-\section{Strategy}
-
When we are trying to do a merge of some kind, in general,
-we want to merge some commits $S_0 \ldots S_n$.
+we want to merge some source commits $S_0 \ldots S_n$.
We'll write $S_0 = L$. We require that $L$ is the current git ref
for $\patchof{L}$.
-%Let $\set E_{\pc} = \bigcup_i \pendsof{S_i}{\pc}$.
-
-\subsection{Notation}
+\stdsection{Notation}
\begin{basedescript}{
\desclabelwidth{5em}
The set of direct dependencies (in the form $\py$)
requested in the commit $K$ ($K \in \pn$) for the patch $\p$.
-\item[ $\pc \succ_1 \{ \p, \pq \ldots \}$ ]
-The Topbloke commit set $\pc$ has as direct contributors
-(see below) exactly $\p, \pq, \ldots$. This is an acyclic relation.
+\item[ $\pc \hasdirdep \p$ ]
+The Topbloke commit set $\pc$ has as a direct contributors the
+commit set $\p$. This is an acyclic relation.
-\item[ $\p \succ \pq$ ]
+\item[ $\p \hasdep \pq$ ]
The commit set $\p$ has as direct or indirect contributor the commit
set $\pq$.
-This is an acyclic relation, and is the completion of $\succ_1$ into a
+Acyclic; the completion of $\hasdirdep$ into a
partial order.
+\item[ $\set E_{\pc}$ ]
+$ \bigcup_i \pendsof{S_i}{\pc} $.
+All the ends of $\pc$ in the sources.
+
+\item[ $ \tipzc, \tipcc, \tipuc, \tipfc $ ]
+The git ref for the Topbloke commit set $\pc$: respectively,
+the original, current, updated, and final values.
+
\end{basedescript}
-\subsection{Planning phase}
+\section{Planning phase}
+
+The planning phase computes:
+\begin{itemize*}
+\item{ The relation $\hasdirdep$ and hence the ordering $\hasdep$. }
+\item{ For each commit set $\pc$, the order in which to merge
+ $E_{\pc,j} \in \set E_{\pc}$. }
+\item{ For each $E_{\pc,j}$ an intended merge base $M_{\pc,j}$. }
+\end{itemize*}
We use a recursive planning algorith, recursing over Topbloke commit
sets (ie, sets $\py$ or $\pn$). We'll call the commit set we're
-processing at each step $\pc$. We start with $\pc = \pl$
-where $\pl = \patchof{L}$.
-
+processing at each step $\pc$.
At each recursive step
-we intend to merge all $\set E_{\pc} = \{ E_{\pc,j \ldots} \}$
+we make a plan to merge all $\set E_{\pc} = \{ E_{\pc,j \ldots} \}$
and all the direct contributors of $\pc$ (as determined below)
-into the existing git ref for $\pc$, to make $T_{\pc}$.
-The direct contributors of $\pcn$ are the Topbloke commit sets
-corresponding to the tip branches for the direct dependencies of
-$\pc$.
-The sole direct contributor of $\pcy$ is $\pcn$.
+into $\tipzc$, to make $\tipfc$.
-\subsubsection{Planning step for $\pc = \pcn$.}
+We start with $\pc = \pl$ where $\pl = \patchof{L}$.
-FIXME DEFINE $\set E$
+
+\subsection{Direct contributors for $\pc = \pcn$}
+
+The direct contributors of $\pcn$ are the commit sets corresponding to
+the tip branches for the direct dependencies of the patch $\pc$. We
+need to calculate what the direct dependencies are going to be.
Choose an (arbitrary, but ideally somehow optimal in
-a way not discussed here) ordering of $\set E_{\pc}$, $E_j$ (for
-$j = 1 \ldots m$). Remove from that set (and ordering) any $E_j$ which
+a way not discussed here) ordering of $\set E_{\pc}$, $E_{\pc,j}$
+($j = 1 \ldots m$).
+For brevity we will write $E_j$ for $E_{\pc,j}$.
+Remove from that set (and ordering) any $E_j$ which
are $\le$ and $\neq$ some other $E_k$.
-Initially let $T_{\pc,0}$ be the git ref for $\pcn$. And let
-$\set D_0 = \depsreqof{T_{\pc,0}}$.
+Initially let $\set D_0 = \depsreqof{\tipzc}$.
For each $E_j$ starting with $j=1$ choose a corresponding intended
merge base $M_j$ such that $M_j \le E_j \land M_j \le T_{\pc,j-1}$.
Calculate $\set D_j$ as the 3-way merge of the sets $\set D_{j-1}$ and
$\depsreqof{E_j}$ using as a base $\depsreqof{M_j}$. This will
-generate $D_m$ as the putative direct contributors for $\pcn$.
+generate $D_m$ as the putative direct contributors of $\pcn$.
+
+However, the invocation may give instructions that certain direct
+dependencies are definitely to be included, or excluded. As a result
+the set of actual direct contributors is some arbitrary set of patches
+(strictly, some arbitrary set of Topbloke tip commit sets).
+
+\subsection{Direct contributors for $\pc = \pcy$}
+
+The sole direct contributor of $\pcy$ is $\pcn$.
+
+\subsection{Recursive step}
+
+For each direct contributor $\p$, we add the edge $\pc \hasdirdep \p$
+and augment the ordering $\hasdep$ accordingly.
+
+If this would make a cycle in $\hasdep$, we abort . The operation must
+then be retried by the user, if desired, but with different or
+additional instructions for modifying the direct contributors of some
+$\pqn$ involved in the cycle.
+
+For each such $\p$, after updating $\hasdep$, we recursively make a plan
+for $\pc' = \p$.
+
+\section{Execution phase}
+
+We process commit sets from the bottom up according to the relation
+$\hasdep$. For each commit set $\pc$ we construct $\tipfc$ from
+$\tipzc$, as planned. By construction, $\hasdep$ has $\patchof{L}$
+as its maximum, so this operation will finish by updating
+$\tipfa{\patchof{L}}$.
+
+After we are done, the result has the following properties:
+\[ \eqn{Tip Inputs}{
+ \bigforall_{E_i \in \set E_{\pc}} \tipfc \ge E_i
+}\]
+\[ \eqn{Tip Dependencies}{
+ \bigforall_{\pc \hasdep \p} \tipfc \ge \tipfa \p
+}\]
+\[ \eqn{Perfect Contents}{
+ \tipfc \haspatch \p \equiv \pc \hasdep \py
+}\]
+
+For brevity we will sometimes write $\tipu$ for $\tipuc$, etc. We will start
+out with $\tipc = \tipz$, and at each step of the way construct some
+$\tipu$ from $\tipc$. The final $\tipu$ becomes $\tipf$.
+
+\subsection{Preparation}
+
+Firstly, we will check each $E_i$ for being $\ge \tipc$. If
+it is, are we fast forward to $E_i$
+--- formally, $\tipu = \text{max}(\tipc, E_i)$ ---
+and drop $E_i$ from the planned ordering.
+
+Then we will merge the direct contributors and the sources' ends.
+
+This generates more commits $\tipuc \in \pc$, but none in any other
+commit set. We maintain XXX FIXME IS THIS THE BEST THING?
+$$
+ \bigforall_{\p \isdep \pc}
+ \pancsof{\tipcc}{\p} \subset \left[
+ \tipfa \p \cup
+ \bigcup_{E \in \set E_{\pc}} \pancsof{E}{\p}
+ \right]
+$$
+
+\subsection{Merge Contributors for $\pcy$}
+
+Merge $\pcn$ into $\tipc$. That is, merge with
+$L = \tipc, R = \tipfa{\pcn}, M = \baseof{\tipc}$.
+to construct $\tipu$.
-However, the invocation may specify that certain direct dependencies
-are definitely to be included, or excluded. As a result the set
-of actual direct contributors is some arbitrary set of patches.
+Merge conditions: Ingredients satisfied by construction.
+Tip Merge satisfied by construction. Merge Acyclic follows
+from Perfect Contents and $\hasdep$ being acyclic.
+Removal Merge Ends: For $\p = \pc$, $M \nothaspatch \p$.
+For $p \neq \pc$, by Tip Contents,
+$M \haspatch \p \equiv L \haspatch \p$, so we need only
+worry about $X = R, Y = L$; ie $L \haspatch \p$,
+$M = \baseof{L} \haspatch \p$.
+By Tip Contents for $L$, $D \le L \equiv D \le M$. $\qed$
+WIP UP TO HERE
+Addition Merge Ends: If $\py \isdep \pcn$, we have already
+done the execution phase for $\pcn$ and $\py$. By
+Perfect Contents for $\pcn$, $\tipfa \pcn \haspatch \p$ i.e.
+$R \haspatch \p$. So we only need to worry about $Y = R = \tipfa \pcn$.
+By Tip Dependencies $\tipfa \pcn \ge \tipfa \py$.
+And by Tip Inputs $\tipfa \py \ge $
+computed $\tipfa \py$, and by Perfect Contents for $\py$
-Imagine that we will merge the direct
with $M=M_j, L=T_{\pc,j-1}, R=E_j$,
and calculate what the resulting desired direct dependencies file
~ian / topbloke-formulae.git / blobdiff