github.com/andy-kimball/arenaskl@v0.0.0-20200617143215-f701008588b9/arena_test.go (about)

     1  /*
     2   * Copyright 2017 Dgraph Labs, Inc. and Contributors
     3   * Modifications copyright (C) 2017 Andy Kimball and Contributors
     4   *
     5   * Licensed under the Apache License, Version 2.0 (the "License");
     6   * you may not use this file except in compliance with the License.
     7   * You may obtain a copy of the License at
     8   *
     9   *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  
    18  package arenaskl
    19  
    20  import (
    21  	"math"
    22  	"testing"
    23  
    24  	"github.com/stretchr/testify/require"
    25  )
    26  
    27  // TestArenaSizeOverflow tests that large allocations do not cause Arena's
    28  // internal size accounting to overflow and produce incorrect results.
    29  func TestArenaSizeOverflow(t *testing.T) {
    30  	a := NewArena(math.MaxUint32)
    31  
    32  	// Allocating under the limit throws no error.
    33  	offset, err := a.Alloc(math.MaxUint16, 0, Align1)
    34  	require.Nil(t, err)
    35  	require.Equal(t, uint32(1), offset)
    36  	require.Equal(t, uint32(math.MaxUint16)+1, a.Size())
    37  
    38  	// Allocating over the limit could cause an accounting
    39  	// overflow if 32-bit arithmetic was used. It shouldn't.
    40  	_, err = a.Alloc(math.MaxUint32, 0, Align1)
    41  	require.Equal(t, ErrArenaFull, err)
    42  	require.Equal(t, uint32(math.MaxUint32), a.Size())
    43  
    44  	// Continuing to allocate continues to throw an error.
    45  	_, err = a.Alloc(math.MaxUint16, 0, Align1)
    46  	require.Equal(t, ErrArenaFull, err)
    47  	require.Equal(t, uint32(math.MaxUint32), a.Size())
    48  }