public void Process(ExecutionContext context)
{
Guid sourceId = (Input as IMerge).FromId;
CmdStore cs = context.Store;
Branch target = cs.Current;
Branch source = cs.FindBranch(sourceId);
if (source == null)
{
throw new ApplicationException($"Cannot locate branch {sourceId}");
}
// Merges can only be done between branches that are part
// of the local store (fetches from remote stores should
// involve a totally different set of branches)
//if (target.Info.StoreId != source.Info.StoreId)
// throw new NotSupportedException("Attempt to merge with a remote store");
// Determine the first command that needs to be merged from
// the source branch. The source branch doesn't know anything
// about merges that have already been done, so figuring this
// out involves scanning back from the end of the target branch
// to locate the last merge (if any).
// How far we go back depends on whether we're merging from
// a child branch to its parent, or vice versa. If the target
// is the child we go back as far as command 0. If the target
// is the parent, we go back as far the command that followed
// the branch start point.
bool targetIsParent = target.Id.Equals(source.Info.ParentId);
// Define the range of commands to be merged from the source
uint minCmd = 0;
if (targetIsParent)
{
// Merging into the parent, so start from the command immediately
// after the last command that was previously merged (or 0 if this
// is the first time the parent has merged from the child).
if (target.Info.LastMerge.TryGetValue(sourceId, out MergeInfo mi))
{
minCmd = mi.ChildCount;
}
}
else
{
// Merging from the parent into the child, so start from the command
// immediately after the last command that was previously merged (it
// could potentially be 0)
minCmd = target.Info.RefreshCount;
}
uint maxCmd = (uint)source.Info.CommandCount - 1;
// TODO: Round about here we need to actually include the new stuff
// as part of the current stream. Replaying the commands may then
// lead to some sort of conflict (things are not guaranteed to work),
// so there needs to be some way to preview the results.
// Write the command data
Input.Add(nameof(IMerge.MinCmd), minCmd);
Input.Add(nameof(IMerge.MaxCmd), maxCmd);
target.SaveData(Input);
}