Ejemplo n.º 1
0
// GetResponse looks up a response matching the specified cmdID and
// returns true if found. The response is deserialized into the
// supplied reply parameter. If no response is found, returns
// false. If a command is pending already for the cmdID, then this
// method will block until the the command is completed or the
// response cache is cleared.
func (rc *ResponseCache) GetResponse(cmdID ClientCmdID, reply interface{}) (bool, error) {
	// Do nothing if command ID is empty.
	if cmdID.IsEmpty() {
		return false, nil
	}
	// If the command is inflight, wait for it to complete.
	rc.Lock()
	for {
		if cond, ok := rc.inflight[cmdID]; ok {
			cond.Wait()
		} else {
			break
		}
	}
	// Adding inflight here is preemptive; we don't want to hold lock
	// while fetching from the on-disk cache. The vast, vast majority of
	// calls to GetResponse will be cache misses, so this saves us
	// from acquiring the lock twice: once here and once below in the
	// event we experience a cache miss.
	rc.addInflightLocked(cmdID)
	rc.Unlock()

	// If the response is in the cache or we experienced an error, return.
	if ok, err := engine.GetI(rc.engine, rc.makeKey(cmdID), reply); ok || err != nil {
		rc.Lock() // Take lock after fetching response from cache.
		defer rc.Unlock()
		rc.removeInflightLocked(cmdID)
		return ok, err
	}
	// There's no command result cached for this ID; but inflight was added above.
	return false, nil
}
Ejemplo n.º 2
0
// CreateRange allocates a new range ID and stores range metadata.
// On success, returns the new range.
func (s *Store) CreateRange(startKey, endKey engine.Key, replicas []Replica) (*Range, error) {
	rangeID, err := engine.Increment(s.engine, engine.KeyLocalRangeIDGenerator, 1)
	if err != nil {
		return nil, err
	}
	if ok, _ := engine.GetI(s.engine, makeRangeKey(rangeID), nil); ok {
		return nil, util.Error("newly allocated range ID already in use")
	}
	// RangeMetadata is stored local to this store only. It is neither
	// replicated via raft nor available via the global kv store.
	meta := RangeMetadata{
		ClusterID: s.Ident.ClusterID,
		RangeID:   rangeID,
		RangeDescriptor: RangeDescriptor{
			StartKey: startKey,
			EndKey:   endKey,
			Replicas: replicas,
		},
	}
	err = engine.PutI(s.engine, makeRangeKey(rangeID), meta)
	if err != nil {
		return nil, err
	}
	rng := NewRange(meta, s.clock, s.engine, s.allocator, s.gossip)
	rng.Start()
	s.mu.Lock()
	defer s.mu.Unlock()
	s.ranges[rangeID] = rng
	return rng, nil
}
Ejemplo n.º 3
0
// IsBootstrapped returns true if the store has already been
// bootstrapped. If the store ident is corrupt, IsBootstrapped will
// return true; the exact error can be retrieved via a call to Init().
func (s *Store) IsBootstrapped() bool {
	ok, err := engine.GetI(s.engine, engine.KeyLocalIdent, &s.Ident)
	if err != nil || ok {
		return true
	}
	return false
}
Ejemplo n.º 4
0
// Init reads the StoreIdent from the underlying engine.
func (s *Store) Init() error {
	ok, err := engine.GetI(s.engine, engine.KeyLocalIdent, &s.Ident)
	if err != nil {
		return err
	} else if !ok {
		return util.Error("store has not been bootstrapped")
	}

	// TODO(spencer): scan through all range metadata and instantiate
	//   ranges. Right now we just get range ID hardcoded as 1.
	var meta RangeMetadata
	ok, err = engine.GetI(s.engine, makeRangeKey(1), &meta)
	if err != nil || !ok {
		return err
	}

	rng := NewRange(meta, s.clock, s.engine, s.allocator, s.gossip)
	rng.Start()

	s.mu.Lock()
	defer s.mu.Unlock()
	s.ranges[meta.RangeID] = rng
	return nil
}
Ejemplo n.º 5
0
// HeartbeatTransaction updates the transaction status and heartbeat timestamp
// on heartbeat message from a txn coordinator. The range will return the
// current status of this transaction to the coordinator.
func (r *Range) HeartbeatTransaction(args *HeartbeatTransactionRequest, reply *HeartbeatTransactionResponse) {
	var txn Transaction
	_, err := engine.GetI(r.engine, args.Key, &txn)
	if err != nil {
		reply.Error = err
		return
	}
	if txn.Status == PENDING {
		if !args.Timestamp.Less(txn.LastHeartbeat) {
			txn.LastHeartbeat = args.Timestamp
		}
		if err := engine.PutI(r.engine, args.Key, txn); err != nil {
			reply.Error = err
			return
		}
	}

	reply.Status = txn.Status
}