Merge branch 'jk/diff-tree-t-fix'
[gitweb.git] / builtin / blame.c
index 6a284ce46b4f3b46a47d033fca607cae710806bc..17d30d00aa3f6c4d0f62cae6603f9003dd2f2395 100644 (file)
@@ -1,7 +1,8 @@
 /*
  * Blame
  *
- * Copyright (c) 2006, Junio C Hamano
+ * Copyright (c) 2006, 2014 by its authors
+ * See COPYING for licensing conditions
  */
 
 #include "cache.h"
@@ -18,7 +19,9 @@
 #include "cache-tree.h"
 #include "string-list.h"
 #include "mailmap.h"
+#include "mergesort.h"
 #include "parse-options.h"
+#include "prio-queue.h"
 #include "utf8.h"
 #include "userdiff.h"
 #include "line-range.h"
@@ -83,11 +86,42 @@ static unsigned blame_copy_score;
  */
 struct origin {
        int refcnt;
+       /* Record preceding blame record for this blob */
        struct origin *previous;
+       /* origins are put in a list linked via `next' hanging off the
+        * corresponding commit's util field in order to make finding
+        * them fast.  The presence in this chain does not count
+        * towards the origin's reference count.  It is tempting to
+        * let it count as long as the commit is pending examination,
+        * but even under circumstances where the commit will be
+        * present multiple times in the priority queue of unexamined
+        * commits, processing the first instance will not leave any
+        * work requiring the origin data for the second instance.  An
+        * interspersed commit changing that would have to be
+        * preexisting with a different ancestry and with the same
+        * commit date in order to wedge itself between two instances
+        * of the same commit in the priority queue _and_ produce
+        * blame entries relevant for it.  While we don't want to let
+        * us get tripped up by this case, it certainly does not seem
+        * worth optimizing for.
+        */
+       struct origin *next;
        struct commit *commit;
+       /* `suspects' contains blame entries that may be attributed to
+        * this origin's commit or to parent commits.  When a commit
+        * is being processed, all suspects will be moved, either by
+        * assigning them to an origin in a different commit, or by
+        * shipping them to the scoreboard's ent list because they
+        * cannot be attributed to a different commit.
+        */
+       struct blame_entry *suspects;
        mmfile_t file;
        unsigned char blob_sha1[20];
        unsigned mode;
+       /* guilty gets set when shipping any suspects to the final
+        * blame list instead of other commits
+        */
+       char guilty;
        char path[FLEX_ARRAY];
 };
 
@@ -176,10 +210,22 @@ static inline struct origin *origin_incref(struct origin *o)
 static void origin_decref(struct origin *o)
 {
        if (o && --o->refcnt <= 0) {
+               struct origin *p, *l = NULL;
                if (o->previous)
                        origin_decref(o->previous);
                free(o->file.ptr);
-               free(o);
+               /* Should be present exactly once in commit chain */
+               for (p = o->commit->util; p; l = p, p = p->next) {
+                       if (p == o) {
+                               if (l)
+                                       l->next = p->next;
+                               else
+                                       o->commit->util = p->next;
+                               free(o);
+                               return;
+                       }
+               }
+               die("internal error in blame::origin_decref");
        }
 }
 
@@ -193,8 +239,12 @@ static void drop_origin_blob(struct origin *o)
 
 /*
  * Each group of lines is described by a blame_entry; it can be split
- * as we pass blame to the parents.  They form a linked list in the
- * scoreboard structure, sorted by the target line number.
+ * as we pass blame to the parents.  They are arranged in linked lists
+ * kept as `suspects' of some unprocessed origin, or entered (when the
+ * blame origin has been finalized) into the scoreboard structure.
+ * While the scoreboard structure is only sorted at the end of
+ * processing (according to final image line number), the lists
+ * attached to an origin are sorted by the target line number.
  */
 struct blame_entry {
        struct blame_entry *next;
@@ -210,15 +260,6 @@ struct blame_entry {
        /* the commit that introduced this group into the final image */
        struct origin *suspect;
 
-       /* true if the suspect is truly guilty; false while we have not
-        * checked if the group came from one of its parents.
-        */
-       char guilty;
-
-       /* true if the entry has been scanned for copies in the current parent
-        */
-       char scanned;
-
        /* the line number of the first line of this group in the
         * suspect's file; internally all line numbers are 0 based.
         */
@@ -230,12 +271,113 @@ struct blame_entry {
        unsigned score;
 };
 
+/*
+ * Any merge of blames happens on lists of blames that arrived via
+ * different parents in a single suspect.  In this case, we want to
+ * sort according to the suspect line numbers as opposed to the final
+ * image line numbers.  The function body is somewhat longish because
+ * it avoids unnecessary writes.
+ */
+
+static struct blame_entry *blame_merge(struct blame_entry *list1,
+                                      struct blame_entry *list2)
+{
+       struct blame_entry *p1 = list1, *p2 = list2,
+               **tail = &list1;
+
+       if (!p1)
+               return p2;
+       if (!p2)
+               return p1;
+
+       if (p1->s_lno <= p2->s_lno) {
+               do {
+                       tail = &p1->next;
+                       if ((p1 = *tail) == NULL) {
+                               *tail = p2;
+                               return list1;
+                       }
+               } while (p1->s_lno <= p2->s_lno);
+       }
+       for (;;) {
+               *tail = p2;
+               do {
+                       tail = &p2->next;
+                       if ((p2 = *tail) == NULL)  {
+                               *tail = p1;
+                               return list1;
+                       }
+               } while (p1->s_lno > p2->s_lno);
+               *tail = p1;
+               do {
+                       tail = &p1->next;
+                       if ((p1 = *tail) == NULL) {
+                               *tail = p2;
+                               return list1;
+                       }
+               } while (p1->s_lno <= p2->s_lno);
+       }
+}
+
+static void *get_next_blame(const void *p)
+{
+       return ((struct blame_entry *)p)->next;
+}
+
+static void set_next_blame(void *p1, void *p2)
+{
+       ((struct blame_entry *)p1)->next = p2;
+}
+
+/*
+ * Final image line numbers are all different, so we don't need a
+ * three-way comparison here.
+ */
+
+static int compare_blame_final(const void *p1, const void *p2)
+{
+       return ((struct blame_entry *)p1)->lno > ((struct blame_entry *)p2)->lno
+               ? 1 : -1;
+}
+
+static int compare_blame_suspect(const void *p1, const void *p2)
+{
+       const struct blame_entry *s1 = p1, *s2 = p2;
+       /*
+        * to allow for collating suspects, we sort according to the
+        * respective pointer value as the primary sorting criterion.
+        * The actual relation is pretty unimportant as long as it
+        * establishes a total order.  Comparing as integers gives us
+        * that.
+        */
+       if (s1->suspect != s2->suspect)
+               return (intptr_t)s1->suspect > (intptr_t)s2->suspect ? 1 : -1;
+       if (s1->s_lno == s2->s_lno)
+               return 0;
+       return s1->s_lno > s2->s_lno ? 1 : -1;
+}
+
+static struct blame_entry *blame_sort(struct blame_entry *head,
+                                     int (*compare_fn)(const void *, const void *))
+{
+       return llist_mergesort (head, get_next_blame, set_next_blame, compare_fn);
+}
+
+static int compare_commits_by_reverse_commit_date(const void *a,
+                                                 const void *b,
+                                                 void *c)
+{
+       return -compare_commits_by_commit_date(a, b, c);
+}
+
 /*
  * The current state of the blame assignment.
  */
 struct scoreboard {
        /* the final commit (i.e. where we started digging from) */
        struct commit *final;
+       /* Priority queue for commits with unassigned blame records */
+       struct prio_queue commits;
        struct rev_info *revs;
        const char *path;
 
@@ -268,7 +410,6 @@ static void coalesce(struct scoreboard *sb)
 
        for (ent = sb->ent; ent && (next = ent->next); ent = next) {
                if (ent->suspect == next->suspect &&
-                   ent->guilty == next->guilty &&
                    ent->s_lno + ent->num_lines == next->s_lno) {
                        ent->num_lines += next->num_lines;
                        ent->next = next->next;
@@ -283,6 +424,30 @@ static void coalesce(struct scoreboard *sb)
                sanity_check_refcnt(sb);
 }
 
+/*
+ * Merge the given sorted list of blames into a preexisting origin.
+ * If there were no previous blames to that commit, it is entered into
+ * the commit priority queue of the score board.
+ */
+
+static void queue_blames(struct scoreboard *sb, struct origin *porigin,
+                        struct blame_entry *sorted)
+{
+       if (porigin->suspects)
+               porigin->suspects = blame_merge(porigin->suspects, sorted);
+       else {
+               struct origin *o;
+               for (o = porigin->commit->util; o; o = o->next) {
+                       if (o->suspects) {
+                               porigin->suspects = sorted;
+                               return;
+                       }
+               }
+               porigin->suspects = sorted;
+               prio_queue_put(&sb->commits, porigin->commit);
+       }
+}
+
 /*
  * Given a commit and a path in it, create a new origin structure.
  * The callers that add blame to the scoreboard should use
@@ -295,23 +460,32 @@ static struct origin *make_origin(struct commit *commit, const char *path)
        o = xcalloc(1, sizeof(*o) + strlen(path) + 1);
        o->commit = commit;
        o->refcnt = 1;
+       o->next = commit->util;
+       commit->util = o;
        strcpy(o->path, path);
        return o;
 }
 
 /*
  * Locate an existing origin or create a new one.
+ * This moves the origin to front position in the commit util list.
  */
 static struct origin *get_origin(struct scoreboard *sb,
                                 struct commit *commit,
                                 const char *path)
 {
-       struct blame_entry *e;
+       struct origin *o, *l;
 
-       for (e = sb->ent; e; e = e->next) {
-               if (e->suspect->commit == commit &&
-                   !strcmp(e->suspect->path, path))
-                       return origin_incref(e->suspect);
+       for (o = commit->util, l = NULL; o; l = o, o = o->next) {
+               if (!strcmp(o->path, path)) {
+                       /* bump to front */
+                       if (l) {
+                               l->next = o->next;
+                               o->next = commit->util;
+                               commit->util = o;
+                       }
+                       return origin_incref(o);
+               }
        }
        return make_origin(commit, path);
 }
@@ -350,41 +524,19 @@ static struct origin *find_origin(struct scoreboard *sb,
                                  struct commit *parent,
                                  struct origin *origin)
 {
-       struct origin *porigin = NULL;
+       struct origin *porigin;
        struct diff_options diff_opts;
        const char *paths[2];
 
-       if (parent->util) {
-               /*
-                * Each commit object can cache one origin in that
-                * commit.  This is a freestanding copy of origin and
-                * not refcounted.
-                */
-               struct origin *cached = parent->util;
-               if (!strcmp(cached->path, origin->path)) {
+       /* First check any existing origins */
+       for (porigin = parent->util; porigin; porigin = porigin->next)
+               if (!strcmp(porigin->path, origin->path)) {
                        /*
                         * The same path between origin and its parent
                         * without renaming -- the most common case.
                         */
-                       porigin = get_origin(sb, parent, cached->path);
-
-                       /*
-                        * If the origin was newly created (i.e. get_origin
-                        * would call make_origin if none is found in the
-                        * scoreboard), it does not know the blob_sha1/mode,
-                        * so copy it.  Otherwise porigin was in the
-                        * scoreboard and already knows blob_sha1/mode.
-                        */
-                       if (porigin->refcnt == 1) {
-                               hashcpy(porigin->blob_sha1, cached->blob_sha1);
-                               porigin->mode = cached->mode;
-                       }
-                       return porigin;
+                       return origin_incref (porigin);
                }
-               /* otherwise it was not very useful; free it */
-               free(parent->util);
-               parent->util = NULL;
-       }
 
        /* See if the origin->path is different between parent
         * and origin first.  Most of the time they are the
@@ -450,19 +602,6 @@ static struct origin *find_origin(struct scoreboard *sb,
        }
        diff_flush(&diff_opts);
        free_pathspec(&diff_opts.pathspec);
-       if (porigin) {
-               /*
-                * Create a freestanding copy that is not part of
-                * the refcounted origin found in the scoreboard, and
-                * cache it in the commit.
-                */
-               struct origin *cached;
-
-               cached = make_origin(porigin->commit, porigin->path);
-               hashcpy(cached->blob_sha1, porigin->blob_sha1);
-               cached->mode = porigin->mode;
-               parent->util = cached;
-       }
        return porigin;
 }
 
@@ -509,46 +648,31 @@ static struct origin *find_rename(struct scoreboard *sb,
 }
 
 /*
- * Link in a new blame entry to the scoreboard.  Entries that cover the
- * same line range have been removed from the scoreboard previously.
+ * Append a new blame entry to a given output queue.
  */
-static void add_blame_entry(struct scoreboard *sb, struct blame_entry *e)
+static void add_blame_entry(struct blame_entry ***queue, struct blame_entry *e)
 {
-       struct blame_entry *ent, *prev = NULL;
-
        origin_incref(e->suspect);
 
-       for (ent = sb->ent; ent && ent->lno < e->lno; ent = ent->next)
-               prev = ent;
-
-       /* prev, if not NULL, is the last one that is below e */
-
-       if (prev) {
-               e->next = prev->next;
-               prev->next = e;
-       }
-       else {
-               e->next = sb->ent;
-               sb->ent = e;
-       }
+       e->next = **queue;
+       **queue = e;
+       *queue = &e->next;
 }
 
 /*
  * src typically is on-stack; we want to copy the information in it to
- * a malloced blame_entry that is already on the linked list of the
- * scoreboard.  The origin of dst loses a refcnt while the origin of src
- * gains one.
+ * a malloced blame_entry that gets added to the given queue.  The
+ * origin of dst loses a refcnt.
  */
-static void dup_entry(struct blame_entry *dst, struct blame_entry *src)
+static void dup_entry(struct blame_entry ***queue,
+                     struct blame_entry *dst, struct blame_entry *src)
 {
-       struct blame_entry *n;
-
-       n = dst->next;
        origin_incref(src->suspect);
        origin_decref(dst->suspect);
        memcpy(dst, src, sizeof(*src));
-       dst->next = n;
-       dst->score = 0;
+       dst->next = **queue;
+       **queue = dst;
+       *queue = &dst->next;
 }
 
 static const char *nth_line(struct scoreboard *sb, long lno)
@@ -620,10 +744,11 @@ static void split_overlap(struct blame_entry *split,
 
 /*
  * split_overlap() divided an existing blame e into up to three parts
- * in split.  Adjust the linked list of blames in the scoreboard to
+ * in split.  Any assigned blame is moved to queue to
  * reflect the split.
  */
-static void split_blame(struct scoreboard *sb,
+static void split_blame(struct blame_entry ***blamed,
+                       struct blame_entry ***unblamed,
                        struct blame_entry *split,
                        struct blame_entry *e)
 {
@@ -631,61 +756,39 @@ static void split_blame(struct scoreboard *sb,
 
        if (split[0].suspect && split[2].suspect) {
                /* The first part (reuse storage for the existing entry e) */
-               dup_entry(e, &split[0]);
+               dup_entry(unblamed, e, &split[0]);
 
                /* The last part -- me */
                new_entry = xmalloc(sizeof(*new_entry));
                memcpy(new_entry, &(split[2]), sizeof(struct blame_entry));
-               add_blame_entry(sb, new_entry);
+               add_blame_entry(unblamed, new_entry);
 
                /* ... and the middle part -- parent */
                new_entry = xmalloc(sizeof(*new_entry));
                memcpy(new_entry, &(split[1]), sizeof(struct blame_entry));
-               add_blame_entry(sb, new_entry);
+               add_blame_entry(blamed, new_entry);
        }
        else if (!split[0].suspect && !split[2].suspect)
                /*
                 * The parent covers the entire area; reuse storage for
                 * e and replace it with the parent.
                 */
-               dup_entry(e, &split[1]);
+               dup_entry(blamed, e, &split[1]);
        else if (split[0].suspect) {
                /* me and then parent */
-               dup_entry(e, &split[0]);
+               dup_entry(unblamed, e, &split[0]);
 
                new_entry = xmalloc(sizeof(*new_entry));
                memcpy(new_entry, &(split[1]), sizeof(struct blame_entry));
-               add_blame_entry(sb, new_entry);
+               add_blame_entry(blamed, new_entry);
        }
        else {
                /* parent and then me */
-               dup_entry(e, &split[1]);
+               dup_entry(blamed, e, &split[1]);
 
                new_entry = xmalloc(sizeof(*new_entry));
                memcpy(new_entry, &(split[2]), sizeof(struct blame_entry));
-               add_blame_entry(sb, new_entry);
-       }
-
-       if (DEBUG) { /* sanity */
-               struct blame_entry *ent;
-               int lno = sb->ent->lno, corrupt = 0;
-
-               for (ent = sb->ent; ent; ent = ent->next) {
-                       if (lno != ent->lno)
-                               corrupt = 1;
-                       if (ent->s_lno < 0)
-                               corrupt = 1;
-                       lno += ent->num_lines;
-               }
-               if (corrupt) {
-                       lno = sb->ent->lno;
-                       for (ent = sb->ent; ent; ent = ent->next) {
-                               printf("L %8d l %8d n %8d\n",
-                                      lno, ent->lno, ent->num_lines);
-                               lno = ent->lno + ent->num_lines;
-                       }
-                       die("oops");
-               }
+               add_blame_entry(unblamed, new_entry);
        }
 }
 
@@ -702,74 +805,146 @@ static void decref_split(struct blame_entry *split)
 }
 
 /*
- * Helper for blame_chunk().  blame_entry e is known to overlap with
- * the patch hunk; split it and pass blame to the parent.
+ * reverse_blame reverses the list given in head, appending tail.
+ * That allows us to build lists in reverse order, then reverse them
+ * afterwards.  This can be faster than building the list in proper
+ * order right away.  The reason is that building in proper order
+ * requires writing a link in the _previous_ element, while building
+ * in reverse order just requires placing the list head into the
+ * _current_ element.
  */
-static void blame_overlap(struct scoreboard *sb, struct blame_entry *e,
-                         int tlno, int plno, int same,
-                         struct origin *parent)
-{
-       struct blame_entry split[3];
 
-       split_overlap(split, e, tlno, plno, same, parent);
-       if (split[1].suspect)
-               split_blame(sb, split, e);
-       decref_split(split);
-}
-
-/*
- * Find the line number of the last line the target is suspected for.
- */
-static int find_last_in_target(struct scoreboard *sb, struct origin *target)
+static struct blame_entry *reverse_blame(struct blame_entry *head,
+                                        struct blame_entry *tail)
 {
-       struct blame_entry *e;
-       int last_in_target = -1;
-
-       for (e = sb->ent; e; e = e->next) {
-               if (e->guilty || e->suspect != target)
-                       continue;
-               if (last_in_target < e->s_lno + e->num_lines)
-                       last_in_target = e->s_lno + e->num_lines;
+       while (head) {
+               struct blame_entry *next = head->next;
+               head->next = tail;
+               tail = head;
+               head = next;
        }
-       return last_in_target;
+       return tail;
 }
 
 /*
  * Process one hunk from the patch between the current suspect for
- * blame_entry e and its parent.  Find and split the overlap, and
- * pass blame to the overlapping part to the parent.
+ * blame_entry e and its parent.  This first blames any unfinished
+ * entries before the chunk (which is where target and parent start
+ * differing) on the parent, and then splits blame entries at the
+ * start and at the end of the difference region.  Since use of -M and
+ * -C options may lead to overlapping/duplicate source line number
+ * ranges, all we can rely on from sorting/merging is the order of the
+ * first suspect line number.
  */
-static void blame_chunk(struct scoreboard *sb,
-                       int tlno, int plno, int same,
-                       struct origin *target, struct origin *parent)
+static void blame_chunk(struct blame_entry ***dstq, struct blame_entry ***srcq,
+                       int tlno, int offset, int same,
+                       struct origin *parent)
 {
-       struct blame_entry *e;
+       struct blame_entry *e = **srcq;
+       struct blame_entry *samep = NULL, *diffp = NULL;
 
-       for (e = sb->ent; e; e = e->next) {
-               if (e->guilty || e->suspect != target)
-                       continue;
-               if (same <= e->s_lno)
-                       continue;
-               if (tlno < e->s_lno + e->num_lines)
-                       blame_overlap(sb, e, tlno, plno, same, parent);
+       while (e && e->s_lno < tlno) {
+               struct blame_entry *next = e->next;
+               /*
+                * current record starts before differing portion.  If
+                * it reaches into it, we need to split it up and
+                * examine the second part separately.
+                */
+               if (e->s_lno + e->num_lines > tlno) {
+                       /* Move second half to a new record */
+                       int len = tlno - e->s_lno;
+                       struct blame_entry *n = xcalloc(1, sizeof (struct blame_entry));
+                       n->suspect = e->suspect;
+                       n->lno = e->lno + len;
+                       n->s_lno = e->s_lno + len;
+                       n->num_lines = e->num_lines - len;
+                       e->num_lines = len;
+                       e->score = 0;
+                       /* Push new record to diffp */
+                       n->next = diffp;
+                       diffp = n;
+               } else
+                       origin_decref(e->suspect);
+               /* Pass blame for everything before the differing
+                * chunk to the parent */
+               e->suspect = origin_incref(parent);
+               e->s_lno += offset;
+               e->next = samep;
+               samep = e;
+               e = next;
+       }
+       /*
+        * As we don't know how much of a common stretch after this
+        * diff will occur, the currently blamed parts are all that we
+        * can assign to the parent for now.
+        */
+
+       if (samep) {
+               **dstq = reverse_blame(samep, **dstq);
+               *dstq = &samep->next;
        }
+       /*
+        * Prepend the split off portions: everything after e starts
+        * after the blameable portion.
+        */
+       e = reverse_blame(diffp, e);
+
+       /*
+        * Now retain records on the target while parts are different
+        * from the parent.
+        */
+       samep = NULL;
+       diffp = NULL;
+       while (e && e->s_lno < same) {
+               struct blame_entry *next = e->next;
+
+               /*
+                * If current record extends into sameness, need to split.
+                */
+               if (e->s_lno + e->num_lines > same) {
+                       /*
+                        * Move second half to a new record to be
+                        * processed by later chunks
+                        */
+                       int len = same - e->s_lno;
+                       struct blame_entry *n = xcalloc(1, sizeof (struct blame_entry));
+                       n->suspect = origin_incref(e->suspect);
+                       n->lno = e->lno + len;
+                       n->s_lno = e->s_lno + len;
+                       n->num_lines = e->num_lines - len;
+                       e->num_lines = len;
+                       e->score = 0;
+                       /* Push new record to samep */
+                       n->next = samep;
+                       samep = n;
+               }
+               e->next = diffp;
+               diffp = e;
+               e = next;
+       }
+       **srcq = reverse_blame(diffp, reverse_blame(samep, e));
+       /* Move across elements that are in the unblamable portion */
+       if (diffp)
+               *srcq = &diffp->next;
 }
 
 struct blame_chunk_cb_data {
-       struct scoreboard *sb;
-       struct origin *target;
        struct origin *parent;
-       long plno;
-       long tlno;
+       long offset;
+       struct blame_entry **dstq;
+       struct blame_entry **srcq;
 };
 
+/* diff chunks are from parent to target */
 static int blame_chunk_cb(long start_a, long count_a,
                          long start_b, long count_b, void *data)
 {
        struct blame_chunk_cb_data *d = data;
-       blame_chunk(d->sb, d->tlno, d->plno, start_b, d->target, d->parent);
-       d->plno = start_a + count_a;
-       d->tlno = start_b + count_b;
+       if (start_a - start_b != d->offset)
+               die("internal error in blame::blame_chunk_cb");
+       blame_chunk(&d->dstq, &d->srcq, start_b, start_a - start_b,
+                   start_b + count_b, d->parent);
+       d->offset = start_a + count_a - (start_b + count_b);
        return 0;
 }
 
@@ -778,29 +953,32 @@ static int blame_chunk_cb(long start_a, long count_a,
  * for the lines it is suspected to its parent.  Run diff to find
  * which lines came from parent and pass blame for them.
  */
-static int pass_blame_to_parent(struct scoreboard *sb,
-                               struct origin *target,
-                               struct origin *parent)
+static void pass_blame_to_parent(struct scoreboard *sb,
+                                struct origin *target,
+                                struct origin *parent)
 {
-       int last_in_target;
        mmfile_t file_p, file_o;
        struct blame_chunk_cb_data d;
+       struct blame_entry *newdest = NULL;
 
-       memset(&d, 0, sizeof(d));
-       d.sb = sb; d.target = target; d.parent = parent;
-       last_in_target = find_last_in_target(sb, target);
-       if (last_in_target < 0)
-               return 1; /* nothing remains for this target */
+       if (!target->suspects)
+               return; /* nothing remains for this target */
+
+       d.parent = parent;
+       d.offset = 0;
+       d.dstq = &newdest; d.srcq = &target->suspects;
 
        fill_origin_blob(&sb->revs->diffopt, parent, &file_p);
        fill_origin_blob(&sb->revs->diffopt, target, &file_o);
        num_get_patch++;
 
        diff_hunks(&file_p, &file_o, 0, blame_chunk_cb, &d);
-       /* The rest (i.e. anything after tlno) are the same as the parent */
-       blame_chunk(sb, d.tlno, d.plno, last_in_target, target, parent);
+       /* The rest are the same as the parent */
+       blame_chunk(&d.dstq, &d.srcq, INT_MAX, d.offset, INT_MAX, parent);
+       *d.dstq = NULL;
+       queue_blames(sb, parent, newdest);
 
-       return 0;
+       return;
 }
 
 /*
@@ -945,43 +1123,80 @@ static void find_copy_in_blob(struct scoreboard *sb,
        handle_split(sb, ent, d.tlno, d.plno, ent->num_lines, parent, split);
 }
 
+/* Move all blame entries from list *source that have a score smaller
+ * than score_min to the front of list *small.
+ * Returns a pointer to the link pointing to the old head of the small list.
+ */
+
+static struct blame_entry **filter_small(struct scoreboard *sb,
+                                        struct blame_entry **small,
+                                        struct blame_entry **source,
+                                        unsigned score_min)
+{
+       struct blame_entry *p = *source;
+       struct blame_entry *oldsmall = *small;
+       while (p) {
+               if (ent_score(sb, p) <= score_min) {
+                       *small = p;
+                       small = &p->next;
+                       p = *small;
+               } else {
+                       *source = p;
+                       source = &p->next;
+                       p = *source;
+               }
+       }
+       *small = oldsmall;
+       *source = NULL;
+       return small;
+}
+
 /*
  * See if lines currently target is suspected for can be attributed to
  * parent.
  */
-static int find_move_in_parent(struct scoreboard *sb,
-                              struct origin *target,
-                              struct origin *parent)
+static void find_move_in_parent(struct scoreboard *sb,
+                               struct blame_entry ***blamed,
+                               struct blame_entry **toosmall,
+                               struct origin *target,
+                               struct origin *parent)
 {
-       int last_in_target, made_progress;
        struct blame_entry *e, split[3];
+       struct blame_entry *unblamed = target->suspects;
+       struct blame_entry *leftover = NULL;
        mmfile_t file_p;
 
-       last_in_target = find_last_in_target(sb, target);
-       if (last_in_target < 0)
-               return 1; /* nothing remains for this target */
+       if (!unblamed)
+               return; /* nothing remains for this target */
 
        fill_origin_blob(&sb->revs->diffopt, parent, &file_p);
        if (!file_p.ptr)
-               return 0;
+               return;
 
-       made_progress = 1;
-       while (made_progress) {
-               made_progress = 0;
-               for (e = sb->ent; e; e = e->next) {
-                       if (e->guilty || e->suspect != target ||
-                           ent_score(sb, e) < blame_move_score)
-                               continue;
+       /* At each iteration, unblamed has a NULL-terminated list of
+        * entries that have not yet been tested for blame.  leftover
+        * contains the reversed list of entries that have been tested
+        * without being assignable to the parent.
+        */
+       do {
+               struct blame_entry **unblamedtail = &unblamed;
+               struct blame_entry *next;
+               for (e = unblamed; e; e = next) {
+                       next = e->next;
                        find_copy_in_blob(sb, e, parent, split, &file_p);
                        if (split[1].suspect &&
                            blame_move_score < ent_score(sb, &split[1])) {
-                               split_blame(sb, split, e);
-                               made_progress = 1;
+                               split_blame(blamed, &unblamedtail, split, e);
+                       } else {
+                               e->next = leftover;
+                               leftover = e;
                        }
                        decref_split(split);
                }
-       }
-       return 0;
+               *unblamedtail = NULL;
+               toosmall = filter_small(sb, toosmall, &unblamed, blame_move_score);
+       } while (unblamed);
+       target->suspects = reverse_blame(leftover, NULL);
 }
 
 struct blame_list {
@@ -993,62 +1208,46 @@ struct blame_list {
  * Count the number of entries the target is suspected for,
  * and prepare a list of entry and the best split.
  */
-static struct blame_list *setup_blame_list(struct scoreboard *sb,
-                                          struct origin *target,
-                                          int min_score,
+static struct blame_list *setup_blame_list(struct blame_entry *unblamed,
                                           int *num_ents_p)
 {
        struct blame_entry *e;
        int num_ents, i;
        struct blame_list *blame_list = NULL;
 
-       for (e = sb->ent, num_ents = 0; e; e = e->next)
-               if (!e->scanned && !e->guilty &&
-                   e->suspect == target &&
-                   min_score < ent_score(sb, e))
-                       num_ents++;
+       for (e = unblamed, num_ents = 0; e; e = e->next)
+               num_ents++;
        if (num_ents) {
                blame_list = xcalloc(num_ents, sizeof(struct blame_list));
-               for (e = sb->ent, i = 0; e; e = e->next)
-                       if (!e->scanned && !e->guilty &&
-                           e->suspect == target &&
-                           min_score < ent_score(sb, e))
-                               blame_list[i++].ent = e;
+               for (e = unblamed, i = 0; e; e = e->next)
+                       blame_list[i++].ent = e;
        }
        *num_ents_p = num_ents;
        return blame_list;
 }
 
-/*
- * Reset the scanned status on all entries.
- */
-static void reset_scanned_flag(struct scoreboard *sb)
-{
-       struct blame_entry *e;
-       for (e = sb->ent; e; e = e->next)
-               e->scanned = 0;
-}
-
 /*
  * For lines target is suspected for, see if we can find code movement
  * across file boundary from the parent commit.  porigin is the path
  * in the parent we already tried.
  */
-static int find_copy_in_parent(struct scoreboard *sb,
-                              struct origin *target,
-                              struct commit *parent,
-                              struct origin *porigin,
-                              int opt)
+static void find_copy_in_parent(struct scoreboard *sb,
+                               struct blame_entry ***blamed,
+                               struct blame_entry **toosmall,
+                               struct origin *target,
+                               struct commit *parent,
+                               struct origin *porigin,
+                               int opt)
 {
        struct diff_options diff_opts;
        int i, j;
-       int retval;
        struct blame_list *blame_list;
        int num_ents;
+       struct blame_entry *unblamed = target->suspects;
+       struct blame_entry *leftover = NULL;
 
-       blame_list = setup_blame_list(sb, target, blame_copy_score, &num_ents);
-       if (!blame_list)
-               return 1; /* nothing remains for this target */
+       if (!unblamed)
+               return; /* nothing remains for this target */
 
        diff_setup(&diff_opts);
        DIFF_OPT_SET(&diff_opts, RECURSIVE);
@@ -1078,9 +1277,9 @@ static int find_copy_in_parent(struct scoreboard *sb,
        if (!DIFF_OPT_TST(&diff_opts, FIND_COPIES_HARDER))
                diffcore_std(&diff_opts);
 
-       retval = 0;
-       while (1) {
-               int made_progress = 0;
+       do {
+               struct blame_entry **unblamedtail = &unblamed;
+               blame_list = setup_blame_list(unblamed, &num_ents);
 
                for (i = 0; i < diff_queued_diff.nr; i++) {
                        struct diff_filepair *p = diff_queued_diff.queue[i];
@@ -1117,27 +1316,21 @@ static int find_copy_in_parent(struct scoreboard *sb,
                        struct blame_entry *split = blame_list[j].split;
                        if (split[1].suspect &&
                            blame_copy_score < ent_score(sb, &split[1])) {
-                               split_blame(sb, split, blame_list[j].ent);
-                               made_progress = 1;
+                               split_blame(blamed, &unblamedtail, split,
+                                           blame_list[j].ent);
+                       } else {
+                               blame_list[j].ent->next = leftover;
+                               leftover = blame_list[j].ent;
                        }
-                       else
-                               blame_list[j].ent->scanned = 1;
                        decref_split(split);
                }
                free(blame_list);
-
-               if (!made_progress)
-                       break;
-               blame_list = setup_blame_list(sb, target, blame_copy_score, &num_ents);
-               if (!blame_list) {
-                       retval = 1;
-                       break;
-               }
-       }
-       reset_scanned_flag(sb);
+               *unblamedtail = NULL;
+               toosmall = filter_small(sb, toosmall, &unblamed, blame_copy_score);
+       } while (unblamed);
+       target->suspects = reverse_blame(leftover, NULL);
        diff_flush(&diff_opts);
        free_pathspec(&diff_opts.pathspec);
-       return retval;
 }
 
 /*
@@ -1147,20 +1340,21 @@ static int find_copy_in_parent(struct scoreboard *sb,
 static void pass_whole_blame(struct scoreboard *sb,
                             struct origin *origin, struct origin *porigin)
 {
-       struct blame_entry *e;
+       struct blame_entry *e, *suspects;
 
        if (!porigin->file.ptr && origin->file.ptr) {
                /* Steal its file */
                porigin->file = origin->file;
                origin->file.ptr = NULL;
        }
-       for (e = sb->ent; e; e = e->next) {
-               if (e->suspect != origin)
-                       continue;
+       suspects = origin->suspects;
+       origin->suspects = NULL;
+       for (e = suspects; e; e = e->next) {
                origin_incref(porigin);
                origin_decref(e->suspect);
                e->suspect = porigin;
        }
+       queue_blames(sb, porigin, suspects);
 }
 
 /*
@@ -1177,11 +1371,29 @@ static struct commit_list *first_scapegoat(struct rev_info *revs, struct commit
 
 static int num_scapegoats(struct rev_info *revs, struct commit *commit)
 {
-       int cnt;
        struct commit_list *l = first_scapegoat(revs, commit);
-       for (cnt = 0; l; l = l->next)
-               cnt++;
-       return cnt;
+       return commit_list_count(l);
+}
+
+/* Distribute collected unsorted blames to the respected sorted lists
+ * in the various origins.
+ */
+static void distribute_blame(struct scoreboard *sb, struct blame_entry *blamed)
+{
+       blamed = blame_sort(blamed, compare_blame_suspect);
+       while (blamed)
+       {
+               struct origin *porigin = blamed->suspect;
+               struct blame_entry *suspects = NULL;
+               do {
+                       struct blame_entry *next = blamed->next;
+                       blamed->next = suspects;
+                       suspects = blamed;
+                       blamed = next;
+               } while (blamed && blamed->suspect == porigin);
+               suspects = reverse_blame(suspects, NULL);
+               queue_blames(sb, porigin, suspects);
+       }
 }
 
 #define MAXSG 16
@@ -1194,6 +1406,8 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
        struct commit_list *sg;
        struct origin *sg_buf[MAXSG];
        struct origin *porigin, **sg_origin = sg_buf;
+       struct blame_entry *toosmall = NULL;
+       struct blame_entry *blames, **blametail = &blames;
 
        num_sg = num_scapegoats(revs, commit);
        if (!num_sg)
@@ -1255,38 +1469,71 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
                        origin_incref(porigin);
                        origin->previous = porigin;
                }
-               if (pass_blame_to_parent(sb, origin, porigin))
+               pass_blame_to_parent(sb, origin, porigin);
+               if (!origin->suspects)
                        goto finish;
        }
 
        /*
         * Optionally find moves in parents' files.
         */
-       if (opt & PICKAXE_BLAME_MOVE)
-               for (i = 0, sg = first_scapegoat(revs, commit);
-                    i < num_sg && sg;
-                    sg = sg->next, i++) {
-                       struct origin *porigin = sg_origin[i];
-                       if (!porigin)
-                               continue;
-                       if (find_move_in_parent(sb, origin, porigin))
-                               goto finish;
+       if (opt & PICKAXE_BLAME_MOVE) {
+               filter_small(sb, &toosmall, &origin->suspects, blame_move_score);
+               if (origin->suspects) {
+                       for (i = 0, sg = first_scapegoat(revs, commit);
+                            i < num_sg && sg;
+                            sg = sg->next, i++) {
+                               struct origin *porigin = sg_origin[i];
+                               if (!porigin)
+                                       continue;
+                               find_move_in_parent(sb, &blametail, &toosmall, origin, porigin);
+                               if (!origin->suspects)
+                                       break;
+                       }
                }
+       }
 
        /*
         * Optionally find copies from parents' files.
         */
-       if (opt & PICKAXE_BLAME_COPY)
+       if (opt & PICKAXE_BLAME_COPY) {
+               if (blame_copy_score > blame_move_score)
+                       filter_small(sb, &toosmall, &origin->suspects, blame_copy_score);
+               else if (blame_copy_score < blame_move_score) {
+                       origin->suspects = blame_merge(origin->suspects, toosmall);
+                       toosmall = NULL;
+                       filter_small(sb, &toosmall, &origin->suspects, blame_copy_score);
+               }
+               if (!origin->suspects)
+                       goto finish;
+
                for (i = 0, sg = first_scapegoat(revs, commit);
                     i < num_sg && sg;
                     sg = sg->next, i++) {
                        struct origin *porigin = sg_origin[i];
-                       if (find_copy_in_parent(sb, origin, sg->item,
-                                               porigin, opt))
+                       find_copy_in_parent(sb, &blametail, &toosmall,
+                                           origin, sg->item, porigin, opt);
+                       if (!origin->suspects)
                                goto finish;
                }
+       }
 
- finish:
+finish:
+       *blametail = NULL;
+       distribute_blame(sb, blames);
+       /*
+        * prepend toosmall to origin->suspects
+        *
+        * There is no point in sorting: this ends up on a big
+        * unsorted list in the caller anyway.
+        */
+       if (toosmall) {
+               struct blame_entry **tail = &toosmall;
+               while (*tail)
+                       tail = &(*tail)->next;
+               *tail = origin->suspects;
+               origin->suspects = toosmall;
+       }
        for (i = 0; i < num_sg; i++) {
                if (sg_origin[i]) {
                        drop_origin_blob(sg_origin[i]);
@@ -1481,14 +1728,11 @@ static int emit_one_suspect_detail(struct origin *suspect, int repeat)
 }
 
 /*
- * The blame_entry is found to be guilty for the range.  Mark it
- * as such, and show it in incremental output.
+ * The blame_entry is found to be guilty for the range.
+ * Show it in incremental output.
  */
 static void found_guilty_entry(struct blame_entry *ent)
 {
-       if (ent->guilty)
-               return;
-       ent->guilty = 1;
        if (incremental) {
                struct origin *suspect = ent->suspect;
 
@@ -1502,32 +1746,34 @@ static void found_guilty_entry(struct blame_entry *ent)
 }
 
 /*
- * The main loop -- while the scoreboard has lines whose true origin
- * is still unknown, pick one blame_entry, and allow its current
- * suspect to pass blames to its parents.
- */
+ * The main loop -- while we have blobs with lines whose true origin
+ * is still unknown, pick one blob, and allow its lines to pass blames
+ * to its parents. */
 static void assign_blame(struct scoreboard *sb, int opt)
 {
        struct rev_info *revs = sb->revs;
+       struct commit *commit = prio_queue_get(&sb->commits);
 
-       while (1) {
+       while (commit) {
                struct blame_entry *ent;
-               struct commit *commit;
-               struct origin *suspect = NULL;
+               struct origin *suspect = commit->util;
 
                /* find one suspect to break down */
-               for (ent = sb->ent; !suspect && ent; ent = ent->next)
-                       if (!ent->guilty)
-                               suspect = ent->suspect;
-               if (!suspect)
-                       return; /* all done */
+               while (suspect && !suspect->suspects)
+                       suspect = suspect->next;
+
+               if (!suspect) {
+                       commit = prio_queue_get(&sb->commits);
+                       continue;
+               }
+
+               assert(commit == suspect->commit);
 
                /*
                 * We will use this suspect later in the loop,
                 * so hold onto it in the meantime.
                 */
                origin_incref(suspect);
-               commit = suspect->commit;
                parse_commit(commit);
                if (reverse ||
                    (!(commit->object.flags & UNINTERESTING) &&
@@ -1543,9 +1789,22 @@ static void assign_blame(struct scoreboard *sb, int opt)
                        commit->object.flags |= UNINTERESTING;
 
                /* Take responsibility for the remaining entries */
-               for (ent = sb->ent; ent; ent = ent->next)
-                       if (ent->suspect == suspect)
+               ent = suspect->suspects;
+               if (ent) {
+                       suspect->guilty = 1;
+                       for (;;) {
+                               struct blame_entry *next = ent->next;
                                found_guilty_entry(ent);
+                               if (next) {
+                                       ent = next;
+                                       continue;
+                               }
+                               ent->next = sb->ent;
+                               sb->ent = suspect->suspects;
+                               suspect->suspects = NULL;
+                               break;
+                       }
+               }
                origin_decref(suspect);
 
                if (DEBUG) /* sanity */
@@ -1609,9 +1868,8 @@ static void emit_porcelain(struct scoreboard *sb, struct blame_entry *ent,
        char hex[41];
 
        strcpy(hex, sha1_to_hex(suspect->commit->object.sha1));
-       printf("%s%c%d %d %d\n",
+       printf("%s %d %d %d\n",
               hex,
-              ent->guilty ? ' ' : '*', /* purely for debugging */
               ent->s_lno + 1,
               ent->lno + 1,
               ent->num_lines);
@@ -1724,17 +1982,16 @@ static void output(struct scoreboard *sb, int option)
 
        if (option & OUTPUT_PORCELAIN) {
                for (ent = sb->ent; ent; ent = ent->next) {
-                       struct blame_entry *oth;
-                       struct origin *suspect = ent->suspect;
-                       struct commit *commit = suspect->commit;
+                       int count = 0;
+                       struct origin *suspect;
+                       struct commit *commit = ent->suspect->commit;
                        if (commit->object.flags & MORE_THAN_ONE_PATH)
                                continue;
-                       for (oth = ent->next; oth; oth = oth->next) {
-                               if ((oth->suspect->commit != commit) ||
-                                   !strcmp(oth->suspect->path, suspect->path))
-                                       continue;
-                               commit->object.flags |= MORE_THAN_ONE_PATH;
-                               break;
+                       for (suspect = commit->util; suspect; suspect = suspect->next) {
+                               if (suspect->guilty && count++) {
+                                       commit->object.flags |= MORE_THAN_ONE_PATH;
+                                       break;
+                               }
                        }
                }
        }
@@ -1748,6 +2005,12 @@ static void output(struct scoreboard *sb, int option)
        }
 }
 
+static const char *get_next_line(const char *start, const char *end)
+{
+       const char *nl = memchr(start, '\n', end - start);
+       return nl ? nl + 1 : end;
+}
+
 /*
  * To allow quick access to the contents of nth line in the
  * final image, prepare an index in the scoreboard.
@@ -1759,39 +2022,19 @@ static int prepare_lines(struct scoreboard *sb)
        const char *end = buf + len;
        const char *p;
        int *lineno;
-       int num = 0, incomplete = 0;
-
-       for (p = buf;;) {
-               p = memchr(p, '\n', end - p);
-               if (p) {
-                       p++;
-                       num++;
-                       continue;
-               }
-               break;
-       }
+       int num = 0;
 
-       if (len && end[-1] != '\n')
-               incomplete++; /* incomplete line at the end */
+       for (p = buf; p < end; p = get_next_line(p, end))
+               num++;
 
-       sb->lineno = xmalloc(sizeof(*sb->lineno) * (num + incomplete + 1));
-       lineno = sb->lineno;
+       sb->lineno = lineno = xmalloc(sizeof(*sb->lineno) * (num + 1));
 
-       *lineno++ = 0;
-       for (p = buf;;) {
-               p = memchr(p, '\n', end - p);
-               if (p) {
-                       p++;
-                       *lineno++ = p - buf;
-                       continue;
-               }
-               break;
-       }
+       for (p = buf; p < end; p = get_next_line(p, end))
+               *lineno++ = p - buf;
 
-       if (incomplete)
-               *lineno++ = len;
+       *lineno = len;
 
-       sb->num_lines = num + incomplete;
+       sb->num_lines = num;
        return sb->num_lines;
 }
 
@@ -2041,7 +2284,6 @@ static struct commit *fake_working_tree_commit(struct diff_options *opt,
        commit = alloc_commit_node();
        commit->object.parsed = 1;
        commit->date = now;
-       commit->object.type = OBJ_COMMIT;
        parent_tail = &commit->parents;
 
        if (!resolve_ref_unsafe("HEAD", head_sha1, 1, NULL))
@@ -2110,7 +2352,6 @@ static struct commit *fake_working_tree_commit(struct diff_options *opt,
        origin->file.ptr = buf.buf;
        origin->file.size = buf.len;
        pretend_sha1_file(buf.buf, buf.len, OBJ_BLOB, origin->blob_sha1);
-       commit->util = origin;
 
        /*
         * Read the current index, replace the path entry with
@@ -2144,7 +2385,7 @@ static struct commit *fake_working_tree_commit(struct diff_options *opt,
         * right now, but someday we might optimize diff-index --cached
         * with cache-tree information.
         */
-       cache_tree_invalidate_path(active_cache_tree, path);
+       cache_tree_invalidate_path(&the_index, path);
 
        return commit;
 }
@@ -2428,12 +2669,16 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
        memset(&sb, 0, sizeof(sb));
 
        sb.revs = &revs;
-       if (!reverse)
+       if (!reverse) {
                final_commit_name = prepare_final(&sb);
+               sb.commits.compare = compare_commits_by_commit_date;
+       }
        else if (contents_from)
                die("--contents and --children do not blend well.");
-       else
+       else {
                final_commit_name = prepare_initial(&sb);
+               sb.commits.compare = compare_commits_by_reverse_commit_date;
+       }
 
        if (!sb.final) {
                /*
@@ -2519,12 +2764,16 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
                ent->next = next;
                origin_incref(o);
        }
+
+       o->suspects = ent;
+       prio_queue_put(&sb.commits, o->commit);
+
        origin_decref(o);
 
        range_set_release(&ranges);
        string_list_clear(&range_list, 0);
 
-       sb.ent = ent;
+       sb.ent = NULL;
        sb.path = path;
 
        read_mailmap(&mailmap, NULL);
@@ -2537,6 +2786,8 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
        if (incremental)
                return 0;
 
+       sb.ent = blame_sort(sb.ent, compare_blame_final);
+
        coalesce(&sb);
 
        if (!(output_option & OUTPUT_PORCELAIN))