From 9cc33308feb5ab74cd72a563d03d1d2b92326bbd Mon Sep 17 00:00:00 2001
From: Mergen Imeev <imeevma@gmail.com>
Date: Thu, 9 Sep 2021 18:19:53 +0300
Subject: [PATCH] sql: refactor AVG() function
Part of #4145
---
src/box/sql/func.c | 116 ++++++++++++++++++++-------------------------
src/box/sql/mem.h | 8 ++++
2 files changed, 59 insertions(+), 65 deletions(-)
diff --git a/src/box/sql/func.c b/src/box/sql/func.c
index c3c7ebec06..8be5531103 100644
--- a/src/box/sql/func.c
+++ b/src/box/sql/func.c
@@ -102,6 +102,55 @@ fin_total(struct sql_context *ctx)
mem_copy_as_ephemeral(ctx->pOut, ctx->pMem);
}
+/** Implementation of the AVG() function. */
+static void
+step_avg(struct sql_context *ctx, int argc, struct Mem **argv)
+{
+ assert(argc == 1);
+ (void)argc;
+ assert(mem_is_null(ctx->pMem) || mem_is_bin(ctx->pMem));
+ if (mem_is_null(argv[0]))
+ return;
+ struct Mem *mem;
+ uint32_t *count;
+ if (mem_is_null(ctx->pMem)) {
+ uint32_t size = sizeof(struct Mem) + sizeof(uint32_t);
+ mem = sqlDbMallocRawNN(sql_get(), size);
+ if (mem == NULL) {
+ ctx->is_aborted = true;
+ return;
+ }
+ count = (uint32_t *)(mem + 1);
+ mem_create(mem);
+ *count = 1;
+ mem_copy_as_ephemeral(mem, argv[0]);
+ mem_set_bin_allocated(ctx->pMem, (char *)mem, size);
+ return;
+ }
+ mem = (struct Mem *)ctx->pMem->z;
+ count = (uint32_t *)(mem + 1);
+ ++*count;
+ if (mem_add(mem, argv[0], mem) != 0)
+ ctx->is_aborted = true;
+}
+
+/** Finalizer for the AVG() function. */
+static void
+fin_avg(struct sql_context *ctx)
+{
+ assert(mem_is_null(ctx->pMem) || mem_is_bin(ctx->pMem));
+ if (mem_is_null(ctx->pMem))
+ return mem_set_null(ctx->pOut);
+ struct Mem *sum = (struct Mem *)ctx->pMem->z;
+ uint32_t *count_val = (uint32_t *)(sum + 1);
+ assert(mem_is_trivial(sum));
+ struct Mem count;
+ mem_create(&count);
+ mem_set_uint(&count, *count_val);
+ if (mem_div(sum, &count, ctx->pOut) != 0)
+ ctx->is_aborted = true;
+}
+
static const unsigned char *
mem_as_ustr(struct Mem *mem)
{
@@ -1663,69 +1712,6 @@ soundexFunc(sql_context * context, int argc, sql_value ** argv)
}
}
-/*
- * An instance of the following structure holds the context of a
- * sum() or avg() aggregate computation.
- */
-typedef struct SumCtx SumCtx;
-struct SumCtx {
- struct Mem mem;
- uint32_t count;
-};
-
-/*
- * Routines used to compute the sum, average, and total.
- *
- * The SUM() function follows the (broken) SQL standard which means
- * that it returns NULL if it sums over no inputs. TOTAL returns
- * 0.0 in that case. In addition, TOTAL always returns a float where
- * SUM might return an integer if it never encounters a floating point
- * value. TOTAL never fails, but SUM might through an exception if
- * it overflows an integer.
- */
-static void
-sum_step(struct sql_context *context, int argc, sql_value **argv)
-{
- assert(argc == 1);
- UNUSED_PARAMETER(argc);
- struct SumCtx *p = sql_aggregate_context(context, sizeof(*p));
- if (p == NULL) {
- context->is_aborted = true;
- return;
- }
- if (p->count == 0) {
- mem_create(&p->mem);
- assert(context->func->def->returns == FIELD_TYPE_INTEGER ||
- context->func->def->returns == FIELD_TYPE_DOUBLE);
- if (context->func->def->returns == FIELD_TYPE_INTEGER)
- mem_set_uint(&p->mem, 0);
- else
- mem_set_double(&p->mem, 0.0);
- }
- if (argv[0]->type == MEM_TYPE_NULL)
- return;
- ++p->count;
- assert(mem_is_num(argv[0]));
- if (mem_add(&p->mem, argv[0], &p->mem) != 0)
- context->is_aborted = true;
-}
-
-static void
-avgFinalize(sql_context * context)
-{
- SumCtx *p;
- p = sql_aggregate_context(context, 0);
- if (p == NULL || p->count == 0) {
- mem_set_null(context->pOut);
- return;
- }
- struct Mem mem;
- mem_create(&mem);
- mem_set_uint(&mem, p->count);
- if (mem_div(&p->mem, &mem, context->pOut) != 0)
- context->is_aborted = true;
-}
-
/*
* The following structure keeps track of state information for the
* count() aggregate function.
@@ -2022,8 +2008,8 @@ struct sql_func_definition {
static struct sql_func_definition definitions[] = {
{"ABS", 1, {FIELD_TYPE_INTEGER}, FIELD_TYPE_INTEGER, absFunc, NULL},
{"ABS", 1, {FIELD_TYPE_DOUBLE}, FIELD_TYPE_DOUBLE, absFunc, NULL},
- {"AVG", 1, {FIELD_TYPE_INTEGER}, FIELD_TYPE_INTEGER, sum_step, avgFinalize},
- {"AVG", 1, {FIELD_TYPE_DOUBLE}, FIELD_TYPE_DOUBLE, sum_step, avgFinalize},
+ {"AVG", 1, {FIELD_TYPE_INTEGER}, FIELD_TYPE_INTEGER, step_avg, fin_avg},
+ {"AVG", 1, {FIELD_TYPE_DOUBLE}, FIELD_TYPE_DOUBLE, step_avg, fin_avg},
{"CHAR", -1, {FIELD_TYPE_INTEGER}, FIELD_TYPE_STRING, charFunc, NULL},
{"CHAR_LENGTH", 1, {FIELD_TYPE_STRING}, FIELD_TYPE_INTEGER, lengthFunc,
NULL},
diff --git a/src/box/sql/mem.h b/src/box/sql/mem.h
index 7d5a750f55..52a63949af 100644
--- a/src/box/sql/mem.h
+++ b/src/box/sql/mem.h
@@ -237,6 +237,14 @@ mem_is_allocated(const struct Mem *mem)
return mem_is_bytes(mem) && mem->z == mem->zMalloc;
}
+/** Return TRUE if MEM does not need to be freed or destroyed. */
+static inline bool
+mem_is_trivial(const struct Mem *mem)
+{
+ return mem->szMalloc == 0 && (mem->flags & MEM_Dyn) == 0 &&
+ (mem->type & (MEM_TYPE_FRAME | MEM_TYPE_AGG)) == 0;
+}
+
static inline bool
mem_is_cleared(const struct Mem *mem)
{
--
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