[PATCH] [Outreachy] cleanup: use list.h in mru.h and mru.c

["Оля Тележная" <olyatelezhnaya@gmail.com>]

Remove implementation of double-linked list in mru.c and mru.h and use
implementation from list.h.

Signed-off-by: Olga Telezhnaia <olyatelezhnaya@gmail.com>
Mentored-by: Christian Couder <christian.couder@gmail.com>, Jeff King
<peff@peff.net>
---
 builtin/pack-objects.c |  5 +++--
 mru.c                  | 51 +++++++++++++++-----------------------------------
 mru.h                  | 31 +++++++++++++-----------------
 packfile.c             |  6 ++++--
 4 files changed, 35 insertions(+), 58 deletions(-)

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index f721137ea..fb4c9be89 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -995,8 +995,8 @@ static int want_object_in_pack(const unsigned char *sha1,
         struct packed_git **found_pack,
         off_t *found_offset)
 {
- struct mru_entry *entry;
  int want;
+        struct list_head *pos;

  if (!exclude && local && has_loose_object_nonlocal(sha1))
  return 0;
@@ -1012,7 +1012,8 @@ static int want_object_in_pack(const unsigned char *sha1,
  return want;
  }

- for (entry = packed_git_mru.head; entry; entry = entry->next) {
+ list_for_each(pos, &packed_git_mru.list) {
+ struct mru *entry = list_entry(pos, struct mru, list);
  struct packed_git *p = entry->item;
  off_t offset;

diff --git a/mru.c b/mru.c
index 9dedae028..8b6ba3d9b 100644
--- a/mru.c
+++ b/mru.c
@@ -1,50 +1,29 @@
 #include "cache.h"
 #include "mru.h"

-void mru_append(struct mru *mru, void *item)
+void mru_append(struct mru *head, void *item)
 {
- struct mru_entry *cur = xmalloc(sizeof(*cur));
+ struct mru *cur = xmalloc(sizeof(*cur));
  cur->item = item;
- cur->prev = mru->tail;
- cur->next = NULL;
-
- if (mru->tail)
- mru->tail->next = cur;
- else
- mru->head = cur;
- mru->tail = cur;
+ list_add_tail(&cur->list, &head->list);
 }

-void mru_mark(struct mru *mru, struct mru_entry *entry)
+void mru_mark(struct mru *head, struct mru *entry)
 {
- /* If we're already at the front of the list, nothing to do */
- if (mru->head == entry)
- return;
-
- /* Otherwise, remove us from our current slot... */
- if (entry->prev)
- entry->prev->next = entry->next;
- if (entry->next)
- entry->next->prev = entry->prev;
- else
- mru->tail = entry->prev;
-
- /* And insert us at the beginning. */
- entry->prev = NULL;
- entry->next = mru->head;
- if (mru->head)
- mru->head->prev = entry;
- mru->head = entry;
+ /* To mark means to put at the front of the list. */
+ list_del(&entry->list);
+ list_add(&entry->list, &head->list);
 }

-void mru_clear(struct mru *mru)
+void mru_clear(struct mru *head)
 {
- struct mru_entry *p = mru->head;
-
- while (p) {
- struct mru_entry *to_free = p;
- p = p->next;
+ struct list_head *p1;
+ struct list_head *p2;
+ struct mru *to_free;
+
+ list_for_each_safe(p1, p2, &head->list) {
+ to_free = list_entry(p1, struct mru, list);
  free(to_free);
  }
- mru->head = mru->tail = NULL;
+ INIT_LIST_HEAD(&head->list);
 }
diff --git a/mru.h b/mru.h
index 42e4aeaa1..36a332af0 100644
--- a/mru.h
+++ b/mru.h
@@ -1,6 +1,8 @@
 #ifndef MRU_H
 #define MRU_H

+#include "list.h"
+
 /**
  * A simple most-recently-used cache, backed by a doubly-linked list.
  *
@@ -8,18 +10,15 @@
  *
  *   // Create a list.  Zero-initialization is required.
  *   static struct mru cache;
- *   mru_append(&cache, item);
- *   ...
+ *   INIT_LIST_HEAD(&cache.list);
  *
- *   // Iterate in MRU order.
- *   struct mru_entry *p;
- *   for (p = cache.head; p; p = p->next) {
- * if (matches(p->item))
- * break;
- *   }
+ *   // Add new item to the end of the list.
+ *   void *item;
+ *   ...
+ *   mru_append(&cache, item);
  *
  *   // Mark an item as used, moving it to the front of the list.
- *   mru_mark(&cache, p);
+ *   mru_mark(&cache, item);
  *
  *   // Reset the list to empty, cleaning up all resources.
  *   mru_clear(&cache);
@@ -29,17 +28,13 @@
  * you will begin traversing the whole list again.
  */

-struct mru_entry {
- void *item;
- struct mru_entry *prev, *next;
-};
-
 struct mru {
- struct mru_entry *head, *tail;
+ struct list_head list;
+        void *item;
 };

-void mru_append(struct mru *mru, void *item);
-void mru_mark(struct mru *mru, struct mru_entry *entry);
-void mru_clear(struct mru *mru);
+void mru_append(struct mru *head, void *item);
+void mru_mark(struct mru *head, struct mru *entry);
+void mru_clear(struct mru *head);

 #endif /* MRU_H */
diff --git a/packfile.c b/packfile.c
index f69a5c8d6..ae3b0b2e9 100644
--- a/packfile.c
+++ b/packfile.c
@@ -876,6 +876,7 @@ void prepare_packed_git(void)
  for (alt = alt_odb_list; alt; alt = alt->next)
  prepare_packed_git_one(alt->path, 0);
  rearrange_packed_git();
+ INIT_LIST_HEAD(&packed_git_mru.list);
  prepare_packed_git_mru();
  prepare_packed_git_run_once = 1;
 }
@@ -1824,13 +1825,14 @@ static int fill_pack_entry(const unsigned char *sha1,
  */
 int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
 {
- struct mru_entry *p;
+ struct list_head *pos;

  prepare_packed_git();
  if (!packed_git)
  return 0;

- for (p = packed_git_mru.head; p; p = p->next) {
+ list_for_each(pos, &packed_git_mru.list) {
+ struct mru *p = list_entry(pos, struct mru, list);
  if (fill_pack_entry(sha1, e, p->item)) {
  mru_mark(&packed_git_mru, p);
  return 1;
-- 
2.14.1.727.g9ddaf86b0