github.com/cockroachdb/cockroach@v20.2.0-alpha.1+incompatible/pkg/kv/kvserver/batcheval/cmd_refresh.go (about)

     1  // Copyright 2017 The Cockroach Authors.
     2  //
     3  // Use of this software is governed by the Business Source License
     4  // included in the file licenses/BSL.txt.
     5  //
     6  // As of the Change Date specified in that file, in accordance with
     7  // the Business Source License, use of this software will be governed
     8  // by the Apache License, Version 2.0, included in the file
     9  // licenses/APL.txt.
    10  
    11  package batcheval
    12  
    13  import (
    14  	"context"
    15  
    16  	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/batcheval/result"
    17  	"github.com/cockroachdb/cockroach/pkg/roachpb"
    18  	"github.com/cockroachdb/cockroach/pkg/storage"
    19  	"github.com/cockroachdb/cockroach/pkg/util/log"
    20  	"github.com/cockroachdb/errors"
    21  )
    22  
    23  func init() {
    24  	RegisterReadOnlyCommand(roachpb.Refresh, DefaultDeclareKeys, Refresh)
    25  }
    26  
    27  // Refresh checks whether the key has any values written in the interval
    28  // [args.RefreshFrom, header.Timestamp].
    29  func Refresh(
    30  	ctx context.Context, reader storage.Reader, cArgs CommandArgs, resp roachpb.Response,
    31  ) (result.Result, error) {
    32  	args := cArgs.Args.(*roachpb.RefreshRequest)
    33  	h := cArgs.Header
    34  
    35  	if h.Txn == nil {
    36  		return result.Result{}, errors.Errorf("no transaction specified to %s", args.Method())
    37  	}
    38  
    39  	// We're going to refresh up to the transaction's read timestamp.
    40  	if h.Timestamp != h.Txn.WriteTimestamp {
    41  		// We're expecting the read and write timestamp to have converged before the
    42  		// Refresh request was sent.
    43  		log.Fatalf(ctx, "expected provisional commit ts %s == read ts %s. txn: %s", h.Timestamp,
    44  			h.Txn.WriteTimestamp, h.Txn)
    45  	}
    46  	refreshTo := h.Timestamp
    47  
    48  	refreshFrom := args.RefreshFrom
    49  	if refreshFrom.IsEmpty() {
    50  		// Compatibility with 19.2 nodes, which didn't set the args.RefreshFrom field.
    51  		refreshFrom = h.Txn.DeprecatedOrigTimestamp
    52  	}
    53  
    54  	// Get the most recent committed value and return any intent by
    55  	// specifying consistent=false. Note that we include tombstones,
    56  	// which must be considered as updates on refresh.
    57  	log.VEventf(ctx, 2, "refresh %s @[%s-%s]", args.Span(), refreshFrom, refreshTo)
    58  	val, intent, err := storage.MVCCGet(ctx, reader, args.Key, refreshTo, storage.MVCCGetOptions{
    59  		Inconsistent: true,
    60  		Tombstones:   true,
    61  	})
    62  
    63  	if err != nil {
    64  		return result.Result{}, err
    65  	} else if val != nil {
    66  		if ts := val.Timestamp; refreshFrom.LessEq(ts) {
    67  			return result.Result{}, errors.Errorf("encountered recently written key %s @%s", args.Key, ts)
    68  		}
    69  	}
    70  
    71  	// Check if an intent which is not owned by this transaction was written
    72  	// at or beneath the refresh timestamp.
    73  	if intent != nil && intent.Txn.ID != h.Txn.ID {
    74  		return result.Result{}, errors.Errorf("encountered recently written intent %s @%s",
    75  			intent.Key, intent.Txn.WriteTimestamp)
    76  	}
    77  
    78  	return result.Result{}, nil
    79  }