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git/commit.c
Jon Seymour ab580acea4 [PATCH] Add a topological sort procedure to commit.c
This introduces an in-place topological sort procedure to commit.c.

Given a list of commits, sort_in_topological_order() will perform an in-place
topological sort of that list.

The invariant that applies to the resulting list is:

       a reachable from b => ord(b) < ord(a)

This invariant is weaker than the --merge-order invariant, but is cheaper
to calculate (assuming the list has been identified) and will serve any
purpose where only a minimal topological order guarantee is required.

Signed-off-by: Jon Seymour <jon.seymour@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-06 10:19:04 -07:00

455 lines
10 KiB
C

#include <ctype.h>
#include "tag.h"
#include "commit.h"
#include "cache.h"
struct sort_node
{
/*
* the number of children of the associated commit
* that also occur in the list being sorted.
*/
unsigned int indegree;
/*
* reference to original list item that we will re-use
* on output.
*/
struct commit_list * list_item;
};
const char *commit_type = "commit";
enum cmit_fmt get_commit_format(const char *arg)
{
if (!*arg)
return CMIT_FMT_DEFAULT;
if (!strcmp(arg, "=raw"))
return CMIT_FMT_RAW;
if (!strcmp(arg, "=medium"))
return CMIT_FMT_MEDIUM;
if (!strcmp(arg, "=short"))
return CMIT_FMT_SHORT;
if (!strcmp(arg, "=full"))
return CMIT_FMT_FULL;
die("invalid --pretty format");
}
static struct commit *check_commit(struct object *obj, const unsigned char *sha1)
{
if (obj->type != commit_type) {
error("Object %s is a %s, not a commit",
sha1_to_hex(sha1), obj->type);
return NULL;
}
return (struct commit *) obj;
}
struct commit *lookup_commit_reference(const unsigned char *sha1)
{
struct object *obj = parse_object(sha1);
if (!obj)
return NULL;
if (obj->type == tag_type)
obj = ((struct tag *)obj)->tagged;
return check_commit(obj, sha1);
}
struct commit *lookup_commit(const unsigned char *sha1)
{
struct object *obj = lookup_object(sha1);
if (!obj) {
struct commit *ret = xmalloc(sizeof(struct commit));
memset(ret, 0, sizeof(struct commit));
created_object(sha1, &ret->object);
ret->object.type = commit_type;
return ret;
}
if (!obj->type)
obj->type = commit_type;
return check_commit(obj, sha1);
}
static unsigned long parse_commit_date(const char *buf)
{
unsigned long date;
if (memcmp(buf, "author", 6))
return 0;
while (*buf++ != '\n')
/* nada */;
if (memcmp(buf, "committer", 9))
return 0;
while (*buf++ != '>')
/* nada */;
date = strtoul(buf, NULL, 10);
if (date == ULONG_MAX)
date = 0;
return date;
}
int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
{
void *bufptr = buffer;
unsigned char parent[20];
struct commit_list **pptr;
if (item->object.parsed)
return 0;
item->object.parsed = 1;
get_sha1_hex(bufptr + 5, parent);
item->tree = lookup_tree(parent);
if (item->tree)
add_ref(&item->object, &item->tree->object);
bufptr += 46; /* "tree " + "hex sha1" + "\n" */
pptr = &item->parents;
while (!memcmp(bufptr, "parent ", 7) &&
!get_sha1_hex(bufptr + 7, parent)) {
struct commit *new_parent = lookup_commit(parent);
if (new_parent) {
pptr = &commit_list_insert(new_parent, pptr)->next;
add_ref(&item->object, &new_parent->object);
}
bufptr += 48;
}
item->date = parse_commit_date(bufptr);
return 0;
}
int parse_commit(struct commit *item)
{
char type[20];
void *buffer;
unsigned long size;
int ret;
if (item->object.parsed)
return 0;
buffer = read_sha1_file(item->object.sha1, type, &size);
if (!buffer)
return error("Could not read %s",
sha1_to_hex(item->object.sha1));
if (strcmp(type, commit_type)) {
free(buffer);
return error("Object %s not a commit",
sha1_to_hex(item->object.sha1));
}
ret = parse_commit_buffer(item, buffer, size);
if (!ret) {
item->buffer = buffer;
return 0;
}
free(buffer);
return ret;
}
struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
{
struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
new_list->item = item;
new_list->next = *list_p;
*list_p = new_list;
return new_list;
}
void free_commit_list(struct commit_list *list)
{
while (list) {
struct commit_list *temp = list;
list = temp->next;
free(temp);
}
}
struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
{
struct commit_list **pp = list;
struct commit_list *p;
while ((p = *pp) != NULL) {
if (p->item->date < item->date) {
break;
}
pp = &p->next;
}
return commit_list_insert(item, pp);
}
void sort_by_date(struct commit_list **list)
{
struct commit_list *ret = NULL;
while (*list) {
insert_by_date((*list)->item, &ret);
*list = (*list)->next;
}
*list = ret;
}
struct commit *pop_most_recent_commit(struct commit_list **list,
unsigned int mark)
{
struct commit *ret = (*list)->item;
struct commit_list *parents = ret->parents;
struct commit_list *old = *list;
*list = (*list)->next;
free(old);
while (parents) {
struct commit *commit = parents->item;
parse_commit(commit);
if (!(commit->object.flags & mark)) {
commit->object.flags |= mark;
insert_by_date(commit, list);
}
parents = parents->next;
}
return ret;
}
/*
* Generic support for pretty-printing the header
*/
static int get_one_line(const char *msg, unsigned long len)
{
int ret = 0;
while (len--) {
char c = *msg++;
ret++;
if (c == '\n')
break;
if (!c)
return 0;
}
return ret;
}
static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf, const char *line)
{
char *date;
unsigned int namelen;
unsigned long time;
int tz, ret;
date = strchr(line, '>');
if (!date)
return 0;
namelen = ++date - line;
time = strtoul(date, &date, 10);
tz = strtol(date, NULL, 10);
ret = sprintf(buf, "%s: %.*s\n", what, namelen, line);
if (fmt == CMIT_FMT_MEDIUM)
ret += sprintf(buf + ret, "Date: %s\n", show_date(time, tz));
return ret;
}
static int is_empty_line(const char *line, int len)
{
while (len && isspace(line[len-1]))
len--;
return !len;
}
static int add_parent_info(enum cmit_fmt fmt, char *buf, const char *line, int parents)
{
int offset = 0;
switch (parents) {
case 1:
break;
case 2:
/* Go back to the previous line: 40 characters of previous parent, and one '\n' */
offset = sprintf(buf, "Merge: %.40s\n", line-41);
/* Fallthrough */
default:
/* Replace the previous '\n' with a space */
buf[offset-1] = ' ';
offset += sprintf(buf + offset, "%.40s\n", line+7);
}
return offset;
}
unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, unsigned long len, char *buf, unsigned long space)
{
int hdr = 1, body = 0;
unsigned long offset = 0;
int parents = 0;
for (;;) {
const char *line = msg;
int linelen = get_one_line(msg, len);
if (!linelen)
break;
/*
* We want some slop for indentation and a possible
* final "...". Thus the "+ 20".
*/
if (offset + linelen + 20 > space) {
memcpy(buf + offset, " ...\n", 8);
offset += 8;
break;
}
msg += linelen;
len -= linelen;
if (hdr) {
if (linelen == 1) {
hdr = 0;
buf[offset++] = '\n';
continue;
}
if (fmt == CMIT_FMT_RAW) {
memcpy(buf + offset, line, linelen);
offset += linelen;
continue;
}
if (!memcmp(line, "parent ", 7)) {
if (linelen != 48)
die("bad parent line in commit");
offset += add_parent_info(fmt, buf + offset, line, ++parents);
}
if (!memcmp(line, "author ", 7))
offset += add_user_info("Author", fmt, buf + offset, line + 7);
if (fmt == CMIT_FMT_FULL) {
if (!memcmp(line, "committer ", 10))
offset += add_user_info("Commit", fmt, buf + offset, line + 10);
}
continue;
}
if (is_empty_line(line, linelen)) {
if (!body)
continue;
if (fmt == CMIT_FMT_SHORT)
break;
} else {
body = 1;
}
memset(buf + offset, ' ', 4);
memcpy(buf + offset + 4, line, linelen);
offset += linelen + 4;
}
/* Make sure there is an EOLN */
if (buf[offset - 1] != '\n')
buf[offset++] = '\n';
buf[offset] = '\0';
return offset;
}
struct commit *pop_commit(struct commit_list **stack)
{
struct commit_list *top = *stack;
struct commit *item = top ? top->item : NULL;
if (top) {
*stack = top->next;
free(top);
}
return item;
}
int count_parents(struct commit * commit)
{
int count = 0;
struct commit_list * parents = commit->parents;
for (count=0;parents; parents=parents->next,count++)
;
return count;
}
/*
* Performs an in-place topological sort on the list supplied.
*/
void sort_in_topological_order(struct commit_list ** list)
{
struct commit_list * next = *list;
struct commit_list * work = NULL;
struct commit_list ** pptr = list;
struct sort_node * nodes;
struct sort_node * next_nodes;
int count = 0;
/* determine the size of the list */
while (next) {
next = next->next;
count++;
}
/* allocate an array to help sort the list */
nodes = xcalloc(count, sizeof(*nodes));
/* link the list to the array */
next_nodes = nodes;
next=*list;
while (next) {
next_nodes->list_item = next;
next->item->object.util = next_nodes;
next_nodes++;
next = next->next;
}
/* update the indegree */
next=*list;
while (next) {
struct commit_list * parents = next->item->parents;
while (parents) {
struct commit * parent=parents->item;
struct sort_node * pn = (struct sort_node *)parent->object.util;
if (pn)
pn->indegree++;
parents=parents->next;
}
next=next->next;
}
/*
* find the tips
*
* tips are nodes not reachable from any other node in the list
*
* the tips serve as a starting set for the work queue.
*/
next=*list;
while (next) {
struct sort_node * node = (struct sort_node *)next->item->object.util;
if (node->indegree == 0) {
commit_list_insert(next->item, &work);
}
next=next->next;
}
/* process the list in topological order */
while (work) {
struct commit * work_item = pop_commit(&work);
struct sort_node * work_node = (struct sort_node *)work_item->object.util;
struct commit_list * parents = work_item->parents;
while (parents) {
struct commit * parent=parents->item;
struct sort_node * pn = (struct sort_node *)parent->object.util;
if (pn) {
/*
* parents are only enqueued for emission
* when all their children have been emitted thereby
* guaranteeing topological order.
*/
pn->indegree--;
if (!pn->indegree)
commit_list_insert(parent, &work);
}
parents=parents->next;
}
/*
* work_item is a commit all of whose children
* have already been emitted. we can emit it now.
*/
*pptr = work_node->list_item;
pptr = &(*pptr)->next;
*pptr = NULL;
work_item->object.util = NULL;
}
free(nodes);
}