#include <deal.II/base/logstream.h>

Inheritance diagram for LogStream:

Classes
class	Prefix

Public Member Functions
	LogStream ()

	~LogStream () override

void	attach (std::ostream &o, const bool print_job_id=true, const std::ios_base::fmtflags flags=std::ios::showpoint\|std::ios::left)

void	detach ()

std::ostream &	get_console ()

std::ostream &	get_file_stream ()

bool	has_file () const

const std::string &	get_prefix () const

void	push (const std::string &text)

void	pop ()

unsigned int	depth_console (const unsigned int n)

unsigned int	depth_file (const unsigned int n)

bool	log_thread_id (const bool flag)

std::streamsize	precision (const std::streamsize prec)

std::streamsize	width (const std::streamsize wide)

std::ios::fmtflags	flags (const std::ios::fmtflags f)

LogStream &	operator<< (std::ostream &(*p)(std::ostream &))

std::size_t	memory_consumption () const

Private Member Functions
std::stack< std::string > &	get_prefixes () const

void	print_line_head ()

std::ostringstream &	get_stream ()

Private Attributes
Threads::ThreadLocalStorage< std::stack< std::string > >	prefixes

std::thread::id	parent_thread

std::ostream *	std_out

std::ostream *	file

unsigned int	std_depth

unsigned int	file_depth

bool	print_thread_id

bool	at_newline

Threads::ThreadLocalStorage< std::shared_ptr< std::ostringstream > >	outstreams

Friends
template<typename T >
LogStream &	operator<< (LogStream &log, const T &t)

Subscriptor functionality
Classes derived from Subscriptor provide a facility to subscribe to this object. This is mostly used by the SmartPointer class.
std::atomic< unsigned int >	counter

std::map< std::string, unsigned int >	counter_map

std::vector< std::atomic< bool > * >	validity_pointers

const std::type_info *	object_info

void	subscribe (std::atomic< bool > *const validity, const std::string &identifier="") const

void	unsubscribe (std::atomic< bool > *const validity, const std::string &identifier="") const

unsigned int	n_subscriptions () const

template<typename StreamType >
void	list_subscribers (StreamType &stream) const

void	list_subscribers () const

template<class Archive >
void	serialize (Archive &ar, const unsigned int version)

void	check_no_subscribers () const noexcept

using	map_value_type = decltype(counter_map)::value_type

using	map_iterator = decltype(counter_map)::iterator

static std::mutex	mutex

static ::ExceptionBase &	ExcInUse (int arg1, std::string arg2, std::string arg3)

static ::ExceptionBase &	ExcNoSubscriber (std::string arg1, std::string arg2)

Detailed Description

A class that simplifies the process of execution logging. It does so by providing

a push and pop mechanism for prefixes, and
the possibility of distributing information to files and the console.

The usual usage of this class is through the pregenerated object deallog. Typical setup steps are:

deallog.depth_console(n): restrict output on screen to outer loops.
deallog.attach(std::ostream): write logging information into a file.
deallog.depth_file(n): restrict output to file to outer loops.

Before entering a new phase of your program, e.g. a new loop, a new prefix can be set via LogStream::Prefix p("loopname");. The destructor of the prefix will pop the prefix text from the stack.

Write via the << operator, deallog << "This is a log notice"; will be buffered thread locally until a std::flush or std::endl is encountered, which will trigger a writeout to the console and, if set up, the log file.

LogStream and thread safety

In the vicinity of concurrent threads, LogStream behaves in the following manner:

Every write to a Logstream with operator << (or with one of the special member functions) is buffered in a thread-local storage.
An std::flush or std::endl will trigger a writeout to the console and (if attached) to the file stream. This writeout is sequentialized so that output from concurrent threads don't interleave.
On a new thread, invoking a writeout, as well as a call to push or pop will copy the current prefix of the "blessed" thread that created the LogStream instance to a thread-local storage. After that prefixes are thread-local.

Definition at line 82 of file logstream.h.

Constructor & Destructor Documentation

◆ LogStream()

LogStream::LogStream ( )

Standard constructor. The constructor sets the output stream to std::cout and the depth to zero. (Use attach() and depth_console() to change this.)

Definition at line 75 of file logstream.cc.

◆ ~LogStream()

LogStream::~LogStream ( )

override

Destructor.

Definition at line 89 of file logstream.cc.

Member Function Documentation

◆ attach()

void LogStream::attach	(	std::ostream &	o,
		const bool	print_job_id = `true`,
		const std::ios_base::fmtflags	flags = `std::ios::showpoint \| std::ios::left`
	)

Enable output to a second stream o.

Parameters

	o	Attach this output stream.
[in]	print_job_id	Whether or not the JobIdentifier for the current process should be printed to the stream.
[in]	flags	Format flags to set on the output stream `o`.

Definition at line 219 of file logstream.cc.

◆ detach()

void LogStream::detach ( )

Disable output to the second stream. You may want to call close on the stream that was previously attached to this object.

Definition at line 232 of file logstream.cc.

◆ get_console()

std::ostream & LogStream::get_console ( )

Return the default stream (std_out).

Definition at line 240 of file logstream.cc.

◆ get_file_stream()

std::ostream & LogStream::get_file_stream ( )

Return the file stream.

Definition at line 271 of file logstream.cc.

◆ has_file()

bool LogStream::has_file ( ) const

Return true if file stream has already been attached, false otherwise.

Definition at line 282 of file logstream.cc.

◆ get_prefix()

const std::string & LogStream::get_prefix ( ) const

Return the prefix string.

Definition at line 290 of file logstream.cc.

◆ push()

void LogStream::push ( const std::string & text )

Push another prefix on the stack. Prefixes are automatically separated by a colon and there is a double colon after the last prefix.

A simpler way to add a prefix (without the manual need to add the corresponding pop()) is to use the LogStream::Prefix class. Using that class has the advantage that the corresponding pop() call is issued whenever the Prefix object goes out of scope – either at the end of the code block, at the nearest return statement, or because an intermediate function call results in an exception that is not immediately caught.

Definition at line 303 of file logstream.cc.

◆ pop()

void LogStream::pop ( )

Remove the last prefix added with push().

Definition at line 317 of file logstream.cc.

◆ depth_console()

unsigned int LogStream::depth_console ( const unsigned int n )

Maximum number of levels to be printed on the console. The default is 0, which will not generate any output. This function allows one to restrict console output to the highest levels of iterations. Only output with less than n prefixes is printed. By calling this function with n=0, no console output will be written. See step-3 for an example usage of this method.

The previous value of this parameter is returned.

Definition at line 350 of file logstream.cc.

◆ depth_file()

unsigned int LogStream::depth_file ( const unsigned int n )

Maximum number of levels to be written to the log file. The functionality is the same as depth_console, nevertheless, this function should be used with care, since it may spoil the value of a log file.

The previous value of this parameter is returned.

Definition at line 361 of file logstream.cc.

◆ log_thread_id()

bool LogStream::log_thread_id ( const bool flag )

Log the thread id.

Definition at line 372 of file logstream.cc.

◆ precision()

std::streamsize LogStream::precision ( const std::streamsize prec )

set the precision for the underlying stream and returns the previous stream precision. This function mimics http://www.cplusplus.com/reference/ios/ios_base/precision/

Definition at line 334 of file logstream.cc.

◆ width()

std::streamsize LogStream::width ( const std::streamsize wide )

set the width for the underlying stream and returns the previous stream width. This function mimics http://www.cplusplus.com/reference/ios/ios_base/width/

Definition at line 342 of file logstream.cc.

◆ flags()

std::ios::fmtflags LogStream::flags ( const std::ios::fmtflags f )

set the flags for the underlying stream and returns the previous stream flags. This function mimics http://www.cplusplus.com/reference/ios/ios_base/flags/

Definition at line 326 of file logstream.cc.

◆ operator<<()

LogStream & LogStream::operator<< ( std::ostream &(*)(std::ostream &) p )

Treat ostream manipulators. This passes on the whole thing to the template function with the exception of the std::endl manipulator, for which special action is performed: write the temporary stream buffer including a header to the file and std::cout and empty the buffer.

An overload of this function is needed anyway, since the compiler can't bind manipulators like std::endl directly to template arguments T like in the previous general template. This is due to the fact that std::endl is actually an overloaded set of functions for std::ostream, std::wostream, and potentially more of this kind. This function is therefore necessary to pick one element from this overload set.

Definition at line 125 of file logstream.cc.

◆ memory_consumption()

std::size_t LogStream::memory_consumption ( ) const

Return an estimate for the memory consumption, in bytes, of this object. This is not exact (but will usually be close) because calculating the memory usage of trees (e.g., std::map) is difficult.

◆ get_prefixes()

std::stack< std::string > & LogStream::get_prefixes ( ) const

private

Internal wrapper around thread-local prefixes. This private function will return the correct internal prefix stack. More important, a new thread- local stack will be copied from the current stack of the "blessed" thread that created this LogStream instance (usually, in the case of deallog, the "main" thread).

Definition at line 383 of file logstream.cc.

◆ print_line_head()

void LogStream::print_line_head ( )

private

Print head of line.

Definition at line 403 of file logstream.cc.

◆ get_stream()

std::ostringstream & LogStream::get_stream ( )

private

Internal wrapper around "thread local" outstreams. This private function will return the correct internal ostringstream buffer for operator<<.

Definition at line 248 of file logstream.cc.

Friends And Related Function Documentation

◆ operator<<

template<typename T >

LogStream & operator<<	(	LogStream &	log,
		const T &	t
	)

friend

Output a constant something through LogStream:

Note: We declare this operator as a non-member function so that it is possible to overload it with more specialized templated versions under C++11 overload resolution rules

Definition at line 406 of file logstream.h.

Member Data Documentation

◆ prefixes

Threads::ThreadLocalStorage<std::stack<std::string> > LogStream::prefixes

mutableprivate

Stack of strings which are printed at the beginning of each line to allow identification where the output was generated.

Definition at line 322 of file logstream.h.

◆ parent_thread

std::thread::id LogStream::parent_thread

private

We record the thread id of the thread creating this object. We need this information to "steal" the current prefix from this "parent" thread on first use of deallog on a new thread.

Definition at line 329 of file logstream.h.

◆ std_out

std::ostream* LogStream::std_out

private

Default stream, where the output is to go to. This stream defaults to std::cout, but can be set to another stream through the constructor.

Definition at line 336 of file logstream.h.

◆ file

std::ostream* LogStream::file

private

Pointer to a stream, where a copy of the output is to go to. Usually, this will be a file stream.

You can set and reset this stream by the attach function.

Definition at line 344 of file logstream.h.

◆ std_depth

unsigned int LogStream::std_depth

private

Value denoting the number of prefixes to be printed to the standard output. If more than this number of prefixes is pushed to the stack, then no output will be generated until the number of prefixes shrinks back below this number.

Definition at line 352 of file logstream.h.

◆ file_depth

unsigned int LogStream::file_depth

private

Same for the maximum depth of prefixes for output to a file.

Definition at line 357 of file logstream.h.

◆ print_thread_id

bool LogStream::print_thread_id

private

Flag for printing thread id.

Definition at line 362 of file logstream.h.

◆ at_newline

bool LogStream::at_newline

private

A flag indicating whether output is currently at a new line

Definition at line 367 of file logstream.h.

◆ outstreams

Threads::ThreadLocalStorage<std::shared_ptr<std::ostringstream> > LogStream::outstreams

private

We use our thread local storage facility to generate a stringstream for every thread that sends log messages.

Definition at line 386 of file logstream.h.

The documentation for this class was generated from the following files:

include/deal.II/base/logstream.h
source/base/logstream.cc

Classes

Public Member Functions

Private Member Functions

Private Attributes

Friends

Subscriptor functionality

Detailed Description

LogStream and thread safety

Constructor & Destructor Documentation

◆ LogStream()

◆ ~LogStream()

Member Function Documentation

◆ attach()

◆ detach()

◆ get_console()

◆ get_file_stream()

◆ has_file()

◆ get_prefix()

◆ push()

◆ pop()

◆ depth_console()

◆ depth_file()

◆ log_thread_id()

◆ precision()

◆ width()

◆ flags()

◆ operator<<()

◆ memory_consumption()

◆ get_prefixes()

◆ print_line_head()

◆ get_stream()

Friends And Related Function Documentation

◆ operator<<

Member Data Documentation

◆ prefixes

◆ parent_thread

◆ std_out

◆ file

◆ std_depth

◆ file_depth

◆ print_thread_id

◆ at_newline

◆ outstreams