/*
* Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/queue.h>
#include <sys/stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sha1.h>
#include <zlib.h>
#include <ctype.h>
#include "got_error.h"
#include "got_object.h"
#include "got_commit_graph.h"
#include "got_lib_delta.h"
#include "got_lib_inflate.h"
#include "got_lib_object.h"
#include "got_lib_object_idset.h"
#include "got_lib_path.h"
struct got_commit_graph_node {
struct got_object_id id;
/*
* Each graph node corresponds to a commit object.
* Graph vertices are modelled with an adjacency list.
* Adjacencies of a graph node are parent (older) commits.
*/
int nparents;
struct got_object_id_queue parent_ids;
time_t commit_timestamp;
/* Used during graph iteration. */
TAILQ_ENTRY(got_commit_graph_node) entry;
};
TAILQ_HEAD(got_commit_graph_iter_list, got_commit_graph_node);
struct got_commit_graph_branch_tip {
struct got_object_id id;
struct got_commit_graph_node *node;
};
struct got_commit_graph {
/* The set of all commits we have traversed. */
struct got_object_idset *node_ids;
/* The commit at which traversal began (youngest commit in node_ids). */
struct got_commit_graph_node *head_node;
int flags;
#define GOT_COMMIT_GRAPH_FIRST_PARENT_TRAVERSAL 0x01
/*
* A set of object IDs of known parent commits which we have not yet
* traversed. Each commit ID in this set represents a branch in commit
* history: Either the first-parent branch of the head node, or another
* branch corresponding to a traversed merge commit for which we have
* not traversed a branch point commit yet.
*
* Whenever we add a commit with a matching ID to the graph, we remove
* its corresponding element from this set, and add new elements for
* each of that commit's parent commits which were not traversed yet.
*
* When API users ask us to fetch more commits, we fetch commits from
* all currently open branches. This allows API users to process
* commits in linear order even though the history contains branches.
*/
struct got_object_idset *open_branches;
/* Copy of known branch tips for fetch_commits_from_open_branches(). */
struct got_commit_graph_branch_tip *tips;
size_t ntips;
#define GOT_COMMIT_GRAPH_MIN_TIPS 10 /* minimum amount of tips to allocate */
/* Path of tree entry of interest to the API user. */
char *path;
/* The next commit to return when the API user asks for one. */
struct got_commit_graph_node *iter_node;
/* The graph iteration list contains all nodes in sorted order. */
struct got_commit_graph_iter_list iter_list;
};
static struct got_commit_graph *
alloc_graph(const char *path)
{
struct got_commit_graph *graph;
graph = calloc(1, sizeof(*graph));
if (graph == NULL)
return NULL;
graph->path = strdup(path);
if (graph->path == NULL) {
free(graph);
return NULL;
}
graph->node_ids = got_object_idset_alloc();
if (graph->node_ids == NULL) {
free(graph->path);
free(graph);
return NULL;
}
graph->open_branches = got_object_idset_alloc();
if (graph->open_branches == NULL) {
got_object_idset_free(graph->node_ids);
free(graph->path);
free(graph);
return NULL;
}
TAILQ_INIT(&graph->iter_list);
return graph;
}
#if 0
static int
is_head_node(struct got_commit_graph_node *node)
{
return node->nchildren == 0;
}
int
is_branch_point(struct got_commit_graph_node *node)
{
return node->nchildren > 1;
}
static int
is_root_node(struct got_commit_graph_node *node)
{
return node->nparents == 0;
}
#endif
static int
is_merge_point(struct got_commit_graph_node *node)
{
return node->nparents > 1;
}
static const struct got_error *
detect_changed_path(int *changed, struct got_commit_object *commit,
struct got_object_id *commit_id, const char *path,
struct got_repository *repo)
{
const struct got_error *err = NULL;
struct got_commit_object *pcommit = NULL;
struct got_tree_object *tree = NULL, *ptree = NULL;
struct got_object_qid *pid;
if (got_path_is_root_dir(path)) {
*changed = 1;
return NULL;
}
*changed = 0;
err = got_object_open_as_tree(&tree, repo, commit->tree_id);
if (err)
return err;
pid = SIMPLEQ_FIRST(&commit->parent_ids);
if (pid == NULL) {
struct got_object_id *obj_id;
err = got_object_id_by_path(&obj_id, repo, commit_id, path);
if (err)
err = NULL;
else
*changed = 1;
free(obj_id);
goto done;
}
err = got_object_open_as_commit(&pcommit, repo, pid->id);
if (err)
goto done;
err = got_object_open_as_tree(&ptree, repo, pcommit->tree_id);
if (err)
goto done;
err = got_object_tree_path_changed(changed, tree, ptree, path, repo);
done:
if (tree)
got_object_tree_close(tree);
if (ptree)
got_object_tree_close(ptree);
if (pcommit)
got_object_commit_close(pcommit);
return err;
}
static void
add_node_to_iter_list(struct got_commit_graph *graph,
struct got_commit_graph_node *node,
struct got_commit_graph_node *child_node)
{
struct got_commit_graph_node *n, *next;
if (TAILQ_EMPTY(&graph->iter_list)) {
TAILQ_INSERT_HEAD(&graph->iter_list, node, entry);
graph->iter_node = node;
return;
}
n = graph->iter_node;
/* Ensure that an iteration in progress will see this new commit. */
while (n) {
next = TAILQ_NEXT(n, entry);
if (next && node->commit_timestamp >= next->commit_timestamp) {
TAILQ_INSERT_BEFORE(next, node, entry);
return;
}
n = next;
}
TAILQ_INSERT_TAIL(&graph->iter_list, node, entry);
}
static const struct got_error *
add_vertex(struct got_object_id_queue *ids, struct got_object_id *id)
{
struct got_object_qid *qid;
qid = calloc(1, sizeof(*qid));
if (qid == NULL)
return got_error_from_errno();
qid->id = got_object_id_dup(id);
if (qid->id == NULL) {
const struct got_error *err = got_error_from_errno();
got_object_qid_free(qid);
return err;
}
SIMPLEQ_INSERT_TAIL(ids, qid, entry);
return NULL;
}
static const struct got_error *
close_branch(struct got_commit_graph *graph, struct got_object_id *commit_id)
{
const struct got_error *err;
err = got_object_idset_remove(NULL, graph->open_branches, commit_id);
if (err && err->code != GOT_ERR_NO_OBJ)
return err;
return NULL;
}
static const struct got_error *
advance_branch(struct got_commit_graph *graph,
struct got_commit_graph_node *node,
struct got_object_id *commit_id, struct got_commit_object *commit,
struct got_repository *repo)
{
const struct got_error *err;
struct got_object_qid *qid;
err = close_branch(graph, commit_id);
if (err)
return err;
if (graph->flags & GOT_COMMIT_GRAPH_FIRST_PARENT_TRAVERSAL) {
qid = SIMPLEQ_FIRST(&commit->parent_ids);
if (qid == NULL)
return NULL;
err = got_object_idset_add(NULL, graph->open_branches, qid->id,
node);
if (err && err->code != GOT_ERR_OBJ_EXISTS)
return err;
return NULL;
}
/*
* If we are graphing commits for a specific path, skip branches
* which do not contribute any content to this path.
*/
if (is_merge_point(node) && !got_path_is_root_dir(graph->path)) {
struct got_object_id *id, *merged_id, *prev_id = NULL;
int branches_differ = 0;
err = got_object_id_by_path(&merged_id, repo, commit_id,
graph->path);
if (err)
return err;
SIMPLEQ_FOREACH(qid, &commit->parent_ids, entry) {
if (got_object_idset_get(graph->node_ids, qid->id))
continue; /* parent already traversed */
err = got_object_id_by_path(&id, repo, qid->id,
graph->path);
if (err) {
if (err->code == GOT_ERR_NO_OBJ) {
branches_differ = 1;
continue;
}
return err;
}
if (prev_id) {
if (!branches_differ &&
got_object_id_cmp(merged_id, prev_id) != 0)
branches_differ = 1;
} else
prev_id = id;
/*
* If a branch has created the merged content we can
* skip any other branches.
*/
if (got_object_id_cmp(merged_id, id) == 0) {
err = got_object_idset_add(NULL,
graph->open_branches, qid->id, node);
if (err && err->code != GOT_ERR_OBJ_EXISTS)
return err;
return NULL;
}
}
/*
* If the path's content is the same on all branches,
* follow the first parent only.
*/
if (!branches_differ) {
qid = SIMPLEQ_FIRST(&commit->parent_ids);
if (qid == NULL)
return NULL;
if (got_object_idset_get(graph->node_ids, qid->id))
return NULL; /* parent already traversed */
err = got_object_idset_add(NULL,
graph->open_branches, qid->id, node);
if (err && err->code != GOT_ERR_OBJ_EXISTS)
return err;
return NULL;
}
}
SIMPLEQ_FOREACH(qid, &commit->parent_ids, entry) {
if (got_object_idset_get(graph->node_ids, qid->id))
continue; /* parent already traversed */
err = got_object_idset_add(NULL, graph->open_branches,
qid->id, node);
if (err && err->code != GOT_ERR_OBJ_EXISTS)
return err;
}
return NULL;
}
static void
free_node(struct got_commit_graph_node *node)
{
while (!SIMPLEQ_EMPTY(&node->parent_ids)) {
struct got_object_qid *pid = SIMPLEQ_FIRST(&node->parent_ids);
SIMPLEQ_REMOVE_HEAD(&node->parent_ids, entry);
got_object_qid_free(pid);
}
free(node);
}
static const struct got_error *
add_node(struct got_commit_graph_node **new_node,
struct got_commit_graph *graph, struct got_object_id *commit_id,
struct got_commit_object *commit, struct got_commit_graph_node *child_node,
struct got_repository *repo)
{
const struct got_error *err = NULL;
struct got_commit_graph_node *node;
struct got_object_qid *pid;
int changed = 0, branch_done = 0;
*new_node = NULL;
node = calloc(1, sizeof(*node));
if (node == NULL)
return got_error_from_errno();
memcpy(&node->id, commit_id, sizeof(node->id));
SIMPLEQ_INIT(&node->parent_ids);
SIMPLEQ_FOREACH(pid, &commit->parent_ids, entry) {
err = add_vertex(&node->parent_ids, pid->id);
if (err) {
free_node(node);
return err;
}
node->nparents++;
}
err = got_object_idset_add(NULL, graph->node_ids, &node->id, node);
if (err) {
if (err->code == GOT_ERR_OBJ_EXISTS)
err = NULL;
free_node(node);
return err;
}
err = detect_changed_path(&changed, commit, commit_id, graph->path,
repo);
if (err) {
if (err->code == GOT_ERR_NO_OBJ) {
/*
* History of the path stops here on the current
* branch. Keep going on other branches.
*/
err = NULL;
branch_done = 1;
} else {
free_node(node);
return err;
}
}
node->commit_timestamp = mktime(&commit->tm_committer);
if (node->commit_timestamp == -1) {
free_node(node);
return got_error_from_errno();
}
if (changed)
add_node_to_iter_list(graph, node, child_node);
if (branch_done)
err = close_branch(graph, commit_id);
else
err = advance_branch(graph, node, commit_id, commit, repo);
if (err)
free_node(node);
else
*new_node = node;
return err;
}
const struct got_error *
got_commit_graph_open(struct got_commit_graph **graph,
struct got_object_id *commit_id, const char *path,
int first_parent_traversal, struct got_repository *repo)
{
const struct got_error *err = NULL;
struct got_commit_object *commit;
*graph = NULL;
err = got_object_open_as_commit(&commit, repo, commit_id);
if (err)
return err;
/* The path must exist in our initial commit. */
if (!got_path_is_root_dir(path)) {
struct got_object_id *obj_id;
err = got_object_id_by_path(&obj_id, repo, commit_id, path);
if (err)
return err;
free(obj_id);
}
*graph = alloc_graph(path);
if (*graph == NULL) {
got_object_commit_close(commit);
return got_error_from_errno();
}
if (first_parent_traversal)
(*graph)->flags |= GOT_COMMIT_GRAPH_FIRST_PARENT_TRAVERSAL;
err = add_node(&(*graph)->head_node, *graph, commit_id, commit, NULL,
repo);
got_object_commit_close(commit);
if (err) {
got_commit_graph_close(*graph);
*graph = NULL;
return err;
}
return NULL;
}
struct gather_branch_tips_arg {
struct got_commit_graph_branch_tip *tips;
int ntips;
};
static void
gather_branch_tips(struct got_object_id *id, void *data, void *arg)
{
struct gather_branch_tips_arg *a = arg;
memcpy(&a->tips[a->ntips].id, id, sizeof(*id));
a->tips[a->ntips].node = data;
a->ntips++;
}
static const struct got_error *
fetch_commits_from_open_branches(int *ncommits,
struct got_object_id **changed_id, struct got_commit_graph *graph,
struct got_repository *repo)
{
const struct got_error *err;
struct gather_branch_tips_arg arg;
int i;
*ncommits = 0;
if (changed_id)
*changed_id = NULL;
arg.ntips = got_object_idset_num_elements(graph->open_branches);
if (arg.ntips == 0)
return NULL;
/*
* Adding nodes to the graph might change the graph's open
* branches state. Create a local copy of the current state.
*/
if (graph->ntips < arg.ntips) {
struct got_commit_graph_branch_tip *tips;
if (arg.ntips < GOT_COMMIT_GRAPH_MIN_TIPS)
arg.ntips = GOT_COMMIT_GRAPH_MIN_TIPS;
tips = reallocarray(graph->tips, arg.ntips, sizeof(*tips));
if (tips == NULL)
return got_error_from_errno();
graph->tips = tips;
graph->ntips = arg.ntips;
}
arg.ntips = 0; /* reset; gather_branch_tips() will increment */
arg.tips = graph->tips;
got_object_idset_for_each(graph->open_branches,
gather_branch_tips, &arg);
for (i = 0; i < arg.ntips; i++) {
struct got_object_id *commit_id;
struct got_commit_graph_node *child_node, *new_node;
struct got_commit_object *commit;
int changed;
commit_id = &graph->tips[i].id;
child_node = graph->tips[i].node;
err = got_object_open_as_commit(&commit, repo, commit_id);
if (err)
break;
err = detect_changed_path(&changed, commit, commit_id,
graph->path, repo);
if (err) {
got_object_commit_close(commit);
if (err->code != GOT_ERR_NO_OBJ)
break;
err = close_branch(graph, commit_id);
if (err)
break;
continue;
}
if (changed && changed_id && *changed_id == NULL)
*changed_id = commit_id;
err = add_node(&new_node, graph, commit_id, commit, child_node,
repo);
got_object_commit_close(commit);
if (err)
break;
if (new_node)
(*ncommits)++;
}
return err;
}
const struct got_error *
got_commit_graph_fetch_commits(struct got_commit_graph *graph, int limit,
struct got_repository *repo)
{
const struct got_error *err;
int nfetched = 0, ncommits;
struct got_object_id *changed_id = NULL;
while (nfetched < limit) {
err = fetch_commits_from_open_branches(&ncommits,
&changed_id, graph, repo);
if (err)
return err;
if (ncommits == 0)
break;
if (changed_id)
nfetched += ncommits;
}
return NULL;
}
static void
free_node_iter(struct got_object_id *id, void *data, void *arg)
{
struct got_commit_graph_node *node = data;
free_node(node);
}
void
got_commit_graph_close(struct got_commit_graph *graph)
{
got_object_idset_free(graph->open_branches);
got_object_idset_for_each(graph->node_ids, free_node_iter, NULL);
got_object_idset_free(graph->node_ids);
free(graph->tips);
free(graph->path);
free(graph);
}
const struct got_error *
got_commit_graph_iter_start(struct got_commit_graph *graph,
struct got_object_id *id, struct got_repository *repo)
{
const struct got_error *err = NULL;
struct got_commit_graph_node *start_node;
struct got_commit_object *commit;
int changed;
start_node = got_object_idset_get(graph->node_ids, id);
if (start_node == NULL)
return got_error(GOT_ERR_NO_OBJ);
err = got_object_open_as_commit(&commit, repo, &start_node->id);
if (err)
return err;
err = detect_changed_path(&changed, commit, &start_node->id,
graph->path, repo);
if (err) {
got_object_commit_close(commit);
return err;
}
if (!changed) {
/* Locate first commit which changed graph->path. */
struct got_object_id *changed_id = NULL;
while (changed_id == NULL) {
int ncommits;
err = fetch_commits_from_open_branches(&ncommits,
&changed_id, graph, repo);
if (err) {
got_object_commit_close(commit);
return err;
}
}
start_node = got_object_idset_get(graph->node_ids, changed_id);
}
got_object_commit_close(commit);
graph->iter_node = start_node;
return NULL;
}
const struct got_error *
got_commit_graph_iter_next(struct got_object_id **id,
struct got_commit_graph *graph)
{
*id = NULL;
if (graph->iter_node == NULL) {
/* We are done iterating, or iteration was not started. */
return got_error(GOT_ERR_ITER_COMPLETED);
}
if (graph->iter_node ==
TAILQ_LAST(&graph->iter_list, got_commit_graph_iter_list) &&
got_object_idset_num_elements(graph->open_branches) == 0) {
/* We are done iterating. */
*id = &graph->iter_node->id;
graph->iter_node = NULL;
return NULL;
}
if (TAILQ_NEXT(graph->iter_node, entry) == NULL)
return got_error(GOT_ERR_ITER_NEED_MORE);
*id = &graph->iter_node->id;
graph->iter_node = TAILQ_NEXT(graph->iter_node, entry);
return NULL;
}
