askrene-bias-channel: bias call add up.

The channel bias feature is not being used yet by any plugin, so this
hopefully doesn't break any working code.
When askrene-bias-channel is called the bias quantity is added on top of
any previous biased already present on that channel instead of
overwriting it.

Changelog-Changed: askrene-bias-channel: bias call add up.

Signed-off-by: Lagrang3 <lagrang3@protonmail.com>

Author: Lagrang3

contrib/msggen/msggen/schema.json

@@ -309,6 +309,14 @@
               "The bias, positive being good and negative being bad (0 being no bias).  Useful values are +/-1 through +/-10, though -100 through +100 are possible values."
             ]
           },
+          "relative": {
+            "type": "boolean",
+            "added": "v25.05",
+            "default": false,
+            "description": [
+              "The bias will be added to the previous value."
+            ]
+          },
           "description": {
             "type": "string",
             "description": [
@@ -29248,6 +29256,11 @@
                 "active": true,
                 "dynamic": false
               },
+              {
+                "name": "/root/lightning/plugins/cln-lsps-client",
+                "active": true,
+                "dynamic": false
+              },
               {
                 "name": "/root/lightning/plugins/bookkeeper",
                 "active": true,
@@ -29381,6 +29394,11 @@
                 "active": true,
                 "dynamic": false
               },
+              {
+                "name": "/root/lightning/plugins/cln-lsps-client",
+                "active": true,
+                "dynamic": false
+              },
               {
                 "name": "/root/lightning/plugins/bookkeeper",
                 "active": true,

doc/schemas/askrene-bias-channel.json

@@ -33,6 +33,14 @@
           "The bias, positive being good and negative being bad (0 being no bias).  Useful values are +/-1 through +/-10, though -100 through +100 are possible values."
         ]
       },
+      "relative": {
+        "type": "boolean",
+        "added": "v25.05",
+        "default": false,
+        "description": [
+          "The bias will be added to the previous value."
+        ]
+      },
       "description": {
         "type": "string",
         "description": [

doc/schemas/plugin.json

@@ -297,6 +297,11 @@
             "active": true,
             "dynamic": false
           },
+          {
+            "name": "/root/lightning/plugins/cln-lsps-client",
+            "active": true,
+            "dynamic": false
+          },
           {
             "name": "/root/lightning/plugins/bookkeeper",
             "active": true,
@@ -430,6 +435,11 @@
             "active": true,
             "dynamic": false
           },
+          {
+            "name": "/root/lightning/plugins/cln-lsps-client",
+            "active": true,
+            "dynamic": false
+          },
           {
             "name": "/root/lightning/plugins/bookkeeper",
             "active": true,

plugins/askrene/askrene.c

@@ -1098,18 +1098,20 @@ static struct command_result *json_askrene_bias_channel(struct command *cmd,
 	const char *description;
 	s8 *bias;
 	const struct bias *b;
+	bool *relative;
 
 	if (!param(cmd, buffer, params,
 		   p_req("layer", param_known_layer, &layer),
 		   p_req("short_channel_id_dir", param_short_channel_id_dir, &scidd),
 		   p_req("bias", param_s8_hundred, &bias),
+		   p_opt_def("relative", param_bool, &relative, false),
 		   p_opt("description", param_string, &description),
 		   NULL))
 		return command_param_failed();
 	plugin_log(cmd->plugin, LOG_TRACE, "%s called: %.*s", __func__,
 		   json_tok_full_len(params), json_tok_full(buffer, params));
 
-	b = layer_set_bias(layer, scidd, description, *bias);
+	b = layer_set_bias(layer, scidd, description, *bias, *relative);
 	response = jsonrpc_stream_success(cmd);
 	json_array_start(response, "biases");
 	if (b)

plugins/askrene/layer.c

@@ -10,6 +10,9 @@
 #include <plugins/askrene/layer.h>
 #include <wire/wire.h>
 
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+
 /* Different elements in the datastore */
 enum dstore_layer_type {
 	/* We don't use type 0, which fromwire_u16 returns on trunction */
@@ -285,7 +288,8 @@ static const struct constraint *add_constraint(struct layer *layer,
 static const struct bias *set_bias(struct layer *layer,
 				   const struct short_channel_id_dir *scidd,
 				   const char *description TAKES,
-				   s8 bias_factor)
+				   s8 bias_factor,
+				   bool relative)
 {
 	struct bias *bias;
 
@@ -294,15 +298,18 @@ static const struct bias *set_bias(struct layer *layer,
 		bias = tal(layer, struct bias);
 		bias->scidd = *scidd;
 		bias_hash_add(layer->biases, bias);
+		bias->bias = 0;
 	} else {
 		tal_free(bias->description);
 	}
-
-	bias->bias = bias_factor;
+	int bias_new = relative ? bias->bias + bias_factor : bias_factor;
+	bias_new = MIN(100, bias_new);
+	bias_new = MAX(-100, bias_new);
+	bias->bias = bias_new;
 	bias->description = tal_strdup_or_null(bias, description);
 
 	/* Don't bother keeping around zero biases */
-	if (bias_factor == 0) {
+	if (bias->bias == 0) {
 		bias_hash_del(layer->biases, bias);
 		bias = tal_free(bias);
 	}
@@ -588,7 +595,7 @@ static void load_channel_bias(struct plugin *plugin,
 	description = fromwire_wirestring(tmpctx, cursor, len);
 
 	if (*cursor)
-		set_bias(layer, &scidd, take(description), bias_factor);
+		set_bias(layer, &scidd, take(description), bias_factor, false);
 }
 
 static void towire_save_disabled_node(u8 **data, const struct node_id *node)
@@ -818,11 +825,12 @@ void layer_add_update_channel(struct layer *layer,
 const struct bias *layer_set_bias(struct layer *layer,
 				  const struct short_channel_id_dir *scidd,
 				  const char *description TAKES,
-				  s8 bias_factor)
+				  s8 bias_factor,
+				  bool relative)
 {
 	const struct bias *bias;
 
-	bias = set_bias(layer, scidd, description, bias_factor);
+	bias = set_bias(layer, scidd, description, bias_factor, relative);
 	save_channel_bias(layer, bias);
 	return bias;
 }

plugins/askrene/layer.h

@@ -59,7 +59,8 @@ void layer_add_local_channel(struct layer *layer,
 const struct bias *layer_set_bias(struct layer *layer,
 				  const struct short_channel_id_dir *scidd,
 				  const char *description TAKES,
-				  s8 bias_factor);
+				  s8 bias_factor,
+				  bool relative);
 
 /* Update details on a channel (could be in this layer, or another) */
 void layer_add_update_channel(struct layer *layer,