WriteRestartArea Method (ArraySegment(Byte), SequenceNumber, ReservationCollection)

LogRecordSequence.WriteRestartArea Method (ArraySegment<Byte>, SequenceNumber, ReservationCollection)

 

Writes a restart area to the LogRecordSequence using a reservation, and updates the base sequence number. This method cannot be inherited.

Namespace:   System.IO.Log
Assembly:  System.IO.Log (in System.IO.Log.dll)

public SequenceNumber WriteRestartArea(
	ArraySegment<byte> data,
	SequenceNumber newBaseSeqNum,
	ReservationCollection reservations
)

Parameters

data
Type: System.ArraySegment<Byte>

A list of byte array segments that will be concatenated and appended as the record.

newBaseSeqNum
Type: System.IO.Log.SequenceNumber

The new base sequence number. The specified sequence number must be greater than or equal to the current base sequence number.

reservations
Type: System.IO.Log.ReservationCollection

A ReservationCollection that contains the reservation that should be used for this restart area.

Return Value

Type: System.IO.Log.SequenceNumber

The sequence number of the written restart area.

Exception Condition
ArgumentException

One or more of the arguments is invalid.

IOException

An I/O error occurred while writing the restart area.

SequenceFullException

The record sequence could not make enough free space to contain the new restart area.

ObjectDisposedException

The method was called after the sequence has been disposed of.

A restart area is used to temporarily store information containing a client's last checkpoint operation. The Common Log File System (CLFS) maintains two restart areas to guarantee that at least one valid area is always available. When a recovery is necessary, the CLFS reads its restart area and all the data from the last checkpoint operation. This data initializes the transaction table, dirty pages table, and open file table so they can be used in the recovery process.

A restart area can be read using the ReadRestartAreas method.

When a restart area is written, the data in the byte array segments are concatenated into a single byte array for appending as the record. No provision is made for splitting data back into array segments when the restart area is read.

If a reservation is specified, the written restart area will consume space that has been previously reserved, using a reservation contained in the collection. If the method succeeds, it will consume the smallest reservation that can contain the data, and that reservation will be removed from the collection.

When this method successfully completes, the base sequence number has been updated. All log records with sequence numbers less than the new base sequence number are inaccessible.

If a record sequence has been disposed of, or if you pass an invalid argument, exceptions are thrown immediately within this operation. Errors that occurred during an asynchronous append request, for example, a disk failure during the I/O request, will result in exceptions being thrown when the EndReserveAndAppend method is called.

.NET Framework
Available since 3.0
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