// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).

package org.rocksdb;

/**
 * <p>Defines the interface for a Write Batch which
 * holds a collection of updates to apply atomically to a DB.</p>
 */
public interface WriteBatchInterface {

    /**
     * Returns the number of updates in the batch.
     *
     * @return number of items in WriteBatch
     */
    int count();

    /**
     * <p>Store the mapping "key-&gt;value" in the database.</p>
     *
     * @param key the specified key to be inserted.
     * @param value the value associated with the specified key.
     */
    void put(byte[] key, byte[] value) throws RocksDBException;

    /**
     * <p>Store the mapping "key-&gt;value" within given column
     * family.</p>
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param key the specified key to be inserted.
     * @param value the value associated with the specified key.
     */
    void put(ColumnFamilyHandle columnFamilyHandle,
                    byte[] key, byte[] value) throws RocksDBException;

    /**
     * <p>Merge "value" with the existing value of "key" in the database.
     * "key-&gt;merge(existing, value)"</p>
     *
     * @param key the specified key to be merged.
     * @param value the value to be merged with the current value for
     * the specified key.
     */
    void merge(byte[] key, byte[] value) throws RocksDBException;

    /**
     * <p>Merge "value" with the existing value of "key" in given column family.
     * "key-&gt;merge(existing, value)"</p>
     *
     * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
     * @param key the specified key to be merged.
     * @param value the value to be merged with the current value for
     * the specified key.
     */
    void merge(ColumnFamilyHandle columnFamilyHandle,
                      byte[] key, byte[] value) throws RocksDBException;

    /**
     * <p>If the database contains a mapping for "key", erase it.  Else do nothing.</p>
     *
     * @param key Key to delete within database
     *
     * @deprecated Use {@link #delete(byte[])}
     */
    @Deprecated
    void remove(byte[] key) throws RocksDBException;

    /**
     * <p>If column family contains a mapping for "key", erase it.  Else do nothing.</p>
     *
     * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
     * @param key Key to delete within database
     *
     * @deprecated Use {@link #delete(ColumnFamilyHandle, byte[])}
     */
    @Deprecated
    void remove(ColumnFamilyHandle columnFamilyHandle, byte[] key)
        throws RocksDBException;

    /**
     * <p>If the database contains a mapping for "key", erase it.  Else do nothing.</p>
     *
     * @param key Key to delete within database
     */
    void delete(byte[] key) throws RocksDBException;

    /**
     * <p>If column family contains a mapping for "key", erase it.  Else do nothing.</p>
     *
     * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
     * @param key Key to delete within database
     */
    void delete(ColumnFamilyHandle columnFamilyHandle, byte[] key)
        throws RocksDBException;

    /**
     * Remove the database entry for {@code key}. Requires that the key exists
     * and was not overwritten. It is not an error if the key did not exist
     * in the database.
     *
     * If a key is overwritten (by calling {@link #put(byte[], byte[])} multiple
     * times), then the result of calling SingleDelete() on this key is undefined.
     * SingleDelete() only behaves correctly if there has been only one Put()
     * for this key since the previous call to SingleDelete() for this key.
     *
     * This feature is currently an experimental performance optimization
     * for a very specific workload. It is up to the caller to ensure that
     * SingleDelete is only used for a key that is not deleted using Delete() or
     * written using Merge(). Mixing SingleDelete operations with Deletes and
     * Merges can result in undefined behavior.
     *
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *     native library.
     */
    @Experimental("Performance optimization for a very specific workload")
    void singleDelete(final byte[] key) throws RocksDBException;

    /**
     * Remove the database entry for {@code key}. Requires that the key exists
     * and was not overwritten. It is not an error if the key did not exist
     * in the database.
     *
     * If a key is overwritten (by calling {@link #put(byte[], byte[])} multiple
     * times), then the result of calling SingleDelete() on this key is undefined.
     * SingleDelete() only behaves correctly if there has been only one Put()
     * for this key since the previous call to SingleDelete() for this key.
     *
     * This feature is currently an experimental performance optimization
     * for a very specific workload. It is up to the caller to ensure that
     * SingleDelete is only used for a key that is not deleted using Delete() or
     * written using Merge(). Mixing SingleDelete operations with Deletes and
     * Merges can result in undefined behavior.
     *
     * @param columnFamilyHandle The column family to delete the key from
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *     native library.
     */
    @Experimental("Performance optimization for a very specific workload")
    void singleDelete(final ColumnFamilyHandle columnFamilyHandle,
            final byte[] key) throws RocksDBException;

    /**
     * Removes the database entries in the range ["beginKey", "endKey"), i.e.,
     * including "beginKey" and excluding "endKey". a non-OK status on error. It
     * is not an error if no keys exist in the range ["beginKey", "endKey").
     *
     * Delete the database entry (if any) for "key". Returns OK on success, and a
     * non-OK status on error. It is not an error if "key" did not exist in the
     * database.
     *
     * @param beginKey
     *          First key to delete within database (included)
     * @param endKey
     *          Last key to delete within database (excluded)
     */
    void deleteRange(byte[] beginKey, byte[] endKey) throws RocksDBException;

    /**
     * Removes the database entries in the range ["beginKey", "endKey"), i.e.,
     * including "beginKey" and excluding "endKey". a non-OK status on error. It
     * is not an error if no keys exist in the range ["beginKey", "endKey").
     *
     * Delete the database entry (if any) for "key". Returns OK on success, and a
     * non-OK status on error. It is not an error if "key" did not exist in the
     * database.
     *
     * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
     * @param beginKey
     *          First key to delete within database (included)
     * @param endKey
     *          Last key to delete within database (excluded)
     */
    void deleteRange(ColumnFamilyHandle columnFamilyHandle, byte[] beginKey,
            byte[] endKey) throws RocksDBException;

    /**
     * Append a blob of arbitrary size to the records in this batch. The blob will
     * be stored in the transaction log but not in any other file. In particular,
     * it will not be persisted to the SST files. When iterating over this
     * WriteBatch, WriteBatch::Handler::LogData will be called with the contents
     * of the blob as it is encountered. Blobs, puts, deletes, and merges will be
     * encountered in the same order in thich they were inserted. The blob will
     * NOT consume sequence number(s) and will NOT increase the count of the batch
     *
     * Example application: add timestamps to the transaction log for use in
     * replication.
     *
     * @param blob binary object to be inserted
     */
    void putLogData(byte[] blob) throws RocksDBException;

    /**
     * Clear all updates buffered in this batch
     */
    void clear();

    /**
     * Records the state of the batch for future calls to RollbackToSavePoint().
     * May be called multiple times to set multiple save points.
     */
    void setSavePoint();

    /**
     * Remove all entries in this batch (Put, Merge, Delete, PutLogData) since
     * the most recent call to SetSavePoint() and removes the most recent save
     * point.
     *
     * @throws RocksDBException if there is no previous call to SetSavePoint()
     */
    void rollbackToSavePoint() throws RocksDBException;

    /**
     * Pop the most recent save point.
     *
     * That is to say that it removes the last save point,
     * which was set by {@link #setSavePoint()}.
     *
     * @throws RocksDBException If there is no previous call to
     *     {@link #setSavePoint()}, an exception with
     *     {@link Status.Code#NotFound} will be thrown.
     */
    void popSavePoint() throws RocksDBException;

    /**
     * Set the maximum size of the write batch.
     *
     * @param maxBytes the maximum size in bytes.
     */
    void setMaxBytes(long maxBytes);

    /**
     * Get the underlying Write Batch.
     *
     * @return the underlying WriteBatch.
     */
    WriteBatch getWriteBatch();
}
