Fix a bug in idm.GetIDInRange()

Signed-off-by: Alessandro Boch <aboch@docker.com>

libnetwork/idm/idm.go

@@ -15,7 +15,7 @@ type Idm struct {
 	handle *bitseq.Handle
 }
 
-// New returns an instance of id manager for a set of [start-end] numerical ids
+// New returns an instance of id manager for a [start,end] set of numerical ids
 func New(ds datastore.DataStore, id string, start, end uint64) (*Idm, error) {
 	if id == "" {
 		return nil, fmt.Errorf("Invalid id")
@@ -54,7 +54,7 @@ func (i *Idm) GetSpecificID(id uint64) error {
 	return i.handle.Set(id - i.start)
 }
 
-// GetIDInRange returns the first available id in the set within a range
+// GetIDInRange returns the first available id in the set within a [start,end] range
 func (i *Idm) GetIDInRange(start, end uint64) (uint64, error) {
 	if i.handle == nil {
 		return 0, fmt.Errorf("ID set is not initialized")
@@ -64,7 +64,9 @@ func (i *Idm) GetIDInRange(start, end uint64) (uint64, error) {
 		return 0, fmt.Errorf("Requested range does not belong to the set")
 	}
 
-	return i.handle.SetAnyInRange(start, end-start)
+	ordinal, err := i.handle.SetAnyInRange(start-i.start, end-i.start)
+
+	return i.start + ordinal, err
 }
 
 // Release releases the specified id

libnetwork/idm/idm_test.go

@@ -108,3 +108,129 @@ func TestUninitialized(t *testing.T) {
 		t.Fatalf("Expected failure but succeeded")
 	}
 }
+
+func TestAllocateInRange(t *testing.T) {
+	i, err := New(nil, "myset", 5, 10)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	o, err := i.GetIDInRange(6, 6)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if o != 6 {
+		t.Fatalf("Unexpected id returned. Expected: 6. Got: %d", o)
+	}
+
+	if err = i.GetSpecificID(6); err == nil {
+		t.Fatalf("Expected failure but succeeded")
+	}
+
+	o, err = i.GetID()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if o != 5 {
+		t.Fatalf("Unexpected id returned. Expected: 5. Got: %d", o)
+	}
+
+	i.Release(6)
+
+	o, err = i.GetID()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if o != 6 {
+		t.Fatalf("Unexpected id returned. Expected: 6. Got: %d", o)
+	}
+
+	for n := 7; n <= 10; n++ {
+		o, err := i.GetIDInRange(7, 10)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if o != uint64(n) {
+			t.Fatalf("Unexpected id returned. Expected: %d. Got: %d", n, o)
+		}
+	}
+
+	if err = i.GetSpecificID(7); err == nil {
+		t.Fatalf("Expected failure but succeeded")
+	}
+
+	if err = i.GetSpecificID(10); err == nil {
+		t.Fatalf("Expected failure but succeeded")
+	}
+
+	i.Release(10)
+
+	o, err = i.GetIDInRange(5, 10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if o != 10 {
+		t.Fatalf("Unexpected id returned. Expected: 10. Got: %d", o)
+	}
+
+	i.Release(5)
+
+	o, err = i.GetIDInRange(5, 10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if o != 5 {
+		t.Fatalf("Unexpected id returned. Expected: 5. Got: %d", o)
+	}
+
+	for n := 5; n <= 10; n++ {
+		i.Release(uint64(n))
+	}
+
+	for n := 5; n <= 10; n++ {
+		o, err := i.GetIDInRange(5, 10)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if o != uint64(n) {
+			t.Fatalf("Unexpected id returned. Expected: %d. Got: %d", n, o)
+		}
+	}
+
+	for n := 5; n <= 10; n++ {
+		if err = i.GetSpecificID(uint64(n)); err == nil {
+			t.Fatalf("Expected failure but succeeded for id: %d", n)
+		}
+	}
+
+	// New larger set
+	ul := uint64((1 << 24) - 1)
+	i, err = New(nil, "newset", 0, ul)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	o, err = i.GetIDInRange(4096, ul)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if o != 4096 {
+		t.Fatalf("Unexpected id returned. Expected: 4096. Got: %d", o)
+	}
+
+	o, err = i.GetIDInRange(4096, ul)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if o != 4097 {
+		t.Fatalf("Unexpected id returned. Expected: 4097. Got: %d", o)
+	}
+
+	o, err = i.GetIDInRange(4096, ul)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if o != 4098 {
+		t.Fatalf("Unexpected id returned. Expected: 4098. Got: %d", o)
+	}
+}