X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=blobdiff_plain;f=strategy.tex;h=97c41b9a9b0a1e55ea45e085746a3909f08b317b;hb=13a217e73c1ab13c7899dd2c1be7cbc909fed331;hp=bf136f69c912d185b9531089fafc2dd2922913c6;hpb=8ee16bd8a84437fc51257805eb234c4dee054889;p=topbloke-formulae.git

diff --git a/strategy.tex b/strategy.tex
index bf136f6..97c41b9 100644
--- a/strategy.tex
+++ b/strategy.tex
@@ -50,6 +50,10 @@ the $\le$-maximal elements of $\bigcup_{J \in \set J} \pendsof{J}{\p}$
 Convenience notation for
 $\bigforall_{E \in \pendsof{\set X}{\p}} E \le T$
 
+\item[ $\allsrcs$ ]
+$\bigcup_{\p \in \allpatches} \set H^{\pn} \cup \set H^{\py}$.
+All the input commits to the update algorithm.  (See below.)
+
 %\item[ $\set E_{\pc}$ ]
 %$ \bigcup_i \pendsof{S_{\pc,i}}{\pc} $.
 %All the ends of $\pc$ in the sources.
@@ -70,7 +74,7 @@ $\bigforall_{E \in \pendsof{\set X}{\p}} E \le T$
 The topmost patch which we are trying to update.  This and
 all of its dependencies will be updated.
 
-\item[ $h : \pc^{+/-} \mapsto \set H_{\pc^{+/-}}$ ]
+\item[ $h : \pc^{+/-} \mapsto \set H^{\pc^{+/-}}$ ]
 Function for getting the existing heads $\set H$ of the branch $\pc^{+/-}$.
 These are the heads which will be merged and used in this update.
 This will include the current local and remote git refs, as desired.
@@ -100,8 +104,34 @@ 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.
+all the appropriate commits (and the appropriate other patches),
+as generated by the Traversal phase of the update algorithm.
 
 \end{basedescript}
 
+\stdsection{ WIP tip satisfaction, reachable commits }
+
+Set of all reachable commits, O.
+
+A reachable commit is one we might refer to explicitly in any of these
+algorithms, and any ancestor of such a commit.  We explicitly
+enumerate all of the input commits (U), so the reachable commits are
+originally the input commits and their ancestors.  Each commit we
+generate will have reachable commits as ancestors so when we generate
+a new commit we only add that new commit to O.
+
+So O varies over time as we generate more commits.  We write O_py for
+the set of reachable commits at the point where we have just generated
+T_py, ie jusjt after Merge-Tip(P).
+
+We preserve/ensure
+  Tip_Py >= pendsof( O_py, Py )
+(Tip_py is computed during traversal for the patch P)
+
+We ensure this property by:
+  - we do not generate any commits for py other than
+    during Merge-Tip
+  - so at the start of Merge-Tip pendsof (O, py) = pendsof (U, py)
+  - Merge-Tip itself wip wip wip
+
+