Make name_changed an event property

Whether the name changed or not is an event property and set at the end
of sinsp_parser::process_event(). It does this by checking the original
fd name and comparing it to the fd name that exists after parsing the
event.

userspace/libsinsp/event.h

@@ -238,6 +238,16 @@ class SINSP_PUBLIC sinsp_evt
 		return m_fdinfo;
 	}
 
+	inline bool fdinfo_name_changed()
+	{
+		return m_fdinfo_name_changed;
+	}
+
+	inline void set_fdinfo_name_changed(bool changed)
+	{
+		m_fdinfo_name_changed = changed;
+	}
+
 	/*!
 	  \brief Return the number of the FD associated with this event.
 
@@ -333,6 +343,7 @@ class SINSP_PUBLIC sinsp_evt
 		m_info = &(m_event_info_table[m_pevt->type]);
 		m_tinfo = NULL;
 		m_fdinfo = NULL;
+		m_fdinfo_name_changed = false;
 		m_iosize = 0;
 		m_poriginal_evt = NULL;
 	}
@@ -343,6 +354,7 @@ class SINSP_PUBLIC sinsp_evt
 		m_info = &(m_event_info_table[m_pevt->type]);
 		m_tinfo = NULL;
 		m_fdinfo = NULL;
+		m_fdinfo_name_changed = false;
 		m_iosize = 0;
 		m_cpuid = cpuid;
 		m_evtnum = 0;
@@ -396,6 +408,11 @@ VISIBILITY_PRIVATE
 
 	sinsp_threadinfo* m_tinfo;
 	sinsp_fdinfo_t* m_fdinfo;
+
+	// If true, then the associated fdinfo changed names as a part
+	// of parsing this event.
+	bool m_fdinfo_name_changed;
+
 	uint32_t m_iosize;
 	int32_t m_errorcode;
 	int32_t m_rawbuf_str_len;

userspace/libsinsp/filterchecks.cpp

@@ -1057,7 +1057,7 @@ uint8_t* sinsp_filter_check_fd::extract(sinsp_evt *evt, OUT uint32_t* len, bool
 				return NULL;
 			}
 
-			m_tbool = m_fdinfo->m_name != m_fdinfo->m_oldname;
+			m_tbool = evt->fdinfo_name_changed();
 
 			RETURN_EXTRACT_VAR(m_tbool);
 		}

userspace/libsinsp/parsers.cpp

@@ -491,6 +491,14 @@ void sinsp_parser::process_event(sinsp_evt *evt)
 			evt->m_filtered_out = true;
 		}
 	}
+
+	// Check to see if the name changed as a side-effect of
+	// parsing this event. Try to avoid the overhead of a string
+	// compare for every event.
+	if(evt->m_fdinfo)
+	{
+		evt->set_fdinfo_name_changed(evt->m_fdinfo->m_name != evt->m_fdinfo->m_oldname);
+	}
 }
 
 void sinsp_parser::event_cleanup(sinsp_evt *evt)