MyFavMirrors/minio
1
0
Fork 0
mirror of https://github.com/minio/minio.git synced 2025-11-09 05:34:56 -05:00
Code Issues Packages Projects Releases Wiki Activity

Revert "fix: remove persistence layer for metacache store in memory (#11538)"

Browse Source 
This reverts commit b23659927c.
This commit is contained in:
Harshavardhana
2021-02-24 22:24:38 -08:00
parent ca5c6e3160
commit a8e4f64ff3
14 changed files with 601 additions and 679 deletions
Download Patch File Download Diff File Expand all files Collapse all files

270
pkg/objcache/objcache.go
View File

@@ -1,270 +0,0 @@
/*
* Minio Cloud Storage, (C) 2021 Minio, Inc.
*
* 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 objcache implements in memory caching methods.
package objcache
import (
"bytes"
"errors"
"io"
"sync"
"time"
"github.com/valyala/bytebufferpool"
)
const (
// NoExpiry represents caches to be permanent and can only be deleted.
NoExpiry = time.Duration(0)
// DefaultExpiry represents 1 hour time duration when all entries shall be expired.
DefaultExpiry = time.Hour
// defaultBufferRatio represents default ratio used to calculate the
// individual cache entry buffer size.
defaultBufferRatio = uint64(10)
)
var (
// ErrKeyNotFoundInCache - key not found in cache.
ErrKeyNotFoundInCache = errors.New("Key not found in cache")
// ErrCacheFull - cache is full.
ErrCacheFull = errors.New("Not enough space in cache")
// ErrExcessData - excess data was attempted to be written on cache.
ErrExcessData = errors.New("Attempted excess write on cache")
)
// buffer represents the in memory cache of a single entry.
// buffer carries value of the data and last accessed time.
type buffer struct {
buf *bytebufferpool.ByteBuffer
lastAccessed time.Time // Represents time when value was last accessed.
}
// Cache holds the required variables to compose an in memory cache system
// which also provides expiring key mechanism and also maxSize.
type Cache struct {
// Mutex is used for handling the concurrent
// read/write requests for cache
mutex sync.Mutex
// Once is used for resetting GC once after
// peak cache usage.
onceGC sync.Once
// maxSize is a total size for overall cache
maxSize uint64
// maxCacheEntrySize is a total size per key buffer.
maxCacheEntrySize uint64
// currentSize is a current size in memory
currentSize uint64
// OnEviction - callback function for eviction
OnEviction func(key string)
// totalEvicted counter to keep track of total expirys
totalEvicted int
// map of cached keys and its values
entries map[string]*buffer
// Expiry in time duration.
expiry time.Duration
// Stop garbage collection routine, stops any running GC routine.
stopGC chan struct{}
}
// New - Return a new cache with a given default expiry
// duration. If the expiry duration is less than one
// (or NoExpiry), the items in the cache never expire
// (by default), and must be deleted manually.
func New(maxSize uint64, expiry time.Duration) (c *Cache, err error) {
if maxSize == 0 {
err = errors.New("invalid maximum cache size")
return c, err
}
// Max cache entry size - indicates the
// maximum buffer per key that can be held in
// memory. Currently this value is 1/10th
// the size of requested cache size.
maxCacheEntrySize := func() uint64 {
i := maxSize / defaultBufferRatio
if i == 0 {
i = maxSize
}
return i
}()
c = &Cache{
onceGC: sync.Once{},
maxSize: maxSize,
maxCacheEntrySize: maxCacheEntrySize,
entries: make(map[string]*buffer),
expiry: expiry,
}
// We have expiry start the janitor routine.
if expiry > 0 {
// Initialize a new stop GC channel.
c.stopGC = make(chan struct{})
// Start garbage collection routine to expire objects.
c.StartGC()
}
return c, nil
}
// Create - validates if object size fits with in cache size limit and returns a io.WriteCloser
// to which object contents can be written and finally Close()'d. During Close() we
// checks if the amount of data written is equal to the size of the object, in which
// case it saves the contents to object cache.
func (c *Cache) Create(key string) (wc io.WriteCloser) {
buf := bytebufferpool.Get()
// Function called on close which saves the object contents
// to the object cache.
onClose := func() error {
c.mutex.Lock()
defer c.mutex.Unlock()
if buf.Len() == 0 {
buf.Reset()
bytebufferpool.Put(buf)
// If nothing is written in the buffer
// the key is not stored.
return nil
}
if uint64(buf.Len()) > c.maxCacheEntrySize {
buf.Reset()
bytebufferpool.Put(buf)
return ErrCacheFull
}
// Full object available in buf, save it to cache.
c.entries[key] = &buffer{
buf: buf,
lastAccessed: time.Now().UTC(), // Save last accessed time.
}
// Account for the memory allocated above.
c.currentSize += uint64(buf.Len())
return nil
}
return &writeCloser{ByteBuffer: buf, onClose: onClose}
}
// Open - open the in-memory file, returns an in memory reader.
// returns an error ErrKeyNotFoundInCache, if the key does not
// exist. ErrKeyNotFoundInCache is also returned if lastAccessed
// is older than input atime.
func (c *Cache) Open(key string, atime time.Time) (io.Reader, error) {
// Entry exists, return the readable buffer.
c.mutex.Lock()
defer c.mutex.Unlock()
b, ok := c.entries[key]
if !ok {
return nil, ErrKeyNotFoundInCache
}
// Check if buf was recently accessed.
if b.lastAccessed.Before(atime) {
c.delete(key)
return nil, ErrKeyNotFoundInCache
}
b.lastAccessed = time.Now()
return bytes.NewReader(b.buf.Bytes()), nil
}
// Delete - delete deletes an entry from the cache.
func (c *Cache) Delete(key string) {
c.mutex.Lock()
c.delete(key)
c.mutex.Unlock()
if c.OnEviction != nil {
c.OnEviction(key)
}
}
// gc - garbage collect all the expired entries from the cache.
func (c *Cache) gc() {
var evictedEntries []string
c.mutex.Lock()
for k, v := range c.entries {
if c.expiry > 0 && time.Now().UTC().Sub(v.lastAccessed) > c.expiry {
c.delete(k)
evictedEntries = append(evictedEntries, k)
}
}
c.mutex.Unlock()
for _, k := range evictedEntries {
if c.OnEviction != nil {
c.OnEviction(k)
}
}
}
// StopGC sends a message to the expiry routine to stop
// expiring cached entries. NOTE: once this is called, cached
// entries will not be expired, be careful if you are using this.
func (c *Cache) StopGC() {
if c.stopGC != nil {
c.stopGC <- struct{}{}
}
}
// StartGC starts running a routine ticking at expiry interval,
// on each interval this routine does a sweep across the cache
// entries and garbage collects all the expired entries.
func (c *Cache) StartGC() {
go func() {
for {
select {
// Wait till cleanup interval and initiate delete expired entries.
case <-time.After(c.expiry / 4):
c.gc()
// Stop the routine, usually called by the user of object cache during cleanup.
case <-c.stopGC:
return
}
}
}()
}
// Deletes a requested entry from the cache.
func (c *Cache) delete(key string) {
if _, ok := c.entries[key]; ok {
deletedSize := uint64(c.entries[key].buf.Len())
c.entries[key].buf.Reset()
bytebufferpool.Put(c.entries[key].buf)
delete(c.entries, key)
c.currentSize -= deletedSize
c.totalEvicted++
}
}

309
pkg/objcache/objcache_test.go
View File

@@ -1,309 +0,0 @@
/*
* Minio Cloud Storage, (C) 2021 Minio, Inc.
*
* 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 objcache
import (
"bytes"
"io"
"testing"
"time"
)
// TestObjectCache tests cases of object cache with expiry.
func TestObjExpiry(t *testing.T) {
// Non exhaustive list of all object cache behavior cases.
testCases := []struct {
expiry time.Duration
cacheSize uint64
err error
closeErr error
}{
{
expiry: 100 * time.Millisecond,
cacheSize: 1024,
err: ErrKeyNotFoundInCache,
closeErr: nil,
},
}
// Test case 1 validates running of GC.
testCase := testCases[0]
cache, err := New(testCase.cacheSize, testCase.expiry)
if err != nil {
t.Fatalf("Unable to create new objcache")
}
cache.OnEviction = func(key string) {}
w := cache.Create("test")
// Write a byte.
w.Write([]byte("1"))
if err = w.Close(); err != nil {
t.Errorf("Test case 1 expected to pass, failed instead %s", err)
}
// Wait for 500 millisecond.
time.Sleep(500 * time.Millisecond)
// Setting objModTime to the beginning of golang's time.Time to avoid deletion of stale entry.
fakeObjModTime := time.Time{}
_, err = cache.Open("test", fakeObjModTime)
if err != testCase.err {
t.Errorf("Test case 1 expected %s, got instead %s", testCase.err, err)
}
}
// TestObjCache - tests various cases for object cache behavior.
func TestObjCache(t *testing.T) {
// Setting objModTime to the beginning of golang's time.Time to avoid deletion of stale entry.
fakeObjModTime := time.Time{}
// Non exhaustive list of all object cache behavior cases.
testCases := []struct {
expiry time.Duration
cacheSize uint64
err error
closeErr error
}{
// Validate if a key is not found in cache and Open fails.
{
expiry: NoExpiry,
cacheSize: 1024,
err: ErrKeyNotFoundInCache,
},
// Validate if cache indicates that it is full and Create fails.
{
expiry: NoExpiry,
cacheSize: 1,
err: ErrCacheFull,
},
// Validate if Create succeeds but Close fails to write to buffer.
{
expiry: NoExpiry,
cacheSize: 2,
closeErr: io.ErrShortBuffer,
},
// Validate that Create and Close succeed, making sure to update the cache.
{
expiry: NoExpiry,
cacheSize: 1024,
},
// Validate that Delete succeeds and Open fails with key not found in cache.
{
expiry: NoExpiry,
cacheSize: 1024,
err: ErrKeyNotFoundInCache,
},
// Validate OnEviction function is called upon entry delete.
{
expiry: NoExpiry,
cacheSize: 1024,
},
// Validate error excess data.
{
expiry: NoExpiry,
cacheSize: 5,
closeErr: ErrExcessData,
},
// Validate error excess data during write.
{
expiry: NoExpiry,
cacheSize: 2048,
err: ErrExcessData,
},
}
// Test 1 validating Open failure.
testCase := testCases[0]
cache, err := New(testCase.cacheSize, testCase.expiry)
if err != nil {
t.Fatalf("Unable to create new objcache")
}
_, err = cache.Open("test", fakeObjModTime)
if testCase.err != err {
t.Errorf("Test case 2 expected to pass, failed instead %s", err)
}
// Test 2 validating Create failure.
testCase = testCases[1]
cache, err = New(testCase.cacheSize, testCase.expiry)
if err != nil {
t.Fatalf("Unable to create new objcache")
}
w := cache.Create("test")
if w == nil {
t.Errorf("Test case 2 expected to pass, but returned nil")
}
w.Close()
// Test 3 validating Create succeeds and returns a writer.
// Subsequently we Close() without writing any data, to receive
// `io.ErrShortBuffer`
testCase = testCases[2]
cache, err = New(testCase.cacheSize, testCase.expiry)
if err != nil {
t.Fatalf("Unable to create new objcache")
}
w = cache.Create("test")
// nothing is stored in the key, upon Close() the buf is discarded.
if err = w.Close(); err != nil {
t.Errorf("Test case 3 expected to pass, failed instead %s", err)
}
// Test 4 validates Create and Close succeeds successfully caching
// the writes.
testCase = testCases[3]
cache, err = New(testCase.cacheSize, testCase.expiry)
if err != nil {
t.Fatalf("Unable to create new objcache")
}
w = cache.Create("test")
// Write '5' bytes.
w.Write([]byte("Hello"))
// Close to successfully save into cache.
if err = w.Close(); err != nil {
t.Errorf("Test case 4 expected to pass, failed instead %s", err)
}
r, err := cache.Open("test", fakeObjModTime)
if err != nil {
t.Errorf("Test case 4 expected to pass, failed instead %s", err)
}
// Reads everything stored for key "test".
cbytes := make([]byte, 5)
rat := r.(io.ReaderAt)
_, err = rat.ReadAt(cbytes, 0)
if err != nil {
t.Errorf("Test case 4 expected to pass, failed instead %s", err)
}
// Validate if read bytes match.
if !bytes.Equal(cbytes, []byte("Hello")) {
t.Errorf("Test case 4 expected to pass. wanted \"Hello\", got %s", string(cbytes))
}
// Test 5 validates Delete succeeds and Open fails with err
testCase = testCases[4]
cache, err = New(testCase.cacheSize, testCase.expiry)
if err != nil {
t.Fatalf("Unable to create new objcache")
}
w = cache.Create("test")
// Write '5' bytes.
w.Write([]byte("Hello"))
// Close to successfully save into cache.
if err = w.Close(); err != nil {
t.Errorf("Test case 5 expected to pass, failed instead %s", err)
}
// Delete the cache entry.
cache.Delete("test")
_, err = cache.Open("test", fakeObjModTime)
if testCase.err != err {
t.Errorf("Test case 5 expected to pass, failed instead %s", err)
}
// Test 6 validates OnEviction being called upon Delete is being invoked.
testCase = testCases[5]
cache, err = New(testCase.cacheSize, testCase.expiry)
if err != nil {
t.Fatalf("Unable to create new objcache")
}
w = cache.Create("test")
// Write '5' bytes.
w.Write([]byte("Hello"))
// Close to successfully save into cache.
if err = w.Close(); err != nil {
t.Errorf("Test case 6 expected to pass, failed instead %s", err)
}
var deleteKey string
cache.OnEviction = func(key string) {
deleteKey = key
}
// Delete the cache entry.
cache.Delete("test")
if deleteKey != "test" {
t.Errorf("Test case 6 expected to pass, wanted \"test\", got %s", deleteKey)
}
// Test 7 validates rejecting requests when excess data is being saved.
testCase = testCases[6]
cache, err = New(testCase.cacheSize, testCase.expiry)
if err != nil {
t.Fatalf("Unable to create new objcache")
}
w = cache.Create("test1")
// Write '5' bytes.
w.Write([]byte("Hello"))
// Close to successfully save into cache.
if err = w.Close(); err != nil {
t.Errorf("Test case 7 expected to pass, failed instead %s", err)
}
w = cache.Create("test2")
// nothing got written, Close() will return success.
if err = w.Close(); err != nil {
t.Errorf("Test case 7 expected to pass, failed instead %s", err)
}
// Test 8 validates rejecting Writes which write excess data.
testCase = testCases[7]
cache, err = New(testCase.cacheSize, testCase.expiry)
if err != nil {
t.Fatalf("Unable to create new objcache")
}
w = cache.Create("test1")
defer w.Close()
// Write '5' bytes.
n, err := w.Write([]byte("Hello"))
if err != nil {
t.Errorf("Test case 8 expected to pass, failed instead %s", err)
}
if n != 5 {
t.Errorf("Test case 8 expected 5 bytes written, instead found %d", n)
}
// Write '1' more byte, should return error.
n, err = w.Write([]byte("W"))
if n == 0 && err != testCase.err {
t.Errorf("Test case 8 expected to fail with ErrExcessData, but failed with %s instead", err)
}
}
// TestStateEntryPurge - tests if objCache purges stale entry and returns ErrKeyNotFoundInCache.
func TestStaleEntryPurge(t *testing.T) {
cache, err := New(1024, NoExpiry)
if err != nil {
t.Fatalf("Unable to create new objcache")
}
w := cache.Create("test")
// Write '5' bytes.
w.Write([]byte("Hello"))
// Close to successfully save into cache.
if err = w.Close(); err != nil {
t.Errorf("Test case expected to pass, failed instead %s", err)
}
_, err = cache.Open("test", time.Now().AddDate(0, 0, 1).UTC())
if err != ErrKeyNotFoundInCache {
t.Errorf("Test case expected to return ErrKeyNotFoundInCache, instead returned %s", err)
}
}

34
pkg/objcache/write_closer.go
View File

@@ -1,34 +0,0 @@
/*
* Minio Cloud Storage, (C) 2021 Minio, Inc.
*
* 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 objcache implements in memory caching methods.
package objcache
import "github.com/valyala/bytebufferpool"
// Is an Closer wrapper for bytebufferpool, upon close
// calls the defined onClose function.
type writeCloser struct {
*bytebufferpool.ByteBuffer
onClose func() error
}
// On close, onClose() is called which checks if all object contents
// have been written so that it can save the buffer to the cache.
func (c writeCloser) Close() (err error) {
return c.onClose()
}