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* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

* http://www.apache.org/licenses/LICENSE-2.0

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

package org.lmdbjava;

import static java.lang.Boolean.getBoolean;

import java.lang.reflect.Field;

import sun.misc.Unsafe;

/** Provides access to Unsafe. */

final class UnsafeAccess {

/** Java system property name that can be set to disable unsafe. */

public static final String DISABLE_UNSAFE_PROP = "lmdbjava.disable.unsafe";

/** Indicates whether unsafe use is allowed. */

public static final boolean ALLOW_UNSAFE = !getBoolean(DISABLE_UNSAFE_PROP);

/**

* The actual unsafe. Guaranteed to be non-null if this class can access unsafe and {@link

* #ALLOW_UNSAFE} is true. In other words, this entire class will fail to initialize if unsafe is

* unavailable. This avoids callers from needing to deal with null checks.

static final Unsafe UNSAFE;

/** Unsafe field name (used to reflectively obtain the unsafe instance). */

private static final String FIELD_NAME_THE_UNSAFE = "theUnsafe";

static {

if (!ALLOW_UNSAFE) {

throw new LmdbException("Unsafe disabled by user");

}

try {

final Field field = Unsafe.class.getDeclaredField(FIELD_NAME_THE_UNSAFE);

field.setAccessible(true);

UNSAFE = (Unsafe) field.get(null);

} catch (final NoSuchFieldException

| SecurityException

| IllegalArgumentException

| IllegalAccessException e) {

throw new LmdbException("Unsafe unavailable", e);

}

private UnsafeAccess() {}

}