From 5e02e28f9c8cca7c5d99c2da15a73eda63e2b7ea Mon Sep 17 00:00:00 2001
From: Fabian Reinartz <fab.reinartz@gmail.com>
Date: Sun, 11 Dec 2016 15:49:36 +0100
Subject: [PATCH] Add proper mmap calls

---
 db.go      |  2 +-
 db_unix.go | 72 +++++++++++++++++-------------------------------------
 2 files changed, 24 insertions(+), 50 deletions(-)

diff --git a/db.go b/db.go
index 6decbd6118..c546a4cd30 100644
--- a/db.go
+++ b/db.go
@@ -322,7 +322,7 @@ func (s *SeriesShard) persist() error {
 		}
 	}
 
-	sz := fmt.Sprintf("%fMiB", float64(sw.Size()+iw.Size())/1024/1024)
+	sz := fmt.Sprintf("%.2fMiB", float64(sw.Size()+iw.Size())/1024/1024)
 
 	s.logger.With("size", sz).
 		With("samples", head.samples).
diff --git a/db_unix.go b/db_unix.go
index 216da9af51..2e673f9516 100644
--- a/db_unix.go
+++ b/db_unix.go
@@ -2,52 +2,26 @@
 
 package tsdb
 
-// import (
-// 	"fmt"
-// 	"syscall"
-// 	"unsafe"
-// )
-
-// // mmap memory maps a DB's data file.
-// func mmap(db *DB, sz int) error {
-// 	// Map the data file to memory.
-// 	b, err := syscall.Mmap(int(db.file.Fd()), 0, sz, syscall.PROT_READ, syscall.MAP_SHARED|db.MmapFlags)
-// 	if err != nil {
-// 		return err
-// 	}
-
-// 	// Advise the kernel that the mmap is accessed randomly.
-// 	if err := madvise(b, syscall.MADV_RANDOM); err != nil {
-// 		return fmt.Errorf("madvise: %s", 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
-// }
-
-// // NOTE: This function is copied from stdlib because it is not available on darwin.
-// func madvise(b []byte, advice int) (err error) {
-// 	_, _, e1 := syscall.Syscall(syscall.SYS_MADVISE, uintptr(unsafe.Pointer(&b[0])), uintptr(len(b)), uintptr(advice))
-// 	if e1 != 0 {
-// 		err = e1
-// 	}
-// 	return
-// }
+import (
+	"os"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+func mmap(f *os.File, length int) ([]byte, error) {
+	return unix.Mmap(int(f.Fd()), 0, length, unix.PROT_READ, unix.MAP_SHARED)
+}
+
+func munmap(b []byte) (err error) {
+	return unix.Munmap(b)
+}
+
+// unix.Madvise is not defined for darwin, so we define it ourselves.
+func madvise(b []byte, advice int) (err error) {
+	_, _, e1 := unix.Syscall(unix.SYS_MADVISE, uintptr(unsafe.Pointer(&b[0])), uintptr(len(b)), uintptr(advice))
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}