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• org.apache.derby.impl.store.raw.log: Javadoc index of package org.apache.derby.impl.store.raw.log.


Package Samples:

• org.apache.derby.impl.store.raw.log

Classes:

• LogAccessFile: Wraps a RandomAccessFile file to provide buffering on log writes. Only supports the write calls required for the log! MT - unsafe. Caller of this class must provide synchronization. The one exception is with the log file access, LogAccessFile will touch the log only inside synchronized block protected by the semaphore, which is defined by the creator of this object. Write to the log buffers are allowed when there are free buffers even when dirty buffers are being written(flushed) to the disk by a different thread. Only one flush writes to log file at a time, other wait for it to finish. Except ...
• LogToFile: This is an implementation of the log using a non-circular file system file. No support for incremental log backup or media recovery. Only crash recovery is supported. The 'log' is a stream of log records. The 'log' is implemented as a series of numbered log files. These numbered log files are logically continuous so a transaction can have log records that span multiple log files. A single log record cannot span more then one log file. The log file number is monotonically increasing. The log belongs to a log factory of a RawStore. In the current implementation, each RawStore only has one log factory, ...
• Scan: 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
• LogCounter: A very simple log instant implementation. Within the stored log record a log counter is represented as a long, hence the getValueAsLong() method. Outside the LogFactory the instant is passed around as a LogCounter (through its LogInstant interface). The way the long is encoded is such that correctly tells if one log instant is lessThan, equals or greater than another.
• FlushedScan: 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
• LogRecord: The log record written out to disk. This log record includes: The is a holder object that may be setup using the setValue() and re-used rather than creating a new object for each actual log record. The format of a log record is
• ReadOnly: A read-only version of the log factory. It doesn't do anything, it doesn't check that the database needs recovery or not. It doesn't handle undo. No recovery. Multithreading considerations: This class must be MT-safe.
• FileLogger: Write log records to a log file as a stream (ie. log records added to the end of the file, no concept of pages). The format of a log record that is not a compensation operation is
• StreamLogScan: LogScan provides methods to read a log record and get its LogInstant in an already defined scan. A logscan also needs to know how to advance to the next log record.
• ChecksumOperation: A Log Operation that represents a checksum for a group of log records that are written to the tranaction log file.
• CheckpointOperation: A Log Operation that represents a checkpoint.
• LogAccessFileBuffer: A single buffer of data.
• D_FlushedScan
• D_LogToFile
• FlushedScanHandle

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