Re: [Tarantool-patches] [PATCH v2 10/15] sql: rework COUNT()

[Mergen Imeev via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Thank you for the review! I replaced manual checks of MEM type by mem_is_*()
functions. Diff and new patch below.

On Tue, Sep 21, 2021 at 01:59:23PM +0300, Mergen Imeev via Tarantool-patches wrote:
> This patch does some refactoring for the SQL built-in aggregate function
> COUNT().
> 
> Part of #4145
> ---
>  src/box/sql/func.c | 64 +++++++++++++++++++---------------------------
>  1 file changed, 26 insertions(+), 38 deletions(-)
> 
> diff --git a/src/box/sql/func.c b/src/box/sql/func.c
> index b5f154fb1..113df423a 100644
> --- a/src/box/sql/func.c
> +++ b/src/box/sql/func.c
> @@ -150,6 +150,29 @@ fin_avg(struct sql_context *ctx)
>  		ctx->is_aborted = true;
>  }
>  
> +/** Implementation of the COUNT() function. */
> +static void
> +step_count(struct sql_context *ctx, int argc, struct Mem **argv)
> +{
> +	assert(argc == 0 || argc == 1);
> +	if (ctx->pMem->type == MEM_TYPE_NULL)
> +		mem_set_uint(ctx->pMem, 0);
> +	if (argc == 1 && argv[0]->type == MEM_TYPE_NULL)
> +		return;
> +	assert(ctx->pMem->type == MEM_TYPE_UINT);
> +	++ctx->pMem->u.u;
> +}
> +
> +/** Finalizer for the COUNT() function. */
> +static void
> +fin_count(struct sql_context *ctx)
> +{
> +	assert(ctx->pMem->type == MEM_TYPE_NULL || mem_is_uint(ctx->pMem));
> +	if (ctx->pMem->type == MEM_TYPE_NULL)
> +		return mem_set_uint(ctx->pOut, 0);
> +	mem_copy_as_ephemeral(ctx->pOut, ctx->pMem);
> +}
> +
>  static const unsigned char *
>  mem_as_ustr(struct Mem *mem)
>  {
> @@ -1704,41 +1727,6 @@ soundexFunc(sql_context * context, int argc, sql_value ** argv)
>  	}
>  }
>  
> -/*
> - * The following structure keeps track of state information for the
> - * count() aggregate function.
> - */
> -typedef struct CountCtx CountCtx;
> -struct CountCtx {
> -	i64 n;
> -};
> -
> -/*
> - * Routines to implement the count() aggregate function.
> - */
> -static void
> -countStep(sql_context * context, int argc, sql_value ** argv)
> -{
> -	CountCtx *p;
> -	if (argc != 0 && argc != 1) {
> -		diag_set(ClientError, ER_FUNC_WRONG_ARG_COUNT,
> -			 "COUNT", "0 or 1", argc);
> -		context->is_aborted = true;
> -		return;
> -	}
> -	p = sql_aggregate_context(context, sizeof(*p));
> -	if ((argc == 0 || !mem_is_null(argv[0])) && p != NULL)
> -		p->n++;
> -}
> -
> -static void
> -countFinalize(sql_context * context)
> -{
> -	CountCtx *p;
> -	p = sql_aggregate_context(context, 0);
> -	sql_result_uint(context, p ? p->n : 0);
> -}
> -
>  /*
>   * Routines to implement min() and max() aggregate functions.
>   */
> @@ -2008,9 +1996,9 @@ static struct sql_func_definition definitions[] = {
>  	 NULL},
>  	{"COALESCE", -1, {FIELD_TYPE_ANY}, FIELD_TYPE_SCALAR, sql_builtin_stub,
>  	 NULL},
> -	{"COUNT", 0, {}, FIELD_TYPE_INTEGER, countStep, countFinalize},
> -	{"COUNT", 1, {FIELD_TYPE_ANY}, FIELD_TYPE_INTEGER, countStep,
> -	 countFinalize},
> +	{"COUNT", 0, {}, FIELD_TYPE_INTEGER, step_count, fin_count},
> +	{"COUNT", 1, {FIELD_TYPE_ANY}, FIELD_TYPE_INTEGER, step_count,
> +	 fin_count},
>  
>  	{"GREATEST", -1, {FIELD_TYPE_INTEGER}, FIELD_TYPE_INTEGER, minmaxFunc,
>  	 NULL},
> -- 
> 2.25.1
> 


Diff:

diff --git a/src/box/sql/func.c b/src/box/sql/func.c
index b4c25c935..00db6512a 100644
--- a/src/box/sql/func.c
+++ b/src/box/sql/func.c
@@ -159,11 +159,11 @@ static void
 step_count(struct sql_context *ctx, int argc, struct Mem **argv)
 {
 	assert(argc == 0 || argc == 1);
-	if (ctx->pMem->type == MEM_TYPE_NULL)
+	if (mem_is_null(ctx->pMem))
 		mem_set_uint(ctx->pMem, 0);
-	if (argc == 1 && argv[0]->type == MEM_TYPE_NULL)
+	if (argc == 1 && mem_is_null(argv[0]))
 		return;
-	assert(ctx->pMem->type == MEM_TYPE_UINT);
+	assert(mem_is_uint(ctx->pMem));
 	++ctx->pMem->u.u;
 }
 
@@ -171,8 +171,8 @@ step_count(struct sql_context *ctx, int argc, struct Mem **argv)
 static void
 fin_count(struct sql_context *ctx)
 {
-	assert(ctx->pMem->type == MEM_TYPE_NULL || mem_is_uint(ctx->pMem));
-	if (ctx->pMem->type == MEM_TYPE_NULL)
+	assert(mem_is_null(ctx->pMem) || mem_is_uint(ctx->pMem));
+	if (mem_is_null(ctx->pMem))
 		return mem_set_uint(ctx->pOut, 0);
 	mem_copy_as_ephemeral(ctx->pOut, ctx->pMem);
 }


New patch:

commit 000ac8430821d33aaa939d426c30c1de2d5a7cab
Author: Mergen Imeev <imeevma@gmail.com>
Date:   Thu Sep 9 18:26:04 2021 +0300

    sql: rework COUNT()
    
    This patch does some refactoring for the SQL built-in aggregate function
    COUNT().
    
    Part of #4145

diff --git a/src/box/sql/func.c b/src/box/sql/func.c
index e436ffbe1..00db6512a 100644
--- a/src/box/sql/func.c
+++ b/src/box/sql/func.c
@@ -154,6 +154,29 @@ fin_avg(struct sql_context *ctx)
 		ctx->is_aborted = true;
 }
 
+/** Implementation of the COUNT() function. */
+static void
+step_count(struct sql_context *ctx, int argc, struct Mem **argv)
+{
+	assert(argc == 0 || argc == 1);
+	if (mem_is_null(ctx->pMem))
+		mem_set_uint(ctx->pMem, 0);
+	if (argc == 1 && mem_is_null(argv[0]))
+		return;
+	assert(mem_is_uint(ctx->pMem));
+	++ctx->pMem->u.u;
+}
+
+/** Finalizer for the COUNT() function. */
+static void
+fin_count(struct sql_context *ctx)
+{
+	assert(mem_is_null(ctx->pMem) || mem_is_uint(ctx->pMem));
+	if (mem_is_null(ctx->pMem))
+		return mem_set_uint(ctx->pOut, 0);
+	mem_copy_as_ephemeral(ctx->pOut, ctx->pMem);
+}
+
 static const unsigned char *
 mem_as_ustr(struct Mem *mem)
 {
@@ -1708,41 +1731,6 @@ soundexFunc(sql_context * context, int argc, sql_value ** argv)
 	}
 }
 
-/*
- * The following structure keeps track of state information for the
- * count() aggregate function.
- */
-typedef struct CountCtx CountCtx;
-struct CountCtx {
-	i64 n;
-};
-
-/*
- * Routines to implement the count() aggregate function.
- */
-static void
-countStep(sql_context * context, int argc, sql_value ** argv)
-{
-	CountCtx *p;
-	if (argc != 0 && argc != 1) {
-		diag_set(ClientError, ER_FUNC_WRONG_ARG_COUNT,
-			 "COUNT", "0 or 1", argc);
-		context->is_aborted = true;
-		return;
-	}
-	p = sql_aggregate_context(context, sizeof(*p));
-	if ((argc == 0 || !mem_is_null(argv[0])) && p != NULL)
-		p->n++;
-}
-
-static void
-countFinalize(sql_context * context)
-{
-	CountCtx *p;
-	p = sql_aggregate_context(context, 0);
-	sql_result_uint(context, p ? p->n : 0);
-}
-
 /*
  * Routines to implement min() and max() aggregate functions.
  */
@@ -2012,9 +2000,9 @@ static struct sql_func_definition definitions[] = {
 	 NULL},
 	{"COALESCE", -1, {FIELD_TYPE_ANY}, FIELD_TYPE_SCALAR, sql_builtin_stub,
 	 NULL},
-	{"COUNT", 0, {}, FIELD_TYPE_INTEGER, countStep, countFinalize},
-	{"COUNT", 1, {FIELD_TYPE_ANY}, FIELD_TYPE_INTEGER, countStep,
-	 countFinalize},
+	{"COUNT", 0, {}, FIELD_TYPE_INTEGER, step_count, fin_count},
+	{"COUNT", 1, {FIELD_TYPE_ANY}, FIELD_TYPE_INTEGER, step_count,
+	 fin_count},
 
 	{"GREATEST", -1, {FIELD_TYPE_INTEGER}, FIELD_TYPE_INTEGER, minmaxFunc,
 	 NULL},