X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=topbloke.git;a=blobdiff_plain;f=DESIGN;h=97f06810fe75996cfdfb35d656934e591a376465;hp=f3c3f828720c5f47c5a4646463950202ba99b009;hb=098d1cf209a61beea78d08d84eb50509b132dd6d;hpb=47d533722a17175a58abd30d35f4aa36f8e2e3bd

diff --git a/DESIGN b/DESIGN
index f3c3f82..97f0681 100644
--- a/DESIGN
+++ b/DESIGN
@@ -22,7 +22,7 @@ Basic update algorithm:
 
        Find the (latest) common ancestor.
 
-       Check for unwanted dependency removals.  
+       Check for unwanted dependency removals.
        An unwanted dependency removal is
           A branch in the desired included deps
           Which exists in the common ancestor's actual included deps
@@ -40,6 +40,9 @@ Basic update algorithm:
             stops us looking into the hitory of non-topbloke-controlled
             branches).  This can be done with git-rev-list
             --remove-empty.
+	  * It also stops at any point where we meet a commit which
+	    does have the dep in the actual included deps.  We have
+	    to do this by hand.
           * The the relevant unwanted removal commit for that dep is
             the most recent unwanted removal commit, as defined.
        Select the unwantedly removed dep whose relevant unwanted
@@ -109,7 +112,7 @@ Basic update algorithm:
 The "best order" for merges is in order of recency of common
 ancestor, most recent first, and if that does not distinguish,
 merging from local branches first.
-     
+
 "Recency" refers to the order from git-rev-list --date-order.
 
 Actual included deps:
@@ -222,7 +225,7 @@ OK so here is a plan:
   Check for merge success in the index and compare to exit status
   from git-merge (which is 1 if the merge failed).
   Adjust the metadata.
-  Print appropriate big fat warnings if we have merge conflicts in our 
+  Print appropriate big fat warnings if we have merge conflicts in our
   metadata.
   Commit, adjusting the parents of the new commit to the original
   parents if we made the merge with special massaged parents.
@@ -231,14 +234,110 @@ OK so here is a plan:
 
 Strategies for each metadata file merge:
 
-	in base/tip	same patch's tip	dep -> base	base -> tip
+	in base/tip	same patch & branch	dep -> base	base -> tip
 
  msg		 T	textual merge		rm from src	not in src
- deps		 T	list merge		rm from src	not in src
+ deps		B	list merge		rm from src	rm from src
  deleted	 T	std existence merge	rm from src	not in src
  patch-		BT	must be same		rm from src	must be same
- topgit-	 T	must be same		rm from src	not in src
+ topgit-	B	std exist/text merge	rm from src	rm from src
  [^+]*-		??	textual merge		rm from src	rm from src
  +included	BT	list merge	  rm from non-tb src	list merge
  +*-		??	textual merge	  rm from non-tb src	textual merge
  *[^-]		??	die, aborting all ops, if found in any tb src or branch
+
+
+
+
+
+Unwanted removal search subgraphs:
+
+  rm		relevant removal
+  inc
+
+   rm		impossible to undo removal, arrgh, terminates search
+inc  inc..
+/  ???   \
+
+    rm
+inc..  rm..	merge of a removal, search down the rm path
+/  [inc]  \
+
+  inc		??? call it an inclusion, terminate the search
+  rm
+
+   inc		merge of an inclusion, terminates search
+inc..  rm..
+/  [rm]  \
+
+   inc		??? call it an inclusion, terminate search
+rm..  rm..
+/  ???    \
+
+
+  rm	inc	  inc	       rm	irrelevant
+  rm	inc	inc inc..    rm rm..
+
+
+
+          OUR BASE              SOURCE		       OUR IT TIP
+		| 	       	   |			   |
+		| 	           | 			   |
+   ADD DEP WH/ inc	       	   rm			   |
+    NEEDS IT   /|	       	   /\			   |
+	      /	| 	       	 rm  \			   |
+	     /	| ______________'/    \			   |
+	  inc	|'	       	/      \		   |   	 IT tip
+           /   inc     REMOVAL rm       \              	   |   	elsewhere
+          /     |             /          \             	   |   |   |
+	 /      |           inc           \                |   |   |
+     some IT    |           /              |           	   |   |   |
+                |         inc              |           	   |   |   |
+               /           |               |           	   |   |   |
+              /          inc               |           	   |   |   |
+             |           / |               |           	   |   |   |
+	    /           /  inc             |           	   |   |   |
+	   /           |   | `------------ | ----<-------- | -.|   |
+       	  /           inc  inc             |           	   |   *2  |
+	  |            |`- | ------------- | ----<--------.|   |   |
+	  |            `---inc             |           	  1*  /	   |
+ 	  |                |               |           	   | /	   |
+ 	  |     RE-INCLUDE inc             rm REMOVAL  	   |'	   |
+        inc     \          |               |           	   |	   |
+    	  |      * REMOVAL rm              |           	   |	   |
+       	  |                |              /            	   |	   |
+       	  |`-------------- | ----------. /             	   |	   |
+       	  |                |           inc ANC2        	   |	   |
+ 	 inc               inc         /               	   |	   |
+ 	  |`.____________  |          /                	   |	   |
+ 	  |              `inc ANC1   /                 	   |	   |
+ 	  |                |        /`--------<----------- | ---.  |
+ 	without            inc     /                   	   |	 \/
+ 	  |                |      /                    	   |	 /
+ 	   \    RE-INCLUDE inc   /                     	   |   	/
+       	    \   \          |    /                      	   |   /
+ 	     \   * REMOVAL rm  /                       	   |  /
+              \            |  /                        	   | /
+               \           inc FIRST ADD DEP   	       	   |/
+		\	   |  \	       	       	       	   *3
+		 \	   |   `------------<-------------.|
+       	       	  \    	   | 	      		       	   |
+ 		   \	   without    		       	   |
+		    \_____ |   	      		       	   |
+		 	  `without    		       	   |
+		 	   |   	      		    	   |
+		 		      		       	  IT
+
+
+  Merge 1* and 2*, diff against some relevant base branch commit
+  or something, and apply to proposed. ???
+
+
+After we are done:
+  source tip is included in our base
+
+Each time:
+  * pick common ancestor
+  * compute whether merge from common anc would unwantedly remove
+  * if so we arrange that the common anc is a "rm" but our branch
+    actually contains IT