// commits a transaction
private void aCommit(Transaction context)
{
lock (ManagerLock)
{
TransItem contextData = this.preparedContextMap.Remove(context);
if (null == contextData)
{
// transaction must already have been commited or aborted
// nothing to do
return;
}
List <int> oldStorageContextPages = contextData.StoragePageList;
StorageContext storageContext = contextData.TransactionData;
if (null == storageContext)
{
storageContext = ReadStorageContext(contextData, out oldStorageContextPages);
}
// read in the DB root
DBHdr dbRoot = this.ReadDBRoot();
if (null == dbRoot)
{
throw new InvalidDataException();
}
// merge page table
storageContext.PageTable.ReadPageTableData(
this.dataFile, dbRoot.PageTable);
storageContext.PageTable.ClearDirtyFlags();
// merge resource index
storageContext.ResourceIndex.ReadIndexData(
this.dataFile, dbRoot.ResourceIndex);
storageContext.ResourceIndex.ClearDirtyFlags();
// merge reservation index
storageContext.ReservationIndex.ReadIndexData(
this.dataFile, dbRoot.ReservationIndex);
storageContext.ReservationIndex.ClearDirtyFlags();
// write the page table
List <int> oldPageTablePages = null;
dbRoot.PageTable = storageContext.PageTable.WritePageTableData(
this.dataFile, this.pageManager, out oldPageTablePages);
// write the resource index
List <int> oldResourceIndexPages = null;
dbRoot.ResourceIndex = storageContext.ResourceIndex.WriteIndexData(
this.dataFile, this.pageManager, out oldResourceIndexPages);
// write the reservation index
List <int> oldReservationIndexPages = null;
dbRoot.ReservationIndex = storageContext.ReservationIndex.WriteIndexData(
this.dataFile, this.pageManager, out oldReservationIndexPages);
// write the updated prepared transaction list
List <int> oldPrepedContextMapPages = null;
dbRoot.PrepedTransactions = this.preparedContextMap.WriteTransactionTableData(
this.dataFile, this.pageManager, out oldPrepedContextMapPages);
// update the page manager
this.pageManager.SetFreePages(oldStorageContextPages);
this.pageManager.SetFreePages(oldPageTablePages);
this.pageManager.SetFreePages(oldResourceIndexPages);
this.pageManager.SetFreePages(oldReservationIndexPages);
this.pageManager.SetFreePages(oldPrepedContextMapPages);
this.pageManager.SetFreePages(storageContext.FreedPageList);
dbRoot.PageManager = this.pageManager.WritePageManagerData(
this.dataFile);
this.WriteDBRoot(dbRoot);
this.dataFile.Flush(true);
}
}
private StorageContext ReadStorageContext(TransItem contextData, out List <int> oldStorageContextPages)
{
// allocate the storage page list
oldStorageContextPages = new List <int>();
// look for the context in the map
StorageContext storageContext = new StorageContext();
// read in the page table
if (TransItem.NotStored != contextData.PageTableStartPage)
{
storageContext.PageTable.ReadPageTableData(
this.dataFile, contextData.PageTableStartPage);
oldStorageContextPages.AddRange(
storageContext.PageTable.GetStoragePages());
}
// read in the resource index
if (TransItem.NotStored != contextData.ResourceIndexStartPage)
{
storageContext.ResourceIndex.ReadIndexData(
this.dataFile, contextData.ResourceIndexStartPage);
oldStorageContextPages.AddRange(
storageContext.ResourceIndex.GetStoragePages());
}
// read in the reservation index
if (TransItem.NotStored != contextData.ReservationIndexStartPage)
{
storageContext.ReservationIndex.ReadIndexData(
this.dataFile, contextData.ReservationIndexStartPage);
oldStorageContextPages.AddRange(
storageContext.ReservationIndex.GetStoragePages());
}
// read in the allocated page list
if (TransItem.NotStored != contextData.AllocatedPageListStartPage)
{
List <int> usedPages = null;
List <int> data = null;
ListReader <int> reader = new ListReader <int>();
reader.ReadList(this.dataFile, contextData.AllocatedPageListStartPage, out data, out usedPages);
storageContext.AllocatedPageList = data;
oldStorageContextPages.AddRange(usedPages);
}
// read in the freed page list
if (TransItem.NotStored != contextData.FreedPageListStartPage)
{
List <int> usedPages = null;
List <int> data = null;
ListReader <int> reader = new ListReader <int>();
reader.ReadList(this.dataFile, contextData.FreedPageListStartPage, out data, out usedPages);
storageContext.FreedPageList = data;
oldStorageContextPages.AddRange(usedPages);
}
return(storageContext);
}
// writes a resource or reservation data item
protected virtual bool Write <I, R>(Transaction context, StorageContext storageContext, StorageIndex <I> index, I rID, R data)
{
// look for the resource in the index
IndexItem <I> address = index.GetResourceAddress(rID);
if (null == address &&
null == data)
{
// nothing to do:
// user probably wanted to delete an non-existing item
return(true);
}
else if (null == address &&
null != data)
{
address = new IndexItem <I>
{
Page = storageContext.PageTable.GetLastLogicalPage(),
Record = -1
};
}
// Aquire a lock on the logical page address to ensure that we have access to the page
this.LockPage(context, MyLM.LockMode.Write, address.Page);
// find the physical page
int fileAddress = storageContext.PageTable.GetPhysicalPage(address.Page);
// get the page
StoragePage page = new StoragePage();
if (0 <= fileAddress)
{
this.aReadPageData(page, fileAddress);
}
// write the record
while (true)
{
try
{
if (0 > address.Record)
{
address.Record = page.AddRecord(data);
}
else
{
page.WriteRecord(address.Record, data);
}
}
catch (StoragePage.InsuffcientSpaceException)
{
// did not fit on last page so allocate a new page
page = new StoragePage();
address.Page = -1;
fileAddress = -1;
continue;
}
break;
}
// write the page
fileAddress = this.aWritePageData(page, storageContext, fileAddress);
// update the page table
if (0 > address.Page)
{
address.Page = storageContext.PageTable.SetLogicalPage(fileAddress);
}
else
{
storageContext.PageTable.UpdatePage(address.Page, fileAddress);
}
// update the index
if (null == data)
{
// handle deletes
address = null;
}
index.SetResourceAddress(rID, address);
return(true);
}
