// Send implements the batch.Sender interface. It subdivides
// the Batch into batches admissible for sending (preventing certain
// illegal mixtures of requests), executes each individual part
// (which may span multiple ranges), and recombines the response.
func (ds *DistSender) Send(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
// In the event that timestamp isn't set and read consistency isn't
// required, set the timestamp using the local clock.
// TODO(tschottdorf): right place for this?
if ba.ReadConsistency == roachpb.INCONSISTENT && ba.Timestamp.Equal(roachpb.ZeroTimestamp) {
// Make sure that after the call, args hasn't changed.
defer func(timestamp roachpb.Timestamp) {
ba.Timestamp = timestamp
}(ba.Timestamp)
ba.Timestamp = ds.clock.Now()
}
if ba.Txn != nil && len(ba.Txn.CertainNodes.Nodes) == 0 {
// Ensure the local NodeID is marked as free from clock offset;
// the transaction's timestamp was taken off the local clock.
if nDesc := ds.getNodeDescriptor(); nDesc != nil {
// TODO(tschottdorf): bad style to assume that ba.Txn is ours.
// No race here, but should have a better way of doing this.
// TODO(tschottdorf): future refactoring should move this to txn
// creation in TxnCoordSender, which is currently unaware of the
// NodeID (and wraps *DistSender through client.Sender since it
// also needs test compatibility with *LocalSender).
ba.Txn.CertainNodes.Add(nDesc.NodeID)
}
}
// TODO(tschottdorf): provisional instantiation.
return newChunkingSender(ds.sendChunk).Send(ctx, ba)
}
// Send implements the batch.Sender interface. It subdivides
// the Batch into batches admissible for sending (preventing certain
// illegal mixtures of requests), executes each individual part
// (which may span multiple ranges), and recombines the response.
func (ds *DistSender) Send(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
// In the event that timestamp isn't set and read consistency isn't
// required, set the timestamp using the local clock.
// TODO(tschottdorf): right place for this?
if ba.ReadConsistency == roachpb.INCONSISTENT && ba.Timestamp.Equal(roachpb.ZeroTimestamp) {
// Make sure that after the call, args hasn't changed.
defer func(timestamp roachpb.Timestamp) {
ba.Timestamp = timestamp
}(ba.Timestamp)
ba.Timestamp = ds.clock.Now()
}
// TODO(tschottdorf): provisional instantiation.
return newChunkingSender(ds.sendChunk).Send(ctx, ba)
}
func testPut() roachpb.BatchRequest {
var ba roachpb.BatchRequest
ba.Timestamp = testTS
put := &roachpb.PutRequest{}
put.Key = testKey
ba.Add(put)
return ba
}
func (tc *TxnCoordSender) heartbeat(id string, trace *tracer.Trace, ctx context.Context) bool {
tc.Lock()
proceed := true
txnMeta := tc.txns[id]
// Before we send a heartbeat, determine whether this transaction
// should be considered abandoned. If so, exit heartbeat.
if txnMeta.hasClientAbandonedCoord(tc.clock.PhysicalNow()) {
// TODO(tschottdorf): should we be more proactive here?
// The client might be continuing the transaction
// through another coordinator, but in the most likely
// case it's just gone and the open transaction record
// could block concurrent operations.
if log.V(1) {
log.Infof("transaction %s abandoned; stopping heartbeat",
txnMeta.txn)
}
proceed = false
}
// txnMeta.txn is possibly replaced concurrently,
// so grab a copy before unlocking.
txn := txnMeta.txn
tc.Unlock()
if !proceed {
return false
}
hb := &roachpb.HeartbeatTxnRequest{}
hb.Key = txn.Key
ba := roachpb.BatchRequest{}
ba.Timestamp = tc.clock.Now()
ba.CmdID = ba.GetOrCreateCmdID(ba.Timestamp.WallTime)
ba.Txn = txn.Clone()
ba.Add(hb)
epochEnds := trace.Epoch("heartbeat")
_, err := tc.wrapped.Send(ctx, ba)
epochEnds()
// If the transaction is not in pending state, then we can stop
// the heartbeat. It's either aborted or committed, and we resolve
// write intents accordingly.
if err != nil {
log.Warningf("heartbeat to %s failed: %s", txn, err)
}
// TODO(bdarnell): once we have gotten a heartbeat response with
// Status != PENDING, future heartbeats are useless. However, we
// need to continue the heartbeatLoop until the client either
// commits or abandons the transaction. We could save a little
// pointless work by restructuring this loop to stop sending
// heartbeats between the time that the transaction is aborted and
// the client finds out. Furthermore, we could use this information
// to send TransactionAbortedErrors to the client so it can restart
// immediately instead of running until its EndTransaction.
return true
}
// process iterates through all keys in a replica's range, calling the garbage
// collector for each key and associated set of values. GC'd keys are batched
// into GC calls. Extant intents are resolved if intents are older than
// intentAgeThreshold. The transaction and abort cache records are also
// scanned and old entries evicted. During normal operation, both of these
// records are cleaned up when their respective transaction finishes, so the
// amount of work done here is expected to be small.
//
// Some care needs to be taken to avoid cyclic recreation of entries during GC:
// * a Push initiated due to an intent may recreate a transaction entry
// * resolving an intent may write a new abort cache entry
// * obtaining the transaction for a abort cache entry requires a Push
//
// The following order is taken below:
// 1) collect all intents with sufficiently old txn record
// 2) collect these intents' transactions
// 3) scan the transaction table, collecting abandoned or completed txns
// 4) push all of these transactions (possibly recreating entries)
// 5) resolve all intents (unless the txn is still PENDING), which will recreate
// abort cache entries (but with the txn timestamp; i.e. likely gc'able)
// 6) scan the abort cache table for old entries
// 7) push these transactions (again, recreating txn entries).
// 8) send a GCRequest.
func (gcq *gcQueue) process(
ctx context.Context,
now hlc.Timestamp,
repl *Replica,
sysCfg config.SystemConfig,
) error {
snap := repl.store.Engine().NewSnapshot()
desc := repl.Desc()
defer snap.Close()
// Lookup the GC policy for the zone containing this key range.
zone, err := sysCfg.GetZoneConfigForKey(desc.StartKey)
if err != nil {
return errors.Errorf("could not find zone config for range %s: %s", repl, err)
}
gcKeys, info, err := RunGC(ctx, desc, snap, now, zone.GC,
func(now hlc.Timestamp, txn *roachpb.Transaction, typ roachpb.PushTxnType) {
pushTxn(gcq.store.DB(), now, txn, typ)
},
func(intents []roachpb.Intent, poison bool, wait bool) error {
return repl.store.intentResolver.resolveIntents(ctx, intents, poison, wait)
})
if err != nil {
return err
}
gcq.eventLog.VInfof(true, "completed with stats %+v", info)
var ba roachpb.BatchRequest
var gcArgs roachpb.GCRequest
// TODO(tschottdorf): This is one of these instances in which we want
// to be more careful that the request ends up on the correct Replica,
// and we might have to worry about mixing range-local and global keys
// in a batch which might end up spanning Ranges by the time it executes.
gcArgs.Key = desc.StartKey.AsRawKey()
gcArgs.EndKey = desc.EndKey.AsRawKey()
gcArgs.Keys = gcKeys
gcArgs.Threshold = info.Threshold
// Technically not needed since we're talking directly to the Range.
ba.RangeID = desc.RangeID
ba.Timestamp = now
ba.Add(&gcArgs)
if _, pErr := repl.Send(ctx, ba); pErr != nil {
return pErr.GoError()
}
return nil
}
// Send implements the batch.Sender interface. It subdivides
// the Batch into batches admissible for sending (preventing certain
// illegal mixtures of requests), executes each individual part
// (which may span multiple ranges), and recombines the response.
// When the request spans ranges, it is split up and the corresponding
// ranges queried serially, in ascending order.
// In particular, the first write in a transaction may not be part of the first
// request sent. This is relevant since the first write is a BeginTransaction
// request, thus opening up a window of time during which there may be intents
// of a transaction, but no entry. Pushing such a transaction will succeed, and
// may lead to the transaction being aborted early.
func (ds *DistSender) Send(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
// In the event that timestamp isn't set and read consistency isn't
// required, set the timestamp using the local clock.
if ba.ReadConsistency == roachpb.INCONSISTENT && ba.Timestamp.Equal(roachpb.ZeroTimestamp) {
ba.Timestamp = ds.clock.Now()
}
if ba.Txn != nil && len(ba.Txn.CertainNodes.Nodes) == 0 {
// Ensure the local NodeID is marked as free from clock offset;
// the transaction's timestamp was taken off the local clock.
if nDesc := ds.getNodeDescriptor(); nDesc != nil {
// TODO(tschottdorf): bad style to assume that ba.Txn is ours.
// No race here, but should have a better way of doing this.
// TODO(tschottdorf): future refactoring should move this to txn
// creation in TxnCoordSender, which is currently unaware of the
// NodeID (and wraps *DistSender through client.Sender since it
// also needs test compatibility with *LocalSender).
ba.Txn.CertainNodes.Add(nDesc.NodeID)
}
}
if len(ba.Requests) < 1 {
panic("empty batch")
}
var rplChunks []*roachpb.BatchResponse
parts := ba.Split(false /* don't split ET */)
for len(parts) > 0 {
part := parts[0]
ba.Requests = part
rpl, pErr, shouldSplitET := ds.sendChunk(ctx, ba)
if shouldSplitET {
// If we tried to send a single round-trip EndTransaction but
// it looks like it's going to hit multiple ranges, split it
// here and try again.
if len(parts) != 1 {
panic("EndTransaction not in last chunk of batch")
}
parts = ba.Split(true /* split ET */)
if len(parts) != 2 {
panic("split of final EndTransaction chunk resulted in != 2 parts")
}
continue
}
if pErr != nil {
return nil, pErr
}
// Propagate transaction from last reply to next request. The final
// update is taken and put into the response's main header.
ba.Txn.Update(rpl.Header().Txn)
rplChunks = append(rplChunks, rpl)
parts = parts[1:]
}
reply := rplChunks[0]
for _, rpl := range rplChunks[1:] {
reply.Responses = append(reply.Responses, rpl.Responses...)
}
*reply.Header() = rplChunks[len(rplChunks)-1].BatchResponse_Header
return reply, nil
}
// Send implements the batch.Sender interface. If the request is part of a
// transaction, the TxnCoordSender adds the transaction to a map of active
// transactions and begins heartbeating it. Every subsequent request for the
// same transaction updates the lastUpdate timestamp to prevent live
// transactions from being considered abandoned and garbage collected.
// Read/write mutating requests have their key or key range added to the
// transaction's interval tree of key ranges for eventual cleanup via resolved
// write intents; they're tagged to an outgoing EndTransaction request, with
// the receiving replica in charge of resolving them.
func (tc *TxnCoordSender) Send(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
if err := tc.maybeBeginTxn(&ba); err != nil {
return nil, roachpb.NewError(err)
}
ba.CmdID = ba.GetOrCreateCmdID(tc.clock.PhysicalNow())
var startNS int64
// This is the earliest point at which the request has a ClientCmdID and/or
// TxnID (if applicable). Begin a Trace which follows this request.
trace := tc.tracer.NewTrace(tracer.Coord, &ba)
defer trace.Finalize()
defer trace.Epoch("sending batch")()
ctx = tracer.ToCtx(ctx, trace)
var id string // optional transaction ID
if ba.Txn != nil {
// If this request is part of a transaction...
id = string(ba.Txn.ID)
// Verify that if this Transaction is not read-only, we have it on
// file. If not, refuse writes - the client must have issued a write on
// another coordinator previously.
if ba.Txn.Writing && ba.IsTransactionWrite() {
tc.Lock()
_, ok := tc.txns[id]
tc.Unlock()
if !ok {
return nil, roachpb.NewError(util.Errorf("transaction must not write on multiple coordinators"))
}
}
// Set the timestamp to the original timestamp for read-only
// commands and to the transaction timestamp for read/write
// commands.
if ba.IsReadOnly() {
ba.Timestamp = ba.Txn.OrigTimestamp
} else {
ba.Timestamp = ba.Txn.Timestamp
}
if rArgs, ok := ba.GetArg(roachpb.EndTransaction); ok {
et := rArgs.(*roachpb.EndTransactionRequest)
if len(et.Key) != 0 {
return nil, roachpb.NewError(util.Errorf("EndTransaction must not have a Key set"))
}
et.Key = ba.Txn.Key
// Remember when EndTransaction started in case we want to
// be linearizable.
startNS = tc.clock.PhysicalNow()
if len(et.Intents) > 0 {
// TODO(tschottdorf): it may be useful to allow this later.
// That would be part of a possible plan to allow txns which
// write on multiple coordinators.
return nil, roachpb.NewError(util.Errorf("client must not pass intents to EndTransaction"))
}
tc.Lock()
txnMeta, metaOK := tc.txns[id]
if id != "" && metaOK {
et.Intents = txnMeta.intents()
}
tc.Unlock()
if intents := ba.GetIntents(); len(intents) > 0 {
// Writes in Batch, so EndTransaction is fine. Should add
// outstanding intents to EndTransaction, though.
// TODO(tschottdorf): possible issues when the batch fails,
// but the intents have been added anyways.
// TODO(tschottdorf): some of these intents may be covered
// by others, for example {[a,b), a}). This can lead to
// some extra requests when those are non-local to the txn
// record. But it doesn't seem worth optimizing now.
et.Intents = append(et.Intents, intents...)
} else if !metaOK {
// If we don't have the transaction, then this must be a retry
// by the client. We can no longer reconstruct a correct
// request so we must fail.
//
// TODO(bdarnell): if we had a GetTransactionStatus API then
// we could lookup the transaction and return either nil or
// TransactionAbortedError instead of this ambivalent error.
return nil, roachpb.NewError(util.Errorf("transaction is already committed or aborted"))
}
if len(et.Intents) == 0 {
// If there aren't any intents, then there's factually no
// transaction to end. Read-only txns have all of their state in
// the client.
return nil, roachpb.NewError(util.Errorf("cannot commit a read-only transaction"))
}
if log.V(1) {
for _, intent := range et.Intents {
trace.Event(fmt.Sprintf("intent: [%s,%s)", intent.Key, intent.EndKey))
}
}
}
}
// Send the command through wrapped sender, taking appropriate measures
// on error.
var br *roachpb.BatchResponse
{
var pErr *roachpb.Error
br, pErr = tc.wrapped.Send(ctx, ba)
if _, ok := pErr.GoError().(*roachpb.OpRequiresTxnError); ok {
br, pErr = tc.resendWithTxn(ba)
}
if pErr := tc.updateState(ctx, ba, br, pErr); pErr != nil {
return nil, pErr
}
}
if br.Txn == nil {
return br, nil
}
if _, ok := ba.GetArg(roachpb.EndTransaction); !ok {
return br, nil
}
// If the --linearizable flag is set, we want to make sure that
// all the clocks in the system are past the commit timestamp
// of the transaction. This is guaranteed if either
// - the commit timestamp is MaxOffset behind startNS
// - MaxOffset ns were spent in this function
// when returning to the client. Below we choose the option
// that involves less waiting, which is likely the first one
// unless a transaction commits with an odd timestamp.
if tsNS := br.Txn.Timestamp.WallTime; startNS > tsNS {
startNS = tsNS
}
sleepNS := tc.clock.MaxOffset() -
time.Duration(tc.clock.PhysicalNow()-startNS)
if tc.linearizable && sleepNS > 0 {
defer func() {
if log.V(1) {
log.Infof("%v: waiting %s on EndTransaction for linearizability", br.Txn.Short(), util.TruncateDuration(sleepNS, time.Millisecond))
}
time.Sleep(sleepNS)
}()
}
if br.Txn.Status != roachpb.PENDING {
tc.cleanupTxn(trace, *br.Txn)
}
return br, nil
}
// Send implements the batch.Sender interface. It subdivides
// the Batch into batches admissible for sending (preventing certain
// illegal mixtures of requests), executes each individual part
// (which may span multiple ranges), and recombines the response.
// When the request spans ranges, it is split up and the corresponding
// ranges queried serially, in ascending order.
// In particular, the first write in a transaction may not be part of the first
// request sent. This is relevant since the first write is a BeginTransaction
// request, thus opening up a window of time during which there may be intents
// of a transaction, but no entry. Pushing such a transaction will succeed, and
// may lead to the transaction being aborted early.
func (ds *DistSender) Send(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
tracing.AnnotateTrace()
// In the event that timestamp isn't set and read consistency isn't
// required, set the timestamp using the local clock.
if ba.ReadConsistency == roachpb.INCONSISTENT && ba.Timestamp.Equal(hlc.ZeroTimestamp) {
ba.Timestamp = ds.clock.Now()
}
if ba.Txn != nil {
// Make a copy here since the code below modifies it in different places.
// TODO(tschottdorf): be smarter about this - no need to do it for
// requests that don't get split.
txnClone := ba.Txn.Clone()
ba.Txn = &txnClone
if len(ba.Txn.ObservedTimestamps) == 0 {
// Ensure the local NodeID is marked as free from clock offset;
// the transaction's timestamp was taken off the local clock.
if nDesc := ds.getNodeDescriptor(); nDesc != nil {
// TODO(tschottdorf): future refactoring should move this to txn
// creation in TxnCoordSender, which is currently unaware of the
// NodeID (and wraps *DistSender through client.Sender since it
// also needs test compatibility with *LocalSender).
//
// Taking care below to not modify any memory referenced from
// our BatchRequest which may be shared with others.
//
// We already have a clone of our txn (see above), so we can
// modify it freely.
//
// Zero the existing data. That makes sure that if we had
// something of size zero but with capacity, we don't re-use the
// existing space (which others may also use). This is just to
// satisfy paranoia/OCD and not expected to matter in practice.
ba.Txn.ResetObservedTimestamps()
// OrigTimestamp is the HLC timestamp at which the Txn started, so
// this effectively means no more uncertainty on this node.
ba.Txn.UpdateObservedTimestamp(nDesc.NodeID, ba.Txn.OrigTimestamp)
}
}
}
if len(ba.Requests) < 1 {
panic("empty batch")
}
if ba.MaxSpanRequestKeys != 0 {
// Verify that the batch contains only specific range requests or the
// Begin/EndTransactionRequest. Verify that a batch with a ReverseScan
// only contains ReverseScan range requests.
isReverse := ba.IsReverse()
for _, req := range ba.Requests {
inner := req.GetInner()
switch inner.(type) {
case *roachpb.ScanRequest, *roachpb.DeleteRangeRequest:
// Accepted range requests. All other range requests are still
// not supported.
// TODO(vivek): don't enumerate all range requests.
if isReverse {
return nil, roachpb.NewErrorf("batch with limit contains both forward and reverse scans")
}
case *roachpb.BeginTransactionRequest, *roachpb.EndTransactionRequest, *roachpb.ReverseScanRequest:
continue
default:
return nil, roachpb.NewErrorf("batch with limit contains %T request", inner)
}
}
}
var rplChunks []*roachpb.BatchResponse
parts := ba.Split(false /* don't split ET */)
if len(parts) > 1 && ba.MaxSpanRequestKeys != 0 {
// We already verified above that the batch contains only scan requests of the same type.
// Such a batch should never need splitting.
panic("batch with MaxSpanRequestKeys needs splitting")
}
for len(parts) > 0 {
part := parts[0]
ba.Requests = part
rpl, pErr, shouldSplitET := ds.sendChunk(ctx, ba)
if shouldSplitET {
// If we tried to send a single round-trip EndTransaction but
// it looks like it's going to hit multiple ranges, split it
// here and try again.
if len(parts) != 1 {
panic("EndTransaction not in last chunk of batch")
}
parts = ba.Split(true /* split ET */)
if len(parts) != 2 {
panic("split of final EndTransaction chunk resulted in != 2 parts")
}
continue
}
if pErr != nil {
return nil, pErr
}
// Propagate transaction from last reply to next request. The final
// update is taken and put into the response's main header.
ba.UpdateTxn(rpl.Txn)
rplChunks = append(rplChunks, rpl)
parts = parts[1:]
}
reply := rplChunks[0]
for _, rpl := range rplChunks[1:] {
reply.Responses = append(reply.Responses, rpl.Responses...)
reply.CollectedSpans = append(reply.CollectedSpans, rpl.CollectedSpans...)
}
reply.BatchResponse_Header = rplChunks[len(rplChunks)-1].BatchResponse_Header
return reply, nil
}
// resolveIntents resolves the given intents. For those which are
// local to the range, we submit directly to the local Raft instance;
// all non-local intents are resolved asynchronously in a batch. If
// `wait` is true, all operations are carried out synchronously and an
// error is returned. Otherwise, the call returns without error as
// soon as all local resolve commands have been **proposed** (not
// executed). This ensures that if a waiting client retries
// immediately after calling this function, it will not hit the same
// intents again.
func (ir *intentResolver) resolveIntents(ctx context.Context, r *Replica,
intents []roachpb.Intent, wait bool, poison bool) error {
// We're doing async stuff below; those need new traces.
ctx, cleanup := tracing.EnsureContext(ctx, ir.store.Tracer())
defer cleanup()
log.Trace(ctx, fmt.Sprintf("resolving intents [wait=%t]", wait))
var reqsRemote []roachpb.Request
baLocal := roachpb.BatchRequest{}
baLocal.Timestamp = ir.store.Clock().Now()
for i := range intents {
intent := intents[i] // avoids a race in `i, intent := range ...`
var resolveArgs roachpb.Request
var local bool // whether this intent lives on this Range
{
if len(intent.EndKey) == 0 {
resolveArgs = &roachpb.ResolveIntentRequest{
Span: intent.Span,
IntentTxn: intent.Txn,
Status: intent.Status,
Poison: poison,
}
local = r.ContainsKey(intent.Key)
} else {
resolveArgs = &roachpb.ResolveIntentRangeRequest{
Span: intent.Span,
IntentTxn: intent.Txn,
Status: intent.Status,
Poison: poison,
}
local = r.ContainsKeyRange(intent.Key, intent.EndKey)
}
}
// If the intent isn't (completely) local, we'll need to send an external request.
// We'll batch them all up and send at the end.
if local {
baLocal.Add(resolveArgs)
} else {
reqsRemote = append(reqsRemote, resolveArgs)
}
}
// The local batch goes directly to Raft.
var wg sync.WaitGroup
if len(baLocal.Requests) > 0 {
action := func() error {
// Trace this under the ID of the intent owner.
// Create a new span though, since we do not want to pass a span
// between goroutines or we risk use-after-finish.
sp := r.store.Tracer().StartSpan("resolve intents")
defer sp.Finish()
ctx = opentracing.ContextWithSpan(ctx, sp)
// Always operate with a timeout when resolving intents: this
// prevents rare shutdown timeouts in tests.
ctxWithTimeout, cancel := context.WithTimeout(ctx, base.NetworkTimeout)
defer cancel()
_, pErr := r.addWriteCmd(ctxWithTimeout, baLocal, &wg)
return pErr.GoError()
}
wg.Add(1)
if wait || !r.store.Stopper().RunLimitedAsyncTask(ir.sem, func() {
if err := action(); err != nil {
log.Warningf("unable to resolve local intents; %s", err)
}
}) {
// Still run the task when draining. Our caller already has a task and
// going async here again is merely for performance, but some intents
// need to be resolved because they might block other tasks. See #1684.
// Note that handleSkippedIntents has a TODO in case #1684 comes back.
if err := action(); err != nil {
return err
}
}
}
// Resolve all of the intents which aren't local to the Range.
if len(reqsRemote) > 0 {
b := &client.Batch{}
b.InternalAddRequest(reqsRemote...)
action := func() error {
// TODO(tschottdorf): no tracing here yet.
return r.store.DB().Run(b).GoError()
}
if wait || !r.store.Stopper().RunLimitedAsyncTask(ir.sem, func() {
if err := action(); err != nil {
log.Warningf("unable to resolve external intents: %s", err)
}
}) {
// As with local intents, try async to not keep the caller waiting, but
// when draining just go ahead and do it synchronously. See #1684.
if err := action(); err != nil {
return err
}
}
}
// Wait until the local ResolveIntents batch has been submitted to
// raft. No-op if all were non-local.
wg.Wait()
return nil
}
// processIntentsAsync asynchronously processes intents which were
// encountered during another command but did not interfere with the
// execution of that command. This occurs in two cases: inconsistent
// reads and EndTransaction (which queues its own external intents for
// processing via this method). The two cases are handled somewhat
// differently and would be better served by different entry points,
// but combining them simplifies the plumbing necessary in Replica.
func (ir *intentResolver) processIntentsAsync(r *Replica, intents []intentsWithArg) {
if len(intents) == 0 {
return
}
now := r.store.Clock().Now()
ctx := r.context(context.TODO())
stopper := r.store.Stopper()
for _, item := range intents {
if item.args.Method() != roachpb.EndTransaction {
stopper.RunLimitedAsyncTask(ir.sem, func() {
// Everything here is best effort; give up rather than waiting
// too long (helps avoid deadlocks during test shutdown,
// although this is imperfect due to the use of an
// uninterruptible WaitGroup.Wait in beginCmds).
ctxWithTimeout, cancel := context.WithTimeout(ctx, base.NetworkTimeout)
defer cancel()
h := roachpb.Header{Timestamp: now}
resolveIntents, pushErr := ir.maybePushTransactions(ctxWithTimeout,
item.intents, h, roachpb.PUSH_TOUCH, true /* skipInFlight */)
// resolveIntents with poison=true because we're resolving
// intents outside of the context of an EndTransaction.
//
// Naively, it doesn't seem like we need to poison the abort
// cache since we're pushing with PUSH_TOUCH - meaning that
// the primary way our Push leads to aborting intents is that
// of the transaction having timed out (and thus presumably no
// client being around any more, though at the time of writing
// we don't guarantee that). But there's another path in which
// the Push comes back successful, namely that of the
// transaction already having been aborted by someone else, in
// which case the client may still be running. Thus, we must
// poison.
if err := ir.resolveIntents(ctxWithTimeout, r, resolveIntents,
true /* wait */, true /* poison */); err != nil {
log.Warningc(ctxWithTimeout, "failed to resolve intents: %s", err)
return
}
if pushErr != nil {
log.Warningc(ctxWithTimeout, "failed to push during intent resolution: %s", pushErr)
return
}
})
} else { // EndTransaction
stopper.RunLimitedAsyncTask(ir.sem, func() {
ctxWithTimeout, cancel := context.WithTimeout(ctx, base.NetworkTimeout)
defer cancel()
// For EndTransaction, we know the transaction is finalized so
// we can skip the push and go straight to the resolve.
//
// This mechanism assumes that when an EndTransaction fails,
// the client makes no assumptions about the result. For
// example, an attempt to explicitly rollback the transaction
// may succeed (triggering this code path), but the result may
// not make it back to the client.
if err := ir.resolveIntents(ctxWithTimeout, r, item.intents,
true /* wait */, false /* !poison */); err != nil {
log.Warningc(ctxWithTimeout, "failed to resolve intents: %s", err)
return
}
// We successfully resolved the intents, so we're able to GC from
// the txn span directly.
var ba roachpb.BatchRequest
ba.Timestamp = now
txn := item.intents[0].Txn
gcArgs := roachpb.GCRequest{
Span: roachpb.Span{
Key: r.Desc().StartKey.AsRawKey(),
EndKey: r.Desc().EndKey.AsRawKey(),
},
}
gcArgs.Keys = append(gcArgs.Keys, roachpb.GCRequest_GCKey{
Key: keys.TransactionKey(txn.Key, txn.ID),
})
ba.Add(&gcArgs)
if _, pErr := r.addWriteCmd(ctxWithTimeout, ba, nil /* nil */); pErr != nil {
log.Warningf("could not GC completed transaction: %s", pErr)
}
})
}
}
}
// process iterates through all keys in a replica's range, calling the garbage
// collector for each key and associated set of values. GC'd keys are batched
// into GC calls. Extant intents are resolved if intents are older than
// intentAgeThreshold. The transaction and sequence cache records are also
// scanned and old entries evicted. During normal operation, both of these
// records are cleaned up when their respective transaction finishes, so the
// amount of work done here is expected to be small.
//
// Some care needs to be taken to avoid cyclic recreation of entries during GC:
// * a Push initiated due to an intent may recreate a transaction entry
// * resolving an intent may write a new sequence cache entry
// * obtaining the transaction for a sequence cache entry requires a Push
//
// The following order is taken below:
// 1) collect all intents with sufficiently old txn record
// 2) collect these intents' transactions
// 3) scan the transaction table, collecting abandoned or completed txns
// 4) push all of these transactions (possibly recreating entries)
// 5) resolve all intents (unless the txn is still PENDING), which will recreate
// sequence cache entries (but with the txn timestamp; i.e. likely gc'able)
// 6) scan the sequence table for old entries
// 7) push these transactions (again, recreating txn entries).
// 8) send a GCRequest.
func (gcq *gcQueue) process(now roachpb.Timestamp, repl *Replica,
sysCfg config.SystemConfig) error {
snap := repl.store.Engine().NewSnapshot()
desc := repl.Desc()
iter := newReplicaDataIterator(desc, snap, true /* replicatedOnly */)
defer iter.Close()
defer snap.Close()
// Lookup the GC policy for the zone containing this key range.
zone, err := sysCfg.GetZoneConfigForKey(desc.StartKey)
if err != nil {
return util.Errorf("could not find zone config for range %s: %s", repl, err)
}
gc := engine.NewGarbageCollector(now, zone.GC)
// Compute intent expiration (intent age at which we attempt to resolve).
intentExp := now
intentExp.WallTime -= intentAgeThreshold.Nanoseconds()
txnExp := now
txnExp.WallTime -= txnCleanupThreshold.Nanoseconds()
gcArgs := &roachpb.GCRequest{}
// TODO(tschottdorf): This is one of these instances in which we want
// to be more careful that the request ends up on the correct Replica,
// and we might have to worry about mixing range-local and global keys
// in a batch which might end up spanning Ranges by the time it executes.
gcArgs.Key = desc.StartKey.AsRawKey()
gcArgs.EndKey = desc.EndKey.AsRawKey()
var expBaseKey roachpb.Key
var keys []engine.MVCCKey
var vals [][]byte
// Maps from txn ID to txn and intent key slice.
txnMap := map[uuid.UUID]*roachpb.Transaction{}
intentSpanMap := map[uuid.UUID][]roachpb.Span{}
// processKeysAndValues is invoked with each key and its set of
// values. Intents older than the intent age threshold are sent for
// resolution and values after the MVCC metadata, and possible
// intent, are sent for garbage collection.
var intentCount int
processKeysAndValues := func() {
// If there's more than a single value for the key, possibly send for GC.
if len(keys) > 1 {
meta := &engine.MVCCMetadata{}
if err := proto.Unmarshal(vals[0], meta); err != nil {
log.Errorf("unable to unmarshal MVCC metadata for key %q: %s", keys[0], err)
} else {
// In the event that there's an active intent, send for
// intent resolution if older than the threshold.
startIdx := 1
if meta.Txn != nil {
// Keep track of intent to resolve if older than the intent
// expiration threshold.
if meta.Timestamp.Less(intentExp) {
txnID := *meta.Txn.ID
txn := &roachpb.Transaction{
TxnMeta: *meta.Txn,
}
txnMap[txnID] = txn
intentCount++
intentSpanMap[txnID] = append(intentSpanMap[txnID], roachpb.Span{Key: expBaseKey})
}
// With an active intent, GC ignores MVCC metadata & intent value.
startIdx = 2
}
// See if any values may be GC'd.
if gcTS := gc.Filter(keys[startIdx:], vals[startIdx:]); !gcTS.Equal(roachpb.ZeroTimestamp) {
// TODO(spencer): need to split the requests up into
// multiple requests in the event that more than X keys
// are added to the request.
gcArgs.Keys = append(gcArgs.Keys, roachpb.GCRequest_GCKey{Key: expBaseKey, Timestamp: gcTS})
}
}
}
}
// Iterate through the keys and values of this replica's range.
for ; iter.Valid(); iter.Next() {
iterKey := iter.Key()
if !iterKey.IsValue() || !iterKey.Key.Equal(expBaseKey) {
// Moving to the next key (& values).
processKeysAndValues()
expBaseKey = iterKey.Key
if !iterKey.IsValue() {
keys = []engine.MVCCKey{iter.Key()}
vals = [][]byte{iter.Value()}
continue
}
// An implicit metadata.
keys = []engine.MVCCKey{engine.MakeMVCCMetadataKey(iterKey.Key)}
// A nil value for the encoded MVCCMetadata. This will unmarshal to an
// empty MVCCMetadata which is sufficient for processKeysAndValues to
// determine that there is no intent.
vals = [][]byte{nil}
}
keys = append(keys, iter.Key())
vals = append(vals, iter.Value())
}
if iter.Error() != nil {
return iter.Error()
}
// Handle last collected set of keys/vals.
processKeysAndValues()
gcq.eventLog.Infof(true, "assembled %d transactions from %d old intents; found %d gc'able keys", len(txnMap), intentCount, len(gcArgs.Keys))
txnKeys, err := gcq.processTransactionTable(repl, txnMap, txnExp)
if err != nil {
return err
}
// From now on, all newly added keys are range-local.
// TODO(tschottdorf): Might need to use two requests at some point since we
// hard-coded the full non-local key range in the header, but that does
// not take into account the range-local keys. It will be OK as long as
// we send directly to the Replica, though.
gcArgs.Keys = append(gcArgs.Keys, txnKeys...)
// Process push transactions in parallel.
var wg sync.WaitGroup
gcq.eventLog.Infof(true, "pushing %d txns", len(txnMap))
for _, txn := range txnMap {
if txn.Status != roachpb.PENDING {
continue
}
wg.Add(1)
go gcq.pushTxn(repl, now, txn, roachpb.PUSH_ABORT, &wg)
}
wg.Wait()
// Resolve all intents.
var intents []roachpb.Intent
for txnID, txn := range txnMap {
if txn.Status != roachpb.PENDING {
for _, intent := range intentSpanMap[txnID] {
intents = append(intents, roachpb.Intent{Span: intent, Status: txn.Status, Txn: txn.TxnMeta})
}
}
}
gcq.eventLog.Infof(true, "resolving %d intents", len(intents))
if pErr := repl.store.intentResolver.resolveIntents(repl.context(), repl, intents,
true /* wait */, false /* !poison */); pErr != nil {
return pErr.GoError()
}
// Deal with any leftover sequence cache keys. There shouldn't be many of
// them.
leftoverSeqCacheKeys := gcq.processSequenceCache(repl, now, txnExp, txnMap)
gcq.eventLog.Infof(true, "collected %d leftover sequence cache keys", len(leftoverSeqCacheKeys))
gcArgs.Keys = append(gcArgs.Keys, leftoverSeqCacheKeys...)
gcq.eventLog.Infof(true, "sending gc request for %d keys", len(gcArgs.Keys))
var ba roachpb.BatchRequest
// Technically not needed since we're talking directly to the Range.
ba.RangeID = desc.RangeID
ba.Timestamp = now
ba.Add(gcArgs)
if _, pErr := repl.Send(repl.context(), ba); pErr != nil {
return pErr.GoError()
}
return nil
}
// process iterates through all keys in a replica's range, calling the garbage
// collector for each key and associated set of values. GC'd keys are batched
// into GC calls. Extant intents are resolved if intents are older than
// intentAgeThreshold.
func (gcq *gcQueue) process(now roachpb.Timestamp, repl *Replica,
sysCfg *config.SystemConfig) error {
snap := repl.store.Engine().NewSnapshot()
desc := repl.Desc()
iter := newReplicaDataIterator(desc, snap)
defer iter.Close()
defer snap.Close()
// Lookup the GC policy for the zone containing this key range.
zone, err := sysCfg.GetZoneConfigForKey(desc.StartKey)
if err != nil {
return fmt.Errorf("could not find GC policy for range %s: %s", repl, err)
}
policy := zone.GC
gcMeta := roachpb.NewGCMetadata(now.WallTime)
gc := engine.NewGarbageCollector(now, *policy)
// Compute intent expiration (intent age at which we attempt to resolve).
intentExp := now
intentExp.WallTime -= intentAgeThreshold.Nanoseconds()
txnExp := now
txnExp.WallTime -= txnCleanupThreshold.Nanoseconds()
gcArgs := &roachpb.GCRequest{}
// TODO(tschottdorf): This is one of these instances in which we want
// to be more careful that the request ends up on the correct Replica,
// and we might have to worry about mixing range-local and global keys
// in a batch which might end up spanning Ranges by the time it executes.
gcArgs.Key = desc.StartKey.AsRawKey()
gcArgs.EndKey = desc.EndKey.AsRawKey()
var expBaseKey roachpb.Key
var keys []engine.MVCCKey
var vals [][]byte
// Maps from txn ID to txn and intent key slice.
txnMap := map[string]*roachpb.Transaction{}
intentSpanMap := map[string][]roachpb.Span{}
// processKeysAndValues is invoked with each key and its set of
// values. Intents older than the intent age threshold are sent for
// resolution and values after the MVCC metadata, and possible
// intent, are sent for garbage collection.
processKeysAndValues := func() {
// If there's more than a single value for the key, possibly send for GC.
if len(keys) > 1 {
meta := &engine.MVCCMetadata{}
if err := proto.Unmarshal(vals[0], meta); err != nil {
log.Errorf("unable to unmarshal MVCC metadata for key %q: %s", keys[0], err)
} else {
// In the event that there's an active intent, send for
// intent resolution if older than the threshold.
startIdx := 1
if meta.Txn != nil {
// Keep track of intent to resolve if older than the intent
// expiration threshold.
if meta.Timestamp.Less(intentExp) {
id := string(meta.Txn.ID)
txnMap[id] = meta.Txn
intentSpanMap[id] = append(intentSpanMap[id], roachpb.Span{Key: expBaseKey})
}
// With an active intent, GC ignores MVCC metadata & intent value.
startIdx = 2
}
// See if any values may be GC'd.
if gcTS := gc.Filter(keys[startIdx:], vals[startIdx:]); !gcTS.Equal(roachpb.ZeroTimestamp) {
// TODO(spencer): need to split the requests up into
// multiple requests in the event that more than X keys
// are added to the request.
gcArgs.Keys = append(gcArgs.Keys, roachpb.GCRequest_GCKey{Key: expBaseKey, Timestamp: gcTS})
}
}
}
}
// Iterate through the keys and values of this replica's range.
for ; iter.Valid(); iter.Next() {
baseKey, ts, isValue, err := engine.MVCCDecodeKey(iter.Key())
if err != nil {
log.Errorf("unable to decode MVCC key: %q: %v", iter.Key(), err)
continue
}
if !isValue {
// Moving to the next key (& values).
processKeysAndValues()
expBaseKey = baseKey
keys = []engine.MVCCKey{iter.Key()}
vals = [][]byte{iter.Value()}
} else {
if !baseKey.Equal(expBaseKey) {
log.Errorf("unexpectedly found a value for %q with ts=%s; expected key %q", baseKey, ts, expBaseKey)
continue
}
keys = append(keys, iter.Key())
vals = append(vals, iter.Value())
}
}
if iter.Error() != nil {
return iter.Error()
}
// Handle last collected set of keys/vals.
processKeysAndValues()
txnKeys, err := processTransactionTable(repl, txnMap, txnExp)
if err != nil {
return err
}
// From now on, all newly added keys are range-local.
// TODO(tschottdorf): Might need to use two requests at some point since we
// hard-coded the full non-local key range in the header, but that does
// not take into account the range-local keys. It will be OK as long as
// we send directly to the Replica, though.
gcArgs.Keys = append(gcArgs.Keys, txnKeys...)
// Process push transactions in parallel.
var wg sync.WaitGroup
for _, txn := range txnMap {
if txn.Status != roachpb.PENDING {
continue
}
wg.Add(1)
go pushTxn(repl, now, txn, roachpb.ABORT_TXN, &wg)
}
wg.Wait()
// Resolve all intents.
var intents []roachpb.Intent
for id, txn := range txnMap {
if txn.Status != roachpb.PENDING {
for _, intent := range intentSpanMap[id] {
intents = append(intents, roachpb.Intent{Span: intent, Txn: *txn})
}
}
}
if err := repl.resolveIntents(repl.context(), intents, true /* wait */, false /* !poison */); err != nil {
return err
}
// Deal with any leftover sequence cache keys. There shouldn't be many of
// them.
gcArgs.Keys = append(gcArgs.Keys, processSequenceCache(repl, now, txnExp, txnMap)...)
// Send GC request through range.
gcArgs.GCMeta = *gcMeta
var ba roachpb.BatchRequest
// Technically not needed since we're talking directly to the Range.
ba.RangeID = desc.RangeID
ba.Timestamp = now
ba.Add(gcArgs)
if _, pErr := repl.Send(repl.context(), ba); pErr != nil {
return pErr.GoError()
}
// Store current timestamp as last verification for this replica, as
// we've just successfully scanned.
if err := repl.SetLastVerificationTimestamp(now); err != nil {
log.Errorf("failed to set last verification timestamp for replica %s: %s", repl, err)
}
return nil
}
// InitOrJoinRequest executes a RequestLease command asynchronously and returns a
// channel on which the result will be posted. If there's already a request in
// progress, we join in waiting for the results of that request.
// It is an error to call InitOrJoinRequest() while a request is in progress
// naming another replica as lease holder.
//
// replica is used to schedule and execute async work (proposing a RequestLease
// command). replica.mu is locked when delivering results, so calls from the
// replica happen either before or after a result for a pending request has
// happened.
//
// transfer needs to be set if the request represents a lease transfer (as
// opposed to an extension, or acquiring the lease when none is held).
//
// Note: Once this function gets a context to be used for cancellation, instead
// of replica.store.Stopper().ShouldQuiesce(), care will be needed for cancelling
// the Raft command, similar to replica.addWriteCmd.
func (p *pendingLeaseRequest) InitOrJoinRequest(
replica *Replica,
nextLeaseHolder roachpb.ReplicaDescriptor,
timestamp hlc.Timestamp,
startKey roachpb.Key,
transfer bool,
) <-chan *roachpb.Error {
if nextLease := p.RequestPending(); nextLease != nil {
if nextLease.Replica.ReplicaID == nextLeaseHolder.ReplicaID {
// Join a pending request asking for the same replica to become lease
// holder.
return p.JoinRequest()
}
llChan := make(chan *roachpb.Error, 1)
// We can't join the request in progress.
llChan <- roachpb.NewErrorf("request for different replica in progress "+
"(requesting: %+v, in progress: %+v)",
nextLeaseHolder.ReplicaID, nextLease.Replica.ReplicaID)
return llChan
}
llChan := make(chan *roachpb.Error, 1)
// No request in progress. Let's propose a Lease command asynchronously.
// TODO(tschottdorf): get duration from configuration, either as a
// config flag or, later, dynamically adjusted.
startStasis := timestamp.Add(int64(replica.store.ctx.rangeLeaseActiveDuration), 0)
expiration := startStasis.Add(int64(replica.store.Clock().MaxOffset()), 0)
reqSpan := roachpb.Span{
Key: startKey,
}
var leaseReq roachpb.Request
reqLease := roachpb.Lease{
Start: timestamp,
StartStasis: startStasis,
Expiration: expiration,
Replica: nextLeaseHolder,
}
if transfer {
leaseReq = &roachpb.TransferLeaseRequest{
Span: reqSpan,
Lease: reqLease,
}
} else {
leaseReq = &roachpb.RequestLeaseRequest{
Span: reqSpan,
Lease: reqLease,
}
}
if replica.store.Stopper().RunAsyncTask(func() {
// Propose a RequestLease command and wait for it to apply.
var execPErr *roachpb.Error
ba := roachpb.BatchRequest{}
ba.Timestamp = replica.store.Clock().Now()
ba.RangeID = replica.RangeID
ba.Add(leaseReq)
// Send lease request directly to raft in order to skip unnecessary
// checks from normal request machinery, (e.g. the command queue).
// Note that the command itself isn't traced, but usually the caller
// waiting for the result has an active Trace.
ch, _, err := replica.proposeRaftCommand(
replica.context(context.Background()), ba)
if err != nil {
execPErr = roachpb.NewError(err)
} else {
// If the command was committed, wait for the range to apply it.
select {
case c := <-ch:
if c.Err != nil {
if log.V(1) {
log.Infof("failed to acquire lease for replica %s: %s", replica.store, c.Err)
}
execPErr = c.Err
}
case <-replica.store.Stopper().ShouldQuiesce():
execPErr = roachpb.NewError(
replica.newNotLeaseHolderError(nil, replica.store.StoreID(), replica.Desc()))
}
}
// Send result of lease to all waiter channels.
replica.mu.Lock()
defer replica.mu.Unlock()
for i, llChan := range p.llChans {
// Don't send the same pErr object twice; this can lead to races. We could
// clone every time but it's more efficient to send pErr itself to one of
// the channels (the last one; if we send it earlier the race can still
// happen).
if i == len(p.llChans)-1 {
llChan <- execPErr
} else {
llChan <- protoutil.Clone(execPErr).(*roachpb.Error) // works with `nil`
}
}
p.llChans = p.llChans[:0]
p.nextLease = roachpb.Lease{}
}) != nil {
// We failed to start the asynchronous task. Send a blank NotLeaseHolderError
// back to indicate that we have no idea who the range lease holder might
// be; we've withdrawn from active duty.
llChan <- roachpb.NewError(
replica.newNotLeaseHolderError(nil, replica.store.StoreID(), replica.mu.state.Desc))
return llChan
}
p.llChans = append(p.llChans, llChan)
p.nextLease = reqLease
return llChan
}
// Send implements the batch.Sender interface. It subdivides
// the Batch into batches admissible for sending (preventing certain
// illegal mixtures of requests), executes each individual part
// (which may span multiple ranges), and recombines the response.
// When the request spans ranges, it is split up and the corresponding
// ranges queried serially, in ascending order.
// In particular, the first write in a transaction may not be part of the first
// request sent. This is relevant since the first write is a BeginTransaction
// request, thus opening up a window of time during which there may be intents
// of a transaction, but no entry. Pushing such a transaction will succeed, and
// may lead to the transaction being aborted early.
func (ds *DistSender) Send(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
tracing.AnnotateTrace()
// In the event that timestamp isn't set and read consistency isn't
// required, set the timestamp using the local clock.
if ba.ReadConsistency == roachpb.INCONSISTENT && ba.Timestamp.Equal(roachpb.ZeroTimestamp) {
ba.Timestamp = ds.clock.Now()
}
if ba.Txn != nil && len(ba.Txn.CertainNodes.Nodes) == 0 {
// Ensure the local NodeID is marked as free from clock offset;
// the transaction's timestamp was taken off the local clock.
if nDesc := ds.getNodeDescriptor(); nDesc != nil {
// TODO(tschottdorf): future refactoring should move this to txn
// creation in TxnCoordSender, which is currently unaware of the
// NodeID (and wraps *DistSender through client.Sender since it
// also needs test compatibility with *LocalSender).
//
// Taking care below to not modify any memory referenced from
// our BatchRequest which may be shared with others.
// First, get a shallow clone of our txn (since that holds the
// NodeList struct).
txnShallow := *ba.Txn
// Next, zero out the NodeList pointer. That makes sure that
// if we had something of size zero but with capacity, we don't
// re-use the existing space (which others may also use).
txnShallow.CertainNodes.Nodes = nil
txnShallow.CertainNodes.Add(nDesc.NodeID)
ba.Txn = &txnShallow
}
}
if len(ba.Requests) < 1 {
panic("empty batch")
}
var rplChunks []*roachpb.BatchResponse
parts := ba.Split(false /* don't split ET */)
for len(parts) > 0 {
part := parts[0]
ba.Requests = part
rpl, pErr, shouldSplitET := ds.sendChunk(ctx, ba)
if shouldSplitET {
// If we tried to send a single round-trip EndTransaction but
// it looks like it's going to hit multiple ranges, split it
// here and try again.
if len(parts) != 1 {
panic("EndTransaction not in last chunk of batch")
}
parts = ba.Split(true /* split ET */)
if len(parts) != 2 {
panic("split of final EndTransaction chunk resulted in != 2 parts")
}
continue
}
if pErr != nil {
return nil, pErr
}
// Propagate transaction from last reply to next request. The final
// update is taken and put into the response's main header.
ba.Txn.Update(rpl.Header().Txn)
rplChunks = append(rplChunks, rpl)
parts = parts[1:]
}
reply := rplChunks[0]
for _, rpl := range rplChunks[1:] {
reply.Responses = append(reply.Responses, rpl.Responses...)
}
*reply.Header() = rplChunks[len(rplChunks)-1].BatchResponse_Header
return reply, nil
}
func (tc *TxnCoordSender) heartbeat(txnID uuid.UUID, trace opentracing.Span, ctx context.Context) bool {
tc.Lock()
proceed := true
txnMeta := tc.txns[txnID]
var intentSpans []roachpb.Span
// Before we send a heartbeat, determine whether this transaction
// should be considered abandoned. If so, exit heartbeat.
if txnMeta.hasClientAbandonedCoord(tc.clock.PhysicalNow()) {
// TODO(tschottdorf): should we be more proactive here?
// The client might be continuing the transaction
// through another coordinator, but in the most likely
// case it's just gone and the open transaction record
// could block concurrent operations.
if log.V(1) {
log.Infof("transaction %s abandoned; stopping heartbeat",
txnMeta.txn)
}
proceed = false
// Grab the intents here to avoid potential race.
intentSpans = txnMeta.intentSpans()
txnMeta.keys.Clear()
}
// txnMeta.txn is possibly replaced concurrently,
// so grab a copy before unlocking.
txn := txnMeta.txn.Clone()
tc.Unlock()
ba := roachpb.BatchRequest{}
ba.Timestamp = tc.clock.Now()
ba.Txn = &txn
if !proceed {
// Actively abort the transaction and its intents since we assume it's abandoned.
et := &roachpb.EndTransactionRequest{
Span: roachpb.Span{
Key: txn.Key,
},
Commit: false,
IntentSpans: intentSpans,
}
ba.Add(et)
tc.stopper.RunAsyncTask(func() {
// Use the wrapped sender since the normal Sender
// does not allow clients to specify intents.
// TODO(tschottdorf): not using the existing context here since that
// leads to use-after-finish of the contained trace. Should fork off
// before the goroutine.
if _, pErr := tc.wrapped.Send(context.Background(), ba); pErr != nil {
if log.V(1) {
log.Warningf("abort due to inactivity failed for %s: %s ", txn, pErr)
}
}
})
return false
}
hb := &roachpb.HeartbeatTxnRequest{}
hb.Key = txn.Key
ba.Add(hb)
trace.LogEvent("heartbeat")
_, err := tc.wrapped.Send(ctx, ba)
// If the transaction is not in pending state, then we can stop
// the heartbeat. It's either aborted or committed, and we resolve
// write intents accordingly.
if err != nil {
log.Warningf("heartbeat to %s failed: %s", txn, err)
}
// TODO(bdarnell): once we have gotten a heartbeat response with
// Status != PENDING, future heartbeats are useless. However, we
// need to continue the heartbeatLoop until the client either
// commits or abandons the transaction. We could save a little
// pointless work by restructuring this loop to stop sending
// heartbeats between the time that the transaction is aborted and
// the client finds out. Furthermore, we could use this information
// to send TransactionAbortedErrors to the client so it can restart
// immediately instead of running until its EndTransaction.
return true
}
// Send implements the batch.Sender interface. If the request is part of a
// transaction, the TxnCoordSender adds the transaction to a map of active
// transactions and begins heartbeating it. Every subsequent request for the
// same transaction updates the lastUpdate timestamp to prevent live
// transactions from being considered abandoned and garbage collected.
// Read/write mutating requests have their key or key range added to the
// transaction's interval tree of key ranges for eventual cleanup via resolved
// write intents; they're tagged to an outgoing EndTransaction request, with
// the receiving replica in charge of resolving them.
func (tc *TxnCoordSender) Send(ctx context.Context, ba roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
// Start new or pick up active trace and embed its trace metadata into
// header for use by RPC recipients. From here on, there's always an active
// Trace, though its overhead is small unless it's sampled.
sp, cleanupSp := tracing.SpanFromContext(opTxnCoordSender, tc.tracer, ctx)
defer cleanupSp()
// TODO(tschottdorf): To get rid of the spurious alloc below we need to
// implement the carrier interface on ba.Header or make Span non-nullable,
// both of which force all of ba on the Heap. It's already there, so may
// not be a big deal, but ba should live on the stack. Also not easy to use
// a buffer pool here since anything that goes into the RPC layer could be
// used by goroutines we didn't wait for.
if ba.Header.Trace == nil {
ba.Header.Trace = &tracing.Span{}
}
if err := tc.tracer.Inject(sp, basictracer.Delegator, ba.Trace); err != nil {
return nil, roachpb.NewError(err)
}
if err := tc.maybeBeginTxn(&ba); err != nil {
return nil, roachpb.NewError(err)
}
var startNS int64
ba.SetNewRequest()
// This is the earliest point at which the request has an ID (if
// applicable). Begin a Trace which follows this request.
ctx = opentracing.ContextWithSpan(ctx, sp)
if ba.Txn != nil {
// If this request is part of a transaction...
txnID := *ba.Txn.ID
// Verify that if this Transaction is not read-only, we have it on
// file. If not, refuse writes - the client must have issued a write on
// another coordinator previously.
if ba.Txn.Writing && ba.IsTransactionWrite() {
tc.Lock()
_, ok := tc.txns[txnID]
tc.Unlock()
if !ok {
return nil, roachpb.NewErrorf("transaction must not write on multiple coordinators")
}
}
// Set the timestamp to the original timestamp for read-only
// commands and to the transaction timestamp for read/write
// commands.
if ba.IsReadOnly() {
ba.Timestamp = ba.Txn.OrigTimestamp
} else {
ba.Timestamp = ba.Txn.Timestamp
}
if rArgs, ok := ba.GetArg(roachpb.EndTransaction); ok {
et := rArgs.(*roachpb.EndTransactionRequest)
if len(et.Key) != 0 {
return nil, roachpb.NewErrorf("EndTransaction must not have a Key set")
}
et.Key = ba.Txn.Key
// Remember when EndTransaction started in case we want to
// be linearizable.
startNS = tc.clock.PhysicalNow()
if len(et.IntentSpans) > 0 {
// TODO(tschottdorf): it may be useful to allow this later.
// That would be part of a possible plan to allow txns which
// write on multiple coordinators.
return nil, roachpb.NewErrorf("client must not pass intents to EndTransaction")
}
tc.Lock()
txnMeta, metaOK := tc.txns[txnID]
if metaOK {
et.IntentSpans = txnMeta.intentSpans()
}
tc.Unlock()
if intentSpans := ba.GetIntentSpans(); len(intentSpans) > 0 {
// Writes in Batch, so EndTransaction is fine. Should add
// outstanding intents to EndTransaction, though.
// TODO(tschottdorf): possible issues when the batch fails,
// but the intents have been added anyways.
// TODO(tschottdorf): some of these intents may be covered
// by others, for example {[a,b), a}). This can lead to
// some extra requests when those are non-local to the txn
// record. But it doesn't seem worth optimizing now.
et.IntentSpans = append(et.IntentSpans, intentSpans...)
} else if !metaOK {
// If we don't have the transaction, then this must be a retry
// by the client. We can no longer reconstruct a correct
// request so we must fail.
//
// TODO(bdarnell): if we had a GetTransactionStatus API then
// we could lookup the transaction and return either nil or
// TransactionAbortedError instead of this ambivalent error.
return nil, roachpb.NewErrorf("transaction is already committed or aborted")
}
if len(et.IntentSpans) == 0 {
// If there aren't any intents, then there's factually no
// transaction to end. Read-only txns have all of their state in
// the client.
return nil, roachpb.NewErrorf("cannot commit a read-only transaction")
}
if log.V(1) {
for _, intent := range et.IntentSpans {
sp.LogEvent(fmt.Sprintf("intent: [%s,%s)", intent.Key, intent.EndKey))
}
}
}
}
// Send the command through wrapped sender, taking appropriate measures
// on error.
var br *roachpb.BatchResponse
{
var pErr *roachpb.Error
br, pErr = tc.wrapped.Send(ctx, ba)
if _, ok := pErr.GetDetail().(*roachpb.OpRequiresTxnError); ok {
// TODO(tschottdorf): needs to keep the trace.
br, pErr = tc.resendWithTxn(ba)
}
if pErr = tc.updateState(ctx, ba, br, pErr); pErr != nil {
sp.LogEvent(fmt.Sprintf("error: %s", pErr))
return nil, pErr
}
}
if br.Txn == nil {
return br, nil
}
if _, ok := ba.GetArg(roachpb.EndTransaction); !ok {
return br, nil
}
// If the --linearizable flag is set, we want to make sure that
// all the clocks in the system are past the commit timestamp
// of the transaction. This is guaranteed if either
// - the commit timestamp is MaxOffset behind startNS
// - MaxOffset ns were spent in this function
// when returning to the client. Below we choose the option
// that involves less waiting, which is likely the first one
// unless a transaction commits with an odd timestamp.
if tsNS := br.Txn.Timestamp.WallTime; startNS > tsNS {
startNS = tsNS
}
sleepNS := tc.clock.MaxOffset() -
time.Duration(tc.clock.PhysicalNow()-startNS)
if tc.linearizable && sleepNS > 0 {
defer func() {
if log.V(1) {
log.Infof("%v: waiting %s on EndTransaction for linearizability", br.Txn.Short(), util.TruncateDuration(sleepNS, time.Millisecond))
}
time.Sleep(sleepNS)
}()
}
if br.Txn.Status != roachpb.PENDING {
tc.cleanupTxn(sp, *br.Txn)
}
return br, nil
}