Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 557 insertions, 0 deletions

diff --git a/pack-bitmap-write.c b/pack-bitmap-write.c
new file mode 100644
index 000000000000..fa78a460c9aa
--- /dev/null
+++ b/pack-bitmap-write.c
@@ -0,0 +1,557 @@
+#include "cache.h"
+#include "object-store.h"
+#include "commit.h"
+#include "tag.h"
+#include "diff.h"
+#include "revision.h"
+#include "list-objects.h"
+#include "progress.h"
+#include "pack-revindex.h"
+#include "pack.h"
+#include "pack-bitmap.h"
+#include "sha1-lookup.h"
+#include "pack-objects.h"
+#include "commit-reach.h"
+
+struct bitmapped_commit {
+	struct commit *commit;
+	struct ewah_bitmap *bitmap;
+	struct ewah_bitmap *write_as;
+	int flags;
+	int xor_offset;
+	uint32_t commit_pos;
+};
+
+struct bitmap_writer {
+	struct ewah_bitmap *commits;
+	struct ewah_bitmap *trees;
+	struct ewah_bitmap *blobs;
+	struct ewah_bitmap *tags;
+
+	kh_oid_map_t *bitmaps;
+	kh_oid_map_t *reused;
+	struct packing_data *to_pack;
+
+	struct bitmapped_commit *selected;
+	unsigned int selected_nr, selected_alloc;
+
+	struct progress *progress;
+	int show_progress;
+	unsigned char pack_checksum[GIT_MAX_RAWSZ];
+};
+
+static struct bitmap_writer writer;
+
+void bitmap_writer_show_progress(int show)
+{
+	writer.show_progress = show;
+}
+
+/**
+ * Build the initial type index for the packfile
+ */
+void bitmap_writer_build_type_index(struct packing_data *to_pack,
+				    struct pack_idx_entry **index,
+				    uint32_t index_nr)
+{
+	uint32_t i;
+
+	writer.commits = ewah_new();
+	writer.trees = ewah_new();
+	writer.blobs = ewah_new();
+	writer.tags = ewah_new();
+	ALLOC_ARRAY(to_pack->in_pack_pos, to_pack->nr_objects);
+
+	for (i = 0; i < index_nr; ++i) {
+		struct object_entry *entry = (struct object_entry *)index[i];
+		enum object_type real_type;
+
+		oe_set_in_pack_pos(to_pack, entry, i);
+
+		switch (oe_type(entry)) {
+		case OBJ_COMMIT:
+		case OBJ_TREE:
+		case OBJ_BLOB:
+		case OBJ_TAG:
+			real_type = oe_type(entry);
+			break;
+
+		default:
+			real_type = oid_object_info(to_pack->repo,
+						    &entry->idx.oid, NULL);
+			break;
+		}
+
+		switch (real_type) {
+		case OBJ_COMMIT:
+			ewah_set(writer.commits, i);
+			break;
+
+		case OBJ_TREE:
+			ewah_set(writer.trees, i);
+			break;
+
+		case OBJ_BLOB:
+			ewah_set(writer.blobs, i);
+			break;
+
+		case OBJ_TAG:
+			ewah_set(writer.tags, i);
+			break;
+
+		default:
+			die("Missing type information for %s (%d/%d)",
+			    oid_to_hex(&entry->idx.oid), real_type,
+			    oe_type(entry));
+		}
+	}
+}
+
+/**
+ * Compute the actual bitmaps
+ */
+static struct object **seen_objects;
+static unsigned int seen_objects_nr, seen_objects_alloc;
+
+static inline void push_bitmapped_commit(struct commit *commit, struct ewah_bitmap *reused)
+{
+	if (writer.selected_nr >= writer.selected_alloc) {
+		writer.selected_alloc = (writer.selected_alloc + 32) * 2;
+		REALLOC_ARRAY(writer.selected, writer.selected_alloc);
+	}
+
+	writer.selected[writer.selected_nr].commit = commit;
+	writer.selected[writer.selected_nr].bitmap = reused;
+	writer.selected[writer.selected_nr].flags = 0;
+
+	writer.selected_nr++;
+}
+
+static inline void mark_as_seen(struct object *object)
+{
+	ALLOC_GROW(seen_objects, seen_objects_nr + 1, seen_objects_alloc);
+	seen_objects[seen_objects_nr++] = object;
+}
+
+static inline void reset_all_seen(void)
+{
+	unsigned int i;
+	for (i = 0; i < seen_objects_nr; ++i) {
+		seen_objects[i]->flags &= ~(SEEN | ADDED | SHOWN);
+	}
+	seen_objects_nr = 0;
+}
+
+static uint32_t find_object_pos(const struct object_id *oid)
+{
+	struct object_entry *entry = packlist_find(writer.to_pack, oid, NULL);
+
+	if (!entry) {
+		die("Failed to write bitmap index. Packfile doesn't have full closure "
+			"(object %s is missing)", oid_to_hex(oid));
+	}
+
+	return oe_in_pack_pos(writer.to_pack, entry);
+}
+
+static void show_object(struct object *object, const char *name, void *data)
+{
+	struct bitmap *base = data;
+	bitmap_set(base, find_object_pos(&object->oid));
+	mark_as_seen(object);
+}
+
+static void show_commit(struct commit *commit, void *data)
+{
+	mark_as_seen((struct object *)commit);
+}
+
+static int
+add_to_include_set(struct bitmap *base, struct commit *commit)
+{
+	khiter_t hash_pos;
+	uint32_t bitmap_pos = find_object_pos(&commit->object.oid);
+
+	if (bitmap_get(base, bitmap_pos))
+		return 0;
+
+	hash_pos = kh_get_oid_map(writer.bitmaps, commit->object.oid);
+	if (hash_pos < kh_end(writer.bitmaps)) {
+		struct bitmapped_commit *bc = kh_value(writer.bitmaps, hash_pos);
+		bitmap_or_ewah(base, bc->bitmap);
+		return 0;
+	}
+
+	bitmap_set(base, bitmap_pos);
+	return 1;
+}
+
+static int
+should_include(struct commit *commit, void *_data)
+{
+	struct bitmap *base = _data;
+
+	if (!add_to_include_set(base, commit)) {
+		struct commit_list *parent = commit->parents;
+
+		mark_as_seen((struct object *)commit);
+
+		while (parent) {
+			parent->item->object.flags |= SEEN;
+			mark_as_seen((struct object *)parent->item);
+			parent = parent->next;
+		}
+
+		return 0;
+	}
+
+	return 1;
+}
+
+static void compute_xor_offsets(void)
+{
+	static const int MAX_XOR_OFFSET_SEARCH = 10;
+
+	int i, next = 0;
+
+	while (next < writer.selected_nr) {
+		struct bitmapped_commit *stored = &writer.selected[next];
+
+		int best_offset = 0;
+		struct ewah_bitmap *best_bitmap = stored->bitmap;
+		struct ewah_bitmap *test_xor;
+
+		for (i = 1; i <= MAX_XOR_OFFSET_SEARCH; ++i) {
+			int curr = next - i;
+
+			if (curr < 0)
+				break;
+
+			test_xor = ewah_pool_new();
+			ewah_xor(writer.selected[curr].bitmap, stored->bitmap, test_xor);
+
+			if (test_xor->buffer_size < best_bitmap->buffer_size) {
+				if (best_bitmap != stored->bitmap)
+					ewah_pool_free(best_bitmap);
+
+				best_bitmap = test_xor;
+				best_offset = i;
+			} else {
+				ewah_pool_free(test_xor);
+			}
+		}
+
+		stored->xor_offset = best_offset;
+		stored->write_as = best_bitmap;
+
+		next++;
+	}
+}
+
+void bitmap_writer_build(struct packing_data *to_pack)
+{
+	static const double REUSE_BITMAP_THRESHOLD = 0.2;
+
+	int i, reuse_after, need_reset;
+	struct bitmap *base = bitmap_new();
+	struct rev_info revs;
+
+	writer.bitmaps = kh_init_oid_map();
+	writer.to_pack = to_pack;
+
+	if (writer.show_progress)
+		writer.progress = start_progress("Building bitmaps", writer.selected_nr);
+
+	repo_init_revisions(to_pack->repo, &revs, NULL);
+	revs.tag_objects = 1;
+	revs.tree_objects = 1;
+	revs.blob_objects = 1;
+	revs.no_walk = 0;
+
+	revs.include_check = should_include;
+	reset_revision_walk();
+
+	reuse_after = writer.selected_nr * REUSE_BITMAP_THRESHOLD;
+	need_reset = 0;
+
+	for (i = writer.selected_nr - 1; i >= 0; --i) {
+		struct bitmapped_commit *stored;
+		struct object *object;
+
+		khiter_t hash_pos;
+		int hash_ret;
+
+		stored = &writer.selected[i];
+		object = (struct object *)stored->commit;
+
+		if (stored->bitmap == NULL) {
+			if (i < writer.selected_nr - 1 &&
+			    (need_reset ||
+			     !in_merge_bases(writer.selected[i + 1].commit,
+					     stored->commit))) {
+			    bitmap_reset(base);
+			    reset_all_seen();
+			}
+
+			add_pending_object(&revs, object, "");
+			revs.include_check_data = base;
+
+			if (prepare_revision_walk(&revs))
+				die("revision walk setup failed");
+
+			traverse_commit_list(&revs, show_commit, show_object, base);
+
+			object_array_clear(&revs.pending);
+
+			stored->bitmap = bitmap_to_ewah(base);
+			need_reset = 0;
+		} else
+			need_reset = 1;
+
+		if (i >= reuse_after)
+			stored->flags |= BITMAP_FLAG_REUSE;
+
+		hash_pos = kh_put_oid_map(writer.bitmaps, object->oid, &hash_ret);
+		if (hash_ret == 0)
+			die("Duplicate entry when writing index: %s",
+			    oid_to_hex(&object->oid));
+
+		kh_value(writer.bitmaps, hash_pos) = stored;
+		display_progress(writer.progress, writer.selected_nr - i);
+	}
+
+	bitmap_free(base);
+	stop_progress(&writer.progress);
+
+	compute_xor_offsets();
+}
+
+/**
+ * Select the commits that will be bitmapped
+ */
+static inline unsigned int next_commit_index(unsigned int idx)
+{
+	static const unsigned int MIN_COMMITS = 100;
+	static const unsigned int MAX_COMMITS = 5000;
+
+	static const unsigned int MUST_REGION = 100;
+	static const unsigned int MIN_REGION = 20000;
+
+	unsigned int offset, next;
+
+	if (idx <= MUST_REGION)
+		return 0;
+
+	if (idx <= MIN_REGION) {
+		offset = idx - MUST_REGION;
+		return (offset < MIN_COMMITS) ? offset : MIN_COMMITS;
+	}
+
+	offset = idx - MIN_REGION;
+	next = (offset < MAX_COMMITS) ? offset : MAX_COMMITS;
+
+	return (next > MIN_COMMITS) ? next : MIN_COMMITS;
+}
+
+static int date_compare(const void *_a, const void *_b)
+{
+	struct commit *a = *(struct commit **)_a;
+	struct commit *b = *(struct commit **)_b;
+	return (long)b->date - (long)a->date;
+}
+
+void bitmap_writer_reuse_bitmaps(struct packing_data *to_pack)
+{
+	struct bitmap_index *bitmap_git;
+	if (!(bitmap_git = prepare_bitmap_git(to_pack->repo)))
+		return;
+
+	writer.reused = kh_init_oid_map();
+	rebuild_existing_bitmaps(bitmap_git, to_pack, writer.reused,
+				 writer.show_progress);
+	/*
+	 * NEEDSWORK: rebuild_existing_bitmaps() makes writer.reused reference
+	 * some bitmaps in bitmap_git, so we can't free the latter.
+	 */
+}
+
+static struct ewah_bitmap *find_reused_bitmap(const struct object_id *oid)
+{
+	khiter_t hash_pos;
+
+	if (!writer.reused)
+		return NULL;
+
+	hash_pos = kh_get_oid_map(writer.reused, *oid);
+	if (hash_pos >= kh_end(writer.reused))
+		return NULL;
+
+	return kh_value(writer.reused, hash_pos);
+}
+
+void bitmap_writer_select_commits(struct commit **indexed_commits,
+				  unsigned int indexed_commits_nr,
+				  int max_bitmaps)
+{
+	unsigned int i = 0, j, next;
+
+	QSORT(indexed_commits, indexed_commits_nr, date_compare);
+
+	if (writer.show_progress)
+		writer.progress = start_progress("Selecting bitmap commits", 0);
+
+	if (indexed_commits_nr < 100) {
+		for (i = 0; i < indexed_commits_nr; ++i)
+			push_bitmapped_commit(indexed_commits[i], NULL);
+		return;
+	}
+
+	for (;;) {
+		struct ewah_bitmap *reused_bitmap = NULL;
+		struct commit *chosen = NULL;
+
+		next = next_commit_index(i);
+
+		if (i + next >= indexed_commits_nr)
+			break;
+
+		if (max_bitmaps > 0 && writer.selected_nr >= max_bitmaps) {
+			writer.selected_nr = max_bitmaps;
+			break;
+		}
+
+		if (next == 0) {
+			chosen = indexed_commits[i];
+			reused_bitmap = find_reused_bitmap(&chosen->object.oid);
+		} else {
+			chosen = indexed_commits[i + next];
+
+			for (j = 0; j <= next; ++j) {
+				struct commit *cm = indexed_commits[i + j];
+
+				reused_bitmap = find_reused_bitmap(&cm->object.oid);
+				if (reused_bitmap || (cm->object.flags & NEEDS_BITMAP) != 0) {
+					chosen = cm;
+					break;
+				}
+
+				if (cm->parents && cm->parents->next)
+					chosen = cm;
+			}
+		}
+
+		push_bitmapped_commit(chosen, reused_bitmap);
+
+		i += next + 1;
+		display_progress(writer.progress, i);
+	}
+
+	stop_progress(&writer.progress);
+}
+
+
+static int hashwrite_ewah_helper(void *f, const void *buf, size_t len)
+{
+	/* hashwrite will die on error */
+	hashwrite(f, buf, len);
+	return len;
+}
+
+/**
+ * Write the bitmap index to disk
+ */
+static inline void dump_bitmap(struct hashfile *f, struct ewah_bitmap *bitmap)
+{
+	if (ewah_serialize_to(bitmap, hashwrite_ewah_helper, f) < 0)
+		die("Failed to write bitmap index");
+}
+
+static const unsigned char *sha1_access(size_t pos, void *table)
+{
+	struct pack_idx_entry **index = table;
+	return index[pos]->oid.hash;
+}
+
+static void write_selected_commits_v1(struct hashfile *f,
+				      struct pack_idx_entry **index,
+				      uint32_t index_nr)
+{
+	int i;
+
+	for (i = 0; i < writer.selected_nr; ++i) {
+		struct bitmapped_commit *stored = &writer.selected[i];
+
+		int commit_pos =
+			sha1_pos(stored->commit->object.oid.hash, index, index_nr, sha1_access);
+
+		if (commit_pos < 0)
+			BUG("trying to write commit not in index");
+
+		hashwrite_be32(f, commit_pos);
+		hashwrite_u8(f, stored->xor_offset);
+		hashwrite_u8(f, stored->flags);
+
+		dump_bitmap(f, stored->write_as);
+	}
+}
+
+static void write_hash_cache(struct hashfile *f,
+			     struct pack_idx_entry **index,
+			     uint32_t index_nr)
+{
+	uint32_t i;
+
+	for (i = 0; i < index_nr; ++i) {
+		struct object_entry *entry = (struct object_entry *)index[i];
+		uint32_t hash_value = htonl(entry->hash);
+		hashwrite(f, &hash_value, sizeof(hash_value));
+	}
+}
+
+void bitmap_writer_set_checksum(unsigned char *sha1)
+{
+	hashcpy(writer.pack_checksum, sha1);
+}
+
+void bitmap_writer_finish(struct pack_idx_entry **index,
+			  uint32_t index_nr,
+			  const char *filename,
+			  uint16_t options)
+{
+	static uint16_t default_version = 1;
+	static uint16_t flags = BITMAP_OPT_FULL_DAG;
+	struct strbuf tmp_file = STRBUF_INIT;
+	struct hashfile *f;
+
+	struct bitmap_disk_header header;
+
+	int fd = odb_mkstemp(&tmp_file, "pack/tmp_bitmap_XXXXXX");
+
+	f = hashfd(fd, tmp_file.buf);
+
+	memcpy(header.magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE));
+	header.version = htons(default_version);
+	header.options = htons(flags | options);
+	header.entry_count = htonl(writer.selected_nr);
+	hashcpy(header.checksum, writer.pack_checksum);
+
+	hashwrite(f, &header, sizeof(header) - GIT_MAX_RAWSZ + the_hash_algo->rawsz);
+	dump_bitmap(f, writer.commits);
+	dump_bitmap(f, writer.trees);
+	dump_bitmap(f, writer.blobs);
+	dump_bitmap(f, writer.tags);
+	write_selected_commits_v1(f, index, index_nr);
+
+	if (options & BITMAP_OPT_HASH_CACHE)
+		write_hash_cache(f, index, index_nr);
+
+	finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
+
+	if (adjust_shared_perm(tmp_file.buf))
+		die_errno("unable to make temporary bitmap file readable");
+
+	if (rename(tmp_file.buf, filename))
+		die_errno("unable to rename temporary bitmap file to '%s'", filename);
+
+	strbuf_release(&tmp_file);
+}