SegmentedRaftLog (Apache Ratis Server 1.0.0 API)

java.lang.Object
- org.apache.ratis.server.raftlog.RaftLog
- - org.apache.ratis.server.raftlog.segmented.SegmentedRaftLog

All Implemented Interfaces:

Closeable, AutoCloseable
```
public class SegmentedRaftLog
extends RaftLog
```
The RaftLog implementation that writes log entries into segmented files in local disk. The max log segment size is 8MB. The real log segment size may not be exactly equal to this limit. If a log entry's size exceeds 8MB, this entry will be stored in a single segment. There are two types of segments: closed segment and open segment. The former is named as "log_startindex-endindex", the later is named as "log_inprogress_startindex". There can be multiple closed segments but there is at most one open segment. When the open segment reaches the size limit, or the log term increases, we close the open segment and start a new open segment. A closed segment cannot be appended anymore, but it can be truncated in case that a follower's log is inconsistent with the current leader. Every closed segment should be non-empty, i.e., it should contain at least one entry. There should not be any gap between segments. The first segment may not start from index 0 since there may be snapshots as log compaction. The last index in segments should be no smaller than the last index of snapshot, otherwise we may have hole when append further log.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class RaftLogSequentialOps.Runner
- Nested classes/interfaces inherited from class org.apache.ratis.server.raftlog.RaftLog
  RaftLog.EntryWithData, RaftLog.Metadata

Nested Classes
Modifier and Type	Class and Description
`static class`	`RaftLogSequentialOps.Runner`

Field Summary
- Fields inherited from class org.apache.ratis.server.raftlog.RaftLog
  INVALID_LOG_INDEX, LEAST_VALID_LOG_INDEX, LOG, LOG_SYNC

Constructor Summary

Constructors
Constructor and Description
`SegmentedRaftLog(RaftGroupMemberId memberId, RaftServerImpl server, RaftStorage storage, long lastIndexInSnapshot, RaftProperties properties)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`protected CompletableFuture<Long>`	`appendEntryImpl(org.apache.ratis.proto.RaftProtos.LogEntryProto entry)`
`List<CompletableFuture<Long>>`	`appendImpl(org.apache.ratis.proto.RaftProtos.LogEntryProto... entries)`
`void`	`close()`
`org.apache.ratis.proto.RaftProtos.LogEntryProto`	`get(long index)` Get the log entry of the given index.
`TermIndex[]`	`getEntries(long startIndex, long endIndex)`
`RaftLog.EntryWithData`	`getEntryWithData(long index)` Get the log entry of the given index along with the state machine data.
`long`	`getFlushIndex()`
`TermIndex`	`getLastEntryTermIndex()`
`long`	`getStartIndex()`
`TermIndex`	`getTermIndex(long index)` Get the TermIndex information of the given index.
`boolean`	`isConfigEntry(TermIndex ti)`
`RaftLog.Metadata`	`loadMetadata()`
`protected void`	`openImpl(long lastIndexInSnapshot, Consumer<org.apache.ratis.proto.RaftProtos.LogEntryProto> consumer)`
`protected CompletableFuture<Long>`	`purgeImpl(long index)`
`void`	`syncWithSnapshot(long lastSnapshotIndex)`
`String`	`toLogEntryString(org.apache.ratis.proto.RaftProtos.LogEntryProto logEntry)`
`String`	`toString()`
`protected CompletableFuture<Long>`	`truncateImpl(long index)`
`void`	`writeMetadata(long term, RaftPeerId votedFor)` Write and flush the metadata (votedFor and term) into the meta file.

Methods inherited from class org.apache.ratis.server.raftlog.RaftLog
append, append, append, appendEntry, appendMetadata, checkLogState, contains, getLastCommittedIndex, getName, getNextIndex, getRaftLogMetrics, getSnapshotIndex, hasReadLock, hasWriteLock, isOpened, open, purge, readLock, truncate, updateLastCommitted, updateSnapshotIndex, validateLogEntry, writeLock

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - SegmentedRaftLog
```
public SegmentedRaftLog(RaftGroupMemberId memberId,
                        RaftServerImpl server,
                        RaftStorage storage,
                        long lastIndexInSnapshot,
                        RaftProperties properties)
```
- Method Detail
  - openImpl
```
protected void openImpl(long lastIndexInSnapshot,
                        Consumer<org.apache.ratis.proto.RaftProtos.LogEntryProto> consumer)
                 throws IOException
```
    Overrides:
    
    openImpl in class RaftLog
    
    Throws:
    
    IOException
  - getStartIndex
```
public long getStartIndex()
```
    Specified by:
    
    getStartIndex in class RaftLog
  - get
```
public org.apache.ratis.proto.RaftProtos.LogEntryProto get(long index)
                                                    throws RaftLogIOException
```
    Description copied from class: RaftLog
    
    Get the log entry of the given index.
    
    Specified by:
    
    get in class RaftLog
    
    Parameters:
    
    index - The given index.
    
    Returns:
    
    The log entry associated with the given index. Null if there is no log entry with the index.
    
    Throws:
    
    RaftLogIOException
  - getEntryWithData
```
public RaftLog.EntryWithData getEntryWithData(long index)
                                       throws RaftLogIOException
```
    Description copied from class: RaftLog
    
    Get the log entry of the given index along with the state machine data.
    
    Specified by:
    
    getEntryWithData in class RaftLog
    
    Parameters:
    
    index - The given index.
    
    Returns:
    
    The log entry associated with the given index. Null if there is no log entry with the index.
    
    Throws:
    
    RaftLogIOException
  - getTermIndex
```
public TermIndex getTermIndex(long index)
```
    Description copied from class: RaftLog
    
    Get the TermIndex information of the given index.
    
    Specified by:
    
    getTermIndex in class RaftLog
    
    Parameters:
    
    index - The given index.
    
    Returns:
    
    The TermIndex of the log entry associated with the given index. Null if there is no log entry with the index.
  - getEntries
```
public TermIndex[] getEntries(long startIndex,
                              long endIndex)
```
    Specified by:
    
    getEntries in class RaftLog
    
    Parameters:
    
    startIndex - the starting log index (inclusive)
    
    endIndex - the ending log index (exclusive)
    
    Returns:
    
    TermIndex of all log entries within the given index range. Null if startIndex is greater than the smallest available index.
  - getLastEntryTermIndex
```
public TermIndex getLastEntryTermIndex()
```
    Specified by:
    
    getLastEntryTermIndex in class RaftLog
    
    Returns:
    
    the last log entry's term and index.
  - truncateImpl
```
protected CompletableFuture<Long> truncateImpl(long index)
```
    Specified by:
    
    truncateImpl in class RaftLog
  - purgeImpl
```
protected CompletableFuture<Long> purgeImpl(long index)
```
    Specified by:
    
    purgeImpl in class RaftLog
  - appendEntryImpl
```
protected CompletableFuture<Long> appendEntryImpl(org.apache.ratis.proto.RaftProtos.LogEntryProto entry)
```
    Specified by:
    
    appendEntryImpl in class RaftLog
  - appendImpl
```
public List<CompletableFuture<Long>> appendImpl(org.apache.ratis.proto.RaftProtos.LogEntryProto... entries)
```
    Specified by:
    
    appendImpl in class RaftLog
  - getFlushIndex
```
public long getFlushIndex()
```
    Specified by:
    
    getFlushIndex in class RaftLog
    
    Returns:
    
    the index of the last entry that has been flushed to the local storage.
  - writeMetadata
```
public void writeMetadata(long term,
                          RaftPeerId votedFor)
                   throws IOException
```
    Description copied from class: RaftLog
    
    Write and flush the metadata (votedFor and term) into the meta file. We need to guarantee that the order of writeMetadata calls is the same with that when we change the in-memory term/votedFor. Otherwise we may persist stale term/votedFor in file. Since the leader change is not frequent, currently we simply put this call in the RaftPeer's lock. Later we can use an IO task queue to enforce the order.
    
    Specified by:
    
    writeMetadata in class RaftLog
    
    Throws:
    
    IOException
  - loadMetadata
```
public RaftLog.Metadata loadMetadata()
                              throws IOException
```
    Specified by:
    
    loadMetadata in class RaftLog
    
    Throws:
    
    IOException
  - syncWithSnapshot
```
public void syncWithSnapshot(long lastSnapshotIndex)
```
    Specified by:
    
    syncWithSnapshot in class RaftLog
  - isConfigEntry
```
public boolean isConfigEntry(TermIndex ti)
```
    Specified by:
    
    isConfigEntry in class RaftLog
  - close
```
public void close()
           throws IOException
```
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Overrides:
    
    close in class RaftLog
    
    Throws:
    
    IOException
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class RaftLog
  - toLogEntryString
```
public String toLogEntryString(org.apache.ratis.proto.RaftProtos.LogEntryProto logEntry)
```
    Overrides:
    
    toLogEntryString in class RaftLog

Class SegmentedRaftLog

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.ratis.server.raftlog.RaftLog

Field Summary

Fields inherited from class org.apache.ratis.server.raftlog.RaftLog

Constructor Summary

Method Summary

Methods inherited from class org.apache.ratis.server.raftlog.RaftLog

Methods inherited from class java.lang.Object

Constructor Detail

SegmentedRaftLog

Method Detail

openImpl

getStartIndex

get

getEntryWithData

getTermIndex

getEntries

getLastEntryTermIndex

truncateImpl

purgeImpl

appendEntryImpl

appendImpl

getFlushIndex

writeMetadata

loadMetadata

syncWithSnapshot

isConfigEntry

close

toString

toLogEntryString