com.palantir.atlasdb.keyvalue.api.TargetedSweepMetadata Maven / Gradle / Ivy

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/*
 * (c) Copyright 2018 Palantir Technologies Inc. All rights reserved.
 *
 * 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 com.palantir.atlasdb.keyvalue.api;

import com.palantir.common.persist.Persistable;
import com.palantir.logsafe.Preconditions;
import com.palantir.logsafe.SafeArg;
import org.immutables.value.Value;

@Value.Immutable
public abstract class TargetedSweepMetadata implements Persistable {
    public abstract boolean conservative();

    public abstract boolean dedicatedRow();

    public abstract int shard();

    public abstract long dedicatedRowNumber();

    @Value.Default
    public boolean nonSweepableTransaction() {
        return false;
    }

    public static final int MAX_SHARDS = 256;
    public static final int MAX_DEDICATED_ROWS = 64;
    private static final int SWEEP_STRATEGY_MASK = 0x80;
    private static final int USE_DEDICATED_ROWS_MASK = 0x40;
    private static final int DEDICATED_ROW_NUMBER_MASK = 0x3F;
    private static final int BYTE_MASK = 0xFF;

    @Value.Check
    void checkShardSize() {
        Preconditions.checkArgument(
                shard() >= 0 && shard() < MAX_SHARDS,
                "Shard number must non-negative and strictly less than the maximum.",
                SafeArg.of("maxShards", MAX_SHARDS),
                SafeArg.of("shards", shard()));
    }

    @Value.Check
    void checkRowNumber() {
        Preconditions.checkArgument(
                dedicatedRowNumber() >= 0 && dedicatedRowNumber() < MAX_DEDICATED_ROWS,
                "Dedicated row number must non-negative and strictly less than the maximum.",
                SafeArg.of("maxDedicatedRows", MAX_DEDICATED_ROWS),
                SafeArg.of("dedicatedRows", dedicatedRowNumber()));
    }

    @Value.Check
    void checkDefaultsForNonSweepableTransaction() {
        if (nonSweepableTransaction()) {
            Preconditions.checkArgument(conservative(), "Non sweepable transactions must set the conservative bit.");
            Preconditions.checkArgument(!dedicatedRow(), "Non sweepable transactions must not use dedicated rows.");
            Preconditions.checkArgument(shard() == 0, "Non sweepable transactions must use only shard 0.");
        }
    }

    public static final Hydrator BYTES_HYDRATOR =
            input -> ImmutableTargetedSweepMetadata.builder()
                    .conservative((input[0] & SWEEP_STRATEGY_MASK) != 0)
                    .dedicatedRow((input[0] & USE_DEDICATED_ROWS_MASK) != 0)
                    .shard((input[0] << 2 | (input[1] & BYTE_MASK) >> 6) & BYTE_MASK)
                    .dedicatedRowNumber(input[1] & DEDICATED_ROW_NUMBER_MASK)
                    .nonSweepableTransaction((input[2] & SWEEP_STRATEGY_MASK) != 0)
                    .build();

    @Override
    public byte[] persistToBytes() {
        byte[] result = new byte[] {0, 0, 0, 0};
        result[0] |= (shard() & BYTE_MASK) >> 2;
        if (dedicatedRow()) {
            result[0] |= USE_DEDICATED_ROWS_MASK;
        }
        if (conservative()) {
            result[0] |= SWEEP_STRATEGY_MASK;
        }
        result[1] |= dedicatedRowNumber() & DEDICATED_ROW_NUMBER_MASK;
        result[1] |= (shard() << 6) & BYTE_MASK;
        if (nonSweepableTransaction()) {
            result[2] |= SWEEP_STRATEGY_MASK;
        }
        return result;
    }
}