Re: [PATCH v3 1/2] alloc.c: remove the alloc_raw_commit_node() function

2014-07-10 Thread Ramsay Jones
On 11/07/14 01:09, Jeff King wrote:
> On Fri, Jul 11, 2014 at 12:58:31AM +0100, Ramsay Jones wrote:
> 
>>  #define DEFINE_ALLOCATOR(name, type)\
>> -static unsigned int name##_allocs;  \
>> +static struct alloc_state name##_state; \
>>  void *alloc_##name##_node(void) \
>>  {   \
>> -static int nr;  \
>> -static type *block; \
>> -void *ret;  \
>> -\
>> -if (!nr) {  \
>> -nr = BLOCKING;  \
>> -block = xmalloc(BLOCKING * sizeof(type));   \
>> -}   \
>> -nr--;   \
>> -name##_allocs++;\
>> -ret = block++;  \
>> -memset(ret, 0, sizeof(type));   \
>> -return ret; \
>> +return alloc_node(&name##_state, sizeof(type)); \
>>  }
> 
> Yay. Not only does this solve the problem, but it gets rid of nasty
> multi-line macro. In fact, I kind of wonder if we should just do away
> with the macro entirely, and write out:
> 
>   static struct alloc_state blob_state;
>   void alloc_blob_node(void)
>   {
>   return alloc_node(&blob_state, sizeof(struct blob));
>   }
> 
> It's more lines, but it is probably less obfuscated to a reader.

Yeah, I'm not a fan of _large_ multi-line macros myself.

Now that DEFINE_ALLOCATOR has slimmed down, I don't mind it so much.
However, I agree that doing away with the macro leads to easier to
read code. (I also don't mind the extra lines).

ATB,
Ramsay Jones


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Re: [PATCH v3 1/2] alloc.c: remove the alloc_raw_commit_node() function

2014-07-10 Thread Jeff King
On Fri, Jul 11, 2014 at 12:58:31AM +0100, Ramsay Jones wrote:

>  #define DEFINE_ALLOCATOR(name, type) \
> -static unsigned int name##_allocs;   \
> +static struct alloc_state name##_state;  \
>  void *alloc_##name##_node(void)  \
>  {\
> - static int nr;  \
> - static type *block; \
> - void *ret;  \
> - \
> - if (!nr) {  \
> - nr = BLOCKING;  \
> - block = xmalloc(BLOCKING * sizeof(type));   \
> - }   \
> - nr--;   \
> - name##_allocs++;\
> - ret = block++;  \
> - memset(ret, 0, sizeof(type));   \
> - return ret; \
> + return alloc_node(&name##_state, sizeof(type)); \
>  }

Yay. Not only does this solve the problem, but it gets rid of nasty
multi-line macro. In fact, I kind of wonder if we should just do away
with the macro entirely, and write out:

  static struct alloc_state blob_state;
  void alloc_blob_node(void)
  {
return alloc_node(&blob_state, sizeof(struct blob));
  }

It's more lines, but it is probably less obfuscated to a reader.

-Peff
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[PATCH v3 1/2] alloc.c: remove the alloc_raw_commit_node() function

2014-07-10 Thread Ramsay Jones

In order to encapsulate the setting of the unique commit index, commit
969eba63 ("commit: push commit_index update into alloc_commit_node",
10-06-2014) introduced a (logically private) intermediary allocator
function. However, this function (alloc_raw_commit_node()) was declared
as a public function, which undermines its entire purpose.

Introduce an inline function, alloc_node(), which implements the main
logic of the allocator used by DEFINE_ALLOCATOR, and redefine the macro
in terms of the new function. In addition, use the new function in the
implementation of the alloc_commit_node() allocator, rather than the
intermediary allocator, which can now be removed.

Noticed by sparse ("symbol 'alloc_raw_commit_node' was not declared.
Should it be static?").

Signed-off-by: Ramsay Jones 
---
 alloc.c | 47 +--
 1 file changed, 29 insertions(+), 18 deletions(-)

diff --git a/alloc.c b/alloc.c
index eb22a45..d7c3605 100644
--- a/alloc.c
+++ b/alloc.c
@@ -19,22 +19,10 @@
 #define BLOCKING 1024
 
 #define DEFINE_ALLOCATOR(name, type)   \
-static unsigned int name##_allocs; \
+static struct alloc_state name##_state;\
 void *alloc_##name##_node(void)\
 {  \
-   static int nr;  \
-   static type *block; \
-   void *ret;  \
-   \
-   if (!nr) {  \
-   nr = BLOCKING;  \
-   block = xmalloc(BLOCKING * sizeof(type));   \
-   }   \
-   nr--;   \
-   name##_allocs++;\
-   ret = block++;  \
-   memset(ret, 0, sizeof(type));   \
-   return ret; \
+   return alloc_node(&name##_state, sizeof(type)); \
 }
 
 union any_object {
@@ -45,16 +33,39 @@ union any_object {
struct tag tag;
 };
 
+struct alloc_state {
+   int count; /* total number of nodes allocated */
+   int nr;/* number of nodes left in current allocation */
+   void *p;   /* first free node in current allocation */
+};
+
+static inline void *alloc_node(struct alloc_state *s, size_t node_size)
+{
+   void *ret;
+
+   if (!s->nr) {
+   s->nr = BLOCKING;
+   s->p = xmalloc(BLOCKING * node_size);
+   }
+   s->nr--;
+   s->count++;
+   ret = s->p;
+   s->p = (char *)s->p + node_size;
+   memset(ret, 0, node_size);
+   return ret;
+}
+
 DEFINE_ALLOCATOR(blob, struct blob)
 DEFINE_ALLOCATOR(tree, struct tree)
-DEFINE_ALLOCATOR(raw_commit, struct commit)
 DEFINE_ALLOCATOR(tag, struct tag)
 DEFINE_ALLOCATOR(object, union any_object)
 
+static struct alloc_state commit_state;
+
 void *alloc_commit_node(void)
 {
static int commit_count;
-   struct commit *c = alloc_raw_commit_node();
+   struct commit *c = alloc_node(&commit_state, sizeof(struct commit));
c->index = commit_count++;
return c;
 }
@@ -66,13 +77,13 @@ static void report(const char *name, unsigned int count, 
size_t size)
 }
 
 #define REPORT(name, type) \
-report(#name, name##_allocs, name##_allocs * sizeof(type) >> 10)
+report(#name, name##_state.count, name##_state.count * sizeof(type) >> 10)
 
 void alloc_report(void)
 {
REPORT(blob, struct blob);
REPORT(tree, struct tree);
-   REPORT(raw_commit, struct commit);
+   REPORT(commit, struct commit);
REPORT(tag, struct tag);
REPORT(object, union any_object);
 }
-- 
2.0.0
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