123 lines
4.4 KiB
Go
123 lines
4.4 KiB
Go
// Copyright 2021 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package kv
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// KeyFlags are metadata associated with key
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type KeyFlags uint8
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const (
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flagPresumeKNE KeyFlags = 1 << iota
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flagNeedLocked
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// The following are assertion related flags.
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// There are four choices of the two bits:
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// * 0: Assertion is not set and can be set later.
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// * flagAssertExists: We assert the key exists.
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// * flagAssertNotExists: We assert the key doesn't exist.
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// * flagAssertExists | flagAssertNotExists: Assertion cannot be made on this key (unknown).
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// Once either (or both) of the two flags is set, we say assertion is set (`HasAssertionFlags` becomes true), and
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// it's expected to be unchangeable within the current transaction.
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flagAssertExists
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flagAssertNotExists
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// the flag indicates the conflict and constraint check of the key should be postponed
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// to the next pessimistic lock or prewrite request.
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flagNeedConstraintCheckInPrewrite
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flagPreviousPresumeKNE
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)
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// HasPresumeKeyNotExists returns whether the associated key use lazy check.
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func (f KeyFlags) HasPresumeKeyNotExists() bool {
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return f&flagPresumeKNE != 0
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}
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// HasNeedLocked returns whether the key needed to be locked
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func (f KeyFlags) HasNeedLocked() bool {
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return f&flagNeedLocked != 0
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}
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// HasAssertExists returns whether the key is asserted to already exist before the current transaction.
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func (f KeyFlags) HasAssertExists() bool {
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return f&flagAssertExists != 0 && f&flagAssertNotExists == 0
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}
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// HasAssertNotExists returns whether the key is asserted not to exist before the current transaction.
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func (f KeyFlags) HasAssertNotExists() bool {
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return f&flagAssertNotExists != 0 && f&flagAssertExists == 0
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}
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// HasAssertUnknown returns whether the key is unable to do any assertion.
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func (f KeyFlags) HasAssertUnknown() bool {
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return f&flagAssertExists != 0 && f&flagAssertNotExists != 0
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}
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// HasAssertionFlags returns whether assertion is set on this key.
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func (f KeyFlags) HasAssertionFlags() bool {
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return f&flagAssertExists != 0 || f&flagAssertNotExists != 0
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}
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// HasNeedConstraintCheckInPrewrite returns whether the key needs to do constraint and conflict check in prewrite.
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func (f KeyFlags) HasNeedConstraintCheckInPrewrite() bool {
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return f&flagNeedConstraintCheckInPrewrite != 0
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}
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// FlagsOp describes KeyFlags modify operation.
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type FlagsOp uint16
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const (
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// SetPresumeKeyNotExists marks the existence of the associated key is checked lazily.
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SetPresumeKeyNotExists FlagsOp = iota
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// SetNeedLocked marks the associated key need to be acquired lock.
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SetNeedLocked
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// SetAssertExist marks the associated key must exist.
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SetAssertExist
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// SetAssertNotExist marks the associated key must not exists.
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SetAssertNotExist
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// SetAssertUnknown marks the associated key is unknown and can not apply other assertion.
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SetAssertUnknown
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// SetAssertNone marks the associated key without any assert.
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SetAssertNone
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// SetNeedConstraintCheckInPrewrite sets the flag flagNeedConstraintCheckInPrewrite
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SetNeedConstraintCheckInPrewrite
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// SetPreviousPresumeKeyNotExists marks the PNE flag is set in previous statements, thus it cannot be unset when
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// retrying or rolling back a statement.
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SetPreviousPresumeKeyNotExists
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)
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// ApplyFlagsOps applys flagspos to origin.
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func ApplyFlagsOps(origin KeyFlags, ops ...FlagsOp) KeyFlags {
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for _, op := range ops {
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switch op {
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case SetPresumeKeyNotExists:
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origin |= flagPresumeKNE
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case SetNeedLocked:
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origin |= flagNeedLocked
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case SetAssertExist:
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origin |= flagAssertExists
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origin &= ^flagAssertNotExists
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case SetAssertNotExist:
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origin |= flagAssertNotExists
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origin &= ^flagAssertExists
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case SetAssertUnknown:
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origin |= flagAssertExists
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origin |= flagAssertNotExists
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case SetNeedConstraintCheckInPrewrite:
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origin |= flagNeedConstraintCheckInPrewrite
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case SetPreviousPresumeKeyNotExists:
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origin |= flagPreviousPresumeKNE
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}
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}
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return origin
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}
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