gRPC auto threadiness

falco.yaml

@@ -182,7 +182,7 @@ http_output:
 # grpc:
 #   enabled: true
 #   bind_address: "0.0.0.0:5060"
-#   threadiness: 8
+#   threadiness: 0
 #   private_key: "/etc/falco/certs/server.key"
 #   cert_chain: "/etc/falco/certs/server.crt"
 #   root_certs: "/etc/falco/certs/ca.crt"
@@ -191,7 +191,8 @@ http_output:
 grpc:
   enabled: false
   bind_address: "unix:///var/run/falco.sock"
-  threadiness: 8
+  # when threadiness is 0, Falco automatically guesses it depending on the number of online cores
+  threadiness: 0
 
 # gRPC output service.
 # By default it is off.

userspace/engine/falco_utils.cpp

@@ -52,6 +52,12 @@ std::string wrap_text(const std::string& str, uint32_t initial_pos, uint32_t ind
 	return ret;
 }
 
+uint32_t hardware_concurrency()
+{
+	auto hc = std::thread::hardware_concurrency();
+	return hc ? hc : 1;
+}
+
 void readfile(const std::string& filename, std::string& data)
 {
 	std::ifstream file(filename.c_str(), std::ios::in);

userspace/engine/falco_utils.h

@@ -21,6 +21,7 @@ limitations under the License.
 #include <fstream>
 #include <iostream>
 #include <string>
+#include <thread>
 #include <nonstd/string_view.hpp>
 
 #pragma once
@@ -34,6 +35,9 @@ namespace utils
 std::string wrap_text(const std::string& str, uint32_t initial_pos, uint32_t indent, uint32_t line_len);
 
 void readfile(const std::string& filename, std::string& data);
+
+uint32_t hardware_concurrency();
+
 namespace network
 {
 static const std::string UNIX_SCHEME("unix://");

userspace/falco/configuration.cpp

@@ -1,5 +1,5 @@
 /*
-Copyright (C) 2019 The Falco Authors.
+Copyright (C) 2020 The Falco Authors.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@ limitations under the License.
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include "falco_utils.h"
 
 #include "configuration.h"
 #include "logger.h"
@@ -148,11 +149,12 @@ void falco_configuration::init(string conf_filename, list<string> &cmdline_optio
 
 	m_grpc_enabled = m_config->get_scalar<bool>("grpc", "enabled", false);
 	m_grpc_bind_address = m_config->get_scalar<string>("grpc", "bind_address", "0.0.0.0:5060");
-	m_grpc_threadiness = m_config->get_scalar<uint32_t>("grpc", "threadiness", 8); // todo > limit it to avoid overshubscription? std::thread::hardware_concurrency()
+	m_grpc_threadiness = m_config->get_scalar<uint32_t>("grpc", "threadiness", 0);
 	if(m_grpc_threadiness == 0)
 	{
-		throw logic_error("error reading config file (" + m_config_file + "): gRPC threadiness must be greater than 0");
+		m_grpc_threadiness = falco::utils::hardware_concurrency();
 	}
+	// todo > else limit threadiness to avoid oversubscription?
 	m_grpc_private_key = m_config->get_scalar<string>("grpc", "private_key", "/etc/falco/certs/server.key");
 	m_grpc_cert_chain = m_config->get_scalar<string>("grpc", "cert_chain", "/etc/falco/certs/server.crt");
 	m_grpc_root_certs = m_config->get_scalar<string>("grpc", "root_certs", "/etc/falco/certs/ca.crt");
@@ -344,4 +346,4 @@ void falco_configuration::set_cmdline_option(const string &opt)
 	{
 		m_config->set_scalar(keyval.first, keyval.second);
 	}
-}
+}

userspace/falco/configuration.h

@@ -206,7 +206,7 @@ class falco_configuration
 	bool m_time_format_iso_8601;
 
 	bool m_grpc_enabled;
-	int m_grpc_threadiness;
+	uint32_t m_grpc_threadiness;
 	std::string m_grpc_bind_address;
 	std::string m_grpc_private_key;
 	std::string m_grpc_cert_chain;

userspace/falco/falco.cpp

@@ -1206,6 +1206,7 @@ int falco_init(int argc, char **argv)
 		// gRPC server
 		if(config.m_grpc_enabled)
 		{
+			falco_logger::log(LOG_INFO, "gRPC server threadiness equals to " + to_string(config.m_grpc_threadiness) + "\n");
 			// TODO(fntlnz,leodido): when we want to spawn multiple threads we need to have a queue per thread, or implement
 			// different queuing mechanisms, round robin, fanout? What we want to achieve?
 			grpc_server.init(