1 files changed, 69 insertions, 0 deletions
diff --git a/bolt_unix.go b/bolt_unix.go
new file mode 100644
index 0000000..f7d2fe5
--- /dev/null
+++ b/bolt_unix.go
@@ -0,0 +1,69 @@
+// +build linux darwin
+
+package bolt
+
+import (
+	"os"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+// flock acquires an advisory lock on a file descriptor.
+func flock(f *os.File, timeout time.Duration) error {
+	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
+		}
+
+		// Otherwise attempt to obtain an exclusive lock.
+		err := syscall.Flock(int(f.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
+		if err == nil {
+			return nil
+		} else if err != syscall.EWOULDBLOCK {
+			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(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
+}