1 When we are trying to do a merge of some kind, in general,
2 we want to merge some source commits $S_0 \ldots S_n$.
3 We'll write $S_0 = L$. We require that $L$ is the current git ref
10 \desclabelstyle{\nextlinelabel}
12 \item[ $\depsreqof{K}$ ]
13 The set of direct dependencies (in the form $\py$)
14 requested in the commit $K$ ($K \in \pn$) for the patch $\p$.
16 \item[ $\pc \hasdirdep \p$ ]
17 The Topbloke commit set $\pc$ has as a direct contributors the
18 commit set $\p$. This is an acyclic relation.
20 \item[ $\p \hasdep \pq$ ]
21 The commit set $\p$ has as direct or indirect contributor the commit
23 Acyclic; the completion of $\hasdirdep$ into a
26 \item[ $\set E_{\pc}$ ]
27 $ \bigcup_i \pendsof{S_i}{\pc} $.
28 All the ends of $\pc$ in the sources.
30 \item[ $ \grefzc, \grefcc, \grefuc, \greffc $ ]
31 The git ref for the Topbloke commit set $\pc$: respectively,
32 the original, current, updated, and final values.
36 \section{Planning phase}
38 The planning phase computes:
40 \item{ The relation $\hasdirdep$ and hence the ordering $\hasdep$. }
41 \item{ For each commit set $\pc$, the order in which to merge
42 $E_{\pc,j} \in \set E_{\pc}$. }
43 \item{ For each $E_{\pc,j}$ an intended merge base $M_{\pc,j}$. }
46 We use a recursive planning algorith, recursing over Topbloke commit
47 sets (ie, sets $\py$ or $\pn$). We'll call the commit set we're
48 processing at each step $\pc$.
49 At each recursive step
50 we make a plan to merge all $\set E_{\pc} = \{ E_{\pc,j \ldots} \}$
51 and all the direct contributors of $\pc$ (as determined below)
52 into $\grefzc$, to make $\greffc$.
54 We start with $\pc = \pl$ where $\pl = \patchof{L}$.
57 \subsection{Direct contributors for $\pc = \pcn$}
59 The direct contributors of $\pcn$ are the commit sets corresponding to
60 the tip branches for the direct dependencies of the patch $\pc$. We
61 need to calculate what the direct dependencies are going to be.
63 Choose an (arbitrary, but ideally somehow optimal in
64 a way not discussed here) ordering of $\set E_{\pc}$, $E_{\pc,j}$
66 For brevity we will write $E_j$ for $E_{\pc,j}$.
67 Remove from that set (and ordering) any $E_j$ which
68 are $\le$ and $\neq$ some other $E_k$.
70 Initially let $\set D_0 = \depsreqof{\grefzc}$.
71 For each $E_j$ starting with $j=1$ choose a corresponding intended
72 merge base $M_j$ such that $M_j \le E_j \land M_j \le T_{\pc,j-1}$.
73 Calculate $\set D_j$ as the 3-way merge of the sets $\set D_{j-1}$ and
74 $\depsreqof{E_j}$ using as a base $\depsreqof{M_j}$. This will
75 generate $D_m$ as the putative direct contributors of $\pcn$.
77 However, the invocation may give instructions that certain direct
78 dependencies are definitely to be included, or excluded. As a result
79 the set of actual direct contributors is some arbitrary set of patches
80 (strictly, some arbitrary set of Topbloke tip commit sets).
82 \subsection{Direct contributors for $\pc = \pcy$}
84 The sole direct contributor of $\pcy$ is $\pcn$.
86 \subsection{Recursive step}
88 For each direct contributor $\p$, we add the edge $\pc \hasdirdep \p$
89 and augment the ordering $\hasdep$ accordingly.
91 If this would make a cycle in $\hasdep$, we abort . The operation must
92 then be retried by the user, if desired, but with different or
93 additional instructions for modifying the direct contributors of some
94 $\pqn$ involved in the cycle.
96 For each such $\p$, after updating $\hasdep$, we recursively make a plan
99 \section{Execution phase}
104 with $M=M_j, L=T_{\pc,j-1}, R=E_j$,
105 and calculate what the resulting desired direct dependencies file
106 (ie, the set of patches $\set D_j$)
107 would be. Eventually we
109 So, formally, we select somehow an order of sources $S_i$. For each
112 Make use of the following recursive algorithm, Plan
117 recursively make a plan to merge all $E = \pends$