This repository has been archived by the owner on Feb 20, 2019. It is now read-only.
forked from boltdb/bolt
-
Notifications
You must be signed in to change notification settings - Fork 2
/
bolt_windows.go
144 lines (122 loc) · 3.84 KB
/
bolt_windows.go
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
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
package bolt
import (
"fmt"
"os"
"syscall"
"time"
"unsafe"
)
// LockFileEx code derived from golang build filemutex_windows.go @ v1.5.1
var (
modkernel32 = syscall.NewLazyDLL("kernel32.dll")
procLockFileEx = modkernel32.NewProc("LockFileEx")
procUnlockFileEx = modkernel32.NewProc("UnlockFileEx")
)
const (
lockExt = ".lock"
// see https://msdn.microsoft.com/en-us/library/windows/desktop/aa365203(v=vs.85).aspx
flagLockExclusive = 2
flagLockFailImmediately = 1
// see https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382(v=vs.85).aspx
errLockViolation syscall.Errno = 0x21
)
func lockFileEx(h syscall.Handle, flags, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
r, _, err := procLockFileEx.Call(uintptr(h), uintptr(flags), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)))
if r == 0 {
return err
}
return nil
}
func unlockFileEx(h syscall.Handle, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
r, _, err := procUnlockFileEx.Call(uintptr(h), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)), 0)
if r == 0 {
return err
}
return nil
}
// fdatasync flushes written data to a file descriptor.
func fdatasync(db *DB) error {
return db.file.Sync()
}
// flock acquires an advisory lock on a file descriptor.
func flock(db *DB, mode os.FileMode, exclusive bool, timeout time.Duration) error {
// Create a separate lock file on windows because a process
// cannot share an exclusive lock on the same file. This is
// needed during Tx.WriteTo().
f, err := os.OpenFile(db.path+lockExt, os.O_CREATE, mode)
if err != nil {
return err
}
db.lockfile = f
var t time.Time
for {
// If we're beyond our timeout then return an error.
// This can only occur after we've attempted a flock once.
if t.IsZero() {
t = time.Now()
} else if timeout > 0 && time.Since(t) > timeout {
return ErrTimeout
}
var flag uint32 = flagLockFailImmediately
if exclusive {
flag |= flagLockExclusive
}
err := lockFileEx(syscall.Handle(db.lockfile.Fd()), flag, 0, 1, 0, &syscall.Overlapped{})
if err == nil {
return nil
} else if err != errLockViolation {
return err
}
// Wait for a bit and try again.
time.Sleep(50 * time.Millisecond)
}
}
// funlock releases an advisory lock on a file descriptor.
func funlock(db *DB) error {
err := unlockFileEx(syscall.Handle(db.lockfile.Fd()), 0, 1, 0, &syscall.Overlapped{})
db.lockfile.Close()
os.Remove(db.path + lockExt)
return err
}
// mmap memory maps a DB's data file.
// Based on: https://github.com/edsrzf/mmap-go
func mmap(db *DB, sz int) error {
if !db.readOnly {
// Truncate the database to the size of the mmap.
if err := db.file.Truncate(int64(sz)); err != nil {
return fmt.Errorf("truncate: %s", err)
}
}
// Open a file mapping handle.
sizelo := uint32(sz >> 32)
sizehi := uint32(sz) & 0xffffffff
h, errno := syscall.CreateFileMapping(syscall.Handle(db.file.Fd()), nil, syscall.PAGE_READONLY, sizelo, sizehi, nil)
if h == 0 {
return os.NewSyscallError("CreateFileMapping", errno)
}
// Create the memory map.
addr, errno := syscall.MapViewOfFile(h, syscall.FILE_MAP_READ, 0, 0, uintptr(sz))
if addr == 0 {
return os.NewSyscallError("MapViewOfFile", errno)
}
// Close mapping handle.
if err := syscall.CloseHandle(syscall.Handle(h)); err != nil {
return os.NewSyscallError("CloseHandle", err)
}
// Convert to a byte array.
db.data = ((*[maxMapSize]byte)(unsafe.Pointer(addr)))
db.datasz = sz
return nil
}
// munmap unmaps a pointer from a file.
// Based on: https://github.com/edsrzf/mmap-go
func munmap(db *DB) error {
if db.data == nil {
return nil
}
addr := (uintptr)(unsafe.Pointer(&db.data[0]))
if err := syscall.UnmapViewOfFile(addr); err != nil {
return os.NewSyscallError("UnmapViewOfFile", err)
}
return nil
}