| Interface | Description | 
|---|---|
| MetricsWALSource | Interface of the source that will export metrics about the region server's WAL. | 
| WALActionsListener | Get notification of WAL events. | 
| WALCellCodec.ByteStringCompressor | |
| WALCellCodec.ByteStringUncompressor | 
| Class | Description | 
|---|---|
| AbstractFSWAL<W extends WALProvider.WriterBase> | Implementation of  WALto go againstFileSystem; i.e. | 
| AbstractFSWAL.WalProps | |
| AbstractProtobufLogWriter | Base class for Protobuf log writer. | 
| AsyncFSWAL | An asynchronous implementation of FSWAL. | 
| AsyncProtobufLogWriter | AsyncWriter for protobuf-based WAL. | 
| AsyncProtobufLogWriter.OutputStreamWrapper | |
| CompressionContext | Context that holds the various dictionaries for compression in WAL. | 
| Compressor | A set of static functions for running our custom WAL compression/decompression. | 
| FSHLog | The default implementation of FSWAL. | 
| FSHLog.RingBufferExceptionHandler | Exception handler to pass the disruptor ringbuffer. | 
| FSHLog.SafePointZigZagLatch | This class is used coordinating two threads holding one thread at a 'safe point' while the
 orchestrating thread does some work that requires the first thread paused: e.g. | 
| FSWALEntry | A WAL Entry for  AbstractFSWALimplementation. | 
| MetricsWAL | Class used to push numbers about the WAL into the metrics subsystem. | 
| MetricsWALSourceImpl | Class that transitions metrics from MetricsWAL into the metrics subsystem. | 
| ProtobufLogReader | A Protobuf based WAL has the following structure: | 
| ProtobufLogReader.WALHdrContext | |
| ProtobufLogWriter | Writer for protobuf-based WAL. | 
| ReaderBase | |
| RingBufferTruck | A 'truck' to carry a payload across the ring buffer from Handler to WAL. | 
| SecureAsyncProtobufLogWriter | |
| SecureProtobufLogReader | |
| SecureProtobufLogWriter | |
| SecureWALCellCodec | A WALCellCodec that encrypts the WALedits. | 
| SecureWALCellCodec.EncryptedKvDecoder | |
| SecureWALCellCodec.EncryptedKvEncoder | |
| SequenceIdAccounting | Accounting of sequence ids per region and then by column family. | 
| SyncFuture | A Future on a filesystem sync call. | 
| WALCellCodec | Compression in this class is lifted off Compressor/KeyValueCompression. | 
| WALCellCodec.BaosAndCompressor | |
| WALCellCodec.CompressedKvDecoder | |
| WALCellCodec.CompressedKvEncoder | |
| WALCellCodec.EnsureKvEncoder | |
| WALCellCodec.NoneCompressor | |
| WALCellCodec.NoneUncompressor | |
| WALCellCodec.StatelessUncompressor | |
| WALCoprocessorHost | Implements the coprocessor environment and runtime support for coprocessors
 loaded within a  WAL. | 
| WALCoprocessorHost.WALEnvironment | Encapsulation of the environment of each coprocessor | 
| WALUtil | Helper methods to ease Region Server integration with the Write Ahead Log (WAL). | 
| Enum | Description | 
|---|---|
| CompressionContext.DictionaryIndex | |
| ProtobufLogReader.WALHdrResult | |
| RingBufferTruck.Type | 
| Exception | Description | 
|---|---|
| DamagedWALException | Thrown when a failed append or sync on a WAL. | 
| FailedLogCloseException | Thrown when we fail close of the write-ahead-log file. | 
| FailedSyncBeforeLogCloseException | Thrown when we fail close of the write-ahead-log file. | 
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