sortbydeps: include local pkgs in dep graph

Detecting indirect dependencies by traversing a package's entire
dependency tree is prohibitively slow for larger transactions.  Instead
add local packages to the dependency graph.  This additionally requires
delaying dependency ordering for sync operations so that removed
packages may be excluded from dependency detection.

tests/sync012.py was also updated to ensure that the dependency cycle
was actually detected.

Fixes FS#37380

Signed-off-by: Andrew Gregory <andrew.gregory.8@gmail.com>
Signed-off-by: Allan McRae <allan@archlinux.org>

4 files changed, 80 insertions, 89 deletions

diff --git a/lib/libalpm/deps.c b/lib/libalpm/deps.c
index cf7605ee..9761b2cb 100644
--- a/lib/libalpm/deps.c
+++ b/lib/libalpm/deps.c
@@ -90,69 +90,9 @@ static alpm_pkg_t *find_dep_satisfier(alpm_list_t *pkgs, alpm_depend_t *dep)
 	return NULL;
 }
 
-/** Check if pkg2 is anywhere in pkg1's dependency tree.
- * @param pkg1
- * @param pkg2
- * @param targets if a package in this list is an intermediate dependency
- *        between pkg1 and pkg2, the pkg1 -> pkg2 dependency will not be
- *        reported
- * @param ignore packages which should not be recursively checked for
- *        intermediate dependencies.  Used internally for state to avoid
- *        getting stuck on cyclic dependencies.
- * @return 1 if pkg2 is found in pkg1's dependency tree
- */
-static int _alpm_pkg_in_dep_tree(alpm_pkg_t *pkg1, alpm_pkg_t *pkg2,
-		alpm_list_t *targets, alpm_list_t **ignore)
-{
-	alpm_list_t *i, *pkgs = alpm_db_get_pkgcache(pkg1->handle->db_local);
-
-	if(_alpm_pkg_depends_on(pkg1, pkg2)) {
-		return 1;
-	}
-
-	*ignore = alpm_list_add(*ignore, pkg1);
-
-	 /* pkg1 does not directly depend on pkg2, but if this is an upgrade
-		* operation there may be an indirect dependency through an installed
-		* dependency not part of the current transaction */
-	for(i = alpm_pkg_get_depends(pkg1); i; i = i->next) {
-		alpm_depend_t *dep = i->data;
-		alpm_pkg_t *lpkg = find_dep_satisfier(pkgs, dep);
-
-		if(!lpkg) {
-			continue;
-		} else if(alpm_list_find(targets, lpkg, _alpm_pkg_cmp)) {
-			/* lpkg's upgrade is part of the transaction, any dependency will be
-			 * detected separately as pkg1 -> lpkg and lpkg -> pkg2 */
-			continue;
-		} else if(alpm_list_find(*ignore, lpkg, _alpm_pkg_cmp)) {
-			/* we've already checked lpkg, move on */
-			continue;
-		} else if(_alpm_pkg_in_dep_tree(lpkg, pkg2, targets, ignore)) {
-			/* we have an indirect dependency: pkg1 -> lpkg -> ... -> pkg2 */
-			return 1;
-		}
-	}
-
-	return 0;
-}
-
-/** Check if pkg2 is anywhere in pkg1's dependency tree.
- * Wrapper for _alpm_pkg_in_dep_tree to handle creating and destroying state.
- * @param pkg1
- * @param pkg2
- * @param targets if a package in this list is an intermediate dependency
- *        between pkg1 and pkg2, the pkg1 -> pkg2 dependency will not be
- *        reported
- * @return 1 if pkg2 is found in pkg1's dependency tree
- */
-static int _alpm_dep_edge(alpm_pkg_t *pkg1, alpm_pkg_t *pkg2,
-		alpm_list_t *targets)
+static int ptr_cmp(const void *p, const void *q)
 {
-	alpm_list_t *ignore = NULL;
-	int ret = _alpm_pkg_in_dep_tree(pkg1, pkg2, targets, &ignore);
-	alpm_list_free(ignore);
-	return ret;
+	return (p != q);
 }
 
 /* Convert a list of alpm_pkg_t * to a graph structure,
@@ -160,10 +100,14 @@ static int _alpm_dep_edge(alpm_pkg_t *pkg1, alpm_pkg_t *pkg2,
  * Returns a list of vertices (one vertex = one package)
  * (used by alpm_sortbydeps)
  */
-static alpm_list_t *dep_graph_init(alpm_list_t *targets)
+static alpm_list_t *dep_graph_init(alpm_handle_t *handle,
+		alpm_list_t *targets, alpm_list_t *ignore)
 {
 	alpm_list_t *i, *j;
 	alpm_list_t *vertices = NULL;
+	alpm_list_t *localpkgs = alpm_list_diff(
+			alpm_db_get_pkgcache(handle->db_local), ignore, ptr_cmp);
+
 	/* We create the vertices */
 	for(i = targets; i; i = i->next) {
 		alpm_graph_t *vertex = _alpm_graph_new();
@@ -179,13 +123,32 @@ static alpm_list_t *dep_graph_init(alpm_list_t *targets)
 		for(j = vertices; j; j = j->next) {
 			alpm_graph_t *vertex_j = j->data;
 			alpm_pkg_t *p_j = vertex_j->data;
-			if(_alpm_dep_edge(p_i, p_j, targets)) {
+			if(_alpm_pkg_depends_on(p_i, p_j)) {
+				vertex_i->children =
+					alpm_list_add(vertex_i->children, vertex_j);
+			}
+		}
+
+		/* lazily add local packages to the dep graph so they don't
+		 * get resolved unnecessarily */
+		j = localpkgs;
+		while(j) {
+			alpm_list_t *next = j->next;
+			if(_alpm_pkg_depends_on(p_i, j->data)) {
+				alpm_graph_t *vertex_j = _alpm_graph_new();
+				vertex_j->data = (void *)j->data;
+				vertices = alpm_list_add(vertices, vertex_j);
 				vertex_i->children =
 					alpm_list_add(vertex_i->children, vertex_j);
+				localpkgs = alpm_list_remove_item(localpkgs, j);
+				free(j);
 			}
+			j = next;
 		}
+
 		vertex_i->childptr = vertex_i->children;
 	}
+	alpm_list_free(localpkgs);
 	return vertices;
 }
 
@@ -198,13 +161,15 @@ static alpm_list_t *dep_graph_init(alpm_list_t *targets)
  *
  *   Should be re-ordered to C,A,B,D
  *
+ * packages listed in ignore will not be used to detect indirect dependencies
+ *
  * if reverse is > 0, the dependency order will be reversed.
  *
  * This function returns the new alpm_list_t* target list.
  *
  */
 alpm_list_t *_alpm_sortbydeps(alpm_handle_t *handle,
-		alpm_list_t *targets, int reverse)
+		alpm_list_t *targets, alpm_list_t *ignore, int reverse)
 {
 	alpm_list_t *newtargs = NULL;
 	alpm_list_t *vertices = NULL;
@@ -217,7 +182,7 @@ alpm_list_t *_alpm_sortbydeps(alpm_handle_t *handle,
 
 	_alpm_log(handle, ALPM_LOG_DEBUG, "started sorting dependencies\n");
 
-	vertices = dep_graph_init(targets);
+	vertices = dep_graph_init(handle, targets, ignore);
 
 	vptr = vertices;
 	vertex = vertices->data;
@@ -232,34 +197,56 @@ alpm_list_t *_alpm_sortbydeps(alpm_handle_t *handle,
 				found = 1;
 				nextchild->parent = vertex;
 				vertex = nextchild;
-			}
-			else if(nextchild->state == -1) {
-				alpm_pkg_t *vertexpkg = vertex->data;
-				alpm_pkg_t *childpkg = nextchild->data;
-
-				_alpm_log(handle, ALPM_LOG_WARNING, _("dependency cycle detected:\n"));
-				if(reverse) {
-					_alpm_log(handle, ALPM_LOG_WARNING,
-							_("%s will be removed after its %s dependency\n"),
-							vertexpkg->name, childpkg->name);
+			} else if(nextchild->state == -1) {
+				/* child is an ancestor of vertex */
+				alpm_graph_t *transvertex = vertex;
+
+				if(!alpm_list_find(targets, nextchild->data, ptr_cmp)) {
+					/* child is not part of the transaction, not a problem */
+					continue;
+				}
+
+				/* find the nearest parent that's part of the transaction */
+				while(transvertex) {
+					if(alpm_list_find(targets, transvertex->data, ptr_cmp)) {
+						break;
+					}
+					transvertex = transvertex->parent;
+				}
+
+				if(!transvertex || transvertex == nextchild) {
+					/* no transaction package in our ancestry or the package has
+					 * a circular dependency with itself, not a problem */
 				} else {
-					_alpm_log(handle, ALPM_LOG_WARNING,
-							_("%s will be installed before its %s dependency\n"),
-							vertexpkg->name, childpkg->name);
+					alpm_pkg_t *transpkg = transvertex->data;
+					alpm_pkg_t *childpkg = nextchild->data;
+					_alpm_log(handle, ALPM_LOG_WARNING, _("dependency cycle detected:\n"));
+					if(reverse) {
+						_alpm_log(handle, ALPM_LOG_WARNING,
+								_("%s will be removed after its %s dependency\n"),
+								transpkg->name, childpkg->name);
+					} else {
+						_alpm_log(handle, ALPM_LOG_WARNING,
+								_("%s will be installed before its %s dependency\n"),
+								transpkg->name, childpkg->name);
+					}
 				}
 			}
 		}
 		if(!found) {
-			newtargs = alpm_list_add(newtargs, vertex->data);
+			if(alpm_list_find(targets, vertex->data, ptr_cmp)) {
+				newtargs = alpm_list_add(newtargs, vertex->data);
+			}
 			/* mark that we've left this vertex */
 			vertex->state = 1;
 			vertex = vertex->parent;
 			if(!vertex) {
-				vptr = vptr->next;
-				while(vptr) {
+				/* top level vertex reached, move to the next unprocessed vertex */
+				for( vptr = vptr->next; vptr; vptr = vptr->next) {
 					vertex = vptr->data;
-					if(vertex->state == 0) break;
-					vptr = vptr->next;
+					if(vertex->state == 0) {
+						break;
+					}
 				}
 			}
 		}
diff --git a/lib/libalpm/deps.h b/lib/libalpm/deps.h
index 1fbeff95..8cf5ad22 100644
--- a/lib/libalpm/deps.h
+++ b/lib/libalpm/deps.h
@@ -30,7 +30,8 @@
 void _alpm_dep_free(alpm_depend_t *dep);
 alpm_depend_t *_alpm_dep_dup(const alpm_depend_t *dep);
 void _alpm_depmiss_free(alpm_depmissing_t *miss);
-alpm_list_t *_alpm_sortbydeps(alpm_handle_t *handle, alpm_list_t *targets, int reverse);
+alpm_list_t *_alpm_sortbydeps(alpm_handle_t *handle,
+		alpm_list_t *targets, alpm_list_t *ignore, int reverse);
 int _alpm_recursedeps(alpm_db_t *db, alpm_list_t *targs, int include_explicit);
 int _alpm_resolvedeps(alpm_handle_t *handle, alpm_list_t *localpkgs, alpm_pkg_t *pkg,
 		alpm_list_t *preferred, alpm_list_t **packages, alpm_list_t *remove,
diff --git a/lib/libalpm/remove.c b/lib/libalpm/remove.c
index 7cb86ff6..2e728521 100644
--- a/lib/libalpm/remove.c
+++ b/lib/libalpm/remove.c
@@ -242,7 +242,7 @@ int _alpm_remove_prepare(alpm_handle_t *handle, alpm_list_t **data)
 
 	/* re-order w.r.t. dependencies */
 	_alpm_log(handle, ALPM_LOG_DEBUG, "sorting by dependencies\n");
-	lp = _alpm_sortbydeps(handle, trans->remove, 1);
+	lp = _alpm_sortbydeps(handle, trans->remove, NULL, 1);
 	/* free the old alltargs */
 	alpm_list_free(trans->remove);
 	trans->remove = lp;
diff --git a/lib/libalpm/sync.c b/lib/libalpm/sync.c
index 066f1f22..551f9269 100644
--- a/lib/libalpm/sync.c
+++ b/lib/libalpm/sync.c
@@ -471,10 +471,8 @@ int _alpm_sync_prepare(alpm_handle_t *handle, alpm_list_t **data)
 		 * holds to package objects. */
 		trans->unresolvable = unresolvable;
 
-		/* re-order w.r.t. dependencies */
 		alpm_list_free(trans->add);
-		trans->add = _alpm_sortbydeps(handle, resolved, 0);
-		alpm_list_free(resolved);
+		trans->add = resolved;
 
 		EVENT(handle, ALPM_EVENT_RESOLVEDEPS_DONE, NULL, NULL);
 	}
@@ -628,6 +626,11 @@ int _alpm_sync_prepare(alpm_handle_t *handle, alpm_list_t **data)
 			}
 			goto cleanup;
 		}
+
+		/* re-order w.r.t. dependencies */
+		alpm_list_t *add_orig = trans->add;
+		trans->add = _alpm_sortbydeps(handle, add_orig, trans->remove, 0);
+		alpm_list_free(add_orig);
 	}
 	for(i = trans->add; i; i = i->next) {
 		/* update download size field */