118 lines
2.8 KiB
Go
118 lines
2.8 KiB
Go
package bbolt
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import (
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"fmt"
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"os"
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"syscall"
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"time"
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"unsafe"
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"golang.org/x/sys/windows"
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)
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// fdatasync flushes written data to a file descriptor.
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func fdatasync(db *DB) error {
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return db.file.Sync()
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}
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// flock acquires an advisory lock on a file descriptor.
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func flock(db *DB, exclusive bool, timeout time.Duration) error {
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var t time.Time
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if timeout != 0 {
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t = time.Now()
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}
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var flags uint32 = windows.LOCKFILE_FAIL_IMMEDIATELY
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if exclusive {
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flags |= windows.LOCKFILE_EXCLUSIVE_LOCK
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}
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for {
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// Fix for https://github.com/etcd-io/bbolt/issues/121. Use byte-range
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// -1..0 as the lock on the database file.
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var m1 uint32 = (1 << 32) - 1 // -1 in a uint32
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err := windows.LockFileEx(windows.Handle(db.file.Fd()), flags, 0, 1, 0, &windows.Overlapped{
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Offset: m1,
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OffsetHigh: m1,
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})
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if err == nil {
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return nil
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} else if err != windows.ERROR_LOCK_VIOLATION {
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return err
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}
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// If we timed oumercit then return an error.
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if timeout != 0 && time.Since(t) > timeout-flockRetryTimeout {
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return ErrTimeout
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}
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// Wait for a bit and try again.
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time.Sleep(flockRetryTimeout)
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}
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}
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// funlock releases an advisory lock on a file descriptor.
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func funlock(db *DB) error {
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var m1 uint32 = (1 << 32) - 1 // -1 in a uint32
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return windows.UnlockFileEx(windows.Handle(db.file.Fd()), 0, 1, 0, &windows.Overlapped{
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Offset: m1,
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OffsetHigh: m1,
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})
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}
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// mmap memory maps a DB's data file.
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// Based on: https://github.com/edsrzf/mmap-go
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func mmap(db *DB, sz int) error {
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var sizelo, sizehi uint32
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if !db.readOnly {
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// Truncate the database to the size of the mmap.
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if err := db.file.Truncate(int64(sz)); err != nil {
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return fmt.Errorf("truncate: %s", err)
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}
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sizehi = uint32(sz >> 32)
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sizelo = uint32(sz) & 0xffffffff
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}
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// Open a file mapping handle.
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h, errno := syscall.CreateFileMapping(syscall.Handle(db.file.Fd()), nil, syscall.PAGE_READONLY, sizehi, sizelo, nil)
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if h == 0 {
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return os.NewSyscallError("CreateFileMapping", errno)
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}
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// Create the memory map.
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addr, errno := syscall.MapViewOfFile(h, syscall.FILE_MAP_READ, 0, 0, 0)
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if addr == 0 {
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// Do our best and report error returned from MapViewOfFile.
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_ = syscall.CloseHandle(h)
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return os.NewSyscallError("MapViewOfFile", errno)
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}
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// Close mapping handle.
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if err := syscall.CloseHandle(syscall.Handle(h)); err != nil {
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return os.NewSyscallError("CloseHandle", err)
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}
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// Convert to a byte array.
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db.data = ((*[maxMapSize]byte)(unsafe.Pointer(addr)))
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db.datasz = sz
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return nil
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}
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// munmap unmaps a pointer from a file.
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// Based on: https://github.com/edsrzf/mmap-go
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func munmap(db *DB) error {
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if db.data == nil {
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return nil
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}
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addr := (uintptr)(unsafe.Pointer(&db.data[0]))
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var err1 error
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if err := syscall.UnmapViewOfFile(addr); err != nil {
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err1 = os.NewSyscallError("UnmapViewOfFile", err)
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}
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db.data = nil
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db.datasz = 0
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return err1
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}
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