Common Log File System Functions

The following functions are used to manage logs.

Function	Description
AlignReservedLog	Calculates the sector-aligned reservation size for a set of records.
AllocReservedLog	Allocates sector-aligned space for a set of reserved records.
CloseAndResetLogFile	Resets the log file and then shuts the log.
CreateLogFile	Creates or opens a log.
DeleteLogByHandle	Marks the specified log for deletion.
DeleteLogFile	Marks a log for deletion.
DumpLogRecords	Scans a specified log, filters log records based on record type, and places the records in an output file stream that the caller opens.
FlushLogBuffers	Forces all records that are appended to this marshaling area to be flushed to disk.
FlushLogToLsn	Forces all records that are appended to this marshaling area up to the record with the specified log sequence number (LSN) to be flushed to the disk.
FreeReservedLog	Reduces the number of reserved log records in a marshaling area made by calling ReserveAndAppendLog, ReserveAndAppendLogAligned, or AllocReservedLog.
GetLogFileInformation	Returns a buffer that contains metadata about a specified log and its current state, as defined by the CLFS_INFORMATION structure.
GetLogIoStatistics	Retrieves log I/O statistics for a dedicated or multiplexed log that is associated with the specified handle.
ReadLogRecord	Initiates a sequence of reads from a specified log sequence number (LSN) in one of three modes, and returns the first of the specified log records and a read context.
ReadNextLogRecord	Reads the next record in a sequence that is initiated by a call to ReadLogRecord or ReadLogRestartArea.
ReserveAndAppendLog	Reserves space for log buffers, appends a log record to the log, or does both.
ReserveAndAppendLogAligned	Reserves space for log buffers, appends a log record to the log, or both. This function is like ReserveAndAppendLog, but ReserveAndAppendLogAligned aligns the write entries of the record to the specified byte alignment.
SetEndOfLog	This function has been deprecated. Use TruncateLog instead.
TerminateReadLog	Terminates a read context. This function frees system-allocated resources that are associated with the specified read context.
TruncateLog	Truncates the log.

 

The following functions are used to manage containers.

Function	Description
AddLogContainer	Adds a container to the physical log that is associated with the log handle, if the calling process has write access to the .blf file and the ability to create files in the target directory of the container.
AddLogContainerSet	Adds multiple log containers to the physical log that is associated with the log handle, if the calling process has access to the log handle.
CreateLogContainerScanContext	Creates a scan context to use with ScanLogContainers to enumerate all log containers that are associated with a log, and performs the first scan.
GetLogContainerName	Retrieves the full path name of a container when given its container identifier.
RemoveLogContainer	Removes a single container from a log that is associated with a dedicated or multiplexed log handle.
RemoveLogContainerSet	Removes multiple containers from a log that is associated with a dedicated or multiplexed log handle.
ScanLogContainers	Enumerates log containers. Call this function repeatedly to iterate over all log containers.

 

The following functions are used for crash restart.

Function	Description
AdvanceLogBase	Advances the base log sequence number (LSN) of a log stream to the specified LSN.
ReadLogRestartArea	Returns the last restart area that was written successfully to the log associated with the marshaling area of WriteLogRestartArea. The function also returns a read context that allows the caller to cursor backward or forward through the log from the restart record.
ReadPreviousLogRestartArea	Reads the previous log restart area that is relative to the current restart record specified in the read context.
WriteLogRestartArea	Appends a new client restart area to a log and optionally advances the base log sequence number (LSN) of the log.

 

The following functions are used for archiving.

Function	Description
GetNextLogArchiveExtent	Retrieves the next set of archive extents in a log archive context.
PrepareLogArchive	Prepares a physical log for archiving.
ReadLogArchiveMetadata	Copies a range of the archive view of the metadata to the specified buffer.
SetLogArchiveMode	Enables or disables log archive support for a specified log.
SetLogArchiveTail	Sets the last archived log sequence number (LSN) or archive tail of an archivable log.
TerminateLogArchive	Deallocates system resources that are allocated originally for a log archive context by PrepareLogArchive.
ValidateLog	Validates the consistency of the log metadata and data before log archive and after log restore.

 

The following functions are used for marshaling.

Function	Description
CreateLogMarshallingArea	Creates a marshaling area for a log, and when successful it returns a marshaling context.
DeleteLogMarshallingArea	Deletes a marshaling area that is created by a successful call to CreateLogMarshallingArea.

 

The following functions are used to work with LSNs.

Function	Description
LsnBlockOffset	Returns the sector-aligned block offset that is contained in the specified LSN.
LsnContainer	Retrieves the logical container ID that is contained in a specified LSN.
LsnCreate	Creates a log sequence number (LSN), given a container ID, a block offset, and a record sequence number.
LsnEqual	Determines whether two LSNs from the same stream are equal.
LsnGreater	Determines whether one LSN is greater than another LSN. The two LSNs must be from the same stream.
LsnLess	Determines whether one LSN is less than another LSN. The two LSNs must be from the same stream.
LsnNull	Determines whether a specified LSN is equal to the smallest possible LSN, which is CLFS_LSN_NULL.
LsnRecordSequence	Retrieves the record sequence number that is contained in a specified LSN.