X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=topbloke-formulae.git;a=blobdiff_plain;f=strategy.tex;h=0f03ddb9883200fed514b821df14948994e78aca;hp=62998371becf379d9aea154b32663e7d034c0ae2;hb=d1a680abdf1985a08c1a88157588ef881df7fb29;hpb=fdd5c703b15790389545f3b12264dbe24db5033e

diff --git a/strategy.tex b/strategy.tex
index 6299837..0f03ddb 100644
--- a/strategy.tex
+++ b/strategy.tex
@@ -98,6 +98,11 @@ The desired direct dependencies of $\pc$, a set of patches.
 The set of all the patches we are dealing with (constructed
 during the update algorithm).
 
+\item[ $\tipcn, \tipcy$ ]
+The new tips of the git branches $\pcn$ and $\pcy$, containing
+all the correct commits (and the correct other patches), as
+generated by the Traversal phase of the update algorithm.
+
 \end{basedescript}
 
 \section{Ranking phase}
@@ -224,7 +229,14 @@ this must complete eventually.
 
 $\qed$
 
-\section{Traversal phase}
+\section{Traversal phase --- algorithm}
+
+(In general, unless stated otherwise below, when we generate a new
+commit $C$ using one of the commit kind algorith, we update
+$W \assign C$.  In any such case where we say we're going to Merge
+with $L = W$, if $R \ge W$ we do not Merge but instead simply set
+$W \assign R$.)
+
 
 For each patch $\pc \in \allpatches$ in topological order by $\hasdep$,
 lowest first:
@@ -246,14 +258,15 @@ After processing each $\pc$ we will have created:
 
 \begin{itemize}
 
-\item tip
+\item $\tipcn$ and $\tipcy$ such that $\baseof{\tipcy} = \tipcn$.
 
 \end{itemize}
 
 \subsection{$\alg{Merge-Base}(\pc)$}
 
 This algorithm attempts to construct a suitably updated version of the
-base branch $\pcn$.
+base branch $\pcn$ using some existing version of $\pcn$ as a starting
+point.
 
 It should be executed noninteractively.  Specifically, if any step
 fails with a merge conflict, the whole thing should be abandoned.
@@ -262,17 +275,103 @@ avoids asking the user to pointlessly resolve conflicts in situations
 where we will later discover that $\alg{Merge-Base}$ wasn't feasible
 after all.
 
+If $\pc$ has only one direct dependency, this algorithm should not be
+used as in that case $\alg{Recreate-Base}$ is trivial and guaranteed
+to generate a perfect answer, whereas this algorithm might involve
+merges and therefore might not produce a perfect answer if the
+situation is complicated.
+
+Initially, set $W \iassign W^{\pcn}$.
+
 \subsubsection{Bases and sources}
 
 In some order, perhaps interleaving the two kinds of merge:
 
 \begin{enumerate}
 
-\item For each $\pd \isdirdep \pc$, merge $\pd$
+\item For each $\pd \isdirdep \pc$, find a merge base
+$M \le W,\; \le \tipdy$ and merge $\tipdy$ into $W$.
+That is, use $\alg{Merge}$ with $L = W,\; R = \tipdy$.
+(Dependency Merge.)
+
+\item For each $S \in S^{\pcn}_i$, merge it into $W$.
+That is, use $\alg{Merge}$ with $L = W,\; R = S,\; M = M^{\pcn}_i$.
+(Base Sibling Merge.)
+
+\end{enumerate}
+
+\subsubsection{Fixup}
+
+Execute $\alg{Fixup-Base}(W,\pc)$.
+
+
+\subsection{$\alg{Recreate-Base}(\pc)$}
+
+\begin{enumerate}
+
+\item
+
+Choose a $\hasdep$-maximal direct dependency $\pd$ of $\pc$.
+
+\item
+
+Use $\alg{Create Base}$ with $L$ = $\pdy,\; \pq = \pc$ to generate $C$
+and set $W \iassign C$.  (Recreate Base Beginning.)
+
+\item
+
+Execute the subalgorithm $\alg{Recreate-Recurse}(\pc)$.
 
 \item
 
+Declare that we contain all of the relevant information from the
+sources.  That is, use $\alg{Pseudo-merge}$ with $L = W, \;
+\set R = \{ W \} \cup \set S^{\pcn}$.
+(Recreate Base Final Declaration.)
+
+\end{enumerate}
+
+\subsubsection{$\alg{Recreate-Recurse}(\pd)$}
+
+\begin{enumerate}
+
+\item Is $W \haspatch \pd$ ?  If so, there is nothing to do: return.
+
+\item TODO what about non-Topbloke base branches
+
+\item Use $\alg{Pseudo-Merge}$ with $L = W,\; \set R = \{ \tipdn \}$.
+(Recreate Base Dependency Base Declaration.)
+
+\item For all $\hasdep$-maximal $\pd' \isdirdep \pd$,
+execute $\alg{Recreate-Recurse}(\pd')$.
+
+\item Use $\alg{Merge}$ to apply $\pd$ to $W$.  That is,
+$L = W, \; R = \tipdy, \; M = \baseof{R} = \tipdn$.
+(Recreate Reapply.)
+
 \end{enumerate}
 
 
+\subsection{$\alg{Merge-Tip}(\pc)$}
+
+\begin{enumerate}
+
+\item TODO CHOOSE/REFINE W AND S as was done during Ranking for bases
+
+\item $\alg{Merge}$ from $\tipcn$.  That is, $L = W, \;
+R = \tipcn$ and choose any suitable $M$.  (Tip Base Merge.)
+
+\item For each source $S \in \set S^{\pcy}$,
+$\alg{Merge}$ with $L = W, \; R = S$ and any suitable $M$.
+(Tip Source Merge.)
+
+\end{enumerate}
+
+
+\section{Traversal phase --- proofs}
+
+For each operation called for by the traversal algorithms, we prove
+that the commit generation preconditions are met.
+
+\subsection{Tip Base Merge}