Merge pull request #29 from Oppen/public_free

Add public free method

Author: lemire

free_test/explicit_free.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"syscall"
+
+	"github.com/RoaringBitmap/gocroaring"
+)
+
+// Exits with code 0 on success, 1 on test failure
+// or 2 on program failure (e.g. OOM or syscall error).
+
+func main() {
+	const (
+		N = 10000
+		M = 10000
+	)
+
+	var rusage syscall.Rusage
+	var maxrss_0, maxrss_free, maxrss_gc int64
+
+	fmt.Printf("Starting execution... ")
+	if err := syscall.Getrusage(syscall.RUSAGE_SELF, &rusage); err != nil {
+		fmt.Printf("Getrusage failed with error: %s\n", err)
+		os.Exit(2)
+	}
+	maxrss_0 = rusage.Maxrss
+	fmt.Printf("max RSS: %d bytes\n", maxrss_0)
+
+	bitmap := gocroaring.New()
+	for i := uint32(0); i < M; i++ {
+		bitmap.Add(i*10)
+	}
+	fmt.Printf("Created reference bitmap... ")
+	if err := syscall.Getrusage(syscall.RUSAGE_SELF, &rusage); err != nil {
+		fmt.Printf("Getrusage failed with error: %s\n", err)
+		os.Exit(2)
+	}
+	fmt.Printf("max RSS: %d bytes\n", rusage.Maxrss)
+
+	bitmaps := make([]*gocroaring.Bitmap, N)
+	fmt.Printf("Allocated slice for %d bitmap pointers... ", N)
+	if err := syscall.Getrusage(syscall.RUSAGE_SELF, &rusage); err != nil {
+		fmt.Printf("Getrusage failed with error: %s\n", err)
+		os.Exit(2)
+	}
+	maxrss_free = rusage.Maxrss
+	fmt.Printf("max RSS: %d bytes\n", maxrss_free)
+
+	for i := range bitmaps {
+		bitmaps[i] = bitmap.Clone()
+		bitmaps[i].Free()
+	}
+	fmt.Printf("Copied then explicitly freed %d bitmaps... ", N)
+	if err := syscall.Getrusage(syscall.RUSAGE_SELF, &rusage); err != nil {
+		fmt.Printf("Getrusage failed with error: %s\n", err)
+		os.Exit(2)
+	}
+	fmt.Printf("max RSS: %d bytes\n", rusage.Maxrss)
+
+	bitmaps = nil
+	runtime.GC()
+	fmt.Printf("GC'd old bitmaps... ")
+	if err := syscall.Getrusage(syscall.RUSAGE_SELF, &rusage); err != nil {
+		fmt.Printf("Getrusage failed with error: %s\n", err)
+		os.Exit(2)
+	}
+	fmt.Printf("max RSS: %d bytes\n", rusage.Maxrss)
+
+	bitmaps = make([]*gocroaring.Bitmap, N)
+	fmt.Printf("Allocated slice for %d bitmap pointers... ", N)
+	if err := syscall.Getrusage(syscall.RUSAGE_SELF, &rusage); err != nil {
+		fmt.Printf("Getrusage failed with error: %s\n", err)
+		os.Exit(2)
+	}
+	fmt.Printf("max RSS: %d bytes\n", rusage.Maxrss)
+
+	for i := range bitmaps {
+		bitmaps[i] = bitmap.Clone()
+	}
+	bitmaps = nil
+	runtime.GC()
+	fmt.Printf("Copied then GC'd %d bitmaps... ", N)
+	if err := syscall.Getrusage(syscall.RUSAGE_SELF, &rusage); err != nil {
+		fmt.Printf("Getrusage failed with error: %s\n", err)
+		os.Exit(2)
+	}
+	maxrss_gc = rusage.Maxrss
+	fmt.Printf("max RSS: %d bytes\n", maxrss_gc)
+
+	ballpark_free := maxrss_free - maxrss_0
+	ballpark_gc := maxrss_gc - maxrss_0
+	fmt.Printf("Used ~%d bytes with explicit free\n", ballpark_free)
+	fmt.Printf("Used ~%d bytes without explicit free\n", ballpark_gc)
+
+	if ballpark_gc < 100*ballpark_free {
+		fmt.Printf("Expected a much greater difference!\n")
+		os.Exit(1)
+	}
+}

gocroaring.go

@@ -54,6 +54,12 @@ func New(x ...uint32) *Bitmap {
 	return answer
 }
 
+func (rb *Bitmap) Free() {
+	// Clear the finalizer to avoid double frees
+	runtime.SetFinalizer(rb, nil)
+	free(rb)
+}
+
 // Printf writes a description of the bitmap to stdout
 func (rb *Bitmap) Printf() {
 	fmt.Print("{")

gocroaring_test.go

@@ -3,6 +3,7 @@ package gocroaring
 import (
 	"fmt"
 	"math/rand"
+	"os/exec"
 	"reflect"
 	"runtime"
 	"testing"
@@ -57,6 +58,14 @@ func TestMemoryUsage(t *testing.T) {
 	}
 }
 
+func TestExplicitFree(t *testing.T) {
+	output, err := exec.Command("go", "run", "free_test/explicit_free.go").Output()
+	if err != nil {
+		t.Errorf("Command exited with error: %s", err)
+	}
+	fmt.Printf("TestExplicitFree output:\n%s\n", output)
+}
+
 func TestSimpleCard(t *testing.T) {
 	bitmap := New()
 	for i := 100; i < 1000; i++ {