Class FlushedScan
java.lang.Object
org.apache.derby.impl.store.raw.log.FlushedScan
- All Implemented Interfaces:
LogScan
,StreamLogScan
Scan the the log which is implemented by a series of log files.n
This log scan knows how to move across log file if it is positioned at
the boundary of a log file and needs to getNextRecord.
4 bytes - length of user data, i.e. N 8 bytes - long representing log instant N bytes of supplied data 4 bytes - length of user data, i.e. N
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Field Summary
FieldsModifier and TypeFieldDescription(package private) long
(package private) long
(package private) long
(package private) long
(package private) long
(package private) long
(package private) static final int
(package private) LogToFile
(package private) int
The length of the next record.(package private) boolean
(package private) boolean
Flag to indicate that the length of the next log record has been read by currentLogFileHasUnflushedRecord.private StorageRandomAccessFile
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Close the scan.private boolean
long
Return the log instant (as an integer) the scan is currently on - this is the log instant of the log record that was returned by getNextRecord.Return the log instant the scan is currently on - this is the log instant of the log record that was returned by getNextRecord.long
Get the log instant that is right after the record just retrivedgetNextRecord
(ArrayInputStream input, TransactionId tranId, int groupmask) Read a log record into the byte array provided.boolean
returns true if there is partially writen log records before the crash in the last log file.private boolean
void
resetPosition
(LogInstant instant) Reset the scan to the given LogInstant.private void
private void
private void
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Field Details
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scan
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logFactory
LogToFile logFactory -
open
boolean open -
currentLogFileNumber
long currentLogFileNumber -
currentLogFileFirstUnflushedPosition
long currentLogFileFirstUnflushedPosition -
currentInstant
long currentInstant -
firstUnflushed
long firstUnflushed -
firstUnflushedFileNumber
long firstUnflushedFileNumber -
firstUnflushedFilePosition
long firstUnflushedFilePosition -
LOG_REC_LEN_BYTE_LENGTH
static final int LOG_REC_LEN_BYTE_LENGTH- See Also:
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nextRecordLength
int nextRecordLengthThe length of the next record. Read from scan and set by currentLogFileHasUnflushedRecord. This is used to retain the length of a log record in the case currentLogFileHasUnflushedRecord reads the length and determines that some bytes in the log record are not yet flushed. -
readNextRecordLength
boolean readNextRecordLengthFlag to indicate that the length of the next log record has been read by currentLogFileHasUnflushedRecord. This flag gets reset in two ways:- currentLogFileHasUnflushedRecord determines that the entire log record is flushed and returns true. In this case getNextRecord reads and returns the log record.
- we switch log files --due to a partial log record at the end of an old log file.
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Constructor Details
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FlushedScan
- Throws:
StandardException
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Method Details
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getNextRecord
public LogRecord getNextRecord(ArrayInputStream input, TransactionId tranId, int groupmask) throws StandardException Read a log record into the byte array provided. Resize the input stream byte array if necessary.- Specified by:
getNextRecord
in interfaceStreamLogScan
- Parameters:
input
- the ArrayInputStream to put the log recordtranId
- if non-null, only log record that equals tranId will be returned. If null, log records are not filtered on transaction Id.groupmask
- if non-zero, only log record whose Loggable's group value is included in the groupmask is returned. groupmask can be a bit wise OR of many Loggable groups. If zero, log records are not filtered on the Loggable's group.- Returns:
- the length of the data written into data, or -1 if the end of the scan has been reached.
- Throws:
StandardException
- Standard Derby error policy
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resetPosition
Reset the scan to the given LogInstant.- Specified by:
resetPosition
in interfaceStreamLogScan
- Parameters:
instant
- the position to reset to- Throws:
IOException
- scan cannot access the log at the new position.
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getLogRecordEnd
public long getLogRecordEnd()Get the log instant that is right after the record just retrived- Specified by:
getLogRecordEnd
in interfaceStreamLogScan
- Returns:
- INVALID_LOG_INSTANT if this is not a FORWARD scan or, no record have been returned yet or the scan has completed.
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isLogEndFuzzy
public boolean isLogEndFuzzy()returns true if there is partially writen log records before the crash in the last log file. Partiall wrires are identified during forward scans for log recovery.- Specified by:
isLogEndFuzzy
in interfaceStreamLogScan
- Returns:
- true if fuzzy log end found during forward scan, this happens if there was a partially written log records before the crash.
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getInstant
public long getInstant()Return the log instant (as an integer) the scan is currently on - this is the log instant of the log record that was returned by getNextRecord.- Specified by:
getInstant
in interfaceStreamLogScan
- Returns:
- INVALID_LOG_INSTANT if no records have been returned yet or the scan has completed.
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getLogInstant
Return the log instant the scan is currently on - this is the log instant of the log record that was returned by getNextRecord.- Specified by:
getLogInstant
in interfaceStreamLogScan
- Returns:
- null if no records have been returned yet or the scan has completed.
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close
public void close()Close the scan.- Specified by:
close
in interfaceStreamLogScan
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setFirstUnflushed
- Throws:
StandardException
IOException
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setCurrentLogFileFirstUnflushedPosition
- Throws:
IOException
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switchLogFile
- Throws:
StandardException
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currentLogFileHasUnflushedRecord
- Throws:
IOException
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positionToNextRecord
- Throws:
StandardException
IOException
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