Possible to Do Get with Unknown Buffer Size?

[belsokar]

I am currently doing the following:

I have a LinkedList object of a custom type.

Example:

            LinkedList<TransactionType> transactions = new LinkedList<TransactionType>();

I continuously grow that list of transactions, and then I serialize that data using a BinaryFormatter and then write to DB doing the following:

           //Write out transactions to database? memory?
            DbEntry keyEntry;
            DbEntry dataEntry;

            keyEntry = dbs.Fmt.ToDbEntry<string>(key);

            MemoryStream ms = new MemoryStream();
            BinaryFormatter bf = new BinaryFormatter();
            bf.Serialize(ms, transactions);

            dataEntry = DbEntry.InOut(ms.GetBuffer());

            WriteStatus status = dbs.TransactionsDB.Put(null, ref keyEntry, ref dataEntry);

When it comes time to read, I'm doing the following:

LinkedList<Transaction> results = null;

            DbEntry keyEntry;
            DbEntry dataEntry = DbEntry.Out(new byte[1024]);

            BinaryFormatter bf = new BinaryFormatter();

            BerkeleyDb.ReadStatus result;

            keyEntry = dbs.Fmt.ToDbEntry<string>(key);

            result = dbs.TransactionsDB.Get(null, ref keyEntry, ref dataEntry, DbFile.ReadFlags.None);

            if (result == ReadStatus.Success)
            {
                byte[] buffer = dataEntry.Buffer;
                MemoryStream ms = new MemoryStream(buffer);
                results = (LinkedList<Transaction>)bf.Deserialize(ms);

            }

This works fine as long as the dataEntry.Buffer size is not too small of course.  So my main question is whether or not there is a way to pull that data back without specifying an initial buffer size?  I could size the buffer appropriately, but in most cases, I would be over allocating, which wouldn't be a huge deal, but ideally I wouldn't allocate too much memory when I didn't have to.

Thanks!

[Karl Waclawek]

In a way, yes, but it requires two calls to the Get() function.
Have a look at the Overview demo app. There is a method GetNextRecord() in MainFrm.cs, and it deals with ReadStatus.BufferSmall.

Karl