/*
* 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"
struct got_commit_graph_node {
struct got_object_id id;
/*
* Each graph node corresponds to a commit object.
* Graph vertices are modelled with two separate adjacency lists:
* Adjacencies of a graph node are either parent (older) commits,
* and child (younger) commits.
*/
int nparents;
struct got_object_id_queue parent_ids;
int nchildren;
struct got_object_id_queue child_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 {
/* 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;
/* 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(void)
{
struct got_commit_graph *graph;
graph = calloc(1, sizeof(*graph));
if (graph == NULL)
return NULL;
graph->node_ids = got_object_idset_alloc();
if (graph->node_ids == NULL) {
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);
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;
}
static int
is_merge_point(struct got_commit_graph_node *node)
{
return node->nparents > 1;
}
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 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_TAIL(&graph->iter_list, node, entry);
return;
}
/* Ensure that an iteration in progress will see this new commit. */
if (graph->iter_node) {
n = graph->iter_node;
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_AFTER(&graph->iter_list, graph->iter_node,
node, entry);
return;
}
/*
* If a child node is known, begin looping over the list there
* instead of beginning from the list head.
*/
n = child_node ? child_node : TAILQ_FIRST(&graph->iter_list);
/* Insert into list based on committer timestamp. */
do {
if (node->commit_timestamp == n->commit_timestamp) {
TAILQ_INSERT_AFTER(&graph->iter_list, n, node, entry);
break;
} else if (node->commit_timestamp < n->commit_timestamp) {
next = TAILQ_NEXT(n, entry);
if (next == NULL) {
TAILQ_INSERT_AFTER(&graph->iter_list, n,
node, entry);
break;
}
if (node->commit_timestamp >= next->commit_timestamp) {
TAILQ_INSERT_BEFORE(next, node, entry);
break;
}
} else {
TAILQ_INSERT_BEFORE(n, node, entry);
break;
}
n = TAILQ_NEXT(n, entry);
} while (n);
}
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();
free(qid);
return err;
}
SIMPLEQ_INSERT_TAIL(ids, qid, entry);
return NULL;
}
static const struct got_error *
advance_open_branches(struct got_commit_graph *graph,
struct got_commit_graph_node *node,
struct got_object_id *commit_id, struct got_commit_object *commit)
{
const struct got_error *err;
struct got_object_qid *qid;
err = got_object_idset_remove(NULL, graph->open_branches, commit_id);
if (err && err->code != GOT_ERR_NO_OBJ)
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;
}
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 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)
{
const struct got_error *err = NULL;
struct got_commit_graph_node *node, *existing_node;
struct got_object_qid *qid;
*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_INIT(&node->child_ids);
SIMPLEQ_FOREACH(qid, &commit->parent_ids, entry) {
err = add_vertex(&node->parent_ids, qid->id);
if (err)
return err;
node->nparents++;
}
node->commit_timestamp = mktime(&commit->tm_committer);
if (node->commit_timestamp == -1)
return got_error_from_errno();
err = got_object_idset_add((void **)(&existing_node),
graph->node_ids, &node->id, node);
if (err == NULL) {
add_node_to_iter_list(graph, node, child_node);
err = advance_open_branches(graph, node, commit_id, commit);
*new_node = node;
} else if (err->code == GOT_ERR_OBJ_EXISTS) {
err = NULL;
free(node);
node = existing_node;
} else {
free(node);
return err;
}
if (child_node) {
struct got_object_qid *cid;
/* Prevent linking to self. */
if (got_object_id_cmp(commit_id, &child_node->id) == 0)
return got_error(GOT_ERR_BAD_OBJ_ID);
/* Prevent double-linking to the same child. */
SIMPLEQ_FOREACH(cid, &node->child_ids, entry) {
if (got_object_id_cmp(cid->id, &child_node->id) == 0)
return got_error(GOT_ERR_BAD_OBJ_ID);
}
err = add_vertex(&node->child_ids, &child_node->id);
if (err)
return err;
node->nchildren++;
}
return err;
}
const struct got_error *
got_commit_graph_open(struct got_commit_graph **graph,
struct got_object_id *commit_id, 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;
*graph = alloc_graph();
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);
got_object_commit_close(commit);
if (err) {
got_commit_graph_close(*graph);
*graph = NULL;
return err;
}
return NULL;
}
struct got_commit_graph_branch {
struct got_object_id parent_id;
struct got_commit_graph_node *node;
};
struct gather_branches_arg {
struct got_commit_graph_branch *branches;
int nbranches;
};
static void
gather_branches(struct got_object_id *id, void *data, void *arg)
{
struct gather_branches_arg *a = arg;
memcpy(&a->branches[a->nbranches].parent_id, id, sizeof(*id));
a->branches[a->nbranches].node = data;
a->nbranches++;
}
static const struct got_error *
fetch_commits_from_open_branches(int *ncommits, int *wanted_id_added,
struct got_commit_graph *graph, struct got_repository *repo,
struct got_object_id *wanted_id)
{
const struct got_error *err;
struct got_commit_graph_branch *branches;
struct gather_branches_arg arg;
int i;
*ncommits = 0;
if (wanted_id_added)
*wanted_id_added = 0;
arg.nbranches = got_object_idset_num_elements(graph->open_branches);
if (arg.nbranches == 0)
return NULL;
/*
* Adding nodes to the graph might change the graph's open
* branches state. Create a local copy of the current state.
*/
branches = calloc(arg.nbranches, sizeof(*branches));
if (branches == NULL)
return got_error_from_errno();
arg.nbranches = 0; /* reset; gather_branches() will increment */
arg.branches = branches;
got_object_idset_for_each(graph->open_branches, gather_branches, &arg);
for (i = 0; i < arg.nbranches; i++) {
struct got_object_id *commit_id;
struct got_commit_graph_node *child_node, *new_node;
struct got_commit_object *commit;
commit_id = &branches[i].parent_id;
child_node = branches[i].node;
err = got_object_open_as_commit(&commit, repo, commit_id);
if (err)
break;
err = add_node(&new_node, graph, commit_id, commit, child_node);
got_object_commit_close(commit);
if (err) {
if (err->code != GOT_ERR_OBJ_EXISTS)
break;
err = NULL;
}
if (new_node)
(*ncommits)++;
if (wanted_id && got_object_id_cmp(commit_id, wanted_id) == 0)
*wanted_id_added = 1;
}
free(branches);
return err;
}
const struct got_error *
got_commit_graph_fetch_commits(int *nfetched, struct got_commit_graph *graph,
int limit, struct got_repository *repo)
{
const struct got_error *err;
int ncommits;
*nfetched = 0;
while (*nfetched < limit) {
err = fetch_commits_from_open_branches(&ncommits, NULL,
graph, repo, NULL);
if (err)
return err;
if (ncommits == 0)
break;
*nfetched += ncommits;
}
return NULL;
}
const struct got_error *
got_commit_graph_fetch_commits_up_to(int *nfetched,
struct got_commit_graph *graph, struct got_object_id *wanted_id,
struct got_repository *repo)
{
const struct got_error *err;
int ncommits, wanted_id_added = 0;
*nfetched = 0;
if (got_object_idset_get(graph->node_ids, wanted_id) != NULL)
return NULL;
while (!wanted_id_added) {
err = fetch_commits_from_open_branches(&ncommits,
&wanted_id_added, graph, repo, wanted_id);
if (err)
return err;
if (ncommits == 0)
return NULL;
*nfetched += ncommits;
}
return NULL;
}
static void
free_graph_node(struct got_object_id *id, void *data, void *arg)
{
struct got_commit_graph_node *node = data;
while (!SIMPLEQ_EMPTY(&node->child_ids)) {
struct got_object_qid *child = SIMPLEQ_FIRST(&node->child_ids);
SIMPLEQ_REMOVE_HEAD(&node->child_ids, entry);
free(child);
}
free(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_graph_node, NULL);
got_object_idset_free(graph->node_ids);
free(graph);
}
const struct got_error *
got_commit_graph_iter_start(struct got_commit_graph *graph,
struct got_object_id *id)
{
struct got_commit_graph_node *start_node;
start_node = got_object_idset_get(graph->node_ids, id);
if (start_node == NULL)
return got_error(GOT_ERR_NO_OBJ);
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 interating, 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) {
*id = &graph->iter_node->id;
/* We are done interating. */
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;
}
