docs: clarify "branch -l"

diff --git a/builtin-reflog.c b/builtin-reflog.c
index d95f515f2e32aa71c3a09fe5ed9486f352713360..64e45bd8137bef2b6cfe1f8a3da79e2ff6f8fc47 100644 (file)
--- a/builtin-reflog.c
+++ b/builtin-reflog.c
@@ -52,6 +52,7 @@ struct collect_reflog_cb {
 
 #define INCOMPLETE     (1u<<10)
 #define STUDYING       (1u<<11)
+#define REACHABLE      (1u<<12)
 
 static int tree_is_complete(const unsigned char *sha1)
 {
@@ -209,6 +210,70 @@ static int keep_entry(struct commit **it, unsigned char *sha1)
        return 1;
 }
 
+static int unreachable(struct expire_reflog_cb *cb, struct commit *commit, unsigned char *sha1)
+{
+       /*
+        * We may or may not have the commit yet - if not, look it
+        * up using the supplied sha1.
+        */
+       if (!commit) {
+               if (is_null_sha1(sha1))
+                       return 0;
+
+               commit = lookup_commit_reference_gently(sha1, 1);
+
+               /* Not a commit -- keep it */
+               if (!commit)
+                       return 0;
+       }
+
+       /* Reachable from the current ref?  Don't prune. */
+       if (commit->object.flags & REACHABLE)
+               return 0;
+       if (in_merge_bases(commit, &cb->ref_commit, 1))
+               return 0;
+
+       /* We can't reach it - prune it. */
+       return 1;
+}
+
+static void mark_reachable(struct commit *commit, unsigned long expire_limit)
+{
+       /*
+        * We need to compute whether the commit on either side of a reflog
+        * entry is reachable from the tip of the ref for all entries.
+        * Mark commits that are reachable from the tip down to the
+        * time threshold first; we know a commit marked thusly is
+        * reachable from the tip without running in_merge_bases()
+        * at all.
+        */
+       struct commit_list *pending = NULL;
+
+       commit_list_insert(commit, &pending);
+       while (pending) {
+               struct commit_list *entry = pending;
+               struct commit_list *parent;
+               pending = entry->next;
+               commit = entry->item;
+               free(entry);
+               if (commit->object.flags & REACHABLE)
+                       continue;
+               if (parse_commit(commit))
+                       continue;
+               commit->object.flags |= REACHABLE;
+               if (commit->date < expire_limit)
+                       continue;
+               parent = commit->parents;
+               while (parent) {
+                       commit = parent->item;
+                       parent = parent->next;
+                       if (commit->object.flags & REACHABLE)
+                               continue;
+                       commit_list_insert(commit, &pending);
+               }
+       }
+}
+
 static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
                const char *email, unsigned long timestamp, int tz,
                const char *message, void *cb_data)
@@ -230,12 +295,7 @@ static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
        if (timestamp < cb->cmd->expire_unreachable) {
                if (!cb->ref_commit)
                        goto prune;
-               if (!old && !is_null_sha1(osha1))
-                       old = lookup_commit_reference_gently(osha1, 1);
-               if (!new && !is_null_sha1(nsha1))
-                       new = lookup_commit_reference_gently(nsha1, 1);
-               if ((old && !in_merge_bases(old, &cb->ref_commit, 1)) ||
-                   (new && !in_merge_bases(new, &cb->ref_commit, 1)))
+               if (unreachable(cb, old, osha1) || unreachable(cb, new, nsha1))
                        goto prune;
        }
 
@@ -288,7 +348,11 @@ static int expire_reflog(const char *ref, const unsigned char *sha1, int unused,
        cb.ref_commit = lookup_commit_reference_gently(sha1, 1);
        cb.ref = ref;
        cb.cmd = cmd;
+       if (cb.ref_commit)
+               mark_reachable(cb.ref_commit, cmd->expire_total);
        for_each_reflog_ent(ref, expire_reflog_ent, &cb);
+       if (cb.ref_commit)
+               clear_commit_marks(cb.ref_commit, REACHABLE);
  finish:
        if (cb.newlog) {
                if (fclose(cb.newlog)) {
@@ -298,7 +362,7 @@ static int expire_reflog(const char *ref, const unsigned char *sha1, int unused,
                } else if (cmd->updateref &&
                        (write_in_full(lock->lock_fd,
                                sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
-                        write_in_full(lock->lock_fd, "\n", 1) != 1 ||
+                        write_str_in_full(lock->lock_fd, "\n") != 1 ||
                         close_ref(lock) < 0)) {
                        status |= error("Couldn't write %s",
                                lock->lk->filename);
@@ -466,16 +530,14 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
        int i, status, do_all;
        int explicit_expiry = 0;
 
+       default_reflog_expire_unreachable = now - 30 * 24 * 3600;
+       default_reflog_expire = now - 90 * 24 * 3600;
        git_config(reflog_expire_config, NULL);
 
        save_commit_buffer = 0;
        do_all = status = 0;
        memset(&cb, 0, sizeof(cb));
 
-       if (!default_reflog_expire_unreachable)
-               default_reflog_expire_unreachable = now - 30 * 24 * 3600;
-       if (!default_reflog_expire)
-               default_reflog_expire = now - 90 * 24 * 3600;
        cb.expire_total = default_reflog_expire;
        cb.expire_unreachable = default_reflog_expire_unreachable;
 
@@ -630,10 +692,13 @@ static int cmd_reflog_delete(int argc, const char **argv, const char *prefix)
  */
 
 static const char reflog_usage[] =
-"git reflog (expire | ...)";
+"git reflog [ show | expire | delete ]";
 
 int cmd_reflog(int argc, const char **argv, const char *prefix)
 {
+       if (argc > 1 && !strcmp(argv[1], "-h"))
+               usage(reflog_usage);
+
        /* With no command, we default to showing it. */
        if (argc < 2 || *argv[1] == '-')
                return cmd_log_reflog(argc, argv, prefix);