Mercurial > hg > blitz_condensed
diff src/org/dancres/blitz/txn/UnsyncdOps.java @ 0:3dc0c5604566
Initial checkin of blitz 2.0 fcs - no installer yet.
author | Dan Creswell <dan.creswell@gmail.com> |
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date | Sat, 21 Mar 2009 11:00:06 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/org/dancres/blitz/txn/UnsyncdOps.java Sat Mar 21 11:00:06 2009 +0000 @@ -0,0 +1,31 @@ +package org.dancres.blitz.txn; + +import org.dancres.blitz.BootInfo; + +/** + <p>UnsyncdOps provides boot-time information concerning the maximum number + of log operations which might have occurred since the last full + checkpoint/sync was initiated.</p> + + <p>We deliberately return double the op count to allow for interrupted + checkpoints. An interrupted checkpoint leads to two contiguous + log files with no separating checkpoint image. The maximum number + of operations before the next checkpoint would, therefore be + double the maximum number of ops per checkpoint. A checkpoint can + only be interrupted as the result of violent shutdown and, restart + will immediately resolve state using the UnsyncdOps. If restart + fails to complete, there will be no further log entries or + checkpoints and the next restart will, worst case, apply the + state resolution twice which isn't harmful.</p> + */ +public class UnsyncdOps implements BootInfo, java.io.Serializable { + private int theOpCount; + + UnsyncdOps(int anOpCount) { + theOpCount = 2 * anOpCount; + } + + public int getOpsSinceLastCheckpoint() { + return theOpCount; + } +}