1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
|
// Copyright 2018 Google LLC
//
// 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 lock
import (
"math"
)
// LockSet maps a set of Locks into a file. The key is the file offset.
type lockSetFunctions struct{}
func (lockSetFunctions) MinKey() uint64 {
return 0
}
func (lockSetFunctions) MaxKey() uint64 {
return math.MaxUint64
}
func (lockSetFunctions) ClearValue(l *Lock) {
*l = Lock{}
}
func (lockSetFunctions) Merge(r1 LockRange, val1 Lock, r2 LockRange, val2 Lock) (Lock, bool) {
// Merge only if the Readers/Writers are identical.
if len(val1.Readers) != len(val2.Readers) {
return Lock{}, false
}
for k := range val1.Readers {
if !val2.Readers[k] {
return Lock{}, false
}
}
if val1.HasWriter != val2.HasWriter {
return Lock{}, false
}
if val1.HasWriter {
if val1.Writer != val2.Writer {
return Lock{}, false
}
}
return val1, true
}
func (lockSetFunctions) Split(r LockRange, val Lock, split uint64) (Lock, Lock) {
// Copy the segment so that split segments don't contain map references
// to other segments.
val0 := Lock{Readers: make(map[UniqueID]bool)}
for k, v := range val.Readers {
val0.Readers[k] = v
}
val0.HasWriter = val.HasWriter
val0.Writer = val.Writer
return val, val0
}
|
