[#30] grpc: Cache object getters

Includes:
1. Logic simplification: no need to call `ObjSelector.Reset` from JS code,
everything could be done inside the Go code. Remove unused mutexes.
2. Do not handle object twice ever: Once handled, any error is expected to be
logged on the JS side and never be handled again. It solves "already removed"
error.
3. Object caching: no need to call bolt's `View` on every object removal: it
blocks other calls and slows down the execution. Read 100 objects (or less if
not available yet), cache them and send to buffered channel.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
This commit is contained in:
Pavel Karpy 2022-10-26 22:29:17 +03:00 committed by fyrchik
parent 1434d95e81
commit c43f73704e
5 changed files with 121 additions and 93 deletions

View file

@ -1,6 +1,7 @@
package registry
import (
"context"
"encoding/binary"
"encoding/json"
"errors"
@ -11,6 +12,8 @@ import (
)
type ObjRegistry struct {
ctx context.Context
cancel context.CancelFunc
boltDB *bbolt.DB
}
@ -38,14 +41,20 @@ type ObjectInfo struct {
// about objects in the specified bolt database. As registry uses read-write
// connection to the database, there may be only one instance of object registry
// per database file at a time.
func NewObjRegistry(dbFilePath string) *ObjRegistry {
func NewObjRegistry(ctx context.Context, dbFilePath string) *ObjRegistry {
options := bbolt.Options{Timeout: 100 * time.Millisecond}
boltDB, err := bbolt.Open(dbFilePath, os.ModePerm, &options)
if err != nil {
panic(err)
}
objRepository := &ObjRegistry{boltDB: boltDB}
ctx, cancel := context.WithCancel(ctx)
objRepository := &ObjRegistry{
ctx: ctx,
cancel: cancel,
boltDB: boltDB,
}
return objRepository
}
@ -118,6 +127,7 @@ func (o *ObjRegistry) DeleteObject(id uint64) error {
}
func (o *ObjRegistry) Close() error {
o.cancel()
return o.boltDB.Close()
}

View file

@ -1,8 +1,9 @@
package registry
import (
"context"
"encoding/json"
"sync"
"fmt"
"time"
"go.etcd.io/bbolt"
@ -14,97 +15,40 @@ type ObjFilter struct {
}
type ObjSelector struct {
ctx context.Context
objChan chan *ObjectInfo
boltDB *bbolt.DB
filter *ObjFilter
mu sync.Mutex
lastId uint64
// UTC date&time before which selector is locked for iteration or resetting.
// This lock prevents concurrency issues when some VUs are selecting objects
// while another VU resets the selector and attempts to select the same objects
lockedUntil time.Time
}
// objectSelectCache is a maximum number of the selected objects to be
// cached for the ObjSelector.NextObject.
const objectSelectCache = 100
// NewObjSelector creates a new instance of object selector that can iterate over
// objects in the specified registry.
func NewObjSelector(registry *ObjRegistry, filter *ObjFilter) *ObjSelector {
objSelector := &ObjSelector{boltDB: registry.boltDB, filter: filter}
objSelector := &ObjSelector{
ctx: registry.ctx,
boltDB: registry.boltDB,
filter: filter,
objChan: make(chan *ObjectInfo, objectSelectCache),
}
go objSelector.selectLoop()
return objSelector
}
// NextObject returns the next object from the registry that matches filter of
// the selector. NextObject only roams forward from the current position of the
// selector. If there are no objects that match the filter, then returns nil.
func (o *ObjSelector) NextObject() (*ObjectInfo, error) {
var foundObj *ObjectInfo
err := o.boltDB.View(func(tx *bbolt.Tx) error {
b := tx.Bucket([]byte(bucketName))
if b == nil {
return nil
}
c := b.Cursor()
// We use mutex so that multiple VUs won't attempt to modify lastId simultaneously
// TODO: consider singleton channel that will produce those ids on demand
o.mu.Lock()
defer o.mu.Unlock()
if time.Now().UTC().Before(o.lockedUntil) {
return nil
}
// Establish the start position for searching the next object:
// If we should go from the beginning (lastId=0), then we start from the first element
// Otherwise we start from the key right after the lastId
var keyBytes, objBytes []byte
if o.lastId == 0 {
keyBytes, objBytes = c.First()
} else {
c.Seek(encodeId(o.lastId))
keyBytes, objBytes = c.Next()
}
// Iterate over objects to find the next object matching the filter
var obj ObjectInfo
for ; keyBytes != nil; keyBytes, objBytes = c.Next() {
if objBytes != nil {
if err := json.Unmarshal(objBytes, &obj); err != nil {
// Ignore malformed objects for now. Maybe it should be panic?
continue
}
// If we reached an object that matches filter, stop iterating
if o.filter.match(obj) {
foundObj = &obj
break
}
}
}
// Update the last key
if keyBytes != nil {
o.lastId = decodeId(keyBytes)
return nil
}
return nil
})
return foundObj, err
}
// Resets object selector to start scanning objects from the beginning.
// After resetting the selector is locked for specified lockTime to prevent
// concurrency issues.
func (o *ObjSelector) Reset(lockTime int) bool {
o.mu.Lock()
defer o.mu.Unlock()
if time.Now().UTC().Before(o.lockedUntil) {
return false
}
o.lastId = 0
o.lockedUntil = time.Now().UTC().Add(time.Duration(lockTime) * time.Second)
return true
// selector. If there are no objects that match the filter, blocks until one of
// the following happens:
// - a "new" next object is available;
// - underlying registry context is done, nil objects will be returned on the
// currently blocked and every further NextObject calls.
func (o *ObjSelector) NextObject() *ObjectInfo {
return <-o.objChan
}
// Count returns total number of objects that match filter of the selector.
@ -133,6 +77,88 @@ func (o *ObjSelector) Count() (int, error) {
return count, err
}
func (o *ObjSelector) selectLoop() {
cache := make([]*ObjectInfo, 0, objectSelectCache)
var lastID uint64
defer close(o.objChan)
for {
select {
case <-o.ctx.Done():
return
default:
}
// cache the objects
err := o.boltDB.View(func(tx *bbolt.Tx) error {
b := tx.Bucket([]byte(bucketName))
if b == nil {
return nil
}
c := b.Cursor()
// Establish the start position for searching the next object:
// If we should go from the beginning (lastID=0), then we start
// from the first element. Otherwise, we start from the last
// handled ID + 1.
var keyBytes, objBytes []byte
if lastID == 0 {
keyBytes, objBytes = c.First()
} else {
keyBytes, objBytes = c.Seek(encodeId(lastID))
if keyBytes != nil && decodeId(keyBytes) == lastID {
keyBytes, objBytes = c.Next()
}
}
// Iterate over objects to find the next object matching the filter.
for ; keyBytes != nil && len(cache) != objectSelectCache; keyBytes, objBytes = c.Next() {
if objBytes != nil {
var obj ObjectInfo
if err := json.Unmarshal(objBytes, &obj); err != nil {
// Ignore malformed objects for now. Maybe it should be panic?
continue
}
if o.filter.match(obj) {
cache = append(cache, &obj)
}
}
}
if len(cache) > 0 {
lastID = cache[len(cache)-1].Id
}
return nil
})
if err != nil {
panic(fmt.Errorf("fetching objects failed: %w", err))
}
for _, obj := range cache {
select {
case <-o.ctx.Done():
return
case o.objChan <- obj:
}
}
if len(cache) != objectSelectCache {
// no more objects, wait a little; the logic could be improved.
select {
case <-time.After(time.Second * time.Duration(o.filter.Age/2)):
case <-o.ctx.Done():
return
}
}
// clean handled objects
cache = cache[:0]
}
}
func (f *ObjFilter) match(o ObjectInfo) bool {
if f.Status != "" && f.Status != o.Status {
return false

View file

@ -68,7 +68,7 @@ func (r *Registry) Open(dbFilePath string) *ObjRegistry {
func (r *Registry) open(dbFilePath string) *ObjRegistry {
registry := r.root.registries[dbFilePath]
if registry == nil {
registry = NewObjRegistry(dbFilePath)
registry = NewObjRegistry(r.vu.Context(), dbFilePath)
r.root.registries[dbFilePath] = registry
}
return registry

View file

@ -143,10 +143,6 @@ export function obj_delete() {
const obj = obj_to_delete_selector.nextObject();
if (!obj) {
// If there are no objects to delete, we reset selector to start scanning from the
// beginning of registry. Then we wait for some time until suitable object might appear
obj_to_delete_selector.reset(delete_age);
sleep(delete_age / 2);
return;
}

View file

@ -141,10 +141,6 @@ export function obj_delete() {
const obj = obj_to_delete_selector.nextObject();
if (!obj) {
// If there are no objects to delete, we reset selector to start scanning from the
// beginning of registry. Then we wait for some time until suitable object might appear
obj_to_delete_selector.reset(delete_age);
sleep(delete_age / 2);
return;
}