diff --git a/main/main_async.go b/examples/async/async.go
similarity index 98%
rename from main/main_async.go
rename to examples/async/async.go
index 27c8eb8..d1562d2 100644
--- a/main/main_async.go
+++ b/examples/async/async.go
@@ -8,7 +8,7 @@ import (
 	"github.com/jhunters/bigqueue"
 )
 
-func main2() {
+func main() {
 	var queue = new(bigqueue.FileQueue)
 
 	var DefaultOptions = &bigqueue.Options{
diff --git a/examples/async/go.mod b/examples/async/go.mod
new file mode 100644
index 0000000..382de24
--- /dev/null
+++ b/examples/async/go.mod
@@ -0,0 +1,3 @@
+module async
+
+go 1.13
diff --git a/examples/nomal/go.mod b/examples/nomal/go.mod
new file mode 100644
index 0000000..3e6a1ea
--- /dev/null
+++ b/examples/nomal/go.mod
@@ -0,0 +1,5 @@
+module normal
+
+go 1.13
+
+require github.com/jhunters/bigqueue v1.0.1 // indirect
diff --git a/examples/nomal/go.sum b/examples/nomal/go.sum
new file mode 100644
index 0000000..6b5c505
--- /dev/null
+++ b/examples/nomal/go.sum
@@ -0,0 +1,2 @@
+github.com/jhunters/bigqueue v1.0.1 h1:xIcBuzfm1ILMdGY5M+fukI84sqv87SPFUDEFT7xaKmc=
+github.com/jhunters/bigqueue v1.0.1/go.mod h1:CbEObWKPe9f5OYtOu99fb92F+gJJewLhxeDm/V+WBio=
diff --git a/examples/nomal/normal.go b/examples/nomal/normal.go
new file mode 100644
index 0000000..dcd2eff
--- /dev/null
+++ b/examples/nomal/normal.go
@@ -0,0 +1,55 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+
+	"github.com/jhunters/bigqueue"
+)
+
+// a demo to show how to enqueue and dequeue data
+func main() {
+
+	var queue = new(bigqueue.FileQueue)
+
+	// use custom options
+	var DefaultOptions = &bigqueue.Options{
+		DataPageSize:      bigqueue.DefaultDataPageSize,
+		GcLock:            false,
+		IndexItemsPerPage: bigqueue.DefaultIndexItemsPerPage,
+	}
+
+	// open queue files
+	err := queue.Open("./bin", "testqueue", DefaultOptions)
+
+	if err != nil {
+		fmt.Println(err)
+	}
+	defer queue.Close()
+
+	// do enqueue
+	for i := 1; i < 10; i++ {
+		data := []byte("hello jhunters" + strconv.Itoa(i))
+		i, err := queue.Enqueue(data)
+		if err != nil {
+			fmt.Println(err)
+		} else {
+			fmt.Println("Enqueued index=", i, string(data))
+		}
+	}
+	// do dequeue
+	for i := 1; i < 10; i++ {
+		index, bb, err := queue.Dequeue()
+		if err != nil {
+			fmt.Println(err)
+		}
+		if index != -1 {
+			fmt.Println(index, string(bb))
+		}
+
+	}
+
+	// do gc action to free old data
+	queue.Gc()
+
+}
diff --git a/main/main.go b/examples/subscribe/subscribe.go
similarity index 57%
rename from main/main.go
rename to examples/subscribe/subscribe.go
index 85158ef..0169829 100644
--- a/main/main.go
+++ b/examples/subscribe/subscribe.go
@@ -8,53 +8,6 @@ import (
 	"github.com/jhunters/bigqueue"
 )
 
-// a demo to show how to enqueue and dequeue data
-func main() {
-
-	var queue = new(bigqueue.FileQueue)
-
-	// use custom options
-	var DefaultOptions = &bigqueue.Options{
-		DataPageSize:      bigqueue.DefaultDataPageSize,
-		GcLock:            false,
-		IndexItemsPerPage: bigqueue.DefaultIndexItemsPerPage,
-	}
-
-	// open queue files
-	err := queue.Open("./bin", "testqueue", DefaultOptions)
-
-	if err != nil {
-		fmt.Println(err)
-	}
-	defer queue.Close()
-
-	// do enqueue
-	for i := 1; i < 10; i++ {
-		data := []byte("hello jhunters" + strconv.Itoa(i))
-		i, err := queue.Enqueue(data)
-		if err != nil {
-			fmt.Println(err)
-		} else {
-			fmt.Println("Enqueued index=", i, string(data))
-		}
-	}
-	// do dequeue
-	for i := 1; i < 10; i++ {
-		index, bb, err := queue.Dequeue()
-		if err != nil {
-			fmt.Println(err)
-		}
-		if index != -1 {
-			fmt.Println(index, string(bb))
-		}
-
-	}
-
-	// do gc action to free old data
-	queue.Gc()
-
-}
-
 func mainSubscrib() {
 	var queue = new(bigqueue.FileQueue)
 
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..b47b13b
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/jhunters/bigqueue
+
+go 1.13
diff --git a/mmap_darwin.go b/mmap_darwin.go
new file mode 100644
index 0000000..4a4c0fc
--- /dev/null
+++ b/mmap_darwin.go
@@ -0,0 +1,55 @@
+// +build darwin
+
+package bigqueue
+
+import (
+	"fmt"
+	"syscall"
+	"unsafe"
+)
+
+// fdatasync flushes written data to a file descriptor.
+func fdatasync(db *DB) error {
+	return syscall.Fsync(int(db.file.Fd()))
+}
+
+// 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_WRITE|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]))
+	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.data = nil
+	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
+}
diff --git a/mmap_unix.go b/mmap_unix.go
index f62f449..9024768 100644
--- a/mmap_unix.go
+++ b/mmap_unix.go
@@ -1,4 +1,4 @@
-// +build !windows,!plan9,!solaris
+// +build !windows,!plan9,!solaris,!darwin
 
 package bigqueue