// 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
}
// 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
}
// 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
}
// 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
}
// 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
}