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beneschbenesch
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storage: add a generation counter to RangeDescriptors
Add a generation counter to RangeDescriptors which tracks the number of splits and merges that range has seen. The counter is necessary to avoid a rare edge case when a merge and replica addition occur concurrently. See the comment on TestStoreRangeMergeAddReplicaRace for details. The approach taken here to preserve encoding compatibility with existing RangeDescriptors is to make RangeDescriptor a proto3 message. Adding a new default zero integer field to a proto2 message is complicated because proto2 makes a distinction between an integer that is zero and integer that is unset. Release note: None
1 parent 28c7edc commit ce93650

9 files changed

Lines changed: 312 additions & 82 deletions

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‎c-deps/libroach/protos/roachpb/metadata.pb.cc‎

Lines changed: 35 additions & 4 deletions
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‎c-deps/libroach/protos/roachpb/metadata.pb.h‎

Lines changed: 37 additions & 3 deletions
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‎pkg/roachpb/metadata.go‎

Lines changed: 18 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -22,6 +22,7 @@ import (
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"strings"
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"github.com/cockroachdb/cockroach/pkg/util/humanizeutil"
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"github.com/gogo/protobuf/proto"
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"github.com/pkg/errors"
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)
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@@ -139,6 +140,22 @@ func (r RangeDescriptor) IsInitialized() bool {
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return len(r.EndKey) != 0
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}
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// GetGeneration returns the generation of this RangeDescriptor.
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func (r RangeDescriptor) GetGeneration() int64 {
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if r.Generation != nil {
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return *r.Generation
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}
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return 0
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}
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// IncrementGeneration increments the generation of this RangeDescriptor.
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func (r *RangeDescriptor) IncrementGeneration() {
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// Create a new *int64 for the new generation. We permit shallow copies of
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// RangeDescriptors, so we need to be careful not to mutate the
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// potentially-shared generation counter.
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r.Generation = proto.Int64(r.GetGeneration() + 1)
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}
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// Validate performs some basic validation of the contents of a range descriptor.
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func (r RangeDescriptor) Validate() error {
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if r.NextReplicaID == 0 {
@@ -182,7 +199,7 @@ func (r RangeDescriptor) String() string {
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} else {
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buf.WriteString("<no replicas>")
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}
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fmt.Fprintf(&buf, ", next=%d]", r.NextReplicaID)
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fmt.Fprintf(&buf, ", next=%d, gen=%d]", r.NextReplicaID, r.Generation)
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return buf.String()
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}

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