[v3,27/28] hash-ll, hashmap: move oidhash() to hash-ll

Commit Message

Elijah Newren May 16, 2023, 6:34 a.m. UTC

From: Elijah Newren <[e-mail]>

oidhash() was used by both hashmap and khash, which makes sense.
However, the location of this function in hashmap.[ch] meant that
khash.h had to depend upon hashmap.h, making people unfamiliar with
khash think that it was built upon hashmap.  (Or at least, I personally
was confused for a while about this in the past.)

Move this function to hash-ll, so that khash.h can stop depending upon
hashmap.h.

This has another benefit as well: it allows us to remove hashmap.h's
dependency on hash-ll.h.  While some callers of hashmap.h were making
use of oidhash, most were not, so this change provides another way to
reduce the number of includes.

Diff best viewed with `--color-moved`.

Signed-off-by: Elijah Newren <[e-mail]>
---
 decorate.c |  1 -
 dir.h      |  1 +
 hash-ll.h  | 19 +++++++++++++++++++
 hashmap.h  | 21 ---------------------
 khash.h    |  1 -
 remote.h   |  1 +
 serve.c    |  1 +
 7 files changed, 22 insertions(+), 23 deletions(-)

Patch

diff --git a/decorate.c b/decorate.c
index 71e79daa825..a5c43c0c146 100644
--- a/decorate.c
+++ b/decorate.c
@@ -3,7 +3,6 @@ 
  * data.
  */
 #include "git-compat-util.h"
-#include "hashmap.h"
 #include "object.h"
 #include "decorate.h"
 
diff --git a/dir.h b/dir.h
index 79b85a01ee4..279a0660801 100644
--- a/dir.h
+++ b/dir.h
@@ -1,6 +1,7 @@ 
 #ifndef DIR_H
 #define DIR_H
 
+#include "hash-ll.h"
 #include "hashmap.h"
 #include "pathspec.h"
 #include "statinfo.h"
diff --git a/hash-ll.h b/hash-ll.h
index 80509251370..8d7973769fd 100644
--- a/hash-ll.h
+++ b/hash-ll.h
@@ -270,6 +270,25 @@  static inline void oid_set_algo(struct object_id *oid, const struct git_hash_alg
 	oid->algo = hash_algo_by_ptr(algop);
 }
 
+/*
+ * Converts a cryptographic hash (e.g. SHA-1) into an int-sized hash code
+ * for use in hash tables. Cryptographic hashes are supposed to have
+ * uniform distribution, so in contrast to `memhash()`, this just copies
+ * the first `sizeof(int)` bytes without shuffling any bits. Note that
+ * the results will be different on big-endian and little-endian
+ * platforms, so they should not be stored or transferred over the net.
+ */
+static inline unsigned int oidhash(const struct object_id *oid)
+{
+	/*
+	 * Equivalent to 'return *(unsigned int *)oid->hash;', but safe on
+	 * platforms that don't support unaligned reads.
+	 */
+	unsigned int hash;
+	memcpy(&hash, oid->hash, sizeof(hash));
+	return hash;
+}
+
 const char *empty_tree_oid_hex(void);
 const char *empty_blob_oid_hex(void);
 
diff --git a/hashmap.h b/hashmap.h
index 2695f3d3a6e..c8216e47bb2 100644
--- a/hashmap.h
+++ b/hashmap.h
@@ -1,8 +1,6 @@ 
 #ifndef HASHMAP_H
 #define HASHMAP_H
 
-#include "hash-ll.h"
-
 /*
  * Generic implementation of hash-based key-value mappings.
  *
@@ -120,25 +118,6 @@  unsigned int memhash(const void *buf, size_t len);
 unsigned int memihash(const void *buf, size_t len);
 unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len);
 
-/*
- * Converts a cryptographic hash (e.g. SHA-1) into an int-sized hash code
- * for use in hash tables. Cryptographic hashes are supposed to have
- * uniform distribution, so in contrast to `memhash()`, this just copies
- * the first `sizeof(int)` bytes without shuffling any bits. Note that
- * the results will be different on big-endian and little-endian
- * platforms, so they should not be stored or transferred over the net.
- */
-static inline unsigned int oidhash(const struct object_id *oid)
-{
-	/*
-	 * Equivalent to 'return *(unsigned int *)oid->hash;', but safe on
-	 * platforms that don't support unaligned reads.
-	 */
-	unsigned int hash;
-	memcpy(&hash, oid->hash, sizeof(hash));
-	return hash;
-}
-
 /*
  * struct hashmap_entry is an opaque structure representing an entry in the
  * hash table.
diff --git a/khash.h b/khash.h
index a0a08dad8b7..ff881631778 100644
--- a/khash.h
+++ b/khash.h
@@ -26,7 +26,6 @@ 
 #ifndef __AC_KHASH_H
 #define __AC_KHASH_H
 
-#include "hashmap.h"
 #include "hash.h"
 
 #define AC_VERSION_KHASH_H "0.2.8"
diff --git a/remote.h b/remote.h
index 73638cefeb1..929c7c676d3 100644
--- a/remote.h
+++ b/remote.h
@@ -1,6 +1,7 @@ 
 #ifndef REMOTE_H
 #define REMOTE_H
 
+#include "hash-ll.h"
 #include "hashmap.h"
 #include "refspec.h"
 
diff --git a/serve.c b/serve.c
index 5329c91011f..a1d71134d49 100644
--- a/serve.c
+++ b/serve.c
@@ -1,6 +1,7 @@ 
 #include "git-compat-util.h"
 #include "repository.h"
 #include "config.h"
+#include "hash-ll.h"
 #include "pkt-line.h"
 #include "version.h"
 #include "ls-refs.h"