git/query: fix spurious merge requests
Due to the way LCA is defined, a using a strict LCA
on a graph like this:
<--a--b--c--d--e--f--g
\ /
+-----h-------
can lead to spurious requests to merge. This happens
because 'lca(b, g)' would return 'a', since it can be
reached in one step from 'b', and 2 steps from 'g', while
reaching 'b' from 'a' would be a longer path.
As a result, we need to implement an lca variant that
returns the starting node if one is reachable from the
other, even if it's already found the technically correct
least common ancestor.
This replaces our LCA algorithm with one based on the
painting we do while finding a twixt, making it give
the resutls we want.
git/query: fix spurious merge requests
Due to the way LCA is defined, a using a strict LCA
on a graph like this:
<--a--b--c--d--e--f--g
\ /
+-----h-------
can lead to spurious requests to merge. This happens
because 'lca(b, g)' would return 'a', since it can be
reached in one step from 'b', and 2 steps from 'g', while
reaching 'b' from 'a' would be a longer path.
As a result, we need to implement an lca variant that
returns the starting node if one is reachable from the
other, even if it's already found the technically correct
least common ancestor.
This replaces our LCA algorithm with one based on the
painting we do while finding a twixt.
This commit is contained in:
Ori Bernstein
parent
546f8cfeca
commit
c7dcc82b0b
5 changed files with 278 additions and 251 deletions
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@ -18,6 +18,8 @@ typedef struct Idxent Idxent;
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typedef struct Objlist Objlist;
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typedef struct Dtab Dtab;
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typedef struct Dblock Dblock;
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typedef struct Objq Objq;
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typedef struct Qelt Qelt;
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enum {
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Pathmax = 512,
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@ -151,6 +153,20 @@ struct Objset {
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int sz;
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};
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struct Qelt {
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Object *o;
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vlong mtime;
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int color;
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int dist;
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};
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struct Objq {
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Qelt *heap;
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int nheap;
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int heapsz;
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int nkeep;
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};
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struct Dtab {
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Object *o;
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uchar *base;
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@ -301,3 +317,9 @@ int gitconnect(Conn *, char *, char *);
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int readphase(Conn *);
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int writephase(Conn *);
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void closeconn(Conn *);
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/* queues */
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void qinit(Objq*);
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void qclear(Objq*);
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void qput(Objq*, Object*, int, int);
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int qpop(Objq*, Qelt*);
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@ -15,10 +15,8 @@ char *queryexpr;
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char *commitid;
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int shortlog;
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Object **heap;
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int nheap;
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int heapsz;
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Objset done;
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Objq objq;
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Pfilt *pathfilt;
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void
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@ -191,65 +189,11 @@ showquery(char *q)
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exits(nil);
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}
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static void
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qput(Object *o)
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{
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Object *p;
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int i;
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if(oshas(&done, o->hash))
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return;
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osadd(&done, o);
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if(nheap == heapsz){
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heapsz *= 2;
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heap = earealloc(heap, heapsz, sizeof(Object*));
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}
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heap[nheap++] = o;
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for(i = nheap - 1; i > 0; i = (i-1)/2){
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o = heap[i];
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p = heap[(i-1)/2];
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if(o->commit->mtime < p->commit->mtime)
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break;
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heap[i] = p;
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heap[(i-1)/2] = o;
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}
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}
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static Object*
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qpop(void)
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{
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Object *o, *t;
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int i, l, r, m;
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if(nheap == 0)
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return nil;
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i = 0;
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o = heap[0];
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t = heap[--nheap];
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heap[0] = t;
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while(1){
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m = i;
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l = 2*i+1;
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r = 2*i+2;
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if(l < nheap && heap[m]->commit->mtime < heap[l]->commit->mtime)
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m = l;
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if(r < nheap && heap[m]->commit->mtime < heap[r]->commit->mtime)
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m = r;
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else
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break;
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t = heap[m];
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heap[m] = heap[i];
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heap[i] = t;
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i = m;
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}
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return o;
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}
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static void
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showcommits(char *c)
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{
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Object *o, *p;
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Qelt e;
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int i;
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Hash h;
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@ -259,18 +203,20 @@ showcommits(char *c)
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sysfatal("resolve %s: %r", c);
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if((o = readobject(h)) == nil)
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sysfatal("load %H: %r", h);
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heapsz = 8;
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heap = eamalloc(heapsz, sizeof(Object*));
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qinit(&objq);
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osinit(&done);
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qput(o);
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while((o = qpop()) != nil){
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show(o);
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for(i = 0; i < o->commit->nparent; i++){
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if((p = readobject(o->commit->parent[i])) == nil)
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qput(&objq, o, 0, 0);
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while(qpop(&objq, &e)){
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show(e.o);
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for(i = 0; i < e.o->commit->nparent; i++){
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if(oshas(&done, e.o->commit->parent[i]))
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continue;
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if((p = readobject(e.o->commit->parent[i])) == nil)
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sysfatal("load %H: %r", o->commit->parent[i]);
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qput(p);
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osadd(&done, p);
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qput(&objq, p, 0, 0);
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}
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unref(o);
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unref(e.o);
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}
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}
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@ -158,6 +158,7 @@ main(int argc, char **argv)
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char query[2048], repo[512];
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ARGBEGIN{
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case 'd': chattygit++; break;
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case 'p': fullpath++; break;
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case 'c': changes++; break;
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case 'r': reverse ^= 1; break;
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@ -5,8 +5,20 @@
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#include "git.h"
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typedef struct Eval Eval;
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typedef struct XObject XObject;
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typedef struct Objq Objq;
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typedef struct Lcaq Lcaq;
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struct Lcaq {
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Objq;
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Hash *head;
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Hash *tail;
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int nhead;
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int ntail;
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Object *best;
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int dist;
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};
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enum {
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Blank,
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@ -22,17 +34,10 @@ struct Eval {
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int stksz;
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};
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struct XObject {
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Object *obj;
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Object *mark;
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XObject *queue;
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XObject *next;
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};
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struct Objq {
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Objq *next;
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Object *o;
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int color;
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static char *colors[] = {
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[Keep] "keep",
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[Drop] "drop",
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[Blank] "blank",
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};
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static Object zcommit = {
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@ -128,150 +133,98 @@ take(Eval *ev, char *m)
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return 1;
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}
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XObject*
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hnode(XObject *ht[], Object *o)
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static int
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pickbest(Lcaq *q, Qelt *e, int color)
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{
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XObject *h;
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int hh;
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int i, best, exact;
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hh = o->hash.h[0] & 0xff;
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for(h = ht[hh]; h; h = h->next)
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if(hasheq(&o->hash, &h->obj->hash))
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return h;
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h = emalloc(sizeof(*h));
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h->obj = o;
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h->mark = nil;
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h->queue = nil;
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h->next = ht[hh];
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ht[hh] = h;
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return h;
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best = 0;
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exact = 0;
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if(color == Blank || e->color == color)
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return 0;
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if(e->dist < q->dist){
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dprint(1, "found best (dist %d < %d): %H\n", e->dist, q->dist, e->o->hash);
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best = 1;
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}
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for(i = 0; i < q->nhead; i++)
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if(hasheq(&q->head[i], &e->o->hash)){
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dprint(1, "found best (exact head): %H\n", e->o->hash);
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best = 1;
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exact = 1;
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}
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for(i = 0; i < q->ntail; i++)
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if(hasheq(&q->tail[i], &e->o->hash)){
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dprint(1, "found best (exact tail): %H\n", e->o->hash);
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best = 1;
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exact = 1;
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}
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if(best){
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q->best = e->o;
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q->dist = e->dist;
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}
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return exact;
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}
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Object*
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ancestor(Object *a, Object *b)
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static int
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repaint(Lcaq *lcaq, Objset *keep, Objset *drop, Object *o, int dist, int ancestor)
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{
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Object *o, *p, *r;
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XObject *ht[256];
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XObject *h, *q, *q1, *q2;
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Lcaq objq;
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Qelt e;
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Object *p;
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int i;
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if(a == b)
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return a;
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if(a == nil || b == nil)
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return nil;
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r = nil;
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memset(ht, 0, sizeof(ht));
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q1 = nil;
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h = hnode(ht, a);
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h->mark = a;
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h->queue = q1;
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q1 = h;
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h = hnode(ht, b);
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h->mark = b;
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h->queue = q1;
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q1 = h;
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while(1){
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q2 = nil;
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while(q = q1){
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q1 = q->queue;
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q->queue = nil;
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o = q->obj;
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for(i = 0; i < o->commit->nparent; i++){
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p = readobject(o->commit->parent[i]);
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if(p == nil)
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goto err;
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h = hnode(ht, p);
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if(h->mark != nil){
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if(h->mark != q->mark){
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r = h->obj;
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goto done;
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}
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} else {
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h->mark = q->mark;
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h->queue = q2;
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q2 = h;
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}
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qinit(&objq);
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if((o = readobject(o->hash)) == nil)
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return -1;
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qput(&objq, o, Drop, dist);
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while(qpop(&objq, &e)){
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o = e.o;
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if(oshas(drop, o->hash))
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continue;
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if(ancestor && pickbest(lcaq, &e, Keep))
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goto out;
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if(!oshas(keep, o->hash)){
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dprint(2, "repaint: blank => drop %H\n", o->hash);
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osadd(drop, o);
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continue;
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}
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for(i = 0; i < o->commit->nparent; i++){
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if(oshas(drop, o->commit->parent[i]))
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continue;
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if((p = readobject(o->commit->parent[i])) == nil)
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goto out;
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if(p->type != GCommit){
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fprint(2, "hash %H not commit\n", p->hash);
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unref(p);
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}
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qput(&objq, p, Drop, e.dist+1);
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}
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if(q2 == nil){
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err:
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werrstr("no common ancestor");
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break;
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}
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q1 = q2;
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unref(e.o);
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}
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done:
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for(i=0; i<nelem(ht); i++){
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while(h = ht[i]){
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ht[i] = h->next;
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free(h);
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}
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}
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return r;
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}
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int
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lca(Eval *ev)
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{
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Object *a, *b, *o;
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if(ev->nstk < 2){
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werrstr("ancestor needs 2 objects");
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return -1;
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}
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a = pop(ev);
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b = pop(ev);
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o = ancestor(a, b);
|
||||
if(o == nil)
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return -1;
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push(ev, o);
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out:
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qclear(&objq);
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return 0;
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}
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|
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static int
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repaint(Objset *keep, Objset *drop, Object *o)
|
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paint(Hash *head, int nhead, Hash *tail, int ntail, Object ***res, int *nres, int ancestor)
|
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{
|
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Object *p;
|
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int i;
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|
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if(!oshas(keep, o->hash) && !oshas(drop, o->hash)){
|
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dprint(2, "repaint: blank => drop %H\n", o->hash);
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osadd(drop, o);
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return 0;
|
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}
|
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if(oshas(keep, o->hash))
|
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dprint(2, "repaint: keep => drop %H\n", o->hash);
|
||||
osadd(drop, o);
|
||||
for(i = 0; i < o->commit->nparent; i++){
|
||||
if((p = readobject(o->commit->parent[i])) == nil)
|
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return -1;
|
||||
if(repaint(keep, drop, p) == -1)
|
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return -1;
|
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unref(p);
|
||||
}
|
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return 0;
|
||||
}
|
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|
||||
int
|
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findtwixt(Hash *head, int nhead, Hash *tail, int ntail, Object ***res, int *nres)
|
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{
|
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Objq *q, *e, *n, **p;
|
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Qelt e;
|
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Lcaq objq;
|
||||
Objset keep, drop;
|
||||
Object *o, *c;
|
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int i, ncolor;
|
||||
|
||||
e = nil;
|
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q = nil;
|
||||
p = &q;
|
||||
osinit(&keep);
|
||||
osinit(&drop);
|
||||
qinit(&objq);
|
||||
objq.head = head;
|
||||
objq.nhead = nhead;
|
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objq.tail = tail;
|
||||
objq.ntail = ntail;
|
||||
objq.dist = 1<<30;
|
||||
|
||||
for(i = 0; i < nhead; i++){
|
||||
if(hasheq(&head[i], &Zhash))
|
||||
continue;
|
||||
if((o = readobject(head[i])) == nil){
|
||||
fprint(2, "warning: %H does not point at commit\n", o->hash);
|
||||
werrstr("read head %H: %r", head[i]);
|
||||
|
|
@ -282,17 +235,11 @@ findtwixt(Hash *head, int nhead, Hash *tail, int ntail, Object ***res, int *nres
|
|||
unref(o);
|
||||
continue;
|
||||
}
|
||||
dprint(1, "twixt init: keep %H\n", o->hash);
|
||||
e = emalloc(sizeof(Objq));
|
||||
e->o = o;
|
||||
e->color = Keep;
|
||||
*p = e;
|
||||
p = &e->next;
|
||||
dprint(1, "init: keep %H\n", o->hash);
|
||||
qput(&objq, o, Keep, 0);
|
||||
unref(o);
|
||||
}
|
||||
for(i = 0; i < ntail; i++){
|
||||
if(hasheq(&tail[i], &Zhash))
|
||||
continue;
|
||||
if((o = readobject(tail[i])) == nil){
|
||||
werrstr("read tail %H: %r", tail[i]);
|
||||
return -1;
|
||||
|
|
@ -303,77 +250,117 @@ findtwixt(Hash *head, int nhead, Hash *tail, int ntail, Object ***res, int *nres
|
|||
continue;
|
||||
}
|
||||
dprint(1, "init: drop %H\n", o->hash);
|
||||
e = emalloc(sizeof(Objq));
|
||||
e->o = o;
|
||||
e->color = Drop;
|
||||
*p = e;
|
||||
p = &e->next;
|
||||
qput(&objq, o, Drop, 0);
|
||||
unref(o);
|
||||
}
|
||||
|
||||
dprint(1, "finding twixt commits\n");
|
||||
while(q != nil){
|
||||
if(oshas(&drop, q->o->hash))
|
||||
while(qpop(&objq, &e)){
|
||||
if(oshas(&drop, e.o->hash))
|
||||
ncolor = Drop;
|
||||
else if(oshas(&keep, q->o->hash))
|
||||
else if(oshas(&keep, e.o->hash))
|
||||
ncolor = Keep;
|
||||
else
|
||||
ncolor = Blank;
|
||||
if(ncolor == Drop || ncolor == Keep && q->color == Keep)
|
||||
goto next;
|
||||
if(ncolor == Keep && q->color == Drop){
|
||||
if(repaint(&keep, &drop, q->o) == -1)
|
||||
if(ancestor && pickbest(&objq, &e, ncolor))
|
||||
goto exactlca;
|
||||
if(ncolor == Keep && e.color == Keep || ncolor == Drop)
|
||||
continue;
|
||||
if(ncolor == Keep && e.color == Drop){
|
||||
if(repaint(&objq, &keep, &drop, e.o, e.dist, ancestor) == -1)
|
||||
goto error;
|
||||
}else if (ncolor == Blank) {
|
||||
dprint(2, "visit: %s %H\n", q->color == Keep ? "keep" : "drop", q->o->hash);
|
||||
if(q->color == Keep)
|
||||
osadd(&keep, q->o);
|
||||
if(e.color == Keep)
|
||||
osadd(&keep, e.o);
|
||||
else
|
||||
osadd(&drop, q->o);
|
||||
for(i = 0; i < q->o->commit->nparent; i++){
|
||||
if((c = readobject(q->o->commit->parent[i])) == nil)
|
||||
osadd(&drop, e.o);
|
||||
o = readobject(e.o->hash);
|
||||
for(i = 0; i < o->commit->nparent; i++){
|
||||
if((c = readobject(e.o->commit->parent[i])) == nil)
|
||||
goto error;
|
||||
if(c->type != GCommit){
|
||||
fprint(2, "warning: %H does not point at commit\n", c->hash);
|
||||
unref(c);
|
||||
continue;
|
||||
}
|
||||
dprint(2, "enqueue: %s %H\n", q->color == Keep ? "keep" : "drop", c->hash);
|
||||
n = emalloc(sizeof(Objq));
|
||||
n->color = q->color;
|
||||
n->next = nil;
|
||||
n->o = c;
|
||||
e->next = n;
|
||||
e = n;
|
||||
dprint(2, "\tenqueue: %s %H\n", colors[e.color], c->hash);
|
||||
qput(&objq, c, e.color, e.dist+1);
|
||||
unref(c);
|
||||
}
|
||||
}else{
|
||||
sysfatal("oops");
|
||||
unref(o);
|
||||
}
|
||||
next:
|
||||
n = q->next;
|
||||
free(q);
|
||||
q = n;
|
||||
}
|
||||
*res = eamalloc(keep.nobj, sizeof(Object*));
|
||||
*nres = 0;
|
||||
for(i = 0; i < keep.sz; i++){
|
||||
if(keep.obj[i] != nil && !oshas(&drop, keep.obj[i]->hash)){
|
||||
(*res)[*nres] = keep.obj[i];
|
||||
(*nres)++;
|
||||
exactlca:
|
||||
if(ancestor){
|
||||
dprint(1, "found ancestor\n");
|
||||
if(objq.best == nil){
|
||||
*nres = 0;
|
||||
*res = nil;
|
||||
}else{
|
||||
*nres = 1;
|
||||
*res = eamalloc(1, sizeof(Object*));
|
||||
(*res)[0] = objq.best;
|
||||
}
|
||||
}else{
|
||||
dprint(1, "found twixt\n");
|
||||
*res = eamalloc(keep.nobj, sizeof(Object*));
|
||||
*nres = 0;
|
||||
for(i = 0; i < keep.sz; i++){
|
||||
if(keep.obj[i] != nil && !oshas(&drop, keep.obj[i]->hash)){
|
||||
(*res)[*nres] = keep.obj[i];
|
||||
(*nres)++;
|
||||
}
|
||||
}
|
||||
}
|
||||
osclear(&keep);
|
||||
osclear(&drop);
|
||||
return 0;
|
||||
error:
|
||||
for(; q != nil; q = n) {
|
||||
n = q->next;
|
||||
free(q);
|
||||
}
|
||||
dprint(1, "twixt error: %r\n");
|
||||
free(objq.heap);
|
||||
return -1;
|
||||
}
|
||||
|
||||
int
|
||||
findtwixt(Hash *head, int nhead, Hash *tail, int ntail, Object ***res, int *nres)
|
||||
{
|
||||
return paint(head, nhead, tail, ntail, res, nres, 0);
|
||||
}
|
||||
|
||||
Object*
|
||||
ancestor(Object *a, Object *b)
|
||||
{
|
||||
Object **o, *r;
|
||||
int n;
|
||||
|
||||
if(paint(&a->hash, 1, &b->hash, 1, &o, &n, 1) == -1 || n == 0)
|
||||
return nil;
|
||||
r = o[0];
|
||||
free(o);
|
||||
return ref(r);
|
||||
}
|
||||
|
||||
int
|
||||
lca(Eval *ev)
|
||||
{
|
||||
Object *a, *b, **o;
|
||||
int n;
|
||||
|
||||
if(ev->nstk < 2){
|
||||
werrstr("ancestor needs 2 objects");
|
||||
return -1;
|
||||
}
|
||||
n = 0;
|
||||
b = pop(ev);
|
||||
a = pop(ev);
|
||||
paint(&a->hash, 1, &b->hash, 1, &o, &n, 1);
|
||||
if(n == 0)
|
||||
return -1;
|
||||
push(ev, *o);
|
||||
free(o);
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int
|
||||
parent(Eval *ev)
|
||||
{
|
||||
|
|
|
|||
|
|
@ -321,3 +321,74 @@ showprogress(int x, int pct)
|
|||
}
|
||||
return pct;
|
||||
}
|
||||
|
||||
void
|
||||
qinit(Objq *q)
|
||||
{
|
||||
memset(q, 0, sizeof(Objq));
|
||||
q->nheap = 0;
|
||||
q->heapsz = 8;
|
||||
q->heap = eamalloc(q->heapsz, sizeof(Qelt));
|
||||
}
|
||||
|
||||
void
|
||||
qclear(Objq *q)
|
||||
{
|
||||
free(q->heap);
|
||||
}
|
||||
|
||||
void
|
||||
qput(Objq *q, Object *o, int color, int dist)
|
||||
{
|
||||
Qelt t;
|
||||
int i;
|
||||
|
||||
if(q->nheap == q->heapsz){
|
||||
q->heapsz *= 2;
|
||||
q->heap = earealloc(q->heap, q->heapsz, sizeof(Qelt));
|
||||
}
|
||||
q->heap[q->nheap].o = o;
|
||||
q->heap[q->nheap].color = color;
|
||||
q->heap[q->nheap].dist = dist;
|
||||
q->heap[q->nheap].mtime = o->commit->mtime;
|
||||
for(i = q->nheap; i > 0; i = (i-1)/2){
|
||||
if(q->heap[i].mtime < q->heap[(i-1)/2].mtime)
|
||||
break;
|
||||
t = q->heap[i];
|
||||
q->heap[i] = q->heap[(i-1)/2];
|
||||
q->heap[(i-1)/2] = t;
|
||||
}
|
||||
q->nheap++;
|
||||
}
|
||||
|
||||
int
|
||||
qpop(Objq *q, Qelt *e)
|
||||
{
|
||||
int i, l, r, m;
|
||||
Qelt t;
|
||||
|
||||
if(q->nheap == 0)
|
||||
return 0;
|
||||
*e = q->heap[0];
|
||||
if(--q->nheap == 0)
|
||||
return 1;
|
||||
|
||||
i = 0;
|
||||
q->heap[0] = q->heap[q->nheap];
|
||||
while(1){
|
||||
m = i;
|
||||
l = 2*i+1;
|
||||
r = 2*i+2;
|
||||
if(l < q->nheap && q->heap[m].mtime < q->heap[l].mtime)
|
||||
m = l;
|
||||
if(r < q->nheap && q->heap[m].mtime < q->heap[r].mtime)
|
||||
m = r;
|
||||
if(m == i)
|
||||
break;
|
||||
t = q->heap[m];
|
||||
q->heap[m] = q->heap[i];
|
||||
q->heap[i] = t;
|
||||
i = m;
|
||||
}
|
||||
return 1;
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in a new issue