commonMain.io.realm.VersionId.kt Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of library Show documentation

Library code for Realm Kotlin. This artifact is not supposed to be consumed directly, but through 'io.realm.kotlin:gradle-plugin:0.4.1' instead.

There is a newer version: 0.5.0

Show newest version

/*
 * Copyright 2021 Realm Inc.
 *
 * 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 io.realm

/**
 * A `VersionId` representing the transactional id of the Realm itself or it's objects.
 *
 * Realm is an [MVCC](https://en.wikipedia.org/wiki/Multiversion_concurrency_control) database. This means that at any
 * given time, multiple version of data can be visible. This class describes the version of such data.
 *
 * The version of a Realm will change whenever a write is committed.
 */
public data class VersionId public constructor(public val version: Long) : Comparable {

    init {
        // Realm Core exposes these numbers as uint64_t, but it would be REALLY surprising if this ever
        // overflowed in Kotlin. Instead of adding more complex logic to this or depend on experimental
        // ULong, just throw an exception. We can probably move to ULong support before ever hitting this
        // case.
        if (version < 0) {
            throw IllegalArgumentException("'version' must both be numbers >= 0. It was: $version")
        }
    }

    override fun compareTo(other: VersionId): Int {
        // index is only used internally by Core and isn't used when ordering versions.
        return when {
            version > other.version -> 1
            version < other.version -> -1
            else -> 0
        }
    }
}