70 lines
1.7 KiB
Go
70 lines
1.7 KiB
Go
// Copyright 2018 Google LLC
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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 lock
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import (
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"math"
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)
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// LockSet maps a set of Locks into a file. The key is the file offset.
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type lockSetFunctions struct{}
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func (lockSetFunctions) MinKey() uint64 {
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return 0
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}
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func (lockSetFunctions) MaxKey() uint64 {
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return math.MaxUint64
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}
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func (lockSetFunctions) ClearValue(l *Lock) {
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*l = Lock{}
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}
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func (lockSetFunctions) Merge(r1 LockRange, val1 Lock, r2 LockRange, val2 Lock) (Lock, bool) {
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// Merge only if the Readers/Writers are identical.
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if len(val1.Readers) != len(val2.Readers) {
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return Lock{}, false
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}
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for k := range val1.Readers {
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if !val2.Readers[k] {
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return Lock{}, false
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}
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}
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if val1.HasWriter != val2.HasWriter {
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return Lock{}, false
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}
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if val1.HasWriter {
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if val1.Writer != val2.Writer {
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return Lock{}, false
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}
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}
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return val1, true
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}
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func (lockSetFunctions) Split(r LockRange, val Lock, split uint64) (Lock, Lock) {
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// Copy the segment so that split segments don't contain map references
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// to other segments.
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val0 := Lock{Readers: make(map[UniqueID]bool)}
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for k, v := range val.Readers {
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val0.Readers[k] = v
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}
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val0.HasWriter = val.HasWriter
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val0.Writer = val.Writer
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return val, val0
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}
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