I am implementing logging for a BlackBerry app to track the flow of my application.
What mechanisms do BlackBerry developers use to do this?
The EventLogger is a respectable API to start with. You can view the log on the device by holding 'alt' and hitting 'L' 'G' 'L' 'G'
One difficulty of the built in EventLogger is there's no programmatic way to read out of it.
For that reason I implemented my own logger and included remote diagnostic capability.
I suggest you implement your own logging class as it provides lots of flexibility, e.g.
1) You can make the class send output to multiple locations so you can get quicker access to the logs when using a debugger, e.g.
/**
* Internal function to encapsulate event logging
*
* #param msg - message to log
* #param level - log level to use, e.g. EventLogger.DEBUG_INFO,
* INFORMATION, WARNING, ERROR, SEVERE_ERROR
*/
private void makeLog(String msg, int level)
{
// You can also manipulate logs here, e.g.
// -add the Class and/or Application name
// -truncate or remove repeat logs, etc
// Log to phone event log
EventLogger.logEvent(ID, msg.getBytes(), level);
// In the debugger log to the console
System.err.println(msg);
}
2) For convenience you can add methods with readable names that log at the different severity levels, e.g.
public void debug(String msg)
{
makeLog(msg, EventLogger.DEBUG_INFO);
}
Then you can call MyLogClass.debug("debug message") or MyLogClass.warning("warning message"), which makes it clearer on the importance of the log.
You can use the library https://sourceforge.net/projects/log4bb/
Related
I am new in CAPL (CANoe). I have 2 Nodes here; CAN_Portscanner that scans a vehicle and returns 47 ECUs and their services and a Diagnostic Tester that i want to develop. it has to recognize only a few ECUs from the Portscanner. When I find the service, I need to send a service request to an ECU and extend the ECU function with a response in CANoe to know that my request was successful.
I need to read a message from another .can file and work with it.
I tried something like this:
includes
{
#include "CAN_Portscanner.can"
}
variables
{
int counter;
}
void MainTest()
{
while(diagnose_request_msg.ID <= 0x7E1)
{
counter++;
}
write("Number of ECUs in the Tester: %d",counter);
}
I don't know if the #include is correct and why do i obtain a warning about MainTest.
Warning 2033 at (12,1): Use of function 'MainTest' seems to indicate that this file should be a test module or test unit. Diagnostic Tester.can
I am trying to add support for per-directory viewing settings to the Thunar file browser of the Xfce desktop. So for example if a user chooses to view the contents of a directory as a list rather than as a grid of icons, this setting is remembered for that directory and will be used whenever that directory is viewed.
Now Thunar is built on GLib, and the mechanism we have chosen to use to implement this is to store metadata using GFile attributes, using methods like g_file_set_attributes_async to store
keys with names such as "metadata::thunar-view-type". The per-directory feature can be turned on or off by the user via a checkbox in a preferences dialog. My knowledge of GIO and GLib is pretty limited, but I have now managed to get this all working as desired (you can see my merge request here if you are interested).
Now as I understand it, the functionality that I am using here relies on something called "GVfs metadata", and as I understand it this might not be available on all systems. On systems where GVfs metadata is not available, I want to turn this functionality off and in particular make the checkbox in the preferences dialog insensitive (i.e. greyed out). Thus I need to write a function to detect if gvfs metadata support is available, by which I mean whether I can use functions like g_file_set_attributes_async to successfully save metadata so that it will be available in future.
Thunar is written in C, so this function needs to be written in C using the C API for GLib, GIO, etc.
The function I have come up with (from much reading of API documentation, modifying code scraps I have found, and experimentation) is as follows.
gboolean
thunar_g_vfs_metadata_is_supported (void)
{
GDBusMessage *send, *reply;
GDBusConnection *conn;
GVariant *v1, *v2;
GError *error = NULL;
const gchar **service_names;
gboolean metadata_found;
/* connect to the session bus */
conn = g_bus_get_sync (G_BUS_TYPE_SESSION, NULL, &error);
/* check that the connection was opened sucessfully */
if (error != NULL)
{
g_error_free (error);
return FALSE;
}
/* create the message to send to list the available services */
send = g_dbus_message_new_method_call ("org.freedesktop.DBus",
"/org/freedesktop/DBus",
"org.freedesktop.DBus",
"ListNames");
/* send the message and wait for the reply */
reply = g_dbus_connection_send_message_with_reply_sync (conn, send, G_DBUS_SEND_MESSAGE_FLAGS_NONE,
-1, NULL, NULL, &error);
/* release the connection and the sent message */
g_object_unref (send);
g_object_unref (conn);
/* check if we got a sucessful reply */
if (error != NULL)
{
g_error_free (error);
return FALSE;
}
/* extract the GVariant with the array of strings describing the available services */
v1 = g_dbus_message_get_body (reply); /* v1 belongs to reply and must not be freed */
if (v1 == NULL || !g_variant_is_container (v1) || g_variant_n_children (v1) < 1)
{
g_object_unref (reply);
return FALSE;
}
v2 = g_variant_get_child_value (v1, 0);
g_object_unref (reply);
/* check that the GVariant we have been given does contain an array of strings */
if (!g_variant_is_of_type (v2, G_VARIANT_TYPE_STRING_ARRAY))
{
g_variant_unref (v2);
return FALSE;
}
/* search through the list of service names to see if gvfs metadata is present */
metadata_found = FALSE;
service_names = g_variant_get_strv (v2, NULL);
for (int i=0; service_names[i] != NULL; i++)
if (g_strcmp0 (service_names[i], "org.gtk.vfs.Metadata") == 0)
metadata_found = TRUE;
g_free (service_names);
g_variant_unref (v2);
return metadata_found;
}
As you can see, this function uses DBus to query service names to see if the necessary service is available. Now, as far as I have been able to test it, this function works as I want it to. However, during a code review it has been questioned whether this can be done without relying on DBus (which might itself not be available even though GVfs metadata is).
Thus (at last!) my question: what is the best (i.e. most robust and accurate) way to test for GVfs metadata support via the C API for GLib, GIO, etc?. As I said above, by "GVfs metadata support" I mean "can I use functions like g_file_set_attributes_async to successfully save metadata so that it will be available in future?".
One method I have considered is looking at the list of running processes for the name "gvfsd-metadata", but that seems a bit kludgy to me.
Also, as mentioned above I am very much a novice with these technologies, so I is absolutely possible that I have misunderstood stuff here, so if you spot any errors in the assertions I have made above, please let me know.
Thanks!
(And yes, usual story, I'm a long time reader of SO & co, but a first time asker, so please feel free to edit or let me know if I've done something wrong/bad)
Call g_file_query_settable_attributes() and g_file_query_writable_namespaces() on the GFile, as described in the GFileInfo documentation:
However, not all attributes can be changed in the file. For instance, the actual size of a file cannot be changed via g_file_info_set_size(). You may call g_file_query_settable_attributes() and g_file_query_writable_namespaces() to discover the settable attributes of a particular file at runtime.
I'm debugging an app, but I need to know some values in the fly, I was wondering if there's a way to print a message in console like console.log using Javascript.
I appreciate the help.
print() is probably what you are looking for. Here's some more info on debugging in flutter.
You can use
print()
function or
debugPrint()
The debugPrint() function can print large outputs.
There are more helpful methods in import 'dart:developer' library and one of them is log().
example:
int i = 5;
log("Index number is: $i");
//output
[log] Index number is: 5
void log(String message, {DateTime time, int sequenceNumber, int level
= 0, String name = '', Zone zone, Object error, StackTrace stackTrace})
Emit a log event.
This function was designed to map closely to the logging information
collected by package:logging.
[message] is the log message
[time] (optional) is the timestamp
[sequenceNumber] (optional) is a monotonically increasing sequence number
[level] (optional) is the severity level (a value between 0 and 2000); see the package:logging Level class for an overview of the
possible values
[name] (optional) is the name of the source of the log message
[zone] (optional) the zone where the log was emitted
[error] (optional) an error object associated with this log event
[stackTrace] (optional) a stack trace associated with this log event
Read more.:
print() is from dart:core and its implementation:
/// Prints a string representation of the object to the console.
void print(Object object) {
String line = "$object";
if (printToZone == null) {
printToConsole(line);
} else {
printToZone(line);
}
}
debugPrint():
/// Prints a message to the console, which you can access using the "flutter"
/// tool's "logs" command ("flutter logs").
///
/// If a wrapWidth is provided, each line of the message is word-wrapped to that
/// width. (Lines may be separated by newline characters, as in '\n'.)
///
/// By default, this function very crudely attempts to throttle the rate at
/// which messages are sent to avoid data loss on Android. This means that
/// interleaving calls to this function (directly or indirectly via, e.g.,
/// [debugDumpRenderTree] or [debugDumpApp]) and to the Dart [print] method can
/// result in out-of-order messages in the logs
// read more here: https://api.flutter.dev/flutter/foundation/debugPrint.html
DebugPrintCallback debugPrint = debugPrintThrottled;
/// Alternative implementation of [debugPrint] that does not throttle.
/// Used by tests.
debugPrintSynchronously(String message, { int wrapWidth })
/// Implementation of [debugPrint] that throttles messages. This avoids dropping
/// messages on platforms that rate-limit their logging (for example, Android).
void debugPrintThrottled(String message, { int wrapWidth })
Read more.
Note that only the print() is taking any type and print to the console. debugPrint() and log() only take String. So, you have to add .toString() or use string interpolation like I shown in provided example snippet.
I tend to do something similar to this
Foo foo;
try{
foo = _someMethod(); //some method that returns a new object
} catch (e) {
print('_someMethod: Foo Error ${foo.id} Error:{e.toString()}'); /*my custom error print message. You don't need brackets if you are printing a string variable.*/
}
Use debug print to avoid logging in production application.
debugPrint("Message");
You can also disable or change debug print implementation in main.dart or any other file like this:
debugPrint = (String message, {int wrapWidth})
{
debugPrintThrottled(message);//Or another other custom code
};
print, debugPrint and others have got some word limit restrictions, if you have something long to print on console, you can:
Create this method:
void printWrapped(String text) {
final pattern = RegExp('.{1,800}'); // 800 is the size of each chunk
pattern.allMatches(text).forEach((match) => print(match.group(0)));
}
Usage:
printWrapped("Your very long string ...");
Source
One more answer for Concatenate with String:
// Declaration
int number = 10;
//Button Action
RaisedButton(
child: Text("Subtract Me"),
onPressed: () {
number = number - 1;
print('You have got $number as result');
print('Before Value is ${number - 1} and After value is ${number + 1}');
},
),
//Output:
flutter: You have got 9 as result
flutter: Before Value is 8 and After value is 10
debugPrint()
Might as well use rather than print() as it attempts to reduce log line drop or being out of order on Android kernel
Refs:
Logging in Flutter
I think this might help you, because, I was also got stuck in many ways of knowing the output of my code in the dart file, hence I got the solution by following the steps, shown in the video.
https://www.youtube.com/watch?v=hhP1tE-IHos
here I have shown an instance of how it works after following the video.
check the left side column where it shows about the value which profile variable carry i.e., null
you can simply use print('whatever you want to print') same as console.log() in javascript.
for more info you can check here.
Note that the print() and log() options both add their own labels at the start of the line, and apply additional formatting that can cause long lines to be truncated. In the case of a dart:io app, you can bypass this interception and mangling entirely by going directly to stdout/stderr, etc. as in stdout.write(), stdout.writeln(), etc. Likewise if you are looking to log explicitly to one or the other. I ran into this issue when adding CLI args to a flutter application.
I use something like this. The print() function can print data up to some limit. So I use this log.
import 'dart:developer';
debugLog({String tag = '', required dynamic value}) {
log("TAG $tag : ${value.toString()}");
}
Somewhere in my Vaadin application, I'm getting this exception as soon as I connect using a second browser
Caused by: java.lang.RuntimeException: A connector with id 22 is already registered!
at com.vaadin.ui.ConnectorTracker.registerConnector(ConnectorTracker.java:133)
It happens always in the same place but I don't know why exactly as the reason for this must be somewhere else.
I think I might be stealing UI components from the other session - which is not my intention.
Currently, I don't see any static instances of UI components I might be using in multiple sessions.
How can I debug this? It's become quite a large project.
Any hints to look for?
Yes, this usually happens because you are attaching a component already attached in other session.
Try logging the failed connector with a temporal ConnectorTracker, So the next time that it happens, you can catch it.
For example:
public class SomeUI extends UI {
private ConnectorTracker tracker;
#Override
public ConnectorTracker getConnectorTracker() {
if (this.tracker == null) {
this.tracker = new ConnectorTracker(this) {
#Override
public void registerConnector(ClientConnector connector) {
try {
super.registerConnector(connector);
} catch (RuntimeException e) {
getLogger().log(Level.SEVERE, "Failed connector: {0}", connector.getClass().getSimpleName());
throw e;
}
}
};
}
return tracker;
}
}
I think I might be stealing UI components from the other session - which is not my intention. Currently, I don't see any static instances of UI components I might be using in multiple sessions.
That was it. I was actually stealing UI components without prior knowledge.
It was very well hidden in a part which seems to be same for all instances. Which is true: the algorithm is the same.
Doesn't mean I should've reused the same UI components as well...
Thanks to those who took a closer look.
Here is how I fixed it -
1) look for components you have shared across sessions. For example if you have declared a component as static it will be created once and will be shared.
2) if you are not able to find it and want a work around until you figure out the real problem, put your all addComponent calls in try and in catch add following code -
getUI().getConnectorTracker().markAllConnectorsDirty();
getUI().getConnectorTracker().markAllClientSidesUnititialized();
getPage().reload():
This will clear old connectors and will reload the page properly only when it fails. For me it was failing when I was logged out and logged in back.
Once you find the real problem you can fix it till then inform your customers about the reload.
**** note - only solution is to remove shared components this is just a work around.
By running your application in debug mode (add ?debug at the end of URL in browser) you will be able to browse to the component, e.g:
-UIConnector(0)
--VerticalLayoutConnector(1)
---...
---LabelConnector(22)
where 22 is id from your stack trace. Find this component in your code and make sure that it is not static (yes, I saw such examples).
I'd like my Dart program to print to the dev console of my browser. How can I print to the console (DevTools's console, for example) ?
Use print() to print a string to the console of your browser:
import 'dart:html';
main() {
var value = querySelector('input').value;
print('The value of the input is: $value');
}
You will see a message printed to the developer console.
If you simlpy want to print text to the console you can use print('Text').
But if you want to access the advanced fatures of the DevTools console you need to use the Console class from dart:html: Console.log('Text').
It supports printing on different levels (info, warn, error, debug). It also allows to print tables and other more advanced features. Note that these are not supported in every browser! It's sad that the documentation about the Console class is incomplete, but you can take a look at the documentation of Chrome here and here.
There is log() from import 'dart:developer' library also.
example:
int name = "Something";
log("ClassName: successfully initialized: $name");
//output
[log] ClassName: successfully initialized: Something
Please note that log and debugPrint taking a value of String not like print. So, you have to add .toString() at the end or use with String interpolation like I used in above example.
From doc:
You have two options for logging for your application. The first is to
use stdout and stderr. Generally, this is done using print()
statements, or by importing dart:io and invoking methods on stderr and
stdout. For example:
stderr.writeln('print me');
If you output too much at once, then Android sometimes discards some
log lines. To avoid this, use debugPrint(), from Flutter’s foundation
library. This is a wrapper around print that throttles the output to a
level that avoids being dropped by Android’s kernel.
The other option for application logging is to use the dart:developer
log() function. This allows you to include a bit more granularity and
information in the logging output. Here’s an example:
import 'dart:developer' as developer;
void main() {
developer.log('log me', name: 'my.app.category');
developer.log('log me 1', name: 'my.other.category');
developer.log('log me 2', name: 'my.other.category');
}
You can also pass application data to the log call. The convention for
this is to use the error: named parameter on the log() call, JSON
encode the object you want to send, and pass the encoded string to the
error parameter.
import 'dart:convert'; import 'dart:developer' as developer;
void main() {
var myCustomObject = ...;
developer.log(
'log me',
name: 'my.app.category',
error: jsonEncode(myCustomObject),
);
}
If viewing the logging output in DevTool’s logging view, the JSON
encoded error param is interpreted as a data object and rendered in
the details view for that log entry.
read more(It's cool like a tutorial).
If you are here for Flutter, there's debugPrint which you should use.
Here's the doc text for the same.
/// Prints a message to the console, which you can access using the "flutter"
/// tool's "logs" command ("flutter logs").
/// By default, this function very crudely attempts to throttle the rate at
/// which messages are sent to avoid data loss on Android. This means that
/// interleaving calls to this function (directly or indirectly via, e.g.,
/// [debugDumpRenderTree] or [debugDumpApp]) and to the Dart [print] method can
/// result in out-of-order messages in the logs.
You might get SDK version constraint as it is only for 2.2 and above.
Dart print() function works differently in different environment.
print() when used in console based application it outputs in the terminal console
print() when used in web based application it outputs to the developer console.
void main() {
print("HTML WebApp");
}
The only way I know , which is supported by dartpad ,is through using print();
by the way Dart uses the ${} syntax for expressions, or just a $ for single value.
ex:-
int x=3;
print('hello world') ;
print(x) ;
print('x = $x') ;
and her is the link for the documentation
print method!