summaryrefslogtreecommitdiff
path: root/vendor/github.com/etcd-io/bbolt/bolt_windows.go
blob: fca178bd29082b3075736a90f44b9271d17d9fb6 (plain)
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
package bbolt

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 (
	// 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, exclusive bool, timeout time.Duration) error {
	var t time.Time
	if timeout != 0 {
		t = time.Now()
	}
	var flag uint32 = flagLockFailImmediately
	if exclusive {
		flag |= flagLockExclusive
	}
	for {
		// Fix for https://github.com/etcd-io/bbolt/issues/121. Use byte-range
		// -1..0 as the lock on the database file.
		var m1 uint32 = (1 << 32) - 1 // -1 in a uint32
		err := lockFileEx(syscall.Handle(db.file.Fd()), flag, 0, 1, 0, &syscall.Overlapped{
			Offset:     m1,
			OffsetHigh: m1,
		})

		if err == nil {
			return nil
		} else if err != errLockViolation {
			return err
		}

		// If we timed oumercit then return an error.
		if timeout != 0 && time.Since(t) > timeout-flockRetryTimeout {
			return ErrTimeout
		}

		// Wait for a bit and try again.
		time.Sleep(flockRetryTimeout)
	}
}

// funlock releases an advisory lock on a file descriptor.
func funlock(db *DB) error {
	var m1 uint32 = (1 << 32) - 1 // -1 in a uint32
	err := unlockFileEx(syscall.Handle(db.file.Fd()), 0, 1, 0, &syscall.Overlapped{
		Offset:     m1,
		OffsetHigh: m1,
	})
	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
}