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package bolt
import (
"os"
"syscall"
"unsafe"
)
var odirect = syscall.O_DIRECT
// fdatasync flushes written data to a file descriptor.
func fdatasync(f *os.File) error {
return syscall.Fdatasync(int(f.Fd()))
}
// flock acquires an advisory lock on a file descriptor.
func flock(f *os.File) error {
return syscall.Flock(int(f.Fd()), syscall.LOCK_EX)
}
// funlock releases an advisory lock on a file descriptor.
func funlock(f *os.File) error {
return syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
}
// mmap memory maps a DB's data file.
func mmap(db *DB, sz int) error {
b, err := syscall.Mmap(int(db.file.Fd()), 0, sz, syscall.PROT_READ, syscall.MAP_SHARED)
if err != nil {
return err
}
// Save the original byte slice and convert to a byte array pointer.
db.dataref = b
db.data = (*[maxMapSize]byte)(unsafe.Pointer(&b[0]))
db.datasz = sz
return nil
}
// munmap unmaps a DB's data file from memory.
func munmap(db *DB) error {
// Ignore the unmap if we have no mapped data.
if db.dataref == nil {
return nil
}
// Unmap using the original byte slice.
err := syscall.Munmap(db.dataref)
db.dataref = nil
db.data = nil
db.datasz = 0
return err
}
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