-\section{Strategy}
+When we are trying to do a merge of some kind, in general,
+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 $\patchof{L}$.
+
+\stdsection{Notation}
+
+\begin{basedescript}{
+\desclabelwidth{5em}
+\desclabelstyle{\nextlinelabel}
+}
+\item[ $\depsreqof{K}$ ]
+The set of direct dependencies (in the form $\py$)
+requested in the commit $K$ ($K \in \pn$) for the patch $\p$.
+
+\item[ $\pc \hasdirdep \p$ ]
+The Topbloke commit set $\pc$ has as a direct contributors the
+commit set $\p$. This is an acyclic relation.
+
+\item[ $\p \hasdep \pq$ ]
+The commit set $\p$ has as direct or indirect contributor the commit
+set $\pq$.
+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[ $ \grefzc, \grefcc, \grefuc, \greffc $ ]
+The git ref for the Topbloke commit set $\pc$: respectively,
+the original, current, updated, and final values.
+
+\end{basedescript}
+
+\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 $\pc$.
+At each recursive step
+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 $\grefzc$, to make $\greffc$.
-We start with some commits $S_0 \ldots S_n$
-(where $S_0 = L$ and is the current git ref for $\pl$).
+We start with $\pc = \pl$ where $\pl = \patchof{L}$.
-%Let $\set E_{\pc} = \bigcup_i \pendsof{S_i}{\pc}$.
-Invoke Plan $\patchof \pl$ where the algorithm Plan $\pc$ is as
-follows:
+\subsection{Direct contributors for $\pc = \pcn$}
-Notation:
+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.
- $\pc \succ_1 \{ \p, \pq \ldots \}$
- the Topbloke commit set $py$ has as direct contributors exactly
- $\p, \pq, \ldots$. This is an acyclic relation.
+Choose an (arbitrary, but ideally somehow optimal in
+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 $E_k$.
- Extend this into the partial order $\succ$.
+Initially let $\set D_0 = \depsreqof{\grefzc}$.
+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 of $\pcn$.
-$\py \succ \pq$
+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 $\pc = \pcy$}
-We intend 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 $\pcn$.
+\subsection{Recursive step}
-For $\pc = \pcn$, 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
-are $\le$ and $\neq$ some other $E_k$.
+For each direct contributor $\p$, we add the edge $\pc \hasdirdep \p$
+and augment the ordering $\hasdep$ accordingly.
-Notation: write $\depsreqof{K}$ to mean the direct dependencies
-(in the form $\py$) requested in the commit $K$.
+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.
-Initially let $T_{\pc,0}$ be the git ref for $\pcn$. And let
-$\set D_0 = \depsreqof{T_{\pc,0}}$.
-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 $D_j$ as the 3-way merge of the sets $D_{j-1}$ and
-$\depsreqof{E_j}$ using as a base $\depsreqof{M_j}$. This will
-generate $D_m$ as the putative direct contributors for $\pcn$.
+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 $\greffc$ from
+$\grefzc$, as planned. By construction, $\hasdep$ has $\patchof{L}$
+as its maximum, so this operation will finish by updating
+$\greffa{\patchof{L}}$.
+
+After we are done, the result has the following properties:
+\[ \eqn{Tip Inputs}{
+ \bigforall_{E_i \in \set E_{\pc}} \greffc \ge E_i
+}\]
+\[ \eqn{Tip Dependencies}{
+ \bigforall_{\pc \hasdep \p} \greffc \ge \greffa \p
+}\]
+\[ \eqn{Perfect Contents}{
+ \greffc \haspatch \p \equiv \pc \hasdep \py
+}\]
+
+For brevity we will write $\grefu$ for $\grefuc$, etc. We will start
+out with $\grefc = \grefz$, and at each step of the way construct some
+$\grefu$ from $\grefc$. The final $\grefu$ becomes $\greff$.
+
+\subsection{Preparation}
+
+Firstly, we will check each $E_i$ for being $\ge \grefc$. If
+it is, are we fast forward to $E_i$
+--- formally, $\grefu = \text{max}(\grefc, E_i)$ ---
+and drop $E_i$ from the planned ordering.
+
+\subsection{Merge Contributors for $\pcy$}
-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 $\pcn$ into $\grefc$. That is, merge with
+$L = \grefc, R = \greffa{\pcn}, M = \baseof{\grefc}$.
+to construct $\grefu$.
+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 $\pcn$, $\greffa \pcn \haspatch \p$.
+computed $\greffa \py$, 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