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store.go
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store.go
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package mem
import (
"bytes"
"context"
"encoding/base64"
"fmt"
"sort"
"sync"
"github.com/treeverse/lakefs/pkg/kv"
kvparams "github.com/treeverse/lakefs/pkg/kv/params"
)
type Driver struct{}
// PartitionMap holds key-value pairs of a given partition
type PartitionMap map[string]kv.Entry
type Store struct {
m map[string]PartitionMap
mu sync.RWMutex
}
type EntriesIterator struct {
entry *kv.Entry
err error
start []byte
partition string
store *Store
}
const DriverName = "mem"
//nolint:gochecknoinits
func init() {
kv.Register(DriverName, &Driver{})
}
func (d *Driver) Open(_ context.Context, _ kvparams.Config) (kv.Store, error) {
return &Store{
m: make(map[string]PartitionMap, 0),
}, nil
}
func encodeKey(key []byte) string {
return base64.StdEncoding.EncodeToString(key)
}
func (s *Store) Get(_ context.Context, partitionKey, key []byte) (*kv.ValueWithPredicate, error) {
if len(partitionKey) == 0 {
return nil, kv.ErrMissingPartitionKey
}
if len(key) == 0 {
return nil, kv.ErrMissingKey
}
s.mu.RLock()
defer s.mu.RUnlock()
sKey := encodeKey(key)
value, ok := s.m[string(partitionKey)][sKey]
if !ok {
return nil, fmt.Errorf("partition=%s, key=%v, encoding=%s: %w", partitionKey, key, sKey, kv.ErrNotFound)
}
return &kv.ValueWithPredicate{
Value: value.Value,
Predicate: kv.Predicate(value.Value),
}, nil
}
func (s *Store) Set(_ context.Context, partitionKey, key, value []byte) error {
if len(partitionKey) == 0 {
return kv.ErrMissingPartitionKey
}
if len(key) == 0 {
return kv.ErrMissingKey
}
if value == nil {
return kv.ErrMissingValue
}
s.mu.Lock()
defer s.mu.Unlock()
s.internalSet(partitionKey, key, value)
return nil
}
func (s *Store) internalSet(partitionKey, key, value []byte) {
sKey := encodeKey(key)
if _, ok := s.m[string(partitionKey)]; !ok {
s.m[string(partitionKey)] = make(map[string]kv.Entry)
}
s.m[string(partitionKey)][sKey] = kv.Entry{
PartitionKey: partitionKey,
Key: key,
Value: value,
}
}
func (s *Store) SetIf(_ context.Context, partitionKey, key, value []byte, valuePredicate kv.Predicate) error {
if len(partitionKey) == 0 {
return kv.ErrMissingPartitionKey
}
if len(key) == 0 {
return kv.ErrMissingKey
}
if value == nil {
return kv.ErrMissingValue
}
s.mu.Lock()
defer s.mu.Unlock()
sKey := encodeKey(key)
curr, currOK := s.m[string(partitionKey)][sKey]
switch valuePredicate {
case nil:
if currOK {
return fmt.Errorf("key=%v: %w", key, kv.ErrPredicateFailed)
}
case kv.PrecondConditionalExists:
if !currOK {
return fmt.Errorf("key=%v: %w", key, kv.ErrPredicateFailed)
}
default: // check for predicate
if !bytes.Equal(valuePredicate.([]byte), curr.Value) {
return fmt.Errorf("%w: partition=%s, key=%v, encoding=%s", kv.ErrPredicateFailed, partitionKey, key, sKey)
}
}
s.internalSet(partitionKey, key, value)
return nil
}
func (s *Store) Delete(_ context.Context, partitionKey, key []byte) error {
if len(partitionKey) == 0 {
return kv.ErrMissingPartitionKey
}
if len(key) == 0 {
return kv.ErrMissingKey
}
s.mu.Lock()
defer s.mu.Unlock()
sKey := encodeKey(key)
if _, ok := s.m[string(partitionKey)][sKey]; !ok {
return nil
}
delete(s.m[string(partitionKey)], sKey)
return nil
}
func (s *Store) Scan(_ context.Context, partitionKey []byte, options kv.ScanOptions) (kv.EntriesIterator, error) {
if len(partitionKey) == 0 {
return nil, kv.ErrMissingPartitionKey
}
start := options.KeyStart
if start == nil {
start = []byte{}
}
return &EntriesIterator{
store: s,
start: start,
partition: string(partitionKey),
}, nil
}
func (s *Store) Close() {}
func (e *EntriesIterator) Next() bool {
if e.err != nil || e.start == nil { // start is nil only if last iteration we reached end of keys
return false
}
e.store.mu.RLock()
defer e.store.mu.RUnlock()
l := make([]*kv.Entry, 0)
if _, ok := e.store.m[e.partition]; ok {
for _, v := range e.store.m[e.partition] {
if bytes.Compare(v.Key, e.start) >= 0 {
entry := v
l = append(l, &entry)
}
}
}
if len(l) == 0 { // No results
e.start = nil
return false
}
if len(l) == 1 { // only 1 key >= start, set start to nil, so to indicate next call to return false immediately.
e.start = nil
e.entry = l[0]
return true
}
sort.Slice(l, func(i, j int) bool { return bytes.Compare(l[i].Key, l[j].Key) < 0 })
e.start = l[1].Key
e.entry = l[0]
return true
}
func (e *EntriesIterator) Entry() *kv.Entry {
return e.entry
}
func (e *EntriesIterator) Err() error {
return e.err
}
func (e *EntriesIterator) Close() {
e.err = kv.ErrClosedEntries
}