An internal-use implementation of Logger that logs messages to a given file-system path, blocking the calling thread while the I/O occurs, and usable safely only if logging occurs non-concurrently. More...

#include <serial_file_logger.hpp>

Inheritance diagram for flow::log::Serial_file_logger:

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Collaboration diagram for flow::log::Serial_file_logger:

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Public Member Functions
	Serial_file_logger (Logger backup_logger_ptr, Config config, const fs::path &log_path)
	Constructs logger to subsequently log to the given file-system path. More...

	~Serial_file_logger () override
	Flushes out anything buffered, returns resources/closes output file(s); then returns. More...

bool	should_log (Sev sev, const Component &component) const override
	See Async_file_logger::should_log(). More...

bool	logs_asynchronously () const override
	Implements interface method by returning `false`, indicating that this Logger will not need the contents of `*metadata` and `msg` passed to do_log() after that method returns. More...

void	do_log (Msg_metadata *metadata, util::String_view msg) override
	Implements interface method by synchronously logging the message and some subset of the metadata in a fashion controlled by m_config. More...

void	log_flush_and_reopen ()
	Causes the log at the file-system path to be flushed/closed (if needed) and re-opened; this will occur synchronously meaning it will complete before the method returns. More...

Public Member Functions inherited from flow::log::Logger
virtual bool	should_log (Sev sev, const Component &component) const =0
	Given attributes of a hypothetical message that would be logged, return `true` if that message should be logged and `false` otherwise (e.g., if the verbosity of the message is above the current configured verbosity threshold for the Component specified). More...

virtual bool	logs_asynchronously () const =0
	Must return `true` if do_log() at least sometimes logs the given message and metadata (e.g., time stamp) after do_log() returns; `false` if this never occurs (i.e., it logs synchronously, always). More...

virtual void	do_log (Msg_metadata *metadata, util::String_view msg)=0
	Given a message and its severity, logs that message and possibly severity WITHOUT checking whether it should be logged (i.e., without performing logic that should_log() performs). More...

std::ostream *	this_thread_ostream () const
	Returns the stream dedicated to the executing thread and `this` Logger, so that the caller can apply state-setting formatters to it. More...

Public Member Functions inherited from flow::util::Null_interface
virtual	~Null_interface ()=0
	Boring `virtual` destructor. More...

Public Member Functions inherited from flow::util::Unique_id_holder
	Unique_id_holder ()
	Thread-safely construct an ID whose value is different from any other object of this class, past or future. More...

	Unique_id_holder (const Unique_id_holder &)
	This copy constructor is identical in behavior to Unique_id_holder(), the default ctor. More...

id_t	unique_id () const
	Raw unique ID identifying this object as well as any object of a derived type. More...

const Unique_id_holder &	operator= (const Unique_id_holder &) const
	This assignment operator is a `const` no-op. More...

Public Attributes
Config *const	m_config
	See Async_file_logger::m_config. More...

Private Attributes
const fs::path	m_log_path
	File-system path to which to write subsequently. More...

fs::ofstream	m_ofs
	The file to which to write. Because only the worker thread ever accesses it, no mutex is needed. More...

Ostream_log_msg_writer	m_ofs_writer
	Stream writer via which to log messages to m_ofs. More...

bool	m_reopening
	Starts at `false`, becomes `true` at entry to log_flush_and_reopen(), then becomes `false` again. More...

Additional Inherited Members
Public Types inherited from flow::util::Unique_id_holder
using	id_t = uint64_t
	Raw integer type to uniquely identify a thing. 64-bit width should make overflow extremely hard to reach. More...

Static Public Member Functions inherited from flow::log::Logger
static void	this_thread_set_logged_nickname (util::String_view thread_nickname=util::String_view(), Logger *logger_ptr=0, bool also_set_os_name=true)
	Sets or unsets the current thread's logging-worthy string name; optionally sets the OS thread name (such as visible in `top` output). More...

static std::ostream &	this_thread_logged_name_os_manip (std::ostream &os)
	`ostream` manipulator function that, if output via `operator<<` to an `ostream`, will cause the current thread's logging-worthy string name to be output to that stream. More...

static void	set_thread_info_in_msg_metadata (Msg_metadata *msg_metadata)
	Loads `msg_metadata->m_call_thread_nickname` (if set) or else `msg_metadata->m_call_thread_id`, based on whether/how this_thread_set_logged_nickname() was last called in the current thread. More...

static void	set_thread_info (std::string call_thread_nickname, flow::util::Thread_id call_thread_id)
	Same as set_thread_info_in_msg_metadata() but targets the given two variables as opposed to a Msg_metadata. More...

Static Public Member Functions inherited from flow::util::Unique_id_holder
static id_t	create_unique_id ()
	Short-hand for `Unique_id_holder().unique_id()`; useful when all you want is the unique integer itself. More...

Protected Member Functions inherited from flow::log::Log_context
	Log_context (Logger *logger=0)
	Constructs Log_context by storing the given pointer to a Logger and a null Component. More...

template<typename Component_payload >
	Log_context (Logger *logger, Component_payload component_payload)
	Constructs Log_context by storing the given pointer to a Logger and a new Component storing the specified generically typed payload (an `enum` value). More...

	Log_context (const Log_context &src)
	Copy constructor that stores equal `Logger*` and Component values as the source. More...

	Log_context (Log_context &&src)
	Move constructor that makes this equal to `src`, while the latter becomes as-if default-constructed. More...

Log_context &	operator= (const Log_context &src)
	Assignment operator that behaves similarly to the copy constructor. More...

Log_context &	operator= (Log_context &&src)
	Move assignment operator that behaves similarly to the move constructor. More...

void	swap (Log_context &other)
	Swaps Logger pointers and Component objects held by `*this` and `other`. More...

Logger *	get_logger () const
	Returns the stored Logger pointer, particularly as many `FLOW_LOG_*()` macros expect. More...

const Component &	get_log_component () const
	Returns reference to the stored Component object, particularly as many `FLOW_LOG_*()` macros expect. More...

Detailed Description

An internal-use implementation of Logger that logs messages to a given file-system path, blocking the calling thread while the I/O occurs, and usable safely only if logging occurs non-concurrently.

As of this writing it is essentially an internal component needed by Async_file_logger; but it is a full-fledged Logger nevertheless.

Thread safety

The file I/O-using APIs, notably do_log() and log_flush_and_reopen() but not should_log(), are unsafe to call concurrently. The logging user – as of this writing Async_file_logger but it's fully conceivable other uses exist – must therefore provide any anti-concurrency measures (use one thread; a strand; mutex; etc.).

See thread safety notes and to-dos regarding m_config in Simple_ostream_logger doc header. These apply here also.

Todo:: Consider having Serial_file_logger internally buffer any attempted log requests that it couldn't write to file due to I/O error. The logic already attempts re-open repeatedly but doesn't attempt to re-log failed lines.

Definition at line 46 of file serial_file_logger.hpp.

Constructor & Destructor Documentation

◆ Serial_file_logger()

flow::log::Serial_file_logger::Serial_file_logger	(	Logger *	backup_logger_ptr,
		Config *	config,
		const fs::path &	log_path
	)

explicit

Constructs logger to subsequently log to the given file-system path.

It will append. This constructor itself does not perform any I/O operations.

Parameters

config	See Async_file_logger ctor.
log_path	See Async_file_logger ctor.
backup_logger_ptr	See Async_file_logger ctor.

Definition at line 27 of file serial_file_logger.cpp.

References FLOW_LOG_INFO, log_flush_and_reopen(), and m_log_path.

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◆ ~Serial_file_logger()

flow::log::Serial_file_logger::~Serial_file_logger ( )

override

Flushes out anything buffered, returns resources/closes output file(s); then returns.

Definition at line 50 of file serial_file_logger.cpp.

References FLOW_LOG_INFO, m_log_path, and m_ofs.

Member Function Documentation

◆ do_log()

void flow::log::Serial_file_logger::do_log	(	Msg_metadata *	metadata,
		util::String_view	msg
	)

overridevirtual

Implements interface method by synchronously logging the message and some subset of the metadata in a fashion controlled by m_config.

Parameters

metadata	All information to potentially log in addition to `msg`.
msg	The message.

Implements flow::log::Logger.

Definition at line 63 of file serial_file_logger.cpp.

References FLOW_LOG_WARNING, flow::log::Ostream_log_msg_writer::log(), log_flush_and_reopen(), m_log_path, m_ofs, and m_ofs_writer.

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◆ log_flush_and_reopen()

void flow::log::Serial_file_logger::log_flush_and_reopen ( )

Causes the log at the file-system path to be flushed/closed (if needed) and re-opened; this will occur synchronously meaning it will complete before the method returns.

Definition at line 111 of file serial_file_logger.cpp.

References FLOW_LOG_INFO, FLOW_LOG_SET_LOGGER, FLOW_LOG_TRACE, FLOW_LOG_WARNING, m_log_path, m_ofs, and m_reopening.

Referenced by do_log(), and Serial_file_logger().

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◆ logs_asynchronously()

bool flow::log::Serial_file_logger::logs_asynchronously ( ) const

overridevirtual

Implements interface method by returning false, indicating that this Logger will not need the contents of *metadata and msg passed to do_log() after that method returns.

Returns: See above.

Implements flow::log::Logger.

Definition at line 193 of file serial_file_logger.cpp.

◆ should_log()

bool flow::log::Serial_file_logger::should_log	(	Sev	sev,
		const Component &	component
	)		const

overridevirtual

See Async_file_logger::should_log().

Parameters

sev	See Async_file_logger::should_log().
component	See Async_file_logger::should_log().

Returns: See Async_file_logger::should_log().

Implements flow::log::Logger.

Definition at line 188 of file serial_file_logger.cpp.

Member Data Documentation

◆ m_config

Config* const flow::log::Serial_file_logger::m_config

See Async_file_logger::m_config.

Definition at line 111 of file serial_file_logger.hpp.

◆ m_log_path

const fs::path flow::log::Serial_file_logger::m_log_path

private

File-system path to which to write subsequently.

Definition at line 117 of file serial_file_logger.hpp.

Referenced by do_log(), log_flush_and_reopen(), Serial_file_logger(), and ~Serial_file_logger().

◆ m_ofs

fs::ofstream flow::log::Serial_file_logger::m_ofs

private

The file to which to write. Because only the worker thread ever accesses it, no mutex is needed.

Definition at line 120 of file serial_file_logger.hpp.

Referenced by do_log(), log_flush_and_reopen(), and ~Serial_file_logger().

◆ m_ofs_writer

Ostream_log_msg_writer flow::log::Serial_file_logger::m_ofs_writer

private

Stream writer via which to log messages to m_ofs.

A m_ofs_writer.log() call synchronously writes to m_ofs and flushes it to the output device (file). Same thread safety situation as m_ofs (only worker thread access it).

Definition at line 127 of file serial_file_logger.hpp.

Referenced by do_log().

◆ m_reopening

bool flow::log::Serial_file_logger::m_reopening

private

Starts at false, becomes true at entry to log_flush_and_reopen(), then becomes false again.

Simple anti-recursion measure.

Definition at line 133 of file serial_file_logger.hpp.

Referenced by log_flush_and_reopen().

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

log/detail/serial_file_logger.hpp
log/detail/serial_file_logger.cpp

Public Member Functions

Public Attributes

Private Attributes

Additional Inherited Members

Detailed Description

Thread safety

Constructor & Destructor Documentation

◆ Serial_file_logger()

◆ ~Serial_file_logger()

Member Function Documentation

◆ do_log()

◆ log_flush_and_reopen()

◆ logs_asynchronously()

◆ should_log()

Member Data Documentation

◆ m_config

◆ m_log_path

◆ m_ofs

◆ m_ofs_writer

◆ m_reopening