picoev: support -d picoev_verbose_errors, do not use any naked eprintln by default, since that is a low level module

vlib/picoev/errors.v

@@ -0,0 +1,6 @@
+module picoev
+
+@[if picoev_verbose_errors ?]
+fn elog(msg string) {
+	eprintln(msg)
+}

vlib/picoev/picoev.v

@@ -112,7 +112,7 @@ pub fn (mut pv Picoev) add(fd int, events int, timeout int, callback voidptr) in
 
 	if pv.update_events(fd, events | picoev_add) != 0 {
 		if pv.delete(fd) != 0 {
-			eprintln('Error during del')
+			elog('Error during del')
 		}
 
 		return -1
@@ -143,7 +143,7 @@ pub fn (mut pv Picoev) delete(fd int) int {
 	}
 
 	if pv.update_events(fd, picoev_del) != 0 {
-		eprintln('Error during update_events. event: `picoev.picoev_del`')
+		elog('Error during update_events. event: `picoev.picoev_del`')
 		return -1
 	}
 
@@ -158,7 +158,7 @@ fn (mut pv Picoev) loop_once(max_wait_in_sec int) int {
 	pv.loop.now = get_time()
 
 	if pv.poll_once(max_wait_in_sec) != 0 {
-		eprintln('Error during poll_once')
+		elog('Error during poll_once')
 		return -1
 	}
 
@@ -216,7 +216,7 @@ fn accept_callback(listen_fd int, events int, cb_arg voidptr) {
 			return
 		}
 
-		eprintln('Error during accept')
+		elog('Error during accept')
 		return
 	}
 
@@ -231,7 +231,7 @@ fn accept_callback(listen_fd int, events int, cb_arg voidptr) {
 	}
 
 	setup_sock(accepted_fd) or {
-		eprintln('setup_sock failed, fd: ${accepted_fd}, listen_fd: ${listen_fd}, err: ${err.code()}')
+		elog('setup_sock failed, fd: ${accepted_fd}, listen_fd: ${listen_fd}, err: ${err.code()}')
 		pv.error_callback(pv.user_data, picohttpparser.Request{}, mut &picohttpparser.Response{},
 			err)
 		close_socket(accepted_fd) // Close fd on failure
@@ -244,7 +244,7 @@ fn accept_callback(listen_fd int, events int, cb_arg voidptr) {
 @[inline]
 pub fn (mut pv Picoev) close_conn(fd int) {
 	if pv.delete(fd) != 0 {
-		eprintln('Error during del')
+		elog('Error during del')
 	}
 	close_socket(fd)
 }
@@ -306,7 +306,7 @@ fn raw_callback(fd int, events int, context voidptr) {
 					return
 				}
 
-				eprintln('Error during req_read')
+				elog('Error during req_read')
 
 				// fatal error
 				pv.close_conn(fd)
@@ -344,14 +344,14 @@ fn raw_callback(fd int, events int, context voidptr) {
 }
 
 fn default_error_callback(data voidptr, req picohttpparser.Request, mut res picohttpparser.Response, error IError) {
-	eprintln('picoev: ${error}')
+	elog('picoev: ${error}')
 	res.end()
 }
 
 // new creates a `Picoev` struct and initializes the main loop
 pub fn new(config Config) !&Picoev {
 	listening_socket_fd := listen(config) or {
-		eprintln('Error during listen: ${err}')
+		elog('Error during listen: ${err}')
 		return err
 	}
 
@@ -384,7 +384,7 @@ pub fn new(config Config) !&Picoev {
 	}
 
 	if pv.loop == unsafe { nil } {
-		eprintln('Failed to create loop')
+		elog('Failed to create loop')
 		close_socket(listening_socket_fd)
 		return unsafe { nil }
 	}