/// <summary>
/// returns a handle used to iterate over all changes to a session since tracking began
/// See https://sqlite.org/session/sqlite3session_changeset.html
/// </summary>
/// <param name="session">open session handle currently tracking changes</param>
/// <param name="changeSet">buffer struct holding the returned change set</param>
/// <returns></returns>
public static Result GenerateChangeSet(IntPtr session, out SQLiteChangeSet changeSet)
{
// default to no ChangeSet (returned if any errors)
changeSet = new SQLiteChangeSet(0, new Sqlite3ChangesetBuffer(IntPtr.Zero));
if (session == IntPtr.Zero)
{
return(Result.Misuse);
}
try
{
var result = GenerateChangeSet(session, out int size, out Sqlite3ChangesetBuffer buffer);
if (result == Result.OK)
{
changeSet = new SQLiteChangeSet(size, buffer);
}
return(result);
}
catch (Exception e)
{
System.Diagnostics.Debug.WriteLine(e);
return(Result.Internal);
}
}
/// <summary>
/// Given a changeset, prepares the inverse such that applying In then Out change sets
/// will give the equivalent of no changes to the database.
/// See https://sqlite.org/session/sqlite3changeset_invert.html
/// </summary>
/// <param name="changeSetIn">existing change set</param>
/// <param name="changeSetOut">inverse of In change set</param>
/// <returns>result status of inversion; Result.OK if successful, otherwise corresponding error code</returns>
public static Result InvertChangeSet(SQLiteChangeSet changeSetIn, out SQLiteChangeSet changeSetOut)
{
if (changeSetIn.buffer.IsInvalid)
{
changeSetOut = new SQLiteChangeSet(0, new Sqlite3ChangesetBuffer(IntPtr.Zero));
return(Result.Misuse);
}
var result = InvertChangeSet(changeSetIn.size, changeSetIn.buffer, out int size, out Sqlite3ChangesetBuffer buffer);
changeSetOut = new SQLiteChangeSet(size, buffer);
return(result);
}
/// <summary>
/// Applies a given change set to provided db
/// with possibility to limit which tables are changed via xFilter delegate,
/// and custom conflict resolution via xConflict delegate
/// See https://sqlite.org/session/sqlite3changeset_apply.html
/// </summary>
/// <param name="db">which db ("main" only) to apply changes to</param>
/// <param name="changeSet">change set to apply to db</param>
/// <param name="xFilter">use null to not filter, else delegate to limit tables changes applied to</param>
/// <param name="xConflict">use null to ignore conflicts, else delegate to handle conflicts</param>
/// <param name="ctx">context passed as first argument to xFilter and xConflict delegates</param>
/// <returns></returns>
public static Result ChangeSetApply(SQLite.SQLiteConnection db, SQLiteChangeSet changeSet, FilterCallback xFilter, ConflictCallback xConflict, object ctx)
{
Sqlite3DatabaseHandle dbHandle = db?.Handle ?? IntPtr.Zero;
if (dbHandle == IntPtr.Zero)
{
return(Result.Misuse);
}
if (xConflict == null)
{
xConflict = new ConflictCallback(CallbackIgnoreConflicts);
}
// pinning not needed since just passing back thru; see https://blogs.msdn.microsoft.com/jmstall/2006/10/09/gchandle-tointptr-vs-gchandle-addrofpinnedobject/
// Warning: if conflict handler is in unmanaged code then ctx should be pinned in Alloc and use AddrOfPinnedObject instead of ToIntPtr
GCHandle gch = GCHandle.Alloc(ctx); // ok if ctx is null; pinning is unneeded since not kept past ChangeSetApply call
IntPtr pCtx = (ctx == null) ? IntPtr.Zero : GCHandle.ToIntPtr(gch); // we don't pass GCHandle wrapper if null, instead pass NULL
var result = ChangeSetApply(dbHandle, changeSet.size, changeSet.buffer, xFilter, xConflict, pCtx);
gch.Free();
return(result);
}
public static Result ApplySessionChangeSet(this SQLite.SQLiteConnection db, SQLiteChangeSet changeSet, FilterCallback xFilter, ConflictCallback xConflict, object ctx)
{
return(ChangeSetApply(db, changeSet, xFilter, xConflict, ctx));
}
/// <summary>
/// Obtain a handle to allow iterating through changes in a change set
/// See https://sqlite.org/session/sqlite3changeset_start.html
/// </summary>
/// <param name="iter">handle returned for iteratoring changes</param>
/// <param name="changeSet">the change set to iterate through</param>
/// <returns></returns>
public static Result ChangeSetStart(out Sqlite3ChangesetIterator iter, SQLiteChangeSet changeSet)
{
return(ChangeSetStart(out iter, changeSet.size, changeSet.buffer));
}
