thodg/libgit2

diff --git a/include/git2/pack.h b/include/git2/pack.h
index e7f060d..4cf4262 100644
--- a/include/git2/pack.h
+++ b/include/git2/pack.h
@@ -115,6 +115,19 @@ GIT_EXTERN(int) git_packbuilder_insert_tree(git_packbuilder *pb, const git_oid *
 GIT_EXTERN(int) git_packbuilder_insert_commit(git_packbuilder *pb, const git_oid *id);
 
 /**
+ * Insert objects as given by the walk
+ *
+ * Those commits and all objects they reference will be inserted into
+ * the packbuilder.
+ *
+ * @param pb the packbuilder
+ * @param walk the revwalk to use to fill the packbuilder
+ *
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_packbuilder_insert_walk(git_packbuilder *pb, git_revwalk *walk);
+
+/**
  * Write the contents of the packfile to an in-memory buffer
  *
  * The contents of the buffer will become a valid packfile, even though there
diff --git a/src/describe.c b/src/describe.c
index d4c0dea..68bac2d 100644
--- a/src/describe.c
+++ b/src/describe.c
@@ -19,6 +19,8 @@
 #include "vector.h"
 #include "repository.h"
 
+GIT__USE_OIDMAP;
+
 /* Ported from https://github.com/git/git/blob/89dde7882f71f846ccd0359756d27bebc31108de/builtin/describe.c */
 
 struct commit_name {
diff --git a/src/indexer.c b/src/indexer.c
index 4fb33b6..665d50f 100644
--- a/src/indexer.c
+++ b/src/indexer.c
@@ -18,6 +18,8 @@
 #include "oidmap.h"
 #include "zstream.h"
 
+GIT__USE_OIDMAP;
+
 extern git_mutex git__mwindow_mutex;
 
 #define UINT31_MAX (0x7FFFFFFF)
diff --git a/src/pack-objects.c b/src/pack-objects.c
index f644520..0f43b98 100644
--- a/src/pack-objects.c
+++ b/src/pack-objects.c
@@ -15,6 +15,8 @@
 #include "thread-utils.h"
 #include "tree.h"
 #include "util.h"
+#include "revwalk.h"
+#include "commit_list.h"
 
 #include "git2/pack.h"
 #include "git2/commit.h"
@@ -39,6 +41,8 @@ struct pack_write_context {
 	git_transfer_progress *stats;
 };
 
+GIT__USE_OIDMAP;
+
 #ifdef GIT_THREADS
 
 #define GIT_PACKBUILDER__MUTEX_OP(pb, mtx, op) do { \
@@ -124,10 +128,16 @@ int git_packbuilder_new(git_packbuilder **out, git_repository *repo)
 	GITERR_CHECK_ALLOC(pb);
 
 	pb->object_ix = git_oidmap_alloc();
-
 	if (!pb->object_ix)
 		goto on_error;
 
+	pb->walk_objects = git_oidmap_alloc();
+	if (!pb->walk_objects)
+		goto on_error;
+
+	if (git_pool_init(&pb->object_pool, sizeof(git_walk_object), 0) < 0)
+		goto on_error;
+
 	pb->repo = repo;
 	pb->nr_threads = 1; /* do not spawn any thread by default */
 
@@ -1345,6 +1355,7 @@ const git_oid *git_packbuilder_hash(git_packbuilder *pb)
 	return &pb->pack_oid;
 }
 
+
 static int cb_tree_walk(
 	const char *root, const git_tree_entry *entry, void *payload)
 {
@@ -1403,6 +1414,235 @@ uint32_t git_packbuilder_written(git_packbuilder *pb)
 	return pb->nr_written;
 }
 
+int lookup_walk_object(git_walk_object **out, git_packbuilder *pb, const git_oid *id)
+{
+	git_walk_object *obj;
+
+	obj = git_pool_mallocz(&pb->object_pool, 1);
+	if (!obj) {
+		giterr_set_oom();
+		return -1;
+	}
+
+	git_oid_cpy(&obj->id, id);
+
+	*out = obj;
+	return 0;
+}
+
+static int retrieve_object(git_walk_object **out, git_packbuilder *pb, const git_oid *id)
+{
+	int error;
+	khiter_t pos;
+	git_walk_object *obj;
+
+	pos = git_oidmap_lookup_index(pb->walk_objects, id);
+	if (git_oidmap_valid_index(pb->walk_objects, pos)) {
+		obj = git_oidmap_value_at(pb->walk_objects, pos);
+	} else {
+		if ((error = lookup_walk_object(&obj, pb, id)) < 0)
+			return error;
+
+		git_oidmap_insert(pb->walk_objects, &obj->id, obj, error);
+	}
+
+	*out = obj;
+	return 0;
+}
+
+static int mark_blob_uninteresting(git_packbuilder *pb, const git_oid *id)
+{
+	int error;
+	git_walk_object *obj;
+
+	if ((error = retrieve_object(&obj, pb, id)) < 0)
+		return error;
+
+	obj->uninteresting = 1;
+
+	return 0;
+}
+
+static int mark_tree_uninteresting(git_packbuilder *pb, const git_oid *id)
+{
+	git_walk_object *obj;
+	git_tree *tree;
+	int error;
+	size_t i;
+
+	if ((error = retrieve_object(&obj, pb, id)) < 0)
+		return error;
+
+	if (obj->uninteresting)
+		return 0;
+
+	obj->uninteresting = 1;
+
+	if ((error = git_tree_lookup(&tree, pb->repo, id)) < 0)
+		return error;
+
+	for (i = 0; i < git_tree_entrycount(tree); i++) {
+		const git_tree_entry *entry = git_tree_entry_byindex(tree, i);
+		const git_oid *entry_id = git_tree_entry_id(entry);
+		switch (git_tree_entry_type(entry)) {
+		case GIT_OBJ_TREE:
+			if ((error = mark_tree_uninteresting(pb, entry_id)) < 0)
+				goto cleanup;
+			break;
+		case GIT_OBJ_BLOB:
+			if ((error = mark_blob_uninteresting(pb, entry_id)) < 0)
+				goto cleanup;
+			break;
+		default:
+			/* it's a submodule or something unknown, we don't want it */
+			;
+		}
+	}
+
+cleanup:
+	git_tree_free(tree);
+	return error;
+}
+
+/*
+ * Mark the edges of the graph uninteresting. Since we start from a
+ * git_revwalk, the commits are already uninteresting, but we need to
+ * mark the trees and blobs.
+ */
+static int mark_edges_uninteresting(git_packbuilder *pb, git_commit_list *commits)
+{
+	int error;
+	git_commit_list *list;
+	git_commit *commit;
+
+	for (list = commits; list; list = list->next) {
+		if (!list->item->uninteresting)
+			continue;
+
+		if ((error = git_commit_lookup(&commit, pb->repo, &list->item->oid)) < 0)
+			return error;
+
+		error = mark_tree_uninteresting(pb, git_commit_tree_id(commit));
+		git_commit_free(commit);
+
+		if (error < 0)
+			return error;
+	}
+
+	return 0;
+}
+
+int insert_tree(git_packbuilder *pb, git_tree *tree)
+{
+	size_t i;
+	int error;
+	git_tree *subtree;
+	git_walk_object *obj;
+	const char *name;
+
+	if ((error = retrieve_object(&obj, pb, git_tree_id(tree))) < 0)
+		return error;
+
+	if (obj->seen)
+		return 0;
+
+	obj->seen = 1;
+
+	if ((error = git_packbuilder_insert(pb, &obj->id, NULL)))
+		return error;
+
+	for (i = 0; i < git_tree_entrycount(tree); i++) {
+		const git_tree_entry *entry = git_tree_entry_byindex(tree, i);
+		const git_oid *entry_id = git_tree_entry_id(entry);
+		switch (git_tree_entry_type(entry)) {
+		case GIT_OBJ_TREE:
+			if ((error = git_tree_lookup(&subtree, pb->repo, entry_id)) < 0)
+				return error;
+
+			error = insert_tree(pb, subtree);
+			git_tree_free(subtree);
+
+			if (error < 0)
+				return error;
+
+			break;
+		case GIT_OBJ_BLOB:
+			name = git_tree_entry_name(entry);
+			if ((error = git_packbuilder_insert(pb, entry_id, name)) < 0)
+				return error;
+			break;
+		default:
+			/* it's a submodule or something unknown, we don't want it */
+			;
+		}
+	}
+
+
+	return error;
+}
+
+int insert_commit(git_packbuilder *pb, git_walk_object *obj)
+{
+	int error;
+	git_commit *commit = NULL;
+	git_tree *tree = NULL;
+
+	obj->seen = 1;
+
+	if ((error = git_packbuilder_insert(pb, &obj->id, NULL)) < 0)
+		return error;
+
+	if ((error = git_commit_lookup(&commit, pb->repo, &obj->id)) < 0)
+		return error;
+
+	if ((error = git_tree_lookup(&tree, pb->repo, git_commit_tree_id(commit))) < 0)
+		goto cleanup;
+
+	if ((error = insert_tree(pb, tree)) < 0)
+		goto cleanup;
+
+cleanup:
+	git_commit_free(commit);
+	git_tree_free(tree);
+	return error;
+}
+
+int git_packbuilder_insert_walk(git_packbuilder *pb, git_revwalk *walk)
+{
+	int error;
+	git_oid id;
+	git_walk_object *obj;
+
+	assert(pb && walk);
+
+	if ((error = mark_edges_uninteresting(pb, walk->user_input)) < 0)
+		return error;
+
+	/*
+	 * TODO: git marks the parents of the edges
+	 * uninteresting. This may provide a speed advantage, but does
+	 * seem to assume the remote does not have a single-commit
+	 * history on the other end.
+	 */
+
+	/* walk down each tree up to the blobs and insert them, stopping when uninteresting */
+	while ((error = git_revwalk_next(&id, walk)) == 0) {
+		if ((error = retrieve_object(&obj, pb, &id)) < 0)
+			return error;
+
+		if (obj->seen || obj->uninteresting)
+			continue;
+
+		if ((error = insert_commit(pb, obj)) < 0)
+			return error;
+	}
+
+	if (error == GIT_ITEROVER)
+		error = 0;
+
+	return 0;
+}
+
 int git_packbuilder_set_callbacks(git_packbuilder *pb, git_packbuilder_progress progress_cb, void *progress_cb_payload)
 {
 	if (!pb)
@@ -1436,6 +1676,9 @@ void git_packbuilder_free(git_packbuilder *pb)
 	if (pb->object_list)
 		git__free(pb->object_list);
 
+	git_oidmap_free(pb->walk_objects);
+	git_pool_clear(&pb->object_pool);
+
 	git_hash_ctx_cleanup(&pb->ctx);
 	git_zstream_free(&pb->zstream);
 
diff --git a/src/pack-objects.h b/src/pack-objects.h
index 4647df7..9af5c0b 100644
--- a/src/pack-objects.h
+++ b/src/pack-objects.h
@@ -15,6 +15,7 @@
 #include "oidmap.h"
 #include "netops.h"
 #include "zstream.h"
+#include "pool.h"
 
 #include "git2/oid.h"
 #include "git2/pack.h"
@@ -50,6 +51,12 @@ typedef struct git_pobject {
 	    filled:1;
 } git_pobject;
 
+typedef struct {
+	git_oid id;
+	unsigned int uninteresting:1,
+		seen:1;
+} git_walk_object;
+
 struct git_packbuilder {
 	git_repository *repo; /* associated repository */
 	git_odb *odb; /* associated object database */
@@ -66,6 +73,9 @@ struct git_packbuilder {
 
 	git_oidmap *object_ix;
 
+	git_oidmap *walk_objects;
+	git_pool object_pool;
+
 	git_oid pack_oid; /* hash of written pack */
 
 	/* synchronization objects */
diff --git a/src/pack.c b/src/pack.c
index 3c646b7..5d0a27b 100644
--- a/src/pack.c
+++ b/src/pack.c
@@ -16,6 +16,9 @@
 
 #include <zlib.h>
 
+GIT__USE_OFFMAP;
+GIT__USE_OIDMAP;
+
 static int packfile_open(struct git_pack_file *p);
 static git_off_t nth_packed_object_offset(const struct git_pack_file *p, uint32_t n);
 int packfile_unpack_compressed(
diff --git a/src/pack.h b/src/pack.h
index 3cebd10..b3d5b29 100644
--- a/src/pack.h
+++ b/src/pack.h
@@ -71,9 +71,7 @@ struct pack_chain_elem {
 typedef git_array_t(struct pack_chain_elem) git_dependency_chain;
 
 #include "offmap.h"
-
-GIT__USE_OFFMAP
-GIT__USE_OIDMAP
+#include "oidmap.h"
 
 #define GIT_PACK_CACHE_MEMORY_LIMIT 16 * 1024 * 1024
 #define GIT_PACK_CACHE_SIZE_LIMIT 1024 * 1024 /* don't bother caching anything over 1MB */
diff --git a/src/revwalk.c b/src/revwalk.c
index 2ba000c..a6d823e 100644
--- a/src/revwalk.c
+++ b/src/revwalk.c
@@ -14,6 +14,8 @@
 #include "git2/revparse.h"
 #include "merge.h"
 
+GIT__USE_OIDMAP;
+
 git_commit_list_node *git_revwalk__commit_lookup(
 	git_revwalk *walk, const git_oid *oid)
 {
diff --git a/src/revwalk.h b/src/revwalk.h
index 1148a2a..6b363d4 100644
--- a/src/revwalk.h
+++ b/src/revwalk.h
@@ -14,7 +14,7 @@
 #include "pool.h"
 #include "vector.h"
 
-GIT__USE_OIDMAP
+#include "oidmap.h"
 
 struct git_revwalk {
 	git_repository *repo;
diff --git a/src/transports/local.c b/src/transports/local.c
index 588b7ce..64ddbd9 100644
--- a/src/transports/local.c
+++ b/src/transports/local.c
@@ -513,7 +513,6 @@ static int local_download_pack(
 	git_remote_head *rhead;
 	unsigned int i;
 	int error = -1;
-	git_oid oid;
 	git_packbuilder *pack = NULL;
 	git_odb_writepack *writepack = NULL;
 	git_odb *odb = NULL;
@@ -539,15 +538,22 @@ static int local_download_pack(
 		if (git_object_type(obj) == GIT_OBJ_COMMIT) {
 			/* Revwalker includes only wanted commits */
 			error = git_revwalk_push(walk, &rhead->oid);
-			if (!git_oid_iszero(&rhead->loid))
+			if (!error && !git_oid_iszero(&rhead->loid)) {
 				error = git_revwalk_hide(walk, &rhead->loid);
+				if (error == GIT_ENOTFOUND)
+					error = 0;
+			}
 		} else {
-			/* Tag or some other wanted object. Add it on its own */
 			error = git_packbuilder_insert(pack, &rhead->oid, rhead->name);
 		}
 		git_object_free(obj);
+		if (error < 0)
+			goto cleanup;
 	}
 
+	if ((error = git_packbuilder_insert_walk(pack, walk)))
+		goto cleanup;
+
 	if ((error = git_buf_printf(&progress_info, counting_objects_fmt, git_packbuilder_object_count(pack))) < 0)
 		goto cleanup;
 
@@ -559,35 +565,6 @@ static int local_download_pack(
 	if ((error = git_repository_odb__weakptr(&odb, repo)) < 0)
 		goto cleanup;
 
-	while ((error = git_revwalk_next(&oid, walk)) == 0) {
-		git_commit *commit;
-
-		/* Skip commits we already have */
-		if (git_odb_exists(odb, &oid)) continue;
-
-		if (!git_object_lookup((git_object**)&commit, t->repo, &oid, GIT_OBJ_COMMIT)) {
-			const git_oid *tree_oid = git_commit_tree_id(commit);
-
-			/* Add the commit and its tree */
-			if ((error = git_packbuilder_insert(pack, &oid, NULL)) < 0 ||
-				 (error = git_packbuilder_insert_tree(pack, tree_oid)) < 0) {
-				git_commit_free(commit);
-				goto cleanup;
-			}
-
-			git_commit_free(commit);
-
-			git_buf_clear(&progress_info);
-			if ((error = git_buf_printf(&progress_info, counting_objects_fmt, git_packbuilder_object_count(pack))) < 0)
-				goto cleanup;
-
-			if (t->progress_cb &&
-			    (error = t->progress_cb(git_buf_cstr(&progress_info), git_buf_len(&progress_info), t->message_cb_payload)) < 0)
-				goto cleanup;
-
-		}
-	}
-
 	/* One last one with the newline */
 	git_buf_clear(&progress_info);
 	git_buf_printf(&progress_info, counting_objects_fmt, git_packbuilder_object_count(pack));
@@ -615,6 +592,7 @@ static int local_download_pack(
 		if ((error = git_packbuilder_foreach(pack, foreach_cb, &data)) != 0)
 			goto cleanup;
 	}
+
 	error = writepack->commit(writepack, stats);
 
 cleanup: