strmap: take advantage of FLEXPTR_ALLOC_STR when relevant

By default, we do not use a mempool and strdup_strings is true; in this
case, we can avoid both an extra allocation and an extra free by just
over-allocating for the strmap_entry leaving enough space at the end to
copy the key.  FLEXPTR_ALLOC_STR exists for exactly this purpose, so
make use of it.

Also, adjust the case when we are using a memory pool and strdup_strings
is true to just do one allocation from the memory pool instead of two so
that the strmap_clear() and strmap_remove() code can just avoid freeing
the key in all cases.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/strmap.c b/strmap.c
index 139afb9d4bc03f6a793e8142846ab2f10ff55040..4fb9f6100eccb7b4b3bcdd18d2801cc7b979807f 100644 (file)
--- a/strmap.c
+++ b/strmap.c
@@ -59,11 +59,8 @@ static void strmap_free_entries_(struct strmap *map, int free_values)
        hashmap_for_each_entry(&map->map, &iter, e, ent) {
                if (free_values)
                        free(e->value);
-               if (!map->pool) {
-                       if (map->strdup_strings)
-                               free((char*)e->key);
+               if (!map->pool)
                        free(e);
-               }
        }
 }
 
@@ -84,16 +81,25 @@ static struct strmap_entry *create_entry(struct strmap *map,
                                         void *data)
 {
        struct strmap_entry *entry;
-       const char *key = str;
 
-       entry = map->pool ? mem_pool_alloc(map->pool, sizeof(*entry))
-                         : xmalloc(sizeof(*entry));
+       if (map->strdup_strings) {
+               if (!map->pool) {
+                       FLEXPTR_ALLOC_STR(entry, key, str);
+               } else {
+                       size_t len = st_add(strlen(str), 1); /* include NUL */
+                       entry = mem_pool_alloc(map->pool,
+                                              st_add(sizeof(*entry), len));
+                       memcpy(entry + 1, str, len);
+                       entry->key = (void *)(entry + 1);
+               }
+       } else if (!map->pool) {
+               entry = xmalloc(sizeof(*entry));
+       } else {
+               entry = mem_pool_alloc(map->pool, sizeof(*entry));
+       }
        hashmap_entry_init(&entry->ent, strhash(str));
-
-       if (map->strdup_strings)
-               key = map->pool ? mem_pool_strdup(map->pool, str)
-                               : xstrdup(str);
-       entry->key = key;
+       if (!map->strdup_strings)
+               entry->key = str;
        entry->value = data;
        return entry;
 }
@@ -139,11 +145,8 @@ void strmap_remove(struct strmap *map, const char *str, int free_value)
                return;
        if (free_value)
                free(ret->value);
-       if (!map->pool) {
-               if (map->strdup_strings)
-                       free((char*)ret->key);
+       if (!map->pool)
                free(ret);
-       }
 }
 
 void strintmap_incr(struct strintmap *map, const char *str, intptr_t amt)

diff --git a/strmap.h b/strmap.h
index 8745b7ceb1302babbae2c845eba520f155bba312..c4c104411bf2968e4a808bfba2fc98183c82acc7 100644 (file)
--- a/strmap.h
+++ b/strmap.h
@@ -14,6 +14,7 @@ struct strmap_entry {
        struct hashmap_entry ent;
        const char *key;
        void *value;
+       /* strmap_entry may be allocated extra space to store the key at end */
 };
 
 int cmp_strmap_entry(const void *hashmap_cmp_fn_data,