/// <summary>
/// Delete an page using pageID - transform them in Empty Page and add to EmptyPageList
/// If you delete a page, you can using same old instance of page - page will be converter to EmptyPage
/// If need deleted page, use GetPage again
/// </summary>
public void DeletePage(uint pageID, bool addSequence = false)
{
// get all pages in sequence or a single one
var pages = addSequence ? this.GetSeqPages <BasePage>(pageID).ToArray() : new BasePage[] { this.GetPage <BasePage>(pageID) };
// get my header page
var header = this.GetPage <HeaderPage>(0);
// adding all pages to FreeList
foreach (var page in pages)
{
// create a new empty page based on a normal page
var empty = new EmptyPage(page.PageID);
// add empty page to cache (with now EmptyPage type) and mark as dirty
this.SetDirty(empty);
// add to empty free list
this.AddOrRemoveToFreeList(true, empty, header, ref header.FreeEmptyPageID);
}
}
/// <summary>
/// Initialize new datafile with header page + lock reserved area zone
/// </summary>
public static void CreateDatabase(Stream stream, string password = null, long initialSize = 0)
{
// calculate how many empty pages will be added on disk
var emptyPages = initialSize == 0 ? 0 : (initialSize - (2 * BasePage.PAGE_SIZE)) / BasePage.PAGE_SIZE;
// if too small size (less than 2 pages), assume no initial size
if (emptyPages < 0)
{
emptyPages = 0;
}
// create a new header page in bytes (keep second page empty)
var header = new HeaderPage
{
LastPageID = initialSize == 0 ? 1 : (uint)emptyPages + 1,
FreeEmptyPageID = initialSize == 0 ? uint.MaxValue : 2
};
if (password != null)
{
header.Password = AesEncryption.HashSHA1(password);
header.Salt = AesEncryption.Salt();
}
// point to begin file
stream.Seek(0, SeekOrigin.Begin);
// get header page in bytes
var buffer = header.WritePage();
stream.Write(buffer, 0, BasePage.PAGE_SIZE);
// write second page as an empty AREA (it's not a page) just to use as lock control
stream.Write(new byte[BasePage.PAGE_SIZE], 0, BasePage.PAGE_SIZE);
// create crypto class if has password
var crypto = password != null ? new AesEncryption(password, header.Salt) : null;
// if initial size is defined, lets create empty pages in a linked list
if (emptyPages > 0)
{
stream.SetLength(initialSize);
var pageID = 1u;
while (++pageID < (emptyPages + 2))
{
var empty = new EmptyPage(pageID)
{
PrevPageID = pageID == 2 ? 0 : pageID - 1,
NextPageID = pageID == emptyPages + 1 ? uint.MaxValue : pageID + 1
};
var bytes = empty.WritePage();
if (password != null)
{
bytes = crypto.Encrypt(bytes);
}
stream.Write(bytes, 0, BasePage.PAGE_SIZE);
}
}
if (crypto != null)
{
crypto.Dispose();
}
}