From 727a8f32c44ca81e189674adb215f8778e1ec43c Mon Sep 17 00:00:00 2001
From: Vojtech Vilimek <vojtech.vilimek@nic.cz>
Date: Wed, 20 Jul 2022 17:04:49 +0200
Subject: [PATCH] Add new global counter for stats channel

New symbol is added for each stats protocol channel, the symbol is accessed by
same name as the underlying channel. Symbols evaluate to the sum of all routes
exported from connected table with generation less than max generation of
particular channel. Default max generation is 16.

Beware you shouldn't make cyclic references as the behavior of such
configuration is not defined!
---
 conf/conf.h          | 2 ++
 filter/config.Y      | 3 +++
 filter/f-inst.c      | 6 ++++++
 filter/filter.c      | 1 +
 proto/stats/config.Y | 3 +++
 proto/stats/stats.h  | 9 ++++++++-
 6 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/conf/conf.h b/conf/conf.h
index 4ccaa54e..d193155b 100644
--- a/conf/conf.h
+++ b/conf/conf.h
@@ -124,6 +124,7 @@ struct symbol {
     struct ea_class *attribute;		/* For SYM_ATTRIBUTE */
     struct f_val *val;			/* For SYM_CONSTANT */
     uint offset;			/* For SYM_VARIABLE */
+    struct channel_config *ch_config;	/* For SYM_COUNTER */
   };
 
   char name[0];
@@ -156,6 +157,7 @@ struct bytestring {
 #define SYM_FILTER 4
 #define SYM_TABLE 5
 #define SYM_ATTRIBUTE 6
+#define SYM_COUNTER 7
 
 #define SYM_VARIABLE 0x100	/* 0x100-0x1ff are variable types */
 #define SYM_VARIABLE_RANGE SYM_VARIABLE ... (SYM_VARIABLE | 0xff)
diff --git a/filter/config.Y b/filter/config.Y
index 8cecf936..23b258cd 100644
--- a/filter/config.Y
+++ b/filter/config.Y
@@ -758,6 +758,9 @@ symbol_value: symbol_known
       case SYM_ATTRIBUTE:
 	$$ = f_new_inst(FI_EA_GET, $1->attribute);
 	break;
+      case SYM_COUNTER:
+	$$ = f_new_inst(FI_COUNTER, $1);
+	break;
       default:
 	cf_error("Can't get value of symbol %s", $1->name);
     }
diff --git a/filter/f-inst.c b/filter/f-inst.c
index e7b642ab..4dfd276b 100644
--- a/filter/f-inst.c
+++ b/filter/f-inst.c
@@ -473,6 +473,12 @@
     RESULT_VAL(fstk->vstk[curline.vbase + sym->offset]);
   }
 
+  INST(FI_COUNTER, 0, 1) {
+    SYMBOL;
+    NEVER_CONSTANT;
+    RESULT(T_INT, i, get_stats_sum(sym));
+  }
+
   INST(FI_CONSTANT, 0, 1) {
     FID_MEMBER(
       struct f_val,
diff --git a/filter/filter.c b/filter/filter.c
index ad2fafe2..bd65777f 100644
--- a/filter/filter.c
+++ b/filter/filter.c
@@ -43,6 +43,7 @@
 #include "filter/filter.h"
 #include "filter/f-inst.h"
 #include "filter/data.h"
+#include "proto/stats/stats.h"  /* provides function get_stats_sum used in f-inst.c */
 
 
 /* Exception bits */
diff --git a/proto/stats/config.Y b/proto/stats/config.Y
index b32ea773..087ac75a 100644
--- a/proto/stats/config.Y
+++ b/proto/stats/config.Y
@@ -61,6 +61,9 @@ stats_channel_start: net_type symbol
 {
   this_channel = channel_config_get(&channel_stats, $2->name, $1, this_proto);
   STATS_CC->max_generation = 16;
+  /* from filter/config.Y:
+       cf_define_symbol($3, SYM_VARIABLE | $2, offset, $3->scope->slots++) */
+  $2 = cf_define_symbol($2, SYM_COUNTER, ch_config, this_channel);
 }
 
 stats_proto:
diff --git a/proto/stats/stats.h b/proto/stats/stats.h
index 51802341..d061e4ea 100644
--- a/proto/stats/stats.h
+++ b/proto/stats/stats.h
@@ -35,6 +35,13 @@ struct stats_channel_config {
   u8 max_generation;
 };
 
-
+static inline int
+get_stats_sum(struct symbol *sym)
+{
+  if (sym->ch_config->channel)
+    return (int) ((struct stats_channel *) sym->ch_config->channel)->sum;
+  else
+    return 0;
+}
 
 #endif