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// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package localstore
import (
"encoding/binary"
"encoding/hex"
"errors"
"sync"
"time"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/swarm/chunk"
"github.com/ethereum/go-ethereum/swarm/shed"
"github.com/ethereum/go-ethereum/swarm/storage/mock"
)
var (
// ErrInvalidMode is retuned when an unknown Mode
// is provided to the function.
ErrInvalidMode = errors.New("invalid mode")
// ErrAddressLockTimeout is returned when the same chunk
// is updated in parallel and one of the updates
// takes longer then the configured timeout duration.
ErrAddressLockTimeout = errors.New("address lock timeout")
)
var (
// Default value for Capacity DB option.
defaultCapacity int64 = 5000000
// Limit the number of goroutines created by Getters
// that call updateGC function. Value 0 sets no limit.
maxParallelUpdateGC = 1000
)
// DB is the local store implementation and holds
// database related objects.
type DB struct {
shed *shed.DB
// schema name of loaded data
schemaName shed.StringField
// field that stores number of intems in gc index
storedGCSize shed.Uint64Field
// retrieval indexes
retrievalDataIndex shed.Index
retrievalAccessIndex shed.Index
// push syncing index
pushIndex shed.Index
// push syncing subscriptions triggers
pushTriggers []chan struct{}
pushTriggersMu sync.RWMutex
// pull syncing index
pullIndex shed.Index
// pull syncing subscriptions triggers per bin
pullTriggers map[uint8][]chan struct{}
pullTriggersMu sync.RWMutex
// garbage collection index
gcIndex shed.Index
// index that stores hashes that are not
// counted in and saved to storedGCSize
gcUncountedHashesIndex shed.Index
// number of elements in garbage collection index
// it must be always read by getGCSize and
// set with incGCSize which are locking gcSizeMu
gcSize int64
gcSizeMu sync.RWMutex
// garbage collection is triggered when gcSize exceeds
// the capacity value
capacity int64
// triggers garbage collection event loop
collectGarbageTrigger chan struct{}
// triggers write gc size event loop
writeGCSizeTrigger chan struct{}
// a buffered channel acting as a semaphore
// to limit the maximal number of goroutines
// created by Getters to call updateGC function
updateGCSem chan struct{}
// a wait group to ensure all updateGC goroutines
// are done before closing the database
updateGCWG sync.WaitGroup
baseKey []byte
addressLocks sync.Map
// this channel is closed when close function is called
// to terminate other goroutines
close chan struct{}
// protect Close method from exiting before
// garbage collection and gc size write workers
// are done
collectGarbageWorkerDone chan struct{}
writeGCSizeWorkerDone chan struct{}
}
// Options struct holds optional parameters for configuring DB.
type Options struct {
// MockStore is a mock node store that is used to store
// chunk data in a central store. It can be used to reduce
// total storage space requirements in testing large number
// of swarm nodes with chunk data deduplication provided by
// the mock global store.
MockStore *mock.NodeStore
// Capacity is a limit that triggers garbage collection when
// number of items in gcIndex equals or exceeds it.
Capacity int64
// MetricsPrefix defines a prefix for metrics names.
MetricsPrefix string
}
// New returns a new DB. All fields and indexes are initialized
// and possible conflicts with schema from existing database is checked.
// One goroutine for writing batches is created.
func New(path string, baseKey []byte, o *Options) (db *DB, err error) {
if o == nil {
o = new(Options)
}
db = &DB{
capacity: o.Capacity,
baseKey: baseKey,
// channels collectGarbageTrigger and writeGCSizeTrigger
// need to be buffered with the size of 1
// to signal another event if it
// is triggered during already running function
collectGarbageTrigger: make(chan struct{}, 1),
writeGCSizeTrigger: make(chan struct{}, 1),
close: make(chan struct{}),
collectGarbageWorkerDone: make(chan struct{}),
writeGCSizeWorkerDone: make(chan struct{}),
}
if db.capacity <= 0 {
db.capacity = defaultCapacity
}
if maxParallelUpdateGC > 0 {
db.updateGCSem = make(chan struct{}, maxParallelUpdateGC)
}
db.shed, err = shed.NewDB(path, o.MetricsPrefix)
if err != nil {
return nil, err
}
// Identify current storage schema by arbitrary name.
db.schemaName, err = db.shed.NewStringField("schema-name")
if err != nil {
return nil, err
}
// Persist gc size.
db.storedGCSize, err = db.shed.NewUint64Field("gc-size")
if err != nil {
return nil, err
}
// Functions for retrieval data index.
var (
encodeValueFunc func(fields shed.Item) (value []byte, err error)
decodeValueFunc func(keyItem shed.Item, value []byte) (e shed.Item, err error)
)
if o.MockStore != nil {
encodeValueFunc = func(fields shed.Item) (value []byte, err error) {
b := make([]byte, 8)
binary.BigEndian.PutUint64(b, uint64(fields.StoreTimestamp))
err = o.MockStore.Put(fields.Address, fields.Data)
if err != nil {
return nil, err
}
return b, nil
}
decodeValueFunc = func(keyItem shed.Item, value []byte) (e shed.Item, err error) {
e.StoreTimestamp = int64(binary.BigEndian.Uint64(value[:8]))
e.Data, err = o.MockStore.Get(keyItem.Address)
return e, err
}
} else {
encodeValueFunc = func(fields shed.Item) (value []byte, err error) {
b := make([]byte, 8)
binary.BigEndian.PutUint64(b, uint64(fields.StoreTimestamp))
value = append(b, fields.Data...)
return value, nil
}
decodeValueFunc = func(keyItem shed.Item, value []byte) (e shed.Item, err error) {
e.StoreTimestamp = int64(binary.BigEndian.Uint64(value[:8]))
e.Data = value[8:]
return e, nil
}
}
// Index storing actual chunk address, data and store timestamp.
db.retrievalDataIndex, err = db.shed.NewIndex("Address->StoreTimestamp|Data", shed.IndexFuncs{
EncodeKey: func(fields shed.Item) (key []byte, err error) {
return fields.Address, nil
},
DecodeKey: func(key []byte) (e shed.Item, err error) {
e.Address = key
return e, nil
},
EncodeValue: encodeValueFunc,
DecodeValue: decodeValueFunc,
})
if err != nil {
return nil, err
}
// Index storing access timestamp for a particular address.
// It is needed in order to update gc index keys for iteration order.
db.retrievalAccessIndex, err = db.shed.NewIndex("Address->AccessTimestamp", shed.IndexFuncs{
EncodeKey: func(fields shed.Item) (key []byte, err error) {
return fields.Address, nil
},
DecodeKey: func(key []byte) (e shed.Item, err error) {
e.Address = key
return e, nil
},
EncodeValue: func(fields shed.Item) (value []byte, err error) {
b := make([]byte, 8)
binary.BigEndian.PutUint64(b, uint64(fields.AccessTimestamp))
return b, nil
},
DecodeValue: func(keyItem shed.Item, value []byte) (e shed.Item, err error) {
e.AccessTimestamp = int64(binary.BigEndian.Uint64(value))
return e, nil
},
})
if err != nil {
return nil, err
}
// pull index allows history and live syncing per po bin
db.pullIndex, err = db.shed.NewIndex("PO|StoredTimestamp|Hash->nil", shed.IndexFuncs{
EncodeKey: func(fields shed.Item) (key []byte, err error) {
key = make([]byte, 41)
key[0] = db.po(fields.Address)
binary.BigEndian.PutUint64(key[1:9], uint64(fields.StoreTimestamp))
copy(key[9:], fields.Address[:])
return key, nil
},
DecodeKey: func(key []byte) (e shed.Item, err error) {
e.Address = key[9:]
e.StoreTimestamp = int64(binary.BigEndian.Uint64(key[1:9]))
return e, nil
},
EncodeValue: func(fields shed.Item) (value []byte, err error) {
return nil, nil
},
DecodeValue: func(keyItem shed.Item, value []byte) (e shed.Item, err error) {
return e, nil
},
})
if err != nil {
return nil, err
}
// create a pull syncing triggers used by SubscribePull function
db.pullTriggers = make(map[uint8][]chan struct{})
// push index contains as yet unsynced chunks
db.pushIndex, err = db.shed.NewIndex("StoredTimestamp|Hash->nil", shed.IndexFuncs{
EncodeKey: func(fields shed.Item) (key []byte, err error) {
key = make([]byte, 40)
binary.BigEndian.PutUint64(key[:8], uint64(fields.StoreTimestamp))
copy(key[8:], fields.Address[:])
return key, nil
},
DecodeKey: func(key []byte) (e shed.Item, err error) {
e.Address = key[8:]
e.StoreTimestamp = int64(binary.BigEndian.Uint64(key[:8]))
return e, nil
},
EncodeValue: func(fields shed.Item) (value []byte, err error) {
return nil, nil
},
DecodeValue: func(keyItem shed.Item, value []byte) (e shed.Item, err error) {
return e, nil
},
})
if err != nil {
return nil, err
}
// create a push syncing triggers used by SubscribePush function
db.pushTriggers = make([]chan struct{}, 0)
// gc index for removable chunk ordered by ascending last access time
db.gcIndex, err = db.shed.NewIndex("AccessTimestamp|StoredTimestamp|Hash->nil", shed.IndexFuncs{
EncodeKey: func(fields shed.Item) (key []byte, err error) {
b := make([]byte, 16, 16+len(fields.Address))
binary.BigEndian.PutUint64(b[:8], uint64(fields.AccessTimestamp))
binary.BigEndian.PutUint64(b[8:16], uint64(fields.StoreTimestamp))
key = append(b, fields.Address...)
return key, nil
},
DecodeKey: func(key []byte) (e shed.Item, err error) {
e.AccessTimestamp = int64(binary.BigEndian.Uint64(key[:8]))
e.StoreTimestamp = int64(binary.BigEndian.Uint64(key[8:16]))
e.Address = key[16:]
return e, nil
},
EncodeValue: func(fields shed.Item) (value []byte, err error) {
return nil, nil
},
DecodeValue: func(keyItem shed.Item, value []byte) (e shed.Item, err error) {
return e, nil
},
})
if err != nil {
return nil, err
}
// gc uncounted hashes index keeps hashes that are in gc index
// but not counted in and saved to storedGCSize
db.gcUncountedHashesIndex, err = db.shed.NewIndex("Hash->nil", shed.IndexFuncs{
EncodeKey: func(fields shed.Item) (key []byte, err error) {
return fields.Address, nil
},
DecodeKey: func(key []byte) (e shed.Item, err error) {
e.Address = key
return e, nil
},
EncodeValue: func(fields shed.Item) (value []byte, err error) {
return nil, nil
},
DecodeValue: func(keyItem shed.Item, value []byte) (e shed.Item, err error) {
return e, nil
},
})
if err != nil {
return nil, err
}
// count number of elements in garbage collection index
gcSize, err := db.storedGCSize.Get()
if err != nil {
return nil, err
}
// get number of uncounted hashes
gcUncountedSize, err := db.gcUncountedHashesIndex.Count()
if err != nil {
return nil, err
}
gcSize += uint64(gcUncountedSize)
// remove uncounted hashes from the index and
// save the total gcSize after uncounted hashes are removed
err = db.writeGCSize(int64(gcSize))
if err != nil {
return nil, err
}
db.incGCSize(int64(gcSize))
// start worker to write gc size
go db.writeGCSizeWorker()
// start garbage collection worker
go db.collectGarbageWorker()
return db, nil
}
// Close closes the underlying database.
func (db *DB) Close() (err error) {
close(db.close)
db.updateGCWG.Wait()
// wait for gc worker and gc size write workers to
// return before closing the shed
timeout := time.After(5 * time.Second)
select {
case <-db.collectGarbageWorkerDone:
case <-timeout:
log.Error("localstore: collect garbage worker did not return after db close")
}
select {
case <-db.writeGCSizeWorkerDone:
case <-timeout:
log.Error("localstore: write gc size worker did not return after db close")
}
if err := db.writeGCSize(db.getGCSize()); err != nil {
log.Error("localstore: write gc size", "err", err)
}
return db.shed.Close()
}
// po computes the proximity order between the address
// and database base key.
func (db *DB) po(addr chunk.Address) (bin uint8) {
return uint8(chunk.Proximity(db.baseKey, addr))
}
var (
// Maximal time for lockAddr to wait until it
// returns error.
addressLockTimeout = 3 * time.Second
// duration between two lock checks in lockAddr.
addressLockCheckDelay = 30 * time.Microsecond
)
// lockAddr sets the lock on a particular address
// using addressLocks sync.Map and returns unlock function.
// If the address is locked this function will check it
// in a for loop for addressLockTimeout time, after which
// it will return ErrAddressLockTimeout error.
func (db *DB) lockAddr(addr chunk.Address) (unlock func(), err error) {
start := time.Now()
lockKey := hex.EncodeToString(addr)
for {
_, loaded := db.addressLocks.LoadOrStore(lockKey, struct{}{})
if !loaded {
break
}
time.Sleep(addressLockCheckDelay)
if time.Since(start) > addressLockTimeout {
return nil, ErrAddressLockTimeout
}
}
return func() { db.addressLocks.Delete(lockKey) }, nil
}
// chunkToItem creates new Item with data provided by the Chunk.
func chunkToItem(ch chunk.Chunk) shed.Item {
return shed.Item{
Address: ch.Address(),
Data: ch.Data(),
}
}
// addressToItem creates new Item with a provided address.
func addressToItem(addr chunk.Address) shed.Item {
return shed.Item{
Address: addr,
}
}
// now is a helper function that returns a current unix timestamp
// in UTC timezone.
// It is set in the init function for usage in production, and
// optionally overridden in tests for data validation.
var now func() int64
func init() {
// set the now function
now = func() (t int64) {
return time.Now().UTC().UnixNano()
}
}
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