private void DisposeOldVersions()
{
List <object> disposeList = new List <object>();
lock (versions) {
// size - 1 because we don't want to delete the very last version,
int sz = versions.Count - 1;
bool foundLockedEntry = false;
for (int i = 0; i < sz && foundLockedEntry == false; ++i)
{
VersionInfo vinfo = versions[i];
// If this version isn't locked,
if (vinfo.NotLocked)
{
// Add to the dispose list
disposeList.Add(vinfo);
// And delete from the versions list,
versions.RemoveAt(i);
--sz;
--i;
}
else
{
// If it is locked, we exit the loop
foundLockedEntry = true;
}
}
}
// If there are entries to dispose?
if (disposeList.Count > 0)
{
// We synchronize here to ensure the versions list can't be modified by
// a commit operation while we are disposing this.
lock (this) {
// Run within a write lock on the store
try {
nodeStore.LockForWrite();
// First we write out a modified version header minus the versions we
// are to delete,
// Get the current version list
IMutableArea headerArea = nodeStore.GetMutableArea(headerId);
headerArea.Position = 8;
long versionListId = headerArea.ReadInt8();
// Read information from the old version info,
IArea versionListArea = nodeStore.GetArea(versionListId);
versionListArea.ReadInt4(); // The magic
int versionCount = versionListArea.ReadInt4();
int newVersionCount = versionCount - disposeList.Count;
// Create a new list,
IAreaWriter newVersionList = nodeStore.CreateArea(8 + (8 * newVersionCount));
newVersionList.WriteInt4(0x01433);
newVersionList.WriteInt4(newVersionCount);
// Skip the versions we are deleting,
for (int i = 0; i < disposeList.Count; ++i)
{
versionListArea.ReadInt8();
}
// Now copy the list from the new point
for (int i = 0; i < newVersionCount; ++i)
{
newVersionList.WriteInt8(versionListArea.ReadInt8());
}
newVersionList.Finish();
// Write the new area to the header,
headerArea.Position = 8;
headerArea.WriteInt8(newVersionList.Id);
// Delete the old version list Area,
nodeStore.DeleteArea(versionListId);
// Dispose the version info,
int sz = disposeList.Count;
for (int i = 0; i < sz; ++i)
{
VersionInfo vinfo = (VersionInfo)disposeList[i];
long vRef = vinfo.VersionInfoRef;
IArea versionArea = nodeStore.GetArea(vRef);
int magic = versionArea.ReadInt4();
int rev = versionArea.ReadInt4();
// Check the magic,
if (magic != 0x04EA23)
{
throw new ApplicationException("Magic value for version area is incorrect.");
}
long verId = versionArea.ReadInt8();
long nrnHigh = versionArea.ReadInt8();
long nrnLow = versionArea.ReadInt8();
int nodeCount = versionArea.ReadInt4();
// For each node,
for (int n = 0; n < nodeCount; ++n)
{
// Read the next area
long drnHigh = versionArea.ReadInt8();
long drnLow = versionArea.ReadInt8();
NodeId delNodeId = new NodeId(drnHigh, drnLow);
// Cleanly disposes the node
DoDisposeNode(delNodeId);
}
// Delete the node header,
nodeStore.DeleteArea(vRef);
}
} finally {
nodeStore.UnlockForWrite();
}
}
}
}
private long WriteVersionsList(long versionId, TreeSystemTransaction tran)
{
lock (this) {
// Write the version info and the deleted refs to a new area,
NodeId rootNodeId = tran.RootNodeId;
if (rootNodeId.IsInMemory)
{
throw new ApplicationException("Assertion failed, root_node is on heap.");
}
// Get the list of all nodes deleted in the transaction
List <NodeId> deletedRefs = tran.NodeDeletes;
// Sort it
deletedRefs.Sort();
// Check for any duplicate entries (we shouldn't double delete stuff).
for (int i = 1; i < deletedRefs.Count; ++i)
{
if (deletedRefs[i - 1].Equals(deletedRefs[i]))
{
// Oops, duplicated delete
throw new ApplicationException("PRAGMATIC_CHECK failed: duplicate records in delete list.");
}
}
long theVersionId = WriteSingleVersionInfo(versionId, rootNodeId, deletedRefs);
// Now update the version list by copying the list and adding the new ref
// to the end.
// Get the current version list
IMutableArea headerArea = nodeStore.GetMutableArea(headerId);
headerArea.Position = 8;
long versionListId = headerArea.ReadInt8();
// Read information from the old version info,
IArea versionListArea = nodeStore.GetArea(versionListId);
versionListArea.ReadInt4(); // The magic
int versionCount = versionListArea.ReadInt4();
// Create a new list,
IAreaWriter newVersionList = nodeStore.CreateArea(8 + (8 * (versionCount + 1)));
newVersionList.WriteInt4(0x01433);
newVersionList.WriteInt4(versionCount + 1);
for (int i = 0; i < versionCount; ++i)
{
newVersionList.WriteInt8(versionListArea.ReadInt8());
}
newVersionList.WriteInt8(theVersionId);
newVersionList.Finish();
// Write the new area to the header,
headerArea.Position = 8;
headerArea.WriteInt8(newVersionList.Id);
// Delete the old version list Area,
nodeStore.DeleteArea(versionListId);
// Done,
return(theVersionId);
}
}