void GC::collect(int generation) {
int i;
GCList *young = &generations[generation]; // the generation we are examining
GCList *old; // next older generation
GCList unreachable; // unreachable trash
collect_mutex.lock();
// update collection and allocation counters
if (generation+1 < NUM_GENERATIONS)
generations[generation+1].count += 1;
for (i = 0; i <= generation; i++)
generations[i].count = 0;
// merge younger generations with one we are currently collecting
for (i = 0; i < generation; i++) {
generations[generation].merge(&generations[i]);
}
if (generation < NUM_GENERATIONS-1)
old = &generations[generation+1];
else
old = young;
// Using refcount and gc_refs, calculate which objects in the
// container set are reachable from outside the set (i.e., have a
// refcount greater than 0 when all the references within the
// set are taken into account).
update_refs(young);
subtract_refs(young);
// Leave everything reachable from outside young in young, and move
// everything else (in young) to unreachable.
// NOTE: This used to move the reachable objects into a reachable
// set instead. But most things usually turn out to be reachable,
// so it's more efficient to move the unreachable things.
move_unreachable(young, &unreachable);
// move reachable objects to next generation.
if (young != old)
old->merge(young);
// call clear on objects in the unreachable set. This will cause
// the reference cycles to be broken. It may also cause some objects
// in finalizers to be freed.
delete_garbage(&unreachable, old);
collect_mutex.unlock();
}
int cmd_reset(int argc, const char **argv, const char *prefix)
{
int reset_type = NONE, update_ref_status = 0, quiet = 0;
int patch_mode = 0, unborn;
const char *rev;
unsigned char sha1[20];
const char **pathspec = NULL;
const struct option options[] = {
OPT__QUIET(&quiet, N_("be quiet, only report errors")),
OPT_SET_INT(0, "mixed", &reset_type,
N_("reset HEAD and index"), MIXED),
OPT_SET_INT(0, "soft", &reset_type, N_("reset only HEAD"), SOFT),
OPT_SET_INT(0, "hard", &reset_type,
N_("reset HEAD, index and working tree"), HARD),
OPT_SET_INT(0, "merge", &reset_type,
N_("reset HEAD, index and working tree"), MERGE),
OPT_SET_INT(0, "keep", &reset_type,
N_("reset HEAD but keep local changes"), KEEP),
OPT_BOOL('p', "patch", &patch_mode, N_("select hunks interactively")),
OPT_END()
};
git_config(git_default_config, NULL);
argc = parse_options(argc, argv, prefix, options, git_reset_usage,
PARSE_OPT_KEEP_DASHDASH);
pathspec = parse_args(argv, prefix, &rev);
unborn = !strcmp(rev, "HEAD") && get_sha1("HEAD", sha1);
if (unborn) {
/* reset on unborn branch: treat as reset to empty tree */
hashcpy(sha1, EMPTY_TREE_SHA1_BIN);
} else if (!pathspec) {
struct commit *commit;
if (get_sha1_committish(rev, sha1))
die(_("Failed to resolve '%s' as a valid revision."), rev);
commit = lookup_commit_reference(sha1);
if (!commit)
die(_("Could not parse object '%s'."), rev);
hashcpy(sha1, commit->object.sha1);
} else {
struct tree *tree;
if (get_sha1_treeish(rev, sha1))
die(_("Failed to resolve '%s' as a valid tree."), rev);
tree = parse_tree_indirect(sha1);
if (!tree)
die(_("Could not parse object '%s'."), rev);
hashcpy(sha1, tree->object.sha1);
}
if (patch_mode) {
if (reset_type != NONE)
die(_("--patch is incompatible with --{hard,mixed,soft}"));
return run_add_interactive(sha1_to_hex(sha1), "--patch=reset", pathspec);
}
/* git reset tree [--] paths... can be used to
* load chosen paths from the tree into the index without
* affecting the working tree nor HEAD. */
if (pathspec) {
if (reset_type == MIXED)
warning(_("--mixed with paths is deprecated; use 'git reset -- <paths>' instead."));
else if (reset_type != NONE)
die(_("Cannot do %s reset with paths."),
_(reset_type_names[reset_type]));
}
if (reset_type == NONE)
reset_type = MIXED; /* by default */
if (reset_type != SOFT && reset_type != MIXED)
setup_work_tree();
if (reset_type == MIXED && is_bare_repository())
die(_("%s reset is not allowed in a bare repository"),
_(reset_type_names[reset_type]));
/* Soft reset does not touch the index file nor the working tree
* at all, but requires them in a good order. Other resets reset
* the index file to the tree object we are switching to. */
if (reset_type == SOFT || reset_type == KEEP)
die_if_unmerged_cache(reset_type);
if (reset_type != SOFT) {
struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
int newfd = hold_locked_index(lock, 1);
if (reset_type == MIXED) {
if (read_from_tree(pathspec, sha1))
return 1;
} else {
int err = reset_index(sha1, reset_type, quiet);
if (reset_type == KEEP && !err)
err = reset_index(sha1, MIXED, quiet);
if (err)
die(_("Could not reset index file to revision '%s'."), rev);
}
if (reset_type == MIXED) { /* Report what has not been updated. */
int flags = quiet ? REFRESH_QUIET : REFRESH_IN_PORCELAIN;
refresh_index(&the_index, flags, NULL, NULL,
_("Unstaged changes after reset:"));
}
if (write_cache(newfd, active_cache, active_nr) ||
commit_locked_index(lock))
die(_("Could not write new index file."));
}
if (!pathspec && !unborn) {
/* Any resets without paths update HEAD to the head being
* switched to, saving the previous head in ORIG_HEAD before. */
update_ref_status = update_refs(rev, sha1);
if (reset_type == HARD && !update_ref_status && !quiet)
print_new_head_line(lookup_commit_reference(sha1));
}
if (!pathspec)
remove_branch_state();
return update_ref_status;
}
/* This is the main function. Read this to understand how the
* collection process works. */
static long
collect(int generation)
{
int i;
long m = 0; /* # objects collected */
long n = 0; /* # unreachable objects that couldn't be collected */
PyGC_Head *young; /* the generation we are examining */
PyGC_Head *old; /* next older generation */
PyGC_Head unreachable; /* non-problematic unreachable trash */
PyGC_Head finalizers; /* objects with, & reachable from, __del__ */
PyGC_Head *gc;
if (delstr == NULL) {
delstr = PyString_InternFromString("__del__");
if (delstr == NULL)
Py_FatalError("gc couldn't allocate \"__del__\"");
}
if (debug & DEBUG_STATS) {
PySys_WriteStderr("gc: collecting generation %d...\n",
generation);
PySys_WriteStderr("gc: objects in each generation:");
for (i = 0; i < NUM_GENERATIONS; i++) {
PySys_WriteStderr(" %ld", gc_list_size(GEN_HEAD(i)));
}
PySys_WriteStderr("\n");
}
/* update collection and allocation counters */
if (generation+1 < NUM_GENERATIONS)
generations[generation+1].count += 1;
for (i = 0; i <= generation; i++)
generations[i].count = 0;
/* merge younger generations with one we are currently collecting */
for (i = 0; i < generation; i++) {
gc_list_merge(GEN_HEAD(i), GEN_HEAD(generation));
}
/* handy references */
young = GEN_HEAD(generation);
if (generation < NUM_GENERATIONS-1)
old = GEN_HEAD(generation+1);
else
old = young;
/* Using ob_refcnt and gc_refs, calculate which objects in the
* container set are reachable from outside the set (i.e., have a
* refcount greater than 0 when all the references within the
* set are taken into account).
*/
update_refs(young);
subtract_refs(young);
/* Leave everything reachable from outside young in young, and move
* everything else (in young) to unreachable.
* NOTE: This used to move the reachable objects into a reachable
* set instead. But most things usually turn out to be reachable,
* so it's more efficient to move the unreachable things.
*/
gc_list_init(&unreachable);
move_unreachable(young, &unreachable);
/* Move reachable objects to next generation. */
if (young != old)
gc_list_merge(young, old);
/* All objects in unreachable are trash, but objects reachable from
* finalizers can't safely be deleted. Python programmers should take
* care not to create such things. For Python, finalizers means
* instance objects with __del__ methods. Weakrefs with callbacks
* can also call arbitrary Python code but they will be dealt with by
* handle_weakrefs().
*/
gc_list_init(&finalizers);
move_finalizers(&unreachable, &finalizers);
/* finalizers contains the unreachable objects with a finalizer;
* unreachable objects reachable *from* those are also uncollectable,
* and we move those into the finalizers list too.
*/
move_finalizer_reachable(&finalizers);
/* Collect statistics on collectable objects found and print
* debugging information.
*/
for (gc = unreachable.gc.gc_next; gc != &unreachable;
gc = gc->gc.gc_next) {
m++;
if (debug & DEBUG_COLLECTABLE) {
debug_cycle("collectable", FROM_GC(gc));
}
}
/* Clear weakrefs and invoke callbacks as necessary. */
m += handle_weakrefs(&unreachable, old);
/* Call tp_clear on objects in the unreachable set. This will cause
* the reference cycles to be broken. It may also cause some objects
* in finalizers to be freed.
*/
delete_garbage(&unreachable, old);
/* Collect statistics on uncollectable objects found and print
* debugging information. */
for (gc = finalizers.gc.gc_next;
gc != &finalizers;
gc = gc->gc.gc_next) {
n++;
if (debug & DEBUG_UNCOLLECTABLE)
debug_cycle("uncollectable", FROM_GC(gc));
}
if (debug & DEBUG_STATS) {
if (m == 0 && n == 0) {
PySys_WriteStderr("gc: done.\n");
}
else {
PySys_WriteStderr(
"gc: done, %ld unreachable, %ld uncollectable.\n",
n+m, n);
}
}
/* Append instances in the uncollectable set to a Python
* reachable list of garbage. The programmer has to deal with
* this if they insist on creating this type of structure.
*/
(void)handle_finalizers(&finalizers, old);
if (PyErr_Occurred()) {
if (gc_str == NULL)
gc_str = PyString_FromString("garbage collection");
PyErr_WriteUnraisable(gc_str);
Py_FatalError("unexpected exception during garbage collection");
}
return n+m;
}