number of cached entries -func (c *ARCCache) Len() int { - c.lock.RLock() - defer c.lock.RUnlock() - return c.t1.Len() + c.t2.Len() -} - -// Keys returns all the cached keys -func (c *ARCCache) Keys() []interface{} { - c.lock.RLock() - defer c.lock.RUnlock() - k1 := c.t1.Keys() - k2 := c.t2.Keys() - return append(k1, k2...) -} - -// Remove is used to purge a key from the cache -func (c *ARCCache) Remove(key interface{}) { - c.lock.Lock() - defer c.lock.Unlock() - if c.t1.Remove(key) { - return - } - if c.t2.Remove(key) { - return - } - if c.b1.Remove(key) { - return - } - if c.b2.Remove(key) { - return - } -} - -// Purge is used to clear the cache -func (c *ARCCache) Purge() { - c.lock.Lock() - defer c.lock.Unlock() - c.t1.Purge() - c.t2.Purge() - c.b1.Purge() - c.b2.Purge() -} - -// Contains is used to check if the cache contains a key -// without updating recency or frequency. -func (c *ARCCache) Contains(key interface{}) bool { - c.lock.RLock() - defer c.lock.RUnlock() - return c.t1.Contains(key) || c.t2.Contains(key) -} - -// Peek is used to inspect the cache value of a key -// without updating recency or frequency. -func (c *ARCCache) Peek(key interface{}) (value interface{}, ok bool) { - c.lock.RLock() - defer c.lock.RUnlock() - if val, ok := c.t1.Peek(key); ok { - return val, ok - } - return c.t2.Peek(key) -} diff --git a/arc_test.go b/arc_test.go deleted file mode 100644 index 98402b5..0000000 --- a/arc_test.go +++ /dev/null @@ -1,377 +0,0 @@ -package lru - -import ( - "math/rand" - "testing" - "time" -) - -func init() { - rand.Seed(time.Now().Unix()) -} - -func BenchmarkARC_Rand(b *testing.B) { - l, err := NewARC(8192) - if err != nil { - b.Fatalf("err: %v", err) - } - - trace := make([]int64, b.N*2) - for i := 0; i < b.N*2; i++ { - trace[i] = getRand(b) % 32768 - } - - b.ResetTimer() - - var hit, miss int - for i := 0; i < 2*b.N; i++ { - if i%2 == 0 { - l.Add(trace[i], trace[i]) - } else { - _, ok := l.Get(trace[i]) - if ok { - hit++ - } else { - miss++ - } - } - } - b.Logf("hit: %d miss: %d ratio: %f", hit, miss, float64(hit)/float64(miss)) -} - -func BenchmarkARC_Freq(b *testing.B) { - l, err := NewARC(8192) - if err != nil { - b.Fatalf("err: %v", err) - } - - trace := make([]int64, b.N*2) - for i := 0; i < b.N*2; i++ { - if i%2 == 0 { - trace[i] = getRand(b) % 16384 - } else { - trace[i] = getRand(b) % 32768 - } - } - - b.ResetTimer() - - for i := 0; i < b.N; i++ { - l.Add(trace[i], trace[i]) - } - var hit, miss int - for i := 0; i < b.N; i++ { - _, ok := l.Get(trace[i]) - if ok { - hit++ - } else { - miss++ - } - } - b.Logf("hit: %d miss: %d ratio: %f", hit, miss, float64(hit)/float64(miss)) -} - -func TestARC_RandomOps(t *testing.T) { - size := 128 - l, err := NewARC(128) - if err != nil { - t.Fatalf("err: %v", err) - } - - n := 200000 - for i := 0; i < n; i++ { - key := getRand(t) % 512 - r := getRand(t) - switch r % 3 { - case 0: - l.Add(key, key) - case 1: - l.Get(key) - case 2: - l.Remove(key) - } - - if l.t1.Len()+l.t2.Len() > size { - t.Fatalf("bad: t1: %d t2: %d b1: %d b2: %d p: %d", - l.t1.Len(), l.t2.Len(), l.b1.Len(), l.b2.Len(), l.p) - } - if l.b1.Len()+l.b2.Len() > size { - t.Fatalf("bad: t1: %d t2: %d b1: %d b2: %d p: %d", - l.t1.Len(), l.t2.Len(), l.b1.Len(), l.b2.Len(), l.p) - } - } -} - -func TestARC_Get_RecentToFrequent(t *testing.T) { - l, err := NewARC(128) - if err != nil { - t.Fatalf("err: %v", err) - } - - // Touch all the entries, should be in t1 - for i := 0; i < 128; i++ { - l.Add(i, i) - } - if n := l.t1.Len(); n != 128 { - t.Fatalf("bad: %d", n) - } - if n := l.t2.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - - // Get should upgrade to t2 - for i := 0; i < 128; i++ { - _, ok := l.Get(i) - if !ok { - t.Fatalf("missing: %d", i) - } - } - if n := l.t1.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if n := l.t2.Len(); n != 128 { - t.Fatalf("bad: %d", n) - } - - // Get be from t2 - for i := 0; i < 128; i++ { - _, ok := l.Get(i) - if !ok { - t.Fatalf("missing: %d", i) - } - } - if n := l.t1.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if n := l.t2.Len(); n != 128 { - t.Fatalf("bad: %d", n) - } -} - -func TestARC_Add_RecentToFrequent(t *testing.T) { - l, err := NewARC(128) - if err != nil { - t.Fatalf("err: %v", err) - } - - // Add initially to t1 - l.Add(1, 1) - if n := l.t1.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - if n := l.t2.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - - // Add should upgrade to t2 - l.Add(1, 1) - if n := l.t1.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if n := l.t2.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - - // Add should remain in t2 - l.Add(1, 1) - if n := l.t1.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if n := l.t2.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } -} - -func TestARC_Adaptive(t *testing.T) { - l, err := NewARC(4) - if err != nil { - t.Fatalf("err: %v", err) - } - - // Fill t1 - for i := 0; i < 4; i++ { - l.Add(i, i) - } - if n := l.t1.Len(); n != 4 { - t.Fatalf("bad: %d", n) - } - - // Move to t2 - l.Get(0) - l.Get(1) - if n := l.t2.Len(); n != 2 { - t.Fatalf("bad: %d", n) - } - - // Evict from t1 - l.Add(4, 4) - if n := l.b1.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - - // Current state - // t1 : (MRU) [4, 3] (LRU) - // t2 : (MRU) [1, 0] (LRU) - // b1 : (MRU) [2] (LRU) - // b2 : (MRU) [] (LRU) - - // Add 2, should cause hit on b1 - l.Add(2, 2) - if n := l.b1.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - if l.p != 1 { - t.Fatalf("bad: %d", l.p) - } - if n := l.t2.Len(); n != 3 { - t.Fatalf("bad: %d", n) - } - - // Current state - // t1 : (MRU) [4] (LRU) - // t2 : (MRU) [2, 1, 0] (LRU) - // b1 : (MRU) [3] (LRU) - // b2 : (MRU) [] (LRU) - - // Add 4, should migrate to t2 - l.Add(4, 4) - if n := l.t1.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if n := l.t2.Len(); n != 4 { - t.Fatalf("bad: %d", n) - } - - // Current state - // t1 : (MRU) [] (LRU) - // t2 : (MRU) [4, 2, 1, 0] (LRU) - // b1 : (MRU) [3] (LRU) - // b2 : (MRU) [] (LRU) - - // Add 4, should evict to b2 - l.Add(5, 5) - if n := l.t1.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - if n := l.t2.Len(); n != 3 { - t.Fatalf("bad: %d", n) - } - if n := l.b2.Len(); n != 1 { - t.Fatalf("bad: %d", n) - } - - // Current state - // t1 : (MRU) [5] (LRU) - // t2 : (MRU) [4, 2, 1] (LRU) - // b1 : (MRU) [3] (LRU) - // b2 : (MRU) [0] (LRU) - - // Add 0, should decrease p - l.Add(0, 0) - if n := l.t1.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if n := l.t2.Len(); n != 4 { - t.Fatalf("bad: %d", n) - } - if n := l.b1.Len(); n != 2 { - t.Fatalf("bad: %d", n) - } - if n := l.b2.Len(); n != 0 { - t.Fatalf("bad: %d", n) - } - if l.p != 0 { - t.Fatalf("bad: %d", l.p) - } - - // Current state - // t1 : (MRU) [] (LRU) - // t2 : (MRU) [0, 4, 2, 1] (LRU) - // b1 : (MRU) [5, 3] (LRU) - // b2 : (MRU) [0] (LRU) -} - -func TestARC(t *testing.T) { - l, err := NewARC(128) - if err != nil { - t.Fatalf("err: %v", err) - } - - for i := 0; i < 256; i++ { - l.Add(i, i) - } - if l.Len() != 128 { - t.Fatalf("bad len: %v", l.Len()) - } - - for i, k := range l.Keys() { - if v, ok := l.Get(k); !ok || v != k || v != i+128 { - t.Fatalf("bad key: %v", k) - } - } - for i := 0; i < 128; i++ { - _, ok := l.Get(i) - if ok { - t.Fatalf("should be evicted") - } - } - for i := 128; i < 256; i++ { - _, ok := l.Get(i) - if !ok { - t.Fatalf("should not be evicted") - } - } - for i := 128; i < 192; i++ { - l.Remove(i) - _, ok := l.Get(i) - if ok { - t.Fatalf("should be deleted") - } - } - - l.Purge() - if l.Len() != 0 { - t.Fatalf("bad len: %v", l.Len()) - } - if _, ok := l.Get(200); ok { - t.Fatalf("should contain nothing") - } -} - -// Test that Contains doesn't update recent-ness -func TestARC_Contains(t *testing.T) { - l, err := NewARC(2) - if err != nil { - t.Fatalf("err: %v", err) - } - - l.Add(1, 1) - l.Add(2, 2) - if !l.Contains(1) { - t.Errorf("1 should be contained") - } - - l.Add(3, 3) - if l.Contains(1) { - t.Errorf("Contains should not have updated recent-ness of 1") - } -} - -// Test that Peek doesn't update recent-ness -func TestARC_Peek(t *testing.T) { - l, err := NewARC(2) - if err != nil { - t.Fatalf("err: %v", err) - } - - l.Add(1, 1) - l.Add(2, 2) - if v, ok := l.Peek(1); !ok || v != 1 { - t.Errorf("1 should be set to 1: %v, %v", v, ok) - } - - l.Add(3, 3) - if l.Contains(1) { - t.Errorf("should not have updated recent-ness of 1") - } -} diff --git a/doc.go b/doc.go deleted file mode 100644 index 2547df9..0000000 --- a/doc.go +++ /dev/null @@ -1,21 +0,0 @@ -// Package lru provides three different LRU caches of varying sophistication. -// -// Cache is a simple LRU cache. It is based on the -// LRU implementation in groupcache: -// https://github.com/golang/groupcache/tree/master/lru -// -// TwoQueueCache tracks frequently used and recently used entries separately. -// This avoids a burst of accesses from taking out frequently used entries, -// at the cost of about 2x computational overhead and some extra bookkeeping. -// -// ARCCache is an adaptive replacement cache. It tracks recent evictions as -// well as recent usage in both the frequent and recent caches. Its -// computational overhead is comparable to TwoQueueCache, but the memory -// overhead is linear with the size of the cache. -// -// ARC has been patented by IBM, so do not use it if that is problematic for -// your program. -// -// All caches in this package take locks while operating, and are therefore -// thread-safe for consumers. -package lru diff --git a/lru.go b/lru.go deleted file mode 100644 index 895d8e3..0000000 --- a/lru.go +++ /dev/null @@ -1,231 +0,0 @@ -package lru - -import ( - "sync" - - "github.com/hashicorp/golang-lru/simplelru" -) - -const ( - // DefaultEvictedBufferSize defines the default buffer size to store evicted key/val - DefaultEvictedBufferSize = 16 -) - -// Cache is a thread-safe fixed size LRU cache. -type Cache struct { - lru *simplelru.LRU - evictedKeys, evictedVals []interface{} - onEvictedCB func(k, v interface{}) - lock sync.RWMutex -} - -// New creates an LRU of the given size. -func New(size int) (*Cache, error) { - return NewWithEvict(size, nil) -} - -// NewWithEvict constructs a fixed size cache with the given eviction -// callback. -func NewWithEvict(size int, onEvicted func(key, value interface{})) (c *Cache, err error) { - // create a cache with default settings - c = &Cache{ - onEvictedCB: onEvicted, - } - if onEvicted != nil { - c.initEvictBuffers() - onEvicted = c.onEvicted - } - c.lru, err = simplelru.NewLRU(size, onEvicted) - return -} - -func (c *Cache) initEvictBuffers() { - c.evictedKeys = make([]interface{}, 0, DefaultEvictedBufferSize) - c.evictedVals = make([]interface{}, 0, DefaultEvictedBufferSize) -} - -// onEvicted save evicted key/val and sent in externally registered callback -// outside of critical section -func (c *Cache) onEvicted(k, v interface{}) { - c.evictedKeys = append(c.evictedKeys, k) - c.evictedVals = append(c.evictedVals, v) -} - -// Purge is used to completely clear the cache. -func (c *Cache) Purge() { - var ks, vs []interface{} - c.lock.Lock() - c.lru.Purge() - if c.onEvictedCB != nil && len(c.evictedKeys) > 0 { - ks, vs = c.evictedKeys, c.evictedVals - c.initEvictBuffers() - } - c.lock.Unlock() - // invoke callback outside of critical section - if c.onEvictedCB != nil { - for i := 0; i < len(ks); i++ { - c.onEvictedCB(ks[i], vs[i]) - } - } -} - -// Add adds a value to the cache. Returns true if an eviction occurred. -func (c *Cache) Add(key, value interface{}) (evicted bool) { - var k, v interface{} - c.lock.Lock() - evicted = c.lru.Add(key, value) - if c.onEvictedCB != nil && evicted { - k, v = c.evictedKeys[0], c.evictedVals[0] - c.evictedKeys, c.evictedVals = c.evictedKeys[:0], c.evictedVals[:0] - } - c.lock.Unlock() - if c.onEvictedCB != nil && evicted { - c.onEvictedCB(k, v) - } - return -} - -// Get looks up a key's value from the cache. -func (c *Cache) Get(key interface{}) (value interface{}, ok bool) { - c.lock.Lock() - value, ok = c.lru.Get(key) - c.lock.Unlock() - return value, ok -} - -// Contains checks if a key is in the cache, without updating the -// recent-ness or deleting it for being stale. -func (c *Cache) Contains(key interface{}) bool { - c.lock.RLock() - containKey := c.lru.Contains(key) - c.lock.RUnlock() - return containKey -} - -// Peek returns the key value (or undefined if not found) without updating -// the "recently used"-ness of the key. -func (c *Cache) Peek(key interface{}) (value interface{}, ok bool) { - c.lock.RLock() - value, ok = c.lru.Peek(key) - c.lock.RUnlock() - return value, ok -} - -// ContainsOrAdd checks if a key is in the cache without updating the -// recent-ness or deleting it for being stale, and if not, adds the value. -// Returns whether found and whether an eviction occurred. -func (c *Cache) ContainsOrAdd(key, value interface{}) (ok, evicted bool) { - var k, v interface{} - c.lock.Lock() - if c.lru.Contains(key) { - c.lock.Unlock() - return true, false - } - evicted = c.lru.Add(key, value) - if c.onEvictedCB != nil && evicted { - k, v = c.evictedKeys[0], c.evictedVals[0] - c.evictedKeys, c.evictedVals = c.evictedKeys[:0], c.evictedVals[:0] - } - c.lock.Unlock() - if c.onEvictedCB != nil && evicted { - c.onEvictedCB(k, v) - } - return false, evicted -} - -// PeekOrAdd checks if a key is in the cache without updating the -// recent-ness or deleting it for being stale, and if not, adds the value. -// Returns whether found and whether an eviction occurred. -func (c *Cache) PeekOrAdd(key, value interface{}) (previous interface{}, ok, evicted bool) { - var k, v interface{} - c.lock.Lock() - previous, ok = c.lru.Peek(key) - if ok { - c.lock.Unlock() - return previous, true, false - } - evicted = c.lru.Add(key, value) - if c.onEvictedCB != nil && evicted { - k, v = c.evictedKeys[0], c.evictedVals[0] - c.evictedKeys, c.evictedVals = c.evictedKeys[:0], c.evictedVals[:0] - } - c.lock.Unlock() - if c.onEvictedCB != nil && evicted { - c.onEvictedCB(k, v) - } - return nil, false, evicted -} - -// Remove removes the provided key from the cache. -func (c *Cache) Remove(key interface{}) (present bool) { - var k, v interface{} - c.lock.Lock() - present = c.lru.Remove(key) - if c.onEvictedCB != nil && present { - k, v = c.evictedKeys[0], c.evictedVals[0] - c.evictedKeys, c.evictedVals = c.evictedKeys[:0], c.evictedVals[:0] - } - c.lock.Unlock() - if c.onEvictedCB != nil && present { - c.onEvictedCB(k, v) - } - return -} - -// Resize changes the cache size. -func (c *Cache) Resize(size int) (evicted int) { - var ks, vs []interface{} - c.lock.Lock() - evicted = c.lru.Resize(size) - if c.onEvictedCB != nil && evicted > 0 { - ks, vs = c.evictedKeys, c.evictedVals - c.initEvictBuffers() - } - c.lock.Unlock() - if c.onEvictedCB != nil && evicted > 0 { - for i := 0; i < len(ks); i++ { - c.onEvictedCB(ks[i], vs[i]) - } - } - return evicted -} - -// RemoveOldest removes the oldest item from the cache. -func (c *Cache) RemoveOldest() (key, value interface{}, ok bool) { - var k, v interface{} - c.lock.Lock() - key, value, ok = c.lru.RemoveOldest() - if c.onEvictedCB != nil && ok { - k, v = c.evictedKeys[0], c.evictedVals[0] - c.evictedKeys, c.evictedVals = c.evictedKeys[:0], c.evictedVals[:0] - } - c.lock.Unlock() - if c.onEvictedCB != nil && ok { - c.onEvictedCB(k, v) - } - return -} - -// GetOldest returns the oldest entry -func (c *Cache) GetOldest() (key, value interface{}, ok bool) { - c.lock.RLock() - key, value, ok = c.lru.GetOldest() - c.lock.RUnlock() - return -} - -// Keys returns a slice of the keys in the cache, from oldest to newest. -func (c *Cache) Keys() []interface{} { - c.lock.RLock() - keys := c.lru.Keys() - c.lock.RUnlock() - return keys -} - -// Len returns the number of items in the cache. -func (c *Cache) Len() int { - c.lock.RLock() - length := c.lru.Len() - c.lock.RUnlock() - return length -} diff --git a/lru_test.go b/lru_test.go deleted file mode 100644 index b81705b..0000000 --- a/lru_test.go +++ /dev/null @@ -1,292 +0,0 @@ -package lru - -import ( - "testing" -) - -func BenchmarkLRU_Rand(b *testing.B) { - l, err := New(8192) - if err != nil { - b.Fatalf("err: %v", err) - } - - trace := make([]int64, b.N*2) - for i := 0; i < b.N*2; i++ { - trace[i] = getRand(b) % 32768 - } - - b.ResetTimer() - - var hit, miss int - for i := 0; i < 2*b.N; i++ { - if i%2 == 0 { - l.Add(trace[i], trace[i]) - } else { - _, ok := l.Get(trace[i]) - if ok { - hit++ - } else { - miss++ - } - } - } - b.Logf("hit: %d miss: %d ratio: %f", hit, miss, float64(hit)/float64(miss)) -} - -func BenchmarkLRU_Freq(b *testing.B) { - l, err := New(8192) - if err != nil { - b.Fatalf("err: %v", err) - } - - trace := make([]int64, b.N*2) - for i := 0; i < b.N*2; i++ { - if i%2 == 0 { - trace[i] = getRand(b) % 16384 - } else { - trace[i] = getRand(b) % 32768 - } - } - - b.ResetTimer() - - for i := 0; i < b.N; i++ { - l.Add(trace[i], trace[i]) - } - var hit, miss int - for i := 0; i < b.N; i++ { - _, ok := l.Get(trace[i]) - if ok { - hit++ - } else { - miss++ - } - } - b.Logf("hit: %d miss: %d ratio: %f", hit, miss, float64(hit)/float64(miss)) -} - -func TestLRU(t *testing.T) { - evictCounter := 0 - onEvicted := func(k interface{}, v interface{}) { - if k != v { - t.Fatalf("Evict values not equal (%v!=%v)", k, v) - } - evictCounter++ - } - l, err := NewWithEvict(128, onEvicted) - if err != nil { - t.Fatalf("err: %v", err) - } - - for i := 0; i < 256; i++ { - l.Add(i, i) - } - if l.Len() != 128 { - t.Fatalf("bad len: %v", l.Len()) - } - - if evictCounter != 128 { - t.Fatalf("bad evict count: %v", evictCounter) - } - - for i, k := range l.Keys() { - if v, ok := l.Get(k); !ok || v != k || v != i+128 { - t.Fatalf("bad key: %v", k) - } - } - for i := 0; i < 128; i++ { - _, ok := l.Get(i) - if ok { - t.Fatalf("should be evicted") - } - } - for i := 128; i < 256; i++ { - _, ok := l.Get(i) - if !ok { - t.Fatalf("should not be evicted") - } - } - for i := 128; i < 192; i++ { - l.Remove(i) - _, ok := l.Get(i) - if ok { - t.Fatalf("should be deleted") - } - } - - l.Get(192) // expect 192 to be last key in l.Keys() - - for i, k := range l.Keys() { - if (i < 63 && k != i+193) || (i == 63 && k != 192) { - t.Fatalf("out of order key: %v", k) - } - } - - l.Purge() - if l.Len() != 0 { - t.Fatalf("bad len: %v", l.Len()) - } - if _, ok := l.Get(200); ok { - t.Fatalf("should contain nothing") - } -} - -// test that Add returns true/false if an eviction occurred -func TestLRUAdd(t *testing.T) { - evictCounter := 0 - onEvicted := func(k interface{}, v interface{}) { - evictCounter++ - } - - l, err := NewWithEvict(1, onEvicted) - if err != nil { - t.Fatalf("err: %v", err) - } - - if l.Add(1, 1) == true || evictCounter != 0 { - t.Errorf("should not have an eviction") - } - if l.Add(2, 2) == false || evictCounter != 1 { - t.Errorf("should have an eviction") - } -} - -// test that Contains doesn't update recent-ness -func TestLRUContains(t *testing.T) { - l, err := New(2) - if err != nil { - t.Fatalf("err: %v", err) - } - - l.Add(1, 1) - l.Add(2, 2) - if !l.Contains(1) { - t.Errorf("1 should be contained") - } - - l.Add(3, 3) - if l.Contains(1) { - t.Errorf("Contains should not have updated recent-ness of 1") - } -} - -// test that ContainsOrAdd doesn't update recent-ness -func TestLRUContainsOrAdd(t *testing.T) { - l, err := New(2) - if err != nil { - t.Fatalf("err: %v", err) - } - - l.Add(1, 1) - l.Add(2, 2) - contains, evict := l.ContainsOrAdd(1, 1) - if !contains { - t.Errorf("1 should be contained") - } - if evict { - t.Errorf("nothing should be evicted here") - } - - l.Add(3, 3) - contains, evict = l.ContainsOrAdd(1, 1) - if contains { - t.Errorf("1 should not have been contained") - } - if !evict { - t.Errorf("an eviction should have occurred") - } - if !l.Contains(1) { - t.Errorf("now 1 should be contained") - } -} - -// test that PeekOrAdd doesn't update recent-ness -func TestLRUPeekOrAdd(t *testing.T) { - l, err := New(2) - if err != nil { - t.Fatalf("err: %v", err) - } - - l.Add(1, 1) - l.Add(2, 2) - previous, contains, evict := l.PeekOrAdd(1, 1) - if !contains { - t.Errorf("1 should be contained") - } - if evict { - t.Errorf("nothing should be evicted here") - } - if previous != 1 { - t.Errorf("previous is not equal to 1") - } - - l.Add(3, 3) - contains, evict = l.ContainsOrAdd(1, 1) - if contains { - t.Errorf("1 should not have been contained") - } - if !evict { - t.Errorf("an eviction should have occurred") - } - if !l.Contains(1) { - t.Errorf("now 1 should be contained") - } -} - -// test that Peek doesn't update recent-ness -func TestLRUPeek(t *testing.T) { - l, err := New(2) - if err != nil { - t.Fatalf("err: %v", err) - } - - l.Add(1, 1) - l.Add(2, 2) - if v, ok := l.Peek(1); !ok || v != 1 { - t.Errorf("1 should be set to 1: %v, %v", v, ok) - } - - l.Add(3, 3) - if l.Contains(1) { - t.Errorf("should not have updated recent-ness of 1") - } -} - -// test that Resize can upsize and downsize -func TestLRUResize(t *testing.T) { - onEvictCounter := 0 - onEvicted := func(k interface{}, v interface{}) { - onEvictCounter++ - } - l, err := NewWithEvict(2, onEvicted) - if err != nil { - t.Fatalf("err: %v", err) - } - - // Downsize - l.Add(1, 1) - l.Add(2, 2) - evicted := l.Resize(1) - if evicted != 1 { - t.Errorf("1 element should have been evicted: %v", evicted) - } - if onEvictCounter != 1 { - t.Errorf("onEvicted should have been called 1 time: %v", onEvictCounter) - } - - l.Add(3, 3) - if l.Contains(1) { - t.Errorf("Element 1 should have been evicted") - } - - // Upsize - evicted = l.Resize(2) - if evicted != 0 { - t.Errorf("0 elements should have been evicted: %v", evicted) - } - - l.Add(4, 4) - if !l.Contains(3) || !l.Contains(4) { - t.Errorf("Cache should have contained 2 elements") - } -} diff --git a/simplelru/lru.go b/simplelru/lru.go deleted file mode 100644 index 9233583..0000000 --- a/simplelru/lru.go +++ /dev/null @@ -1,177 +0,0 @@ -package simplelru - -import ( - "container/list" - "errors" -) - -// EvictCallback is used to get a callback when a cache entry is evicted -type EvictCallback func(key interface{}, value interface{}) - -// LRU implements a non-thread safe fixed size LRU cache -type LRU struct { - size int - evictList *list.List - items map[interface{}]*list.Element - onEvict EvictCallback -} - -// entry is used to hold a value in the evictList -type entry struct { - key interface{} - value interface{} -} - -// NewLRU constructs an LRU of the given size -func NewLRU(size int, onEvict EvictCallback) (*LRU, error) { - if size <= 0 { - return nil, errors.New("must provide a positive size") - } - c := &LRU{ - size: size, - evictList: list.New(), - items: make(map[interface{}]*list.Element), - onEvict: onEvict, - } - return c, nil -} - -// Purge is used to completely clear the cache. -func (c *LRU) Purge() { - for k, v := range c.items { - if c.onEvict != nil { - c.onEvict(k, v.Value.(*entry).value) - } - delete(c.items, k) - } - c.evictList.Init() -} - -// Add adds a value to the cache. Returns true if an eviction occurred. -func (c *LRU) Add(key, value interface{}) (evicted bool) { - // Check for existing item - if ent, ok := c.items[key]; ok { - c.evictList.MoveToFront(ent) - ent.Value.(*entry).value = value - return false - } - - // Add new item - ent := &entry{key, value} - entry := c.evictList.PushFront(ent) - c.items[key] = entry - - evict := c.evictList.Len() > c.size - // Verify size not exceeded - if evict { - c.removeOldest() - } - return evict -} - -// Get looks up a key's value from the cache. -func (c *LRU) Get(key interface{}) (value interface{}, ok bool) { - if ent, ok := c.items[key]; ok { - c.evictList.MoveToFront(ent) - if ent.Value.(*entry) == nil { - return nil, false - } - return ent.Value.(*entry).value, true - } - return -} - -// Contains checks if a key is in the cache, without updating the recent-ness -// or deleting it for being stale. -func (c *LRU) Contains(key interface{}) (ok bool) { - _, ok = c.items[key] - return ok -} - -// Peek returns the key value (or undefined if not found) without updating -// the "recently used"-ness of the key. -func (c *LRU) Peek(key interface{}) (value interface{}, ok bool) { - var ent *list.Element - if ent, ok = c.items[key]; ok { - return ent.Value.(*entry).value, true - } - return nil, ok -} - -// Remove removes the provided key from the cache, returning if the -// key was contained. -func (c *LRU) Remove(key interface{}) (present bool) { - if ent, ok := c.items[key]; ok { - c.removeElement(ent) - return true - } - return false -} - -// RemoveOldest removes the oldest item from the cache. -func (c *LRU) RemoveOldest() (key, value interface{}, ok bool) { - ent := c.evictList.Back() - if ent != nil { - c.removeElement(ent) - kv := ent.Value.(*entry) - return kv.key, kv.value, true - } - return nil, nil, false -} - -// GetOldest returns the oldest entry -func (c *LRU) GetOldest() (key, value interface{}, ok bool) { - ent := c.evictList.Back() - if ent != nil { - kv := ent.Value.(*entry) - return kv.key, kv.value, true - } - return nil, nil, false -} - -// Keys returns a slice of the keys in the cache, from oldest to newest. -func (c *LRU) Keys() []interface{} { - keys := make([]interface{}, len(c.items)) - i := 0 - for ent := c.evictList.Back(); ent != nil; ent = ent.Prev() { - keys[i] = ent.Value.(*entry).key - i++ - } - return keys -} - -// Len returns the number of items in the cache. -func (c *LRU) Len() int { - return c.evictList.Len() -} - -// Resize changes the cache size. -func (c *LRU) Resize(size int) (evicted int) { - diff := c.Len() - size - if diff < 0 { - diff = 0 - } - for i := 0; i < diff; i++ { - c.removeOldest() - } - c.size = size - return diff -} - -// removeOldest removes the oldest item from the cache. -func (c *LRU) removeOldest() { - ent := c.evictList.Back() - if ent != nil { - c.removeElement(ent) - } -} - -// removeElement is used to remove a given list element from the cache -func (c *LRU) removeElement(e *list.Element) { - c.evictList.Remove(e) - kv := e.Value.(*entry) - delete(c.items, kv.key) - if c.onEvict != nil { - c.onEvict(kv.key, kv.value) - } -} diff --git a/simplelru/lru_interface.go b/simplelru/lru_interface.go deleted file mode 100644 index cb7f8ca..0000000 --- a/simplelru/lru_interface.go +++ /dev/null @@ -1,40 +0,0 @@ -// Package simplelru provides simple LRU implementation based on build-in container/list. -package simplelru - -// LRUCache is the interface for simple LRU cache. -type LRUCache interface { - // Adds a value to the cache, returns true if an eviction occurred and - // updates the "recently used"-ness of the key. - Add(key, value interface{}) bool - - // Returns key's value from the cache and - // updates the "recently used"-ness of the key. #value, isFound - Get(key interface{}) (value interface{}, ok bool) - - // Checks if a key exists in cache without updating the recent-ness. - Contains(key interface{}) (ok bool) - - // Returns key's value without updating the "recently used"-ness of the key. - Peek(key interface{}) (value interface{}, ok bool) - - // Removes a key from the cache. - Remove(key interface{}) bool - - // Removes the oldest entry from cache. - RemoveOldest() (interface{}, interface{}, bool) - - // Returns the oldest entry from the cache. #key, value, isFound - GetOldest() (interface{}, interface{}, bool) - - // Returns a slice of the keys in the cache, from oldest to newest. - Keys() []interface{} - - // Returns the number of items in the cache. - Len() int - - // Clears all cache entries. - Purge() - - // Resizes cache, returning number evicted - Resize(int) int -} diff --git a/simplelru/lru_test.go b/simplelru/lru_test.go deleted file mode 100644 index a9ffcd5..0000000 --- a/simplelru/lru_test.go +++ /dev/null @@ -1,206 +0,0 @@ -package simplelru - -import "testing" - -func TestLRU(t *testing.T) { - evictCounter := 0 - onEvicted := func(k interface{}, v interface{}) { - if k != v { - t.Fatalf("Evict values not equal (%v!=%v)", k, v) - } - evictCounter++ - } - l, err := NewLRU(128, onEvicted) - if err != nil { - t.Fatalf("err: %v", err) - } - - for i := 0; i < 256; i++ { - l.Add(i, i) - } - if l.Len() != 128 { - t.Fatalf("bad len: %v", l.Len()) - } - - if evictCounter != 128 { - t.Fatalf("bad evict count: %v", evictCounter) - } - - for i, k := range l.Keys() { - if v, ok := l.Get(k); !ok || v != k || v != i+128 { - t.Fatalf("bad key: %v", k) - } - } - for i := 0; i < 128; i++ { - _, ok := l.Get(i) - if ok { - t.Fatalf("should be evicted") - } - } - for i := 128; i < 256; i++ { - _, ok := l.Get(i) - if !ok { - t.Fatalf("should not be evicted") - } - } - for i := 128; i < 192; i++ { - ok := l.Remove(i) - if !ok { - t.Fatalf("should be contained") - } - ok = l.Remove(i) - if ok { - t.Fatalf("should not be contained") - } - _, ok = l.Get(i) - if ok { - t.Fatalf("should be deleted") - } - } - - l.Get(192) // expect 192 to be last key in l.Keys() - - for i, k := range l.Keys() { - if (i < 63 && k != i+193) || (i == 63 && k != 192) { - t.Fatalf("out of order key: %v", k) - } - } - - l.Purge() - if l.Len() != 0 { - t.Fatalf("bad len: %v", l.Len()) - } - if _, ok := l.Get(200); ok { - t.Fatalf("should contain nothing") - } -} - -func TestLRU_GetOldest_RemoveOldest(t *testing.T) { - l, err := NewLRU(128, nil) - if err != nil { - t.Fatalf("err: %v", err) - } - for i := 0; i < 256; i++ { - l.Add(i, i) - } - k, _, ok := l.GetOldest() - if !ok { - t.Fatalf("missing") - } - if k.(int) != 128 { - t.Fatalf("bad: %v", k) - } - - k, _, ok = l.RemoveOldest() - if !ok { - t.Fatalf("missing") - } - if k.(int) != 128 { - t.Fatalf("bad: %v", k) - } - - k, _, ok = l.RemoveOldest() - if !ok { - t.Fatalf("missing") - } - if k.(int) != 129 { - t.Fatalf("bad: %v", k) - } -} - -// Test that Add returns true/false if an eviction occurred -func TestLRU_Add(t *testing.T) { - evictCounter := 0 - onEvicted := func(k interface{}, v interface{}) { - evictCounter++ - } - - l, err := NewLRU(1, onEvicted) - if err != nil { - t.Fatalf("err: %v", err) - } - - if l.Add(1, 1) == true || evictCounter != 0 { - t.Errorf("should not have an eviction") - } - if l.Add(2, 2) == false || evictCounter != 1 { - t.Errorf("should have an eviction") - } -} - -// Test that Contains doesn't update recent-ness -func TestLRU_Contains(t *testing.T) { - l, err := NewLRU(2, nil) - if err != nil { - t.Fatalf("err: %v", err) - } - - l.Add(1, 1) - l.Add(2, 2) - if !l.Contains(1) { - t.Errorf("1 should be contained") - } - - l.Add(3, 3) - if l.Contains(1) { - t.Errorf("Contains should not have updated recent-ness of 1") - } -} - -// Test that Peek doesn't update recent-ness -func TestLRU_Peek(t *testing.T) { - l, err := NewLRU(2, nil) - if err != nil { - t.Fatalf("err: %v", err) - } - - l.Add(1, 1) - l.Add(2, 2) - if v, ok := l.Peek(1); !ok || v != 1 { - t.Errorf("1 should be set to 1: %v, %v", v, ok) - } - - l.Add(3, 3) - if l.Contains(1) { - t.Errorf("should not have updated recent-ness of 1") - } -} - -// Test that Resize can upsize and downsize -func TestLRU_Resize(t *testing.T) { - onEvictCounter := 0 - onEvicted := func(k interface{}, v interface{}) { - onEvictCounter++ - } - l, err := NewLRU(2, onEvicted) - if err != nil { - t.Fatalf("err: %v", err) - } - - // Downsize - l.Add(1, 1) - l.Add(2, 2) - evicted := l.Resize(1) - if evicted != 1 { - t.Errorf("1 element should have been evicted: %v", evicted) - } - if onEvictCounter != 1 { - t.Errorf("onEvicted should have been called 1 time: %v", onEvictCounter) - } - - l.Add(3, 3) - if l.Contains(1) { - t.Errorf("Element 1 should have been evicted") - } - - // Upsize - evicted = l.Resize(2) - if evicted != 0 { - t.Errorf("0 elements should have been evicted: %v", evicted) - } - - l.Add(4, 4) - if !l.Contains(3) || !l.Contains(4) { - t.Errorf("Cache should have contained 2 elements") - } -} diff --git a/testing.go b/testing.go deleted file mode 100644 index 4927607..0000000 --- a/testing.go +++ /dev/null @@ -1,16 +0,0 @@ -package lru - -import ( - "crypto/rand" - "math" - "math/big" - "testing" -) - -func getRand(tb testing.TB) int64 { - out, err := rand.Int(rand.Reader, big.NewInt(math.MaxInt64)) - if err != nil { - tb.Fatal(err) - } - return out.Int64() -}