mirror of
https://github.com/octoleo/restic.git
synced 2024-12-25 12:09:59 +00:00
686 lines
22 KiB
Go
686 lines
22 KiB
Go
/*
|
|
Copyright 2017 Google Inc. All Rights Reserved.
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
package spanner
|
|
|
|
import (
|
|
"bytes"
|
|
"io"
|
|
"sync/atomic"
|
|
"time"
|
|
|
|
log "github.com/golang/glog"
|
|
proto "github.com/golang/protobuf/proto"
|
|
proto3 "github.com/golang/protobuf/ptypes/struct"
|
|
"golang.org/x/net/context"
|
|
|
|
"google.golang.org/api/iterator"
|
|
sppb "google.golang.org/genproto/googleapis/spanner/v1"
|
|
"google.golang.org/grpc/codes"
|
|
)
|
|
|
|
// streamingReceiver is the interface for receiving data from a client side
|
|
// stream.
|
|
type streamingReceiver interface {
|
|
Recv() (*sppb.PartialResultSet, error)
|
|
}
|
|
|
|
// errEarlyReadEnd returns error for read finishes when gRPC stream is still active.
|
|
func errEarlyReadEnd() error {
|
|
return spannerErrorf(codes.FailedPrecondition, "read completed with active stream")
|
|
}
|
|
|
|
// stream is the internal fault tolerant method for streaming data from
|
|
// Cloud Spanner.
|
|
func stream(ctx context.Context, rpc func(ct context.Context, resumeToken []byte) (streamingReceiver, error), setTimestamp func(time.Time), release func(error)) *RowIterator {
|
|
ctx, cancel := context.WithCancel(ctx)
|
|
return &RowIterator{
|
|
streamd: newResumableStreamDecoder(ctx, rpc),
|
|
rowd: &partialResultSetDecoder{},
|
|
setTimestamp: setTimestamp,
|
|
release: release,
|
|
cancel: cancel,
|
|
}
|
|
}
|
|
|
|
// RowIterator is an iterator over Rows.
|
|
type RowIterator struct {
|
|
streamd *resumableStreamDecoder
|
|
rowd *partialResultSetDecoder
|
|
setTimestamp func(time.Time)
|
|
release func(error)
|
|
cancel func()
|
|
err error
|
|
rows []*Row
|
|
}
|
|
|
|
// Next returns the next result. Its second return value is iterator.Done if
|
|
// there are no more results. Once Next returns Done, all subsequent calls
|
|
// will return Done.
|
|
func (r *RowIterator) Next() (*Row, error) {
|
|
if r.err != nil {
|
|
return nil, r.err
|
|
}
|
|
for len(r.rows) == 0 && r.streamd.next() {
|
|
r.rows, r.err = r.rowd.add(r.streamd.get())
|
|
if r.err != nil {
|
|
return nil, r.err
|
|
}
|
|
if !r.rowd.ts.IsZero() && r.setTimestamp != nil {
|
|
r.setTimestamp(r.rowd.ts)
|
|
r.setTimestamp = nil
|
|
}
|
|
}
|
|
if len(r.rows) > 0 {
|
|
row := r.rows[0]
|
|
r.rows = r.rows[1:]
|
|
return row, nil
|
|
}
|
|
if err := r.streamd.lastErr(); err != nil {
|
|
r.err = toSpannerError(err)
|
|
} else if !r.rowd.done() {
|
|
r.err = errEarlyReadEnd()
|
|
} else {
|
|
r.err = iterator.Done
|
|
}
|
|
return nil, r.err
|
|
}
|
|
|
|
// Do calls the provided function once in sequence for each row in the iteration. If the
|
|
// function returns a non-nil error, Do immediately returns that error.
|
|
//
|
|
// If there are no rows in the iterator, Do will return nil without calling the
|
|
// provided function.
|
|
//
|
|
// Do always calls Stop on the iterator.
|
|
func (r *RowIterator) Do(f func(r *Row) error) error {
|
|
defer r.Stop()
|
|
for {
|
|
row, err := r.Next()
|
|
switch err {
|
|
case iterator.Done:
|
|
return nil
|
|
case nil:
|
|
if err = f(row); err != nil {
|
|
return err
|
|
}
|
|
default:
|
|
return err
|
|
}
|
|
}
|
|
}
|
|
|
|
// Stop terminates the iteration. It should be called after every iteration.
|
|
func (r *RowIterator) Stop() {
|
|
if r.cancel != nil {
|
|
r.cancel()
|
|
}
|
|
if r.release != nil {
|
|
r.release(r.err)
|
|
if r.err == nil {
|
|
r.err = spannerErrorf(codes.FailedPrecondition, "Next called after Stop")
|
|
}
|
|
r.release = nil
|
|
|
|
}
|
|
}
|
|
|
|
// partialResultQueue implements a simple FIFO queue. The zero value is a
|
|
// valid queue.
|
|
type partialResultQueue struct {
|
|
q []*sppb.PartialResultSet
|
|
first int
|
|
last int
|
|
n int // number of elements in queue
|
|
}
|
|
|
|
// empty returns if the partialResultQueue is empty.
|
|
func (q *partialResultQueue) empty() bool {
|
|
return q.n == 0
|
|
}
|
|
|
|
// errEmptyQueue returns error for dequeuing an empty queue.
|
|
func errEmptyQueue() error {
|
|
return spannerErrorf(codes.OutOfRange, "empty partialResultQueue")
|
|
}
|
|
|
|
// peekLast returns the last item in partialResultQueue; if the queue
|
|
// is empty, it returns error.
|
|
func (q *partialResultQueue) peekLast() (*sppb.PartialResultSet, error) {
|
|
if q.empty() {
|
|
return nil, errEmptyQueue()
|
|
}
|
|
return q.q[(q.last+cap(q.q)-1)%cap(q.q)], nil
|
|
}
|
|
|
|
// push adds an item to the tail of partialResultQueue.
|
|
func (q *partialResultQueue) push(r *sppb.PartialResultSet) {
|
|
if q.q == nil {
|
|
q.q = make([]*sppb.PartialResultSet, 8 /* arbitrary */)
|
|
}
|
|
if q.n == cap(q.q) {
|
|
buf := make([]*sppb.PartialResultSet, cap(q.q)*2)
|
|
for i := 0; i < q.n; i++ {
|
|
buf[i] = q.q[(q.first+i)%cap(q.q)]
|
|
}
|
|
q.q = buf
|
|
q.first = 0
|
|
q.last = q.n
|
|
}
|
|
q.q[q.last] = r
|
|
q.last = (q.last + 1) % cap(q.q)
|
|
q.n++
|
|
}
|
|
|
|
// pop removes an item from the head of partialResultQueue and returns
|
|
// it.
|
|
func (q *partialResultQueue) pop() *sppb.PartialResultSet {
|
|
if q.n == 0 {
|
|
return nil
|
|
}
|
|
r := q.q[q.first]
|
|
q.q[q.first] = nil
|
|
q.first = (q.first + 1) % cap(q.q)
|
|
q.n--
|
|
return r
|
|
}
|
|
|
|
// clear empties partialResultQueue.
|
|
func (q *partialResultQueue) clear() {
|
|
*q = partialResultQueue{}
|
|
}
|
|
|
|
// dump retrieves all items from partialResultQueue and return them in a slice.
|
|
// It is used only in tests.
|
|
func (q *partialResultQueue) dump() []*sppb.PartialResultSet {
|
|
var dq []*sppb.PartialResultSet
|
|
for i := q.first; len(dq) < q.n; i = (i + 1) % cap(q.q) {
|
|
dq = append(dq, q.q[i])
|
|
}
|
|
return dq
|
|
}
|
|
|
|
// resumableStreamDecoderState encodes resumableStreamDecoder's status.
|
|
// See also the comments for resumableStreamDecoder.Next.
|
|
type resumableStreamDecoderState int
|
|
|
|
const (
|
|
unConnected resumableStreamDecoderState = iota // 0
|
|
queueingRetryable // 1
|
|
queueingUnretryable // 2
|
|
aborted // 3
|
|
finished // 4
|
|
)
|
|
|
|
// resumableStreamDecoder provides a resumable interface for receiving
|
|
// sppb.PartialResultSet(s) from a given query wrapped by
|
|
// resumableStreamDecoder.rpc().
|
|
type resumableStreamDecoder struct {
|
|
// state is the current status of resumableStreamDecoder, see also
|
|
// the comments for resumableStreamDecoder.Next.
|
|
state resumableStreamDecoderState
|
|
// stateWitness when non-nil is called to observe state change,
|
|
// used for testing.
|
|
stateWitness func(resumableStreamDecoderState)
|
|
// ctx is the caller's context, used for cancel/timeout Next().
|
|
ctx context.Context
|
|
// rpc is a factory of streamingReceiver, which might resume
|
|
// a pervious stream from the point encoded in restartToken.
|
|
// rpc is always a wrapper of a Cloud Spanner query which is
|
|
// resumable.
|
|
rpc func(ctx context.Context, restartToken []byte) (streamingReceiver, error)
|
|
// stream is the current RPC streaming receiver.
|
|
stream streamingReceiver
|
|
// q buffers received yet undecoded partial results.
|
|
q partialResultQueue
|
|
// bytesBetweenResumeTokens is the proxy of the byte size of PartialResultSets being queued
|
|
// between two resume tokens. Once bytesBetweenResumeTokens is greater than
|
|
// maxBytesBetweenResumeTokens, resumableStreamDecoder goes into queueingUnretryable state.
|
|
bytesBetweenResumeTokens int32
|
|
// maxBytesBetweenResumeTokens is the max number of bytes that can be buffered
|
|
// between two resume tokens. It is always copied from the global maxBytesBetweenResumeTokens
|
|
// atomically.
|
|
maxBytesBetweenResumeTokens int32
|
|
// np is the next sppb.PartialResultSet ready to be returned
|
|
// to caller of resumableStreamDecoder.Get().
|
|
np *sppb.PartialResultSet
|
|
// resumeToken stores the resume token that resumableStreamDecoder has
|
|
// last revealed to caller.
|
|
resumeToken []byte
|
|
// retryCount is the number of retries that have been carried out so far
|
|
retryCount int
|
|
// err is the last error resumableStreamDecoder has encountered so far.
|
|
err error
|
|
// backoff to compute delays between retries.
|
|
backoff exponentialBackoff
|
|
}
|
|
|
|
// newResumableStreamDecoder creates a new resumeableStreamDecoder instance.
|
|
// Parameter rpc should be a function that creates a new stream
|
|
// beginning at the restartToken if non-nil.
|
|
func newResumableStreamDecoder(ctx context.Context, rpc func(ct context.Context, restartToken []byte) (streamingReceiver, error)) *resumableStreamDecoder {
|
|
return &resumableStreamDecoder{
|
|
ctx: ctx,
|
|
rpc: rpc,
|
|
maxBytesBetweenResumeTokens: atomic.LoadInt32(&maxBytesBetweenResumeTokens),
|
|
backoff: defaultBackoff,
|
|
}
|
|
}
|
|
|
|
// changeState fulfills state transition for resumableStateDecoder.
|
|
func (d *resumableStreamDecoder) changeState(target resumableStreamDecoderState) {
|
|
if d.state == queueingRetryable && d.state != target {
|
|
// Reset bytesBetweenResumeTokens because it is only meaningful/changed under
|
|
// queueingRetryable state.
|
|
d.bytesBetweenResumeTokens = 0
|
|
}
|
|
d.state = target
|
|
if d.stateWitness != nil {
|
|
d.stateWitness(target)
|
|
}
|
|
}
|
|
|
|
// isNewResumeToken returns if the observed resume token is different from
|
|
// the one returned from server last time.
|
|
func (d *resumableStreamDecoder) isNewResumeToken(rt []byte) bool {
|
|
if rt == nil {
|
|
return false
|
|
}
|
|
if bytes.Compare(rt, d.resumeToken) == 0 {
|
|
return false
|
|
}
|
|
return true
|
|
}
|
|
|
|
// Next advances to the next available partial result set. If error or no
|
|
// more, returns false, call Err to determine if an error was encountered.
|
|
// The following diagram illustrates the state machine of resumableStreamDecoder
|
|
// that Next() implements. Note that state transition can be only triggered by
|
|
// RPC activities.
|
|
/*
|
|
rpc() fails retryable
|
|
+---------+
|
|
| | rpc() fails unretryable/ctx timeouts or cancelled
|
|
| | +------------------------------------------------+
|
|
| | | |
|
|
| v | v
|
|
| +---+---+---+ +--------+ +------+--+
|
|
+-----+unConnected| |finished| | aborted |<----+
|
|
| | ++-----+-+ +------+--+ |
|
|
+---+----+--+ ^ ^ ^ |
|
|
| ^ | | | |
|
|
| | | | recv() fails |
|
|
| | | | | |
|
|
| |recv() fails retryable | | | |
|
|
| |with valid ctx | | | |
|
|
| | | | | |
|
|
rpc() succeeds | +-----------------------+ | | |
|
|
| | | recv EOF recv EOF | |
|
|
| | | | | |
|
|
v | | Queue size exceeds | | |
|
|
+---+----+---+----+threshold +-------+-----------+ | |
|
|
+---------->+ +--------------->+ +-+ |
|
|
| |queueingRetryable| |queueingUnretryable| |
|
|
| | +<---------------+ | |
|
|
| +---+----------+--+ pop() returns +--+----+-----------+ |
|
|
| | | resume token | ^ |
|
|
| | | | | |
|
|
| | | | | |
|
|
+---------------+ | | | |
|
|
recv() succeeds | +----+ |
|
|
| recv() succeeds |
|
|
| |
|
|
| |
|
|
| |
|
|
| |
|
|
| |
|
|
+--------------------------------------------------+
|
|
recv() fails unretryable
|
|
|
|
*/
|
|
var (
|
|
// maxBytesBetweenResumeTokens is the maximum amount of bytes that resumableStreamDecoder
|
|
// in queueingRetryable state can use to queue PartialResultSets before getting
|
|
// into queueingUnretryable state.
|
|
maxBytesBetweenResumeTokens = int32(128 * 1024 * 1024)
|
|
)
|
|
|
|
func (d *resumableStreamDecoder) next() bool {
|
|
for {
|
|
select {
|
|
case <-d.ctx.Done():
|
|
// Do context check here so that even gRPC failed to do
|
|
// so, resumableStreamDecoder can still break the loop
|
|
// as expected.
|
|
d.err = errContextCanceled(d.ctx, d.err)
|
|
d.changeState(aborted)
|
|
default:
|
|
}
|
|
switch d.state {
|
|
case unConnected:
|
|
// If no gRPC stream is available, try to initiate one.
|
|
if d.stream, d.err = d.rpc(d.ctx, d.resumeToken); d.err != nil {
|
|
if isRetryable(d.err) {
|
|
d.doBackOff()
|
|
// Be explicit about state transition, although the
|
|
// state doesn't actually change. State transition
|
|
// will be triggered only by RPC activity, regardless of
|
|
// whether there is an actual state change or not.
|
|
d.changeState(unConnected)
|
|
continue
|
|
}
|
|
d.changeState(aborted)
|
|
continue
|
|
}
|
|
d.resetBackOff()
|
|
d.changeState(queueingRetryable)
|
|
continue
|
|
case queueingRetryable:
|
|
fallthrough
|
|
case queueingUnretryable:
|
|
// Receiving queue is not empty.
|
|
last, err := d.q.peekLast()
|
|
if err != nil {
|
|
// Only the case that receiving queue is empty could cause peekLast to
|
|
// return error and in such case, we should try to receive from stream.
|
|
d.tryRecv()
|
|
continue
|
|
}
|
|
if d.isNewResumeToken(last.ResumeToken) {
|
|
// Got new resume token, return buffered sppb.PartialResultSets to caller.
|
|
d.np = d.q.pop()
|
|
if d.q.empty() {
|
|
d.bytesBetweenResumeTokens = 0
|
|
// The new resume token was just popped out from queue, record it.
|
|
d.resumeToken = d.np.ResumeToken
|
|
d.changeState(queueingRetryable)
|
|
}
|
|
return true
|
|
}
|
|
if d.bytesBetweenResumeTokens >= d.maxBytesBetweenResumeTokens && d.state == queueingRetryable {
|
|
d.changeState(queueingUnretryable)
|
|
continue
|
|
}
|
|
if d.state == queueingUnretryable {
|
|
// When there is no resume token observed,
|
|
// only yield sppb.PartialResultSets to caller under
|
|
// queueingUnretryable state.
|
|
d.np = d.q.pop()
|
|
return true
|
|
}
|
|
// Needs to receive more from gRPC stream till a new resume token
|
|
// is observed.
|
|
d.tryRecv()
|
|
continue
|
|
case aborted:
|
|
// Discard all pending items because none of them
|
|
// should be yield to caller.
|
|
d.q.clear()
|
|
return false
|
|
case finished:
|
|
// If query has finished, check if there are still buffered messages.
|
|
if d.q.empty() {
|
|
// No buffered PartialResultSet.
|
|
return false
|
|
}
|
|
// Although query has finished, there are still buffered PartialResultSets.
|
|
d.np = d.q.pop()
|
|
return true
|
|
|
|
default:
|
|
log.Errorf("Unexpected resumableStreamDecoder.state: %v", d.state)
|
|
return false
|
|
}
|
|
}
|
|
}
|
|
|
|
// tryRecv attempts to receive a PartialResultSet from gRPC stream.
|
|
func (d *resumableStreamDecoder) tryRecv() {
|
|
var res *sppb.PartialResultSet
|
|
if res, d.err = d.stream.Recv(); d.err != nil {
|
|
if d.err == io.EOF {
|
|
d.err = nil
|
|
d.changeState(finished)
|
|
return
|
|
}
|
|
if isRetryable(d.err) && d.state == queueingRetryable {
|
|
d.err = nil
|
|
// Discard all queue items (none have resume tokens).
|
|
d.q.clear()
|
|
d.stream = nil
|
|
d.changeState(unConnected)
|
|
d.doBackOff()
|
|
return
|
|
}
|
|
d.changeState(aborted)
|
|
return
|
|
}
|
|
d.q.push(res)
|
|
if d.state == queueingRetryable && !d.isNewResumeToken(res.ResumeToken) {
|
|
// adjusting d.bytesBetweenResumeTokens
|
|
d.bytesBetweenResumeTokens += int32(proto.Size(res))
|
|
}
|
|
d.resetBackOff()
|
|
d.changeState(d.state)
|
|
}
|
|
|
|
// resetBackOff clears the internal retry counter of
|
|
// resumableStreamDecoder so that the next exponential
|
|
// backoff will start at a fresh state.
|
|
func (d *resumableStreamDecoder) resetBackOff() {
|
|
d.retryCount = 0
|
|
}
|
|
|
|
// doBackoff does an exponential backoff sleep.
|
|
func (d *resumableStreamDecoder) doBackOff() {
|
|
ticker := time.NewTicker(d.backoff.delay(d.retryCount))
|
|
defer ticker.Stop()
|
|
d.retryCount++
|
|
select {
|
|
case <-d.ctx.Done():
|
|
case <-ticker.C:
|
|
}
|
|
}
|
|
|
|
// get returns the most recent PartialResultSet generated by a call to next.
|
|
func (d *resumableStreamDecoder) get() *sppb.PartialResultSet {
|
|
return d.np
|
|
}
|
|
|
|
// lastErr returns the last non-EOF error encountered.
|
|
func (d *resumableStreamDecoder) lastErr() error {
|
|
return d.err
|
|
}
|
|
|
|
// partialResultSetDecoder assembles PartialResultSet(s) into Cloud Spanner
|
|
// Rows.
|
|
type partialResultSetDecoder struct {
|
|
row Row
|
|
tx *sppb.Transaction
|
|
chunked bool // if true, next value should be merged with last values entry.
|
|
ts time.Time // read timestamp
|
|
}
|
|
|
|
// yield checks we have a complete row, and if so returns it. A row is not
|
|
// complete if it doesn't have enough columns, or if this is a chunked response
|
|
// and there are no further values to process.
|
|
func (p *partialResultSetDecoder) yield(chunked, last bool) *Row {
|
|
if len(p.row.vals) == len(p.row.fields) && (!chunked || !last) {
|
|
// When partialResultSetDecoder gets enough number of
|
|
// Column values, There are two cases that a new Row
|
|
// should be yield:
|
|
// 1. The incoming PartialResultSet is not chunked;
|
|
// 2. The incoming PartialResultSet is chunked, but the
|
|
// proto3.Value being merged is not the last one in
|
|
// the PartialResultSet.
|
|
//
|
|
// Use a fresh Row to simplify clients that want to use yielded results
|
|
// after the next row is retrieved. Note that fields is never changed
|
|
// so it doesn't need to be copied.
|
|
fresh := Row{
|
|
fields: p.row.fields,
|
|
vals: make([]*proto3.Value, len(p.row.vals)),
|
|
}
|
|
copy(fresh.vals, p.row.vals)
|
|
p.row.vals = p.row.vals[:0] // empty and reuse slice
|
|
return &fresh
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// yieldTx returns transaction information via caller supplied callback.
|
|
func errChunkedEmptyRow() error {
|
|
return spannerErrorf(codes.FailedPrecondition, "got invalid chunked PartialResultSet with empty Row")
|
|
}
|
|
|
|
// add tries to merge a new PartialResultSet into buffered Row. It returns
|
|
// any rows that have been completed as a result.
|
|
func (p *partialResultSetDecoder) add(r *sppb.PartialResultSet) ([]*Row, error) {
|
|
var rows []*Row
|
|
if r.Metadata != nil {
|
|
// Metadata should only be returned in the first result.
|
|
if p.row.fields == nil {
|
|
p.row.fields = r.Metadata.RowType.Fields
|
|
}
|
|
if p.tx == nil && r.Metadata.Transaction != nil {
|
|
p.tx = r.Metadata.Transaction
|
|
if p.tx.ReadTimestamp != nil {
|
|
p.ts = time.Unix(p.tx.ReadTimestamp.Seconds, int64(p.tx.ReadTimestamp.Nanos))
|
|
}
|
|
}
|
|
}
|
|
if len(r.Values) == 0 {
|
|
return nil, nil
|
|
}
|
|
if p.chunked {
|
|
p.chunked = false
|
|
// Try to merge first value in r.Values into
|
|
// uncompleted row.
|
|
last := len(p.row.vals) - 1
|
|
if last < 0 { // sanity check
|
|
return nil, errChunkedEmptyRow()
|
|
}
|
|
var err error
|
|
// If p is chunked, then we should always try to merge p.last with r.first.
|
|
if p.row.vals[last], err = p.merge(p.row.vals[last], r.Values[0]); err != nil {
|
|
return nil, err
|
|
}
|
|
r.Values = r.Values[1:]
|
|
// Merge is done, try to yield a complete Row.
|
|
if row := p.yield(r.ChunkedValue, len(r.Values) == 0); row != nil {
|
|
rows = append(rows, row)
|
|
}
|
|
}
|
|
for i, v := range r.Values {
|
|
// The rest values in r can be appened into p directly.
|
|
p.row.vals = append(p.row.vals, v)
|
|
// Again, check to see if a complete Row can be yielded because of
|
|
// the newly added value.
|
|
if row := p.yield(r.ChunkedValue, i == len(r.Values)-1); row != nil {
|
|
rows = append(rows, row)
|
|
}
|
|
}
|
|
if r.ChunkedValue {
|
|
// After dealing with all values in r, if r is chunked then p must
|
|
// be also chunked.
|
|
p.chunked = true
|
|
}
|
|
return rows, nil
|
|
}
|
|
|
|
// isMergeable returns if a protobuf Value can be potentially merged with
|
|
// other protobuf Values.
|
|
func (p *partialResultSetDecoder) isMergeable(a *proto3.Value) bool {
|
|
switch a.Kind.(type) {
|
|
case *proto3.Value_StringValue:
|
|
return true
|
|
case *proto3.Value_ListValue:
|
|
return true
|
|
default:
|
|
return false
|
|
}
|
|
}
|
|
|
|
// errIncompatibleMergeTypes returns error for incompatible protobuf types
|
|
// that cannot be merged by partialResultSetDecoder.
|
|
func errIncompatibleMergeTypes(a, b *proto3.Value) error {
|
|
return spannerErrorf(codes.FailedPrecondition, "incompatible type in chunked PartialResultSet. expected (%T), got (%T)", a.Kind, b.Kind)
|
|
}
|
|
|
|
// errUnsupportedMergeType returns error for protobuf type that cannot be
|
|
// merged to other protobufs.
|
|
func errUnsupportedMergeType(a *proto3.Value) error {
|
|
return spannerErrorf(codes.FailedPrecondition, "unsupported type merge (%T)", a.Kind)
|
|
}
|
|
|
|
// merge tries to combine two protobuf Values if possible.
|
|
func (p *partialResultSetDecoder) merge(a, b *proto3.Value) (*proto3.Value, error) {
|
|
var err error
|
|
typeErr := errIncompatibleMergeTypes(a, b)
|
|
switch t := a.Kind.(type) {
|
|
case *proto3.Value_StringValue:
|
|
s, ok := b.Kind.(*proto3.Value_StringValue)
|
|
if !ok {
|
|
return nil, typeErr
|
|
}
|
|
return &proto3.Value{
|
|
Kind: &proto3.Value_StringValue{StringValue: t.StringValue + s.StringValue},
|
|
}, nil
|
|
case *proto3.Value_ListValue:
|
|
l, ok := b.Kind.(*proto3.Value_ListValue)
|
|
if !ok {
|
|
return nil, typeErr
|
|
}
|
|
if l.ListValue == nil || len(l.ListValue.Values) <= 0 {
|
|
// b is an empty list, just return a.
|
|
return a, nil
|
|
}
|
|
if t.ListValue == nil || len(t.ListValue.Values) <= 0 {
|
|
// a is an empty list, just return b.
|
|
return b, nil
|
|
}
|
|
if la := len(t.ListValue.Values) - 1; p.isMergeable(t.ListValue.Values[la]) {
|
|
// When the last item in a is of type String,
|
|
// List or Struct(encoded into List by Cloud Spanner),
|
|
// try to Merge last item in a and first item in b.
|
|
t.ListValue.Values[la], err = p.merge(t.ListValue.Values[la], l.ListValue.Values[0])
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
l.ListValue.Values = l.ListValue.Values[1:]
|
|
}
|
|
return &proto3.Value{
|
|
Kind: &proto3.Value_ListValue{
|
|
ListValue: &proto3.ListValue{
|
|
Values: append(t.ListValue.Values, l.ListValue.Values...),
|
|
},
|
|
},
|
|
}, nil
|
|
default:
|
|
return nil, errUnsupportedMergeType(a)
|
|
}
|
|
|
|
}
|
|
|
|
// Done returns if partialResultSetDecoder has already done with all buffered
|
|
// values.
|
|
func (p *partialResultSetDecoder) done() bool {
|
|
// There is no explicit end of stream marker, but ending part way
|
|
// through a row is obviously bad, or ending with the last column still
|
|
// awaiting completion.
|
|
return len(p.row.vals) == 0 && !p.chunked
|
|
}
|