github.com/cockroachdb/pebble@v1.1.1-0.20240513155919-3622ade60459/internal/arenaskl/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/cockroachdb/pebble/internal/constants"
    25  	"github.com/stretchr/testify/require"
    26  )
    27  
    28  func newArena(n uint32) *Arena {
    29  	return NewArena(make([]byte, n))
    30  }
    31  
    32  // TestArenaSizeOverflow tests that large allocations do not cause Arena's
    33  // internal size accounting to overflow and produce incorrect results.
    34  func TestArenaSizeOverflow(t *testing.T) {
    35  	a := newArena(constants.MaxUint32OrInt)
    36  
    37  	// Allocating under the limit throws no error.
    38  	offset, _, err := a.alloc(math.MaxUint16, 1, 0)
    39  	require.Nil(t, err)
    40  	require.Equal(t, uint32(1), offset)
    41  	require.Equal(t, uint32(math.MaxUint16)+1, a.Size())
    42  
    43  	// Allocating over the limit could cause an accounting
    44  	// overflow if 32-bit arithmetic was used. It shouldn't.
    45  	_, _, err = a.alloc(math.MaxUint32, 1, 0)
    46  	require.Equal(t, ErrArenaFull, err)
    47  	require.Equal(t, uint32(constants.MaxUint32OrInt), a.Size())
    48  
    49  	// Continuing to allocate continues to throw an error.
    50  	_, _, err = a.alloc(math.MaxUint16, 1, 0)
    51  	require.Equal(t, ErrArenaFull, err)
    52  	require.Equal(t, uint32(constants.MaxUint32OrInt), a.Size())
    53  }