merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

1 files changed, 67 insertions, 18 deletions

diff --git a/third_party/git/diffcore-rename.c b/third_party/git/diffcore-rename.c
index 9624864858..99e63e90f8 100644
--- a/third_party/git/diffcore-rename.c
+++ b/third_party/git/diffcore-rename.c
@@ -1,4 +1,5 @@
 /*
+ *
  * Copyright (C) 2005 Junio C Hamano
  */
 #include "cache.h"
@@ -7,6 +8,7 @@
 #include "object-store.h"
 #include "hashmap.h"
 #include "progress.h"
+#include "promisor-remote.h"
 
 /* Table of rename/copy destinations */
 
@@ -128,10 +130,46 @@ struct diff_score {
 	short name_score;
 };
 
+struct prefetch_options {
+	struct repository *repo;
+	int skip_unmodified;
+};
+static void prefetch(void *prefetch_options)
+{
+	struct prefetch_options *options = prefetch_options;
+	int i;
+	struct oid_array to_fetch = OID_ARRAY_INIT;
+
+	for (i = 0; i < rename_dst_nr; i++) {
+		if (rename_dst[i].pair)
+			/*
+			 * The loop in diffcore_rename() will not need these
+			 * blobs, so skip prefetching.
+			 */
+			continue; /* already found exact match */
+		diff_add_if_missing(options->repo, &to_fetch,
+				    rename_dst[i].two);
+	}
+	for (i = 0; i < rename_src_nr; i++) {
+		if (options->skip_unmodified &&
+		    diff_unmodified_pair(rename_src[i].p))
+			/*
+			 * The loop in diffcore_rename() will not need these
+			 * blobs, so skip prefetching.
+			 */
+			continue;
+		diff_add_if_missing(options->repo, &to_fetch,
+				    rename_src[i].p->one);
+	}
+	promisor_remote_get_direct(options->repo, to_fetch.oid, to_fetch.nr);
+	oid_array_clear(&to_fetch);
+}
+
 static int estimate_similarity(struct repository *r,
 			       struct diff_filespec *src,
 			       struct diff_filespec *dst,
-			       int minimum_score)
+			       int minimum_score,
+			       int skip_unmodified)
 {
 	/* src points at a file that existed in the original tree (or
 	 * optionally a file in the destination tree) and dst points
@@ -148,6 +186,15 @@ static int estimate_similarity(struct repository *r,
 	 */
 	unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 	int score;
+	struct diff_populate_filespec_options dpf_options = {
+		.check_size_only = 1
+	};
+	struct prefetch_options prefetch_options = {r, skip_unmodified};
+
+	if (r == the_repository && has_promisor_remote()) {
+		dpf_options.missing_object_cb = prefetch;
+		dpf_options.missing_object_data = &prefetch_options;
+	}
 
 	/* We deal only with regular files.  Symlink renames are handled
 	 * only when they are exact matches --- in other words, no edits
@@ -166,10 +213,10 @@ static int estimate_similarity(struct repository *r,
 	 * say whether the size is valid or not!)
 	 */
 	if (!src->cnt_data &&
-	    diff_populate_filespec(r, src, CHECK_SIZE_ONLY))
+	    diff_populate_filespec(r, src, &dpf_options))
 		return 0;
 	if (!dst->cnt_data &&
-	    diff_populate_filespec(r, dst, CHECK_SIZE_ONLY))
+	    diff_populate_filespec(r, dst, &dpf_options))
 		return 0;
 
 	max_size = ((src->size > dst->size) ? src->size : dst->size);
@@ -187,9 +234,11 @@ static int estimate_similarity(struct repository *r,
 	if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 		return 0;
 
-	if (!src->cnt_data && diff_populate_filespec(r, src, 0))
+	dpf_options.check_size_only = 0;
+
+	if (!src->cnt_data && diff_populate_filespec(r, src, &dpf_options))
 		return 0;
-	if (!dst->cnt_data && diff_populate_filespec(r, dst, 0))
+	if (!dst->cnt_data && diff_populate_filespec(r, dst, &dpf_options))
 		return 0;
 
 	if (diffcore_count_changes(r, src, dst,
@@ -261,10 +310,10 @@ static unsigned int hash_filespec(struct repository *r,
 				  struct diff_filespec *filespec)
 {
 	if (!filespec->oid_valid) {
-		if (diff_populate_filespec(r, filespec, 0))
+		if (diff_populate_filespec(r, filespec, NULL))
 			return 0;
-		hash_object_file(filespec->data, filespec->size, "blob",
-				 &filespec->oid);
+		hash_object_file(r->hash_algo, filespec->data, filespec->size,
+				 "blob", &filespec->oid);
 	}
 	return oidhash(&filespec->oid);
 }
@@ -274,18 +323,17 @@ static int find_identical_files(struct hashmap *srcs,
 				struct diff_options *options)
 {
 	int renames = 0;
-
 	struct diff_filespec *target = rename_dst[dst_index].two;
 	struct file_similarity *p, *best = NULL;
 	int i = 100, best_score = -1;
+	unsigned int hash = hash_filespec(options->repo, target);
 
 	/*
 	 * Find the best source match for specified destination.
 	 */
-	p = hashmap_get_from_hash(srcs,
-				  hash_filespec(options->repo, target),
-				  NULL);
-	for (; p; p = hashmap_get_next(srcs, p)) {
+	p = hashmap_get_entry_from_hash(srcs, hash, NULL,
+					struct file_similarity, entry);
+	hashmap_for_each_entry_from(srcs, p, entry) {
 		int score;
 		struct diff_filespec *source = p->filespec;
 
@@ -329,8 +377,8 @@ static void insert_file_table(struct repository *r,
 	entry->index = index;
 	entry->filespec = filespec;
 
-	hashmap_entry_init(entry, hash_filespec(r, filespec));
-	hashmap_add(table, entry);
+	hashmap_entry_init(&entry->entry, hash_filespec(r, filespec));
+	hashmap_add(table, &entry->entry);
 }
 
 /*
@@ -359,7 +407,7 @@ static int find_exact_renames(struct diff_options *options)
 		renames += find_identical_files(&file_table, i, options);
 
 	/* Free the hash data structure and entries */
-	hashmap_free(&file_table, 1);
+	hashmap_free_entries(&file_table, struct file_similarity, entry);
 
 	return renames;
 }
@@ -567,7 +615,8 @@ void diffcore_rename(struct diff_options *options)
 
 			this_src.score = estimate_similarity(options->repo,
 							     one, two,
-							     minimum_score);
+							     minimum_score,
+							     skip_unmodified);
 			this_src.name_score = basename_same(one, two);
 			this_src.dst = i;
 			this_src.src = j;
@@ -585,7 +634,7 @@ void diffcore_rename(struct diff_options *options)
 	stop_progress(&progress);
 
 	/* cost matrix sorted by most to least similar pair */
-	QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
+	STABLE_QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
 
 	rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 	if (detect_rename == DIFF_DETECT_COPY)