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datastore.go
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datastore.go
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package datastore
import (
"fmt"
"strings"
"sync"
"time"
"github.com/docker/docker/libnetwork/discoverapi"
store "github.com/docker/docker/libnetwork/internal/kvstore"
"github.com/docker/docker/libnetwork/internal/kvstore/boltdb"
"github.com/docker/docker/libnetwork/types"
)
// ErrKeyModified is raised for an atomic update when the update is working on a stale state
var (
ErrKeyModified = store.ErrKeyModified
ErrKeyNotFound = store.ErrKeyNotFound
)
type Store struct {
mu sync.Mutex
store store.Store
cache *cache
}
// KVObject is Key/Value interface used by objects to be part of the Store.
type KVObject interface {
// Key method lets an object provide the Key to be used in KV Store
Key() []string
// KeyPrefix method lets an object return immediate parent key that can be used for tree walk
KeyPrefix() []string
// Value method lets an object marshal its content to be stored in the KV store
Value() []byte
// SetValue is used by the datastore to set the object's value when loaded from the data store.
SetValue([]byte) error
// Index method returns the latest DB Index as seen by the object
Index() uint64
// SetIndex method allows the datastore to store the latest DB Index into the object
SetIndex(uint64)
// Exists returns true if the object exists in the datastore, false if it hasn't been stored yet.
// When SetIndex() is called, the object has been stored.
Exists() bool
// Skip provides a way for a KV Object to avoid persisting it in the KV Store
Skip() bool
// New returns a new object which is created based on the
// source object
New() KVObject
// CopyTo deep copies the contents of the implementing object
// to the passed destination object
CopyTo(KVObject) error
}
// ScopeCfg represents Datastore configuration.
type ScopeCfg struct {
Client ScopeClientCfg
}
// ScopeClientCfg represents Datastore Client-only mode configuration
type ScopeClientCfg struct {
Provider string
Address string
Config *store.Config
}
const (
// NetworkKeyPrefix is the prefix for network key in the kv store
NetworkKeyPrefix = "network"
// EndpointKeyPrefix is the prefix for endpoint key in the kv store
EndpointKeyPrefix = "endpoint"
)
var (
defaultRootChain = []string{"docker", "network", "v1.0"}
rootChain = defaultRootChain
)
const defaultPrefix = "/var/lib/docker/network/files"
// DefaultScope returns a default scope config for clients to use.
func DefaultScope(dataDir string) ScopeCfg {
var dbpath string
if dataDir == "" {
dbpath = defaultPrefix + "/local-kv.db"
} else {
dbpath = dataDir + "/network/files/local-kv.db"
}
return ScopeCfg{
Client: ScopeClientCfg{
Provider: string(store.BOLTDB),
Address: dbpath,
Config: &store.Config{
Bucket: "libnetwork",
ConnectionTimeout: time.Minute,
},
},
}
}
// IsValid checks if the scope config has valid configuration.
func (cfg *ScopeCfg) IsValid() bool {
if cfg == nil || strings.TrimSpace(cfg.Client.Provider) == "" || strings.TrimSpace(cfg.Client.Address) == "" {
return false
}
return true
}
// Key provides convenient method to create a Key
func Key(key ...string) string {
var b strings.Builder
for _, parts := range [][]string{rootChain, key} {
for _, part := range parts {
b.WriteString(part)
b.WriteString("/")
}
}
return b.String()
}
// newClient used to connect to KV Store
func newClient(kv string, addr string, config *store.Config) (*Store, error) {
if kv != string(store.BOLTDB) {
return nil, fmt.Errorf("unsupported KV store")
}
if config == nil {
config = &store.Config{}
}
// Parse file path
s, err := boltdb.New(strings.Split(addr, ","), config)
if err != nil {
return nil, err
}
return &Store{store: s, cache: newCache(s)}, nil
}
// New creates a new Store instance.
func New(cfg ScopeCfg) (*Store, error) {
if cfg.Client.Provider == "" || cfg.Client.Address == "" {
cfg = DefaultScope("")
}
return newClient(cfg.Client.Provider, cfg.Client.Address, cfg.Client.Config)
}
// FromConfig creates a new instance of LibKV data store starting from the datastore config data.
func FromConfig(dsc discoverapi.DatastoreConfigData) (*Store, error) {
var (
ok bool
sCfgP *store.Config
)
sCfgP, ok = dsc.Config.(*store.Config)
if !ok && dsc.Config != nil {
return nil, fmt.Errorf("cannot parse store configuration: %v", dsc.Config)
}
ds, err := New(ScopeCfg{
Client: ScopeClientCfg{
Address: dsc.Address,
Provider: dsc.Provider,
Config: sCfgP,
},
})
if err != nil {
return nil, fmt.Errorf("failed to construct datastore client from datastore configuration %v: %v", dsc, err)
}
return ds, err
}
// Close closes the data store.
func (ds *Store) Close() {
ds.store.Close()
}
// PutObjectAtomic provides an atomic add and update operation for a Record.
func (ds *Store) PutObjectAtomic(kvObject KVObject) error {
ds.mu.Lock()
defer ds.mu.Unlock()
if kvObject == nil {
return types.InvalidParameterErrorf("invalid KV Object : nil")
}
kvObjValue := kvObject.Value()
if kvObjValue == nil {
return types.InvalidParameterErrorf("invalid KV Object with a nil Value for key %s", Key(kvObject.Key()...))
}
if !kvObject.Skip() {
var previous *store.KVPair
if kvObject.Exists() {
previous = &store.KVPair{Key: Key(kvObject.Key()...), LastIndex: kvObject.Index()}
}
pair, err := ds.store.AtomicPut(Key(kvObject.Key()...), kvObjValue, previous)
if err != nil {
if err == store.ErrKeyExists {
return ErrKeyModified
}
return err
}
kvObject.SetIndex(pair.LastIndex)
}
// If persistent store is skipped, sequencing needs to
// happen in cache.
return ds.cache.add(kvObject, kvObject.Skip())
}
// GetObject gets data from the store and unmarshals to the specified object.
func (ds *Store) GetObject(key string, o KVObject) error {
ds.mu.Lock()
defer ds.mu.Unlock()
return ds.cache.get(o)
}
func (ds *Store) ensureParent(parent string) error {
exists, err := ds.store.Exists(parent)
if err != nil {
return err
}
if exists {
return nil
}
return ds.store.Put(parent, []byte{})
}
// List returns of a list of KVObjects belonging to the parent key. The caller
// must pass a KVObject of the same type as the objects that need to be listed.
func (ds *Store) List(key string, kvObject KVObject) ([]KVObject, error) {
ds.mu.Lock()
defer ds.mu.Unlock()
return ds.cache.list(kvObject)
}
func (ds *Store) iterateKVPairsFromStore(key string, ctor KVObject, callback func(string, KVObject)) error {
// Make sure the parent key exists
if err := ds.ensureParent(key); err != nil {
return err
}
kvList, err := ds.store.List(key)
if err != nil {
return err
}
for _, kvPair := range kvList {
if len(kvPair.Value) == 0 {
continue
}
dstO := ctor.New()
if err := dstO.SetValue(kvPair.Value); err != nil {
return err
}
// Make sure the object has a correct view of the DB index in
// case we need to modify it and update the DB.
dstO.SetIndex(kvPair.LastIndex)
callback(kvPair.Key, dstO)
}
return nil
}
// Map returns a Map of KVObjects.
func (ds *Store) Map(key string, kvObject KVObject) (map[string]KVObject, error) {
ds.mu.Lock()
defer ds.mu.Unlock()
results := map[string]KVObject{}
err := ds.iterateKVPairsFromStore(key, kvObject, func(key string, val KVObject) {
// Trim the leading & trailing "/" to make it consistent across all stores
results[strings.Trim(key, "/")] = val
})
if err != nil {
return nil, err
}
return results, nil
}
// DeleteObjectAtomic performs atomic delete on a record.
func (ds *Store) DeleteObjectAtomic(kvObject KVObject) error {
ds.mu.Lock()
defer ds.mu.Unlock()
if kvObject == nil {
return types.InvalidParameterErrorf("invalid KV Object : nil")
}
previous := &store.KVPair{Key: Key(kvObject.Key()...), LastIndex: kvObject.Index()}
if !kvObject.Skip() {
if err := ds.store.AtomicDelete(Key(kvObject.Key()...), previous); err != nil {
if err == store.ErrKeyExists {
return ErrKeyModified
}
return err
}
}
// cleanup the cache only if AtomicDelete went through successfully
// If persistent store is skipped, sequencing needs to
// happen in cache.
return ds.cache.del(kvObject, kvObject.Skip())
}