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[Bug 1496] Finish the documentation.

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Also amended scratch-simulator so printing the list of log
components works as advertised.
This commit is contained in:
Peter D. Barnes, Jr.
2013-12-12 14:42:43 -08:00
parent ad1ef6acc0
commit 8ef0956af1
4 changed files with 413 additions and 118 deletions
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1
RELEASE_NOTES
View File

@@ -47,6 +47,7 @@ New user-visible features
Bugs fixed
----------
- Bug 1496 - Option to print log level in NS_LOG messages, and documentation.
- Bug 1778 - Implement TapBridge::IsLinkUp() function
- Bug 1777 - Implement the more direct way of "using" configuration of existing tap interface
- Bug 1776 - Improve CRC performance for CsmaNetDevice in emulation modes

435
doc/manual/source/logging.rst
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@@ -22,16 +22,14 @@ the same over time. Users are cautioned against building simulation output
frameworks on top of logging code, as the output and the way the output
is enabled may change over time.
Logging overview
****************
Overview
********
|ns3| logging statements are typically used to log various program
execution events, such as the occurrence of simulation events or the
use of a particular function.
For example, this code snippet is from ``Ipv4L3Protocol::IsDestinationAddress()``:
::
For example, this code snippet is from ``Ipv4L3Protocol::IsDestinationAddress()``::
if (address == iaddr.GetBroadcast ())
{
@@ -39,71 +37,33 @@ For example, this code snippet is from ``Ipv4L3Protocol::IsDestinationAddress()`
return true;
}
If logging has been enabled for the ``Ipv4L3Protocol`` component at a level
of ``LOGIC`` or above (see below about logging levels), the statement
If logging has been enabled for the ``Ipv4L3Protocol`` component at a severity
of ``LOGIC`` or above (see below about log severity), the statement
will be printed out; otherwise, it will be suppressed.
Logging levels
==============
Enabling Output
===============
The following levels are defined; each level will enable the levels above
it, with the ``ALL`` level being most verbose:
#. ``LOG_NONE``: the default, no logging
#. ``LOG_ERROR``: serious error messages only
#. ``LOG_WARN``: warning messages
#. ``LOG_DEBUG``: for use in debugging
#. ``LOG_FUNCTION``: function tracing
#. ``LOG_LOGIC``: control flow tracing within functions
#. ``LOG_ALL``: print everything
A special logging level will cause logging output to unconditionally
appear on ``std::clog``, regardless of whether the user has explicitly enabled
logging.
This macro, ``NS_LOG_UNCOND()``, can be used like a kind of ``printf()`` in
your code. An example can be found in ``scratch/scratch-simulator.cc``:
::
NS_LOG_UNCOND ("Scratch Simulator");
Logging prefixes
================
This section still needs documentation; bug 1496 is open on this:
.. sourcecode:: bash
$ NS_LOG="*=all|prefix_all" ./waf --run scratch-simulator
Scratch Simulator
ScratchSimulator:main(): [ERROR] error message
ScratchSimulator:main(): [WARN] warn message
ScratchSimulator:main(): [DEBUG] debug message
ScratchSimulator:main(): [INFO] info message
ScratchSimulator:main(function)
ScratchSimulator:main(): [LOGIC] logic message
Enabling logging output
=======================
There are two ways that users typically control logging output. The
first is by setting an ``NS_LOG`` environment variable; e.g.:
There are two ways that users typically control log output. The
first is by setting the ``NS_LOG`` environment variable; e.g.:
.. sourcecode:: bash
$ NS_LOG="*" ./waf --run first
will run the first tutorial program with all logging output. This can
be made more granular by selecting individual components:
will run the ``first`` tutorial program with all logging output. (The
specifics of the ``NS_LOG`` format will be discussed below.)
This can be made more granular by selecting individual components:
.. sourcecode:: bash
$ NS_LOG="Ipv4L3Protocol" ./waf --run first
The second way to enable this is to use explicit statements in your
program, such as in the first tutorial program:
::
The output can be further tailored with prefix options.
The second way to enable logging is to use explicit statements in your
program, such as in the ``first`` tutorial program::
int
main (int argc, char *argv[])
@@ -112,48 +72,357 @@ program, such as in the first tutorial program:
LogComponentEnable ("UdpEchoServerApplication", LOG_LEVEL_INFO);
...
Some helpers have special methods to enable the logging of all components
in a module (across different compilation units, but logically grouped
together such as the |ns3| wifi code:
(The meaning of ``LOG_LEVEL_INFO``, and other possible values,
will be discussed below.)
::
``NS_LOG`` Syntax
=================
The ``NS_LOG`` environment variable contains a list of log components
and options. Log components are separated by \`:' characters:
.. sourcecode:: bash
$ NS_LOG="<log-component>:<log-component>..."
Options for each log component are given as flags after
each log component:
.. sourcecode:: bash
$ NS_LOG="<log-component>=<option>|<option>...:<log-component>..."
Options control the severity and level for that component,
and whether optional information should be included, such as the
simulation time, simulation node, function name, and the symbolic severity.
Log Components
==============
Generally a log component refers to a single source code ``.cc`` file,
and encompasses the entire file.
Some helpers have special methods to enable the logging of all components
in a module, spanning different compilation units, but logically grouped
together, such as the |ns3| wifi code::
WifiHelper wifiHelper;
wifiHelper.EnableLogComponents ();
The ``NS_LOG`` log component wildcard \`*' will enable all components.
To see what log components are defined, any of these will work:
.. sourcecode:: bash
$ NS_LOG="print-list" ./waf --run ...
$ NS_LOG="foo" # a token not matching any log-component
The first form will print the name and enabled flags for all log components
which are linked in; try it with ``scratch-simulator``.
The second form prints all registered log components,
then exit with an error.
Severity and Level Options
==========================
Individual messages belong to a single "severity class," set by the macro
creating the message. In the example above,
``NS_LOG_LOGIC(..)`` creates the message in the ``LOG_LOGIC`` severity class.
The following severity classes are defined as ``enum`` constants:
================ =====================================
Severity Class Meaning
================ =====================================
``LOG_NONE`` The default, no logging
``LOG_ERROR`` Serious error messages only
``LOG_WARN`` Warning messages
``LOG_DEBUG`` For use in debugging
``LOG_INFO`` Informational
``LOG_FUNCTION`` Function tracing
``LOG_LOGIC`` Control flow tracing within functions
================ =====================================
Typically one wants to see messages at a given severity class *and higher*.
This is done by defining inclusive logging "levels":
====================== ===========================================
Level Meaning
====================== ===========================================
``LOG_LEVEL_ERROR`` Only ``LOG_ERROR`` severity class messages.
``LOG_LEVEL_WARN`` ``LOG_WARN`` and above.
``LOG_LEVEL_DEBUG`` ``LOG_DEBUG`` and above.
``LOG_LEVEL_INFO`` ``LOG_INFO`` and above.
``LOG_LEVEL_FUNCTION`` ``LOG_FUNCTION`` and above.
``LOG_LEVEL_LOGIC`` ``LOG_LOGIC`` and above.
``LOG_LEVEL_ALL`` All severity classes.
``LOG_ALL`` Synonym for ``LOG_LEVEL_ALL``
====================== ===========================================
The severity class and level options can be given in the ``NS_LOG``
environment variable by these tokens:
============ =================
Class Level
============ =================
``error`` ``level_error``
``warn`` ``level_warn``
``debug`` ``level_debug``
``info`` ``level_info``
``function`` ``level_function``
``logic`` ``level_logic``
.. | ``level_all``
| ``all``
| ``*``
============ =================
Using a severity class token enables log messages at that severity only.
For example, ``NS_LOG="*=warn"`` won't output messages with severity ``error``.
``NS_LOG="*=level_debug"`` will output messages at severity levels
``debug`` and above.
Severity classes and levels can be combined with the \`|' operator:
``NS_LOG="*=level_warn|logic"`` will output messages at severity levels
``error``, ``warn`` and ``logic``.
The ``NS_LOG`` severity level wildcard \`*' and ``all``
are synonyms for ``level_all``.
For log components merely mentioned in ``NS_LOG``
.. sourcecode:: bash
$ NS_LOG="<log-component>:..."
the default severity is ``LOG_LEVEL_ALL``.
Prefix Options
==============
A number of prefixes can help identify
where and when a message originated, and at what severity.
The available prefix options (as ``enum`` constants) are
====================== ===========================================
Prefix Symbol Meaning
====================== ===========================================
``LOG_PREFIX_FUNC`` Prefix the name of the calling function.
``LOG_PREFIX_TIME`` Prefix the simulation time.
``LOG_PREFIX_NODE`` Prefix the node id.
``LOG_PREFIX_LEVEL`` Prefix the severity level.
``LOG_PREFIX_ALL`` Enable all prefixes.
====================== ===========================================
The prefix options are described briefly below.
The options can be given in the ``NS_LOG``
environment variable by these tokens:
================ =========
Token Alternate
================ =========
``prefix_func`` ``func``
``prefix_time`` ``time``
``prefix_node`` ``node``
``prefix_level`` ``level``
``prefix_all`` | ``all``
| ``*``
================ =========
For log components merely mentioned in ``NS_LOG``
.. sourcecode:: bash
$ NS_LOG="<log-component>:..."
the default prefix options are ``LOG_PREFIX_ALL``.
Severity Prefix
###############
The severity class of a message can be included with the options
``prefix_level`` or ``level``. For example, this value of ``NS_LOG``
enables logging for all log components (\`*') and all severity
classes (``=all``), and prefixes the message with the severity
class (``|prefix_level``).
.. sourcecode:: bash
$ NS_LOG="*=all|prefix_level" ./waf --run scratch-simulator
Scratch Simulator
[ERROR] error message
[WARN] warn message
[DEBUG] debug message
[INFO] info message
[FUNCT] function message
[LOGIC] logic message
Time Prefix
###########
The simulation time can be included with the options
``prefix_time`` or ``time``. This prints the simulation time in seconds.
Node Prefix
###########
The simulation node id can be included with the options
``prefix_node`` or ``node``.
Function Prefix
###############
The name of the calling function can be included with the options
``prefix_func`` or ``func``.
``NS_LOG`` Wildcards
####################
The log component wildcard \`*' will enable all components. To
enable all components at a specific severity level
use ``*=<severity>``.
The severity level option wildcard \`*' is a synonym for ``all``.
This must occur before any \`|' characters separating options.
To enable all severity classes, use ``<log-component>=*``,
or ``<log-component>=*|<options>``.
The option wildcard \`*' or token ``all`` enables all prefix options,
but must occur *after* a \`|' character. To enable a specific
severity class or level, and all prefixes, use
``<log-component>=<severity>|*``.
The combined option wildcard ``**`` enables all severities and all prefixes;
for example, ``<log-component>=**``.
The uber-wildcard ``***`` enables all severities and all prefixes
for all log components. These are all equivalent:
.. sourcecode:: bash
$ NS_LOG="***" ... $ NS_LOG="*=all|*" ... $ NS_LOG="*=*|all" ...
$ NS_LOG="*=**" ... $ NS_LOG="*=level_all|*" ... $ NS_LOG="*=*|prefix_all" ...
$ NS_LOG="*=*|*" ...
Be advised: even the trivial ``scratch-simulator`` produces over
46K lines of output with ``NS_LOG="***"``!
How to add logging to your code
*******************************
To add logging to your code, please follow the below steps:
Adding logging to your code is very simple:
1) Put ``NS_LOG_COMPONENT_DEFINE`` macro outside of namespace ns3
1. Invoke the ``NS_LOG_COMPONENT_DEFINE (...);`` macro
outside of ``namespace ns3``.
Create a unique string identifier (usually based on the name of the file
and/or class defined within the file) and register it with a macro call
such as follows:
Create a unique string identifier (usually based on the name of the file
and/or class defined within the file) and register it with a macro call
such as follows:
::
::
NS_LOG_COMPONENT_DEFINE ("Ipv4L3Protocol");
NS_LOG_COMPONENT_DEFINE ("Ipv4L3Protocol");
namespace ns3 {
...
namespace ns3 {
...
The macro was carefully written to permit inclusion either within or
outside of namespace ``ns3``, and usage will vary across the codebase, but
the original intent was to register this *outside* of namespace ``ns3``.
This registers ``Ipv4L3Protocol`` as a log component.
(The macro was carefully written to permit inclusion either within or
outside of namespace ``ns3``, and usage will vary across the codebase, but
the original intent was to register this *outside* of namespace ``ns3``.)
2. Add logging statements (macro calls) to your functions and function bodies.
Logging Macros
==============
The logging macros and associated severity levels are
================ ==========================
Severity Class Macro
================ ==========================
``LOG_NONE`` (none needed)
``LOG_ERROR`` ``NS_LOG_ERROR (...);``
``LOG_WARN`` ``NS_LOG_WARN (...);``
``LOG_DEBUG`` ``NS_LOG_DEBUG (...);``
``LOG_INFO`` ``NS_LOG_INFO (...);``
``LOG_FUNCTION`` ``NS_LOG_FUNCTION (...);``
``LOG_LOGIC`` ``NS_LOG_LOGIC (...);``
================ ==========================
The macros function as output streamers, so anything you can send to
``std::cout``, joined by ``<<`` operators, is allowed::
void MyClass::Check (int value, char * item)
{
NS_LOG_FUNCTION (this << arg << item);
if (arg > 10)
{
NS_LOG_ERROR ("encountered bad value " << value <<
" while checking " << name << "!");
}
...
}
Note that ``NS_LOG_FUNCTION`` automatically inserts a \`\ :literal:`,\ `'
(comma-space) separator between each of its arguments.
This simplifies logging of function arguments;
just concatenate them with ``<<`` as in the example above.
Unconditional Logging
=====================
As a convenience, the ``NS_LOG_UNCOND (...);`` macro will always log its
arguments, even if the associated log-component is not enabled at any
severity. This macro does not use any of the prefix options. Note that
logging is only enabled in debug builds; this macro won't produce
output in optimized builds.
Guidelines
==========
* Start every class method with ``NS_LOG_FUNCTION (this << args...);``
This enables easy function call tracing.
* Except: don't log operators or explicit copy constructors,
since these will cause infinite recursion and stack overflow.
* For methods without arguments use the same form:
``NS_LOG_FUNCTION (this);``
* For static functions:
* With arguments use ``NS_LOG_FUNCTION (...);`` as normal.
* Without arguments use ``NS_LOG_FUNCTION_NOARGS ();``
* Use ``NS_LOG_ERROR`` for serious error conditions that probably
invalidate the simulation execution.
* Use ``NS_LOG_WARN`` for unusual conditions that may be correctable.
Please give some hints as to the nature of the problem and how
it might be corrected.
* ``NS_LOG_DEBUG`` is usually used in an *ad hoc* way to understand
the execution of a model.
* Use ``NS_LOG_INFO`` for additional information about the execution,
such as the size of a data structure when adding/removing from it.
* Use ``NS_LOG_LOGIC`` to trace important logic branches within a function.
* Test that your logging changes do not break the code.
Run some example programs with all log components turned on (e.g.
``NS_LOG="***"``).
2) Add logging statements to your functions and function bodies.
There are a couple of guidelines on this:
* Do *not* add function logging in operators or explicit copy constructors,
since these will cause infinite recursion and stack overflow.
* Use the ``NS_LOG_FUNCTION_NOARGS()`` variant for static methods *only*. When
a non-static member function has no arguments, it should be logged by
``NS_LOG_FUNCTION (this)`` macro.
* Make sure that you test that your logging changes do not break the code;
running some example programs with all log components turned on (e.g.
``NS_LOG="*"``) is one way to test this.

3
scratch/scratch-simulator.cc
View File

@@ -24,4 +24,7 @@ int
main (int argc, char *argv[])
{
NS_LOG_UNCOND ("Scratch Simulator");
Simulator::Run ();
Simulator::Destroy ();
}

92
src/core/model/log.h
View File

@@ -28,6 +28,43 @@
namespace ns3 {
/**
* \ingroup debugging
* \defgroup logging Logging
* \brief Logging functions and macros
*
* LOG functionality: macros which allow developers to
* send information to the std::clog output stream. All logging messages
* are disabled by default. To enable selected logging
* messages, use the ns3::LogComponentEnable
* function or use the NS_LOG environment variable
*
* Use the environment variable NS_LOG to define a ':'-separated list of
* logging components to enable. For example (using bash syntax),
* NS_LOG="OlsrAgent" would enable one component at all log levels.
* NS_LOG="OlsrAgent:Ipv4L3Protocol" would enable two components,
* at all log levels, etc.
* NS_LOG="*" will enable all available log components at all levels.
*
* To control more selectively the log levels for each component, use
* this syntax: NS_LOG='Component1=func|warn:Component2=error|debug'
* This example would enable the 'func', and 'warn' log
* levels for 'Component1' and the 'error' and 'debug' log levels
* for 'Component2'. The wildcard can be used here as well. For example
* NS_LOG='*=level_all|prefix' would enable all log levels and prefix all
* prints with the component and function names.
*
* A note on NS_LOG_FUNCTION() and NS_LOG_FUNCTION_NOARGS():
* generally, use of (at least) NS_LOG_FUNCTION(this) is preferred.
* Use NS_LOG_FUNCTION_NOARGS() only in static functions.
*/
/**
* \ingroup logging
*
* Logging severity classes and levels.
*/
enum LogLevel {
LOG_NONE = 0x00000000, // no logging
@@ -134,35 +171,51 @@ void LogComponentDisableAll (enum LogLevel level);
#define NS_LOG_COMPONENT_DEFINE(name) \
static ns3::LogComponent g_log = ns3::LogComponent (name)
/**
* \ingroup logging
* Append the simulation time to a log message.
*/
#define NS_LOG_APPEND_TIME_PREFIX \
if (g_log.IsEnabled (ns3::LOG_PREFIX_TIME)) \
{ \
ns3::LogTimePrinter printer = ns3::LogGetTimePrinter (); \
if (printer != 0) \
{ \
(*printer)(std::clog); \
(*printer)(std::clog); \
std::clog << " "; \
} \
}
/**
* \ingroup logging
* Append the simulation node id to a log message.
*/
#define NS_LOG_APPEND_NODE_PREFIX \
if (g_log.IsEnabled (ns3::LOG_PREFIX_NODE)) \
{ \
ns3::LogNodePrinter printer = ns3::LogGetNodePrinter (); \
if (printer != 0) \
{ \
(*printer)(std::clog); \
(*printer)(std::clog); \
std::clog << " "; \
} \
}
/**
* \ingroup logging
* Append the function name to a log message.
*/
#define NS_LOG_APPEND_FUNC_PREFIX \
if (g_log.IsEnabled (ns3::LOG_PREFIX_FUNC)) \
{ \
std::clog << g_log.Name () << ":" << \
__FUNCTION__ << "(): "; \
__FUNCTION__ << "(): "; \
} \
/**
* \ingroup logging
* Append the log severity level to a log message.
*/
#define NS_LOG_APPEND_LEVEL_PREFIX(level) \
if (g_log.IsEnabled (ns3::LOG_PREFIX_LEVEL)) \
{ \
@@ -179,37 +232,6 @@ void LogComponentDisableAll (enum LogLevel level);
#ifdef NS3_LOG_ENABLE
/**
* \ingroup debugging
* \defgroup logging Logging
* \brief Logging functions and macros
*
* LOG functionality: macros which allow developers to
* send information out on screen. All logging messages
* are disabled by default. To enable selected logging
* messages, use the ns3::LogComponentEnable
* function or use the NS_LOG environment variable
*
* Use the environment variable NS_LOG to define a ':'-separated list of
* logging components to enable. For example (using bash syntax),
* NS_LOG="OlsrAgent" would enable one component at all log levels.
* NS_LOG="OlsrAgent:Ipv4L3Protocol" would enable two components,
* at all log levels, etc.
* NS_LOG="*" will enable all available log components at all levels.
*
* To control more selectively the log levels for each component, use
* this syntax: NS_LOG='Component1=func|warn:Component2=error|debug'
* This example would enable the 'func', and 'warn' log
* levels for 'Component1' and the 'error' and 'debug' log levels
* for 'Component2'. The wildcard can be used here as well. For example
* NS_LOG='*=level_all|prefix' would enable all log levels and prefix all
* prints with the component and function names.
*
* A note on NS_LOG_FUNCTION() and NS_LOG_FUNCTION_NOARGS():
* generally, use of (at least) NS_LOG_FUNCTION(this) is preferred.
* Use NS_LOG_FUNCTION_NOARGS() only in static functions.
*/
/**
* \ingroup logging
@@ -330,7 +352,7 @@ void LogComponentDisableAll (enum LogLevel level);
NS_LOG_APPEND_CONTEXT; \
std::clog << g_log.Name () << ":" \
<< __FUNCTION__ << "("; \
ns3::ParameterLogger (std::clog) << parameters; \
ns3::ParameterLogger (std::clog) << parameters; \
std::clog << ")" << std::endl; \
} \
} \