MDEV-15073: Generic UDAF parser code in server for windows functions

Added support for usual agreggate UDF (UDAF)
Added remove() call support for more efficient window function processing
Added example of aggregate UDF with efficient windows function support

1 files changed, 139 insertions, 0 deletions

diff --git a/sql/udf_example.c b/sql/udf_example.c
index 6db2b5e737a..bdc995b51fc 100644
--- a/sql/udf_example.c
+++ b/sql/udf_example.c
@@ -173,6 +173,13 @@ void avgcost_reset( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char *error
 void avgcost_clear( UDF_INIT* initid, char* is_null, char *error );
 void avgcost_add( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char *error );
 double avgcost( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char *error );
+my_bool avg2_init( UDF_INIT* initid, UDF_ARGS* args, char* message );
+void avg2_deinit( UDF_INIT* initid );
+void avg2_reset( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char *error );
+void avg2_clear( UDF_INIT* initid, char* is_null, char *error );
+void avg2_add( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char *error );
+void avg2_remove( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char *error );
+double avg2( UDF_INIT* initid, UDF_ARGS* args, char* is_null, char *error );
 my_bool is_const_init(UDF_INIT *initid, UDF_ARGS *args, char *message);
 char *is_const(UDF_INIT *initid, UDF_ARGS *args, char *result, unsigned long
                *length, char *is_null, char *error);
@@ -1049,6 +1056,138 @@ avgcost( UDF_INIT* initid, UDF_ARGS* args __attribute__((unused)),
   return data->totalprice/(double)data->totalquantity;
 }
 
+
+/*
+** Average 2 (number, sum)*/
+struct avg2_data
+{
+  ulonglong	count;
+  double	sum;
+};
+
+
+my_bool
+avg2_init( UDF_INIT* initid, UDF_ARGS* args, char* message )
+{
+  struct avg2_data*	data;
+
+  if (args->arg_count != 2)
+  {
+    strcpy(
+	   message,
+	   "wrong number of arguments: AVG2() requires two arguments"
+	   );
+    return 1;
+  }
+
+  if ((args->arg_type[0] != INT_RESULT) || (args->arg_type[1] != REAL_RESULT) )
+  {
+    strcpy(
+	   message,
+	   "wrong argument type: AVG2() requires an INT and a REAL"
+	   );
+    return 1;
+  }
+
+  /*
+  **	force arguments to double.
+  */
+  /*args->arg_type[0]	= REAL_RESULT;
+    args->arg_type[1]	= REAL_RESULT;*/
+
+  initid->maybe_null	= 0;		/* The result may be null */
+  initid->decimals	= 4;		/* We want 4 decimals in the result */
+  initid->max_length	= 20;		/* 6 digits + . + 10 decimals */
+
+  if (!(data = (struct avg2_data*) malloc(sizeof(struct avg2_data))))
+  {
+    strmov(message,"Couldn't allocate memory");
+    return 1;
+  }
+  data->count	= 0;
+  data->sum	= 0.0;
+
+  initid->ptr = (char*)data;
+
+  return 0;
+}
+
+void
+avg2_deinit( UDF_INIT* initid )
+{
+  free(initid->ptr);
+}
+
+
+/* This is only for MySQL 4.0 compability */
+void
+avg2_reset(UDF_INIT* initid, UDF_ARGS* args, char* is_null, char* message)
+{
+  avgcost_clear(initid, is_null, message);
+  avgcost_add(initid, args, is_null, message);
+}
+
+/* This is needed to get things to work in MySQL 4.1.1 and above */
+
+void
+avg2_clear(UDF_INIT* initid, char* is_null __attribute__((unused)),
+              char* message __attribute__((unused)))
+{
+  struct avg2_data* data = (struct avg2_data*)initid->ptr;
+  data->sum=	0.0;
+  data->count=	0;
+}
+
+
+void
+avg2_add(UDF_INIT* initid, UDF_ARGS* args,
+            char* is_null __attribute__((unused)),
+            char* message __attribute__((unused)))
+{
+  if (args->args[0] && args->args[1])
+  {
+    struct avg2_data* data	= (struct avg2_data*)initid->ptr;
+    longlong quantity		= *((longlong*)args->args[0]);
+    double sum	                = *((double*)args->args[1]);
+
+    data->count	+= quantity;
+    data->sum	+= sum;
+  }
+}
+
+
+void
+avg2_remove(UDF_INIT* initid, UDF_ARGS* args,
+               char* is_null __attribute__((unused)),
+               char* message __attribute__((unused)))
+{
+  if (args->args[0] && args->args[1])
+  {
+    struct avg2_data* data	= (struct avg2_data*)initid->ptr;
+    longlong quantity		= *((longlong*)args->args[0]);
+    double sum	                = *((double*)args->args[1]);
+
+    data->count	-= quantity;
+    data->sum	-= sum;
+  }
+}
+
+
+double
+avg2( UDF_INIT* initid, UDF_ARGS* args __attribute__((unused)),
+         char* is_null, char* error __attribute__((unused)))
+{
+  struct avg2_data* data = (struct avg2_data*)initid->ptr;
+  if (!data->count)
+  {
+    *is_null = 1;
+    return 0.0;
+  }
+
+  *is_null = 0;
+  return data->sum/(double)data->count;
+}
+
 my_bool myfunc_argument_name_init(UDF_INIT *initid, UDF_ARGS *args,
 				  char *message);
 char *myfunc_argument_name(UDF_INIT *initid, UDF_ARGS *args, char *result,