libplugin: add spamlistcommand

This hammers lightingd with `listinvoices` commands.

	$ VALGRIND=0 TEST_DB_PROVIDER=postgres eatmydata uv run pytest -v tests/benchmark.py::test_spam_listcommands

sqlite3:

   test_spam_listcommands     2.1193  2.4524  2.2343  0.1341  2.2229  0.1709       1;0  0.4476       5           1

PostgreSQL:

   test_spam_listcommands     6.5572  6.8440  6.7067  0.1032  6.6967  0.1063       2;0  0.1491       5           1

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Author: rustyrussell

tests/benchmark.py

@@ -218,4 +218,13 @@ def test_spam_commands(node_factory, bitcoind, benchmark):
     plugin = os.path.join(os.getcwd(), "tests/plugins/test_libplugin")
     l1 = get_bench_node(node_factory, extra_options={"plugin": plugin})
 
+    # This calls "batch" 1M times (which doesn't need a transaction)
     benchmark(l1.rpc.spamcommand, 1_000_000)
+
+
+def test_spam_listcommands(node_factory, bitcoind, benchmark):
+    plugin = os.path.join(os.getcwd(), "tests/plugins/test_libplugin")
+    l1 = get_bench_node(node_factory, extra_options={"plugin": plugin})
+
+    # This calls "listinvoice" 100,000 times (which doesn't need a transaction commit)
+    benchmark(l1.rpc.spamlistcommand, 100_000)

tests/plugins/test_libplugin.c

@@ -234,6 +234,26 @@ static struct command_result *json_spamcommand(struct command *cmd,
 	return batch_done(cmd, batch);
 }
 
+static struct command_result *json_spamlistcommand(struct command *cmd,
+						   const char *buf,
+						   const jsmntok_t *params)
+{
+	u64 *iterations;
+	struct request_batch *batch;
+
+	if (!param(cmd, buf, params,
+		   p_req("iterations", param_u64, &iterations),
+		   NULL))
+		return command_param_failed();
+
+	batch = request_batch_new(cmd, NULL, spam_errcb, spam_done, NULL);
+	for (size_t i = 0; i < *iterations; i++) {
+		struct out_req *req = add_to_batch(cmd, batch, "listinvoices");
+		send_outreq(req);
+	}
+	return batch_done(cmd, batch);
+}
+
 
 static char *set_dynamic(struct plugin *plugin,
 			 const char *arg,
@@ -312,6 +332,10 @@ static const struct plugin_command commands[] = { {
 		"spamcommand",
 		json_spamcommand,
 	},
+	{
+		"spamlistcommand",
+		json_spamlistcommand,
+	},
 };
 
 static const char *before[] = { "dummy", NULL };