feat: enable mmap to alloc on unix-like system

go.mod

@@ -1,3 +1,5 @@
 module github.com/allegro/bigcache/v3
 
-go 1.16
+go 1.17
+
+require golang.org/x/sys v0.1.0

go.sum

@@ -0,0 +1,2 @@
+golang.org/x/sys v0.1.0 h1:kunALQeHf1/185U1i0GOB/fy1IPRDDpuoOOqRReG57U=
+golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

queue/bytes_queue.go

@@ -57,22 +57,6 @@ func getNeededSize(length int) int {
 	return length + header
 }
 
-// NewBytesQueue initialize new bytes queue.
-// capacity is used in bytes array allocation
-// When verbose flag is set then information about memory allocation are printed
-func NewBytesQueue(capacity int, maxCapacity int, verbose bool) *BytesQueue {
-	return &BytesQueue{
-		array:        make([]byte, capacity),
-		capacity:     capacity,
-		maxCapacity:  maxCapacity,
-		headerBuffer: make([]byte, binary.MaxVarintLen32),
-		tail:         leftMarginIndex,
-		head:         leftMarginIndex,
-		rightMargin:  leftMarginIndex,
-		verbose:      verbose,
-	}
-}
-
 // Reset removes all entries from queue
 func (q *BytesQueue) Reset() {
 	// Just reset indexes

queue/bytes_queue_test.go

@@ -94,7 +94,7 @@ func TestResetFullQueue(t *testing.T) {
 
 	// then
 	assertEqual(t, blob('c', 8), pop(queue))
-	assertEqual(t, queue.Capacity(), 10)
+	assertEqual(t, queue.Capacity(), unixOr_int(20, 10))
 }
 
 func TestReset(t *testing.T) {
@@ -416,9 +416,9 @@ func TestPushEntryAfterAllocateAdditionMemory(t *testing.T) {
 	queue.Pop()
 
 	// allocate more memory
-	assertEqual(t, 9, queue.Capacity())
+	assertEqual(t, unixOr_int(20, 9), queue.Capacity())
 	queue.Push([]byte("c"))
-	assertEqual(t, 18, queue.Capacity())
+	assertEqual(t, unixOr_int(20, 18), queue.Capacity())
 
 	// push after allocate
 	_, err := queue.Push([]byte("d"))
@@ -508,3 +508,12 @@ func objectsAreEqual(expected, actual interface{}) bool {
 	}
 	return bytes.Equal(exp, act)
 }
+
+func unixOr_int(unix, other int) int {
+	switch runtime.GOOS {
+	case "aix", "darwin", "dragonfly", "freebsd", "openbsd", "solaris", "zos", "linux", "netbsd":
+		return unix
+	default:
+		return other
+	}
+}

queue/new_others.go

@@ -0,0 +1,22 @@
+//go:build !aix && !darwin && !dragonfly && !freebsd && !openbsd && !solaris && !zos && !linux && !netbsd
+// +build !aix,!darwin,!dragonfly,!freebsd,!openbsd,!solaris,!zos,!linux,!netbsd
+
+package queue
+
+import "encoding/binary"
+
+// NewBytesQueue initialize new bytes queue.
+// capacity is used in bytes array allocation
+// When verbose flag is set then information about memory allocation are printed
+func NewBytesQueue(capacity int, maxCapacity int, verbose bool) *BytesQueue {
+	return &BytesQueue{
+		array:        make([]byte, capacity),
+		capacity:     capacity,
+		maxCapacity:  maxCapacity,
+		headerBuffer: make([]byte, binary.MaxVarintLen32),
+		tail:         leftMarginIndex,
+		head:         leftMarginIndex,
+		rightMargin:  leftMarginIndex,
+		verbose:      verbose,
+	}
+}

queue/new_unix.go

@@ -0,0 +1,57 @@
+//go:build aix || darwin || dragonfly || freebsd || openbsd || solaris || zos || linux || netbsd
+// +build aix darwin dragonfly freebsd openbsd solaris zos linux netbsd
+
+// build tags are sync from:
+// golang.org/x/sys@v0.21.0/unix/mmap_nomremap.go
+// golang.org/x/sys@v0.21.0/unix/mmap_mremap.go
+
+package queue
+
+import (
+	"encoding/binary"
+
+	"golang.org/x/sys/unix"
+)
+
+func pageUpper(in uintptr) uintptr {
+	const pageMask = ((1 << 12) - 1)
+	return (in + pageMask) &^ (pageMask)
+}
+
+// NewBytesQueue initialize new bytes queue.
+// capacity is used in bytes array allocation
+// When verbose flag is set then information about memory allocation are printed
+func NewBytesQueue(capacity int, maxCapacity int, verbose bool) *BytesQueue {
+	var array []byte
+	if maxCapacity != 0 {
+		var err error
+		if maxCapacity >= 1<<12 {
+			array, err = unix.Mmap(
+				0,
+				0,
+				int(pageUpper(uintptr(maxCapacity))),
+				unix.PROT_READ|unix.PROT_WRITE,
+				unix.MAP_ANON|unix.MAP_PRIVATE,
+			)
+			if err != nil {
+				panic(err)
+			}
+		} else {
+			array = make([]byte, maxCapacity)
+		}
+		capacity = maxCapacity
+	} else {
+		array = make([]byte, capacity)
+	}
+
+	return &BytesQueue{
+		array:        array,
+		capacity:     capacity,
+		maxCapacity:  maxCapacity,
+		headerBuffer: make([]byte, binary.MaxVarintLen32),
+		tail:         leftMarginIndex,
+		head:         leftMarginIndex,
+		rightMargin:  leftMarginIndex,
+		verbose:      verbose,
+	}
+}