mainloop.h File Reference

#include "syslog-ng.h"
#include "thread-utils.h"

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Classes
struct	MainLoopOptions

Macros
#define	MAIN_LOOP_ERROR   main_loop_error_quark()

Typedefs
typedef gpointer(*	MainLoopTaskFunc) (gpointer user_data)

Enumerations
enum	MainLoopError { MAIN_LOOP_ERROR_FAILED , MAIN_LOOP_ERROR_RELOAD_FAILED }

Functions
gboolean	main_loop_reload_config_prepare (MainLoop *self, GError **error)
void	main_loop_reload_config_commence (MainLoop *self)
void	main_loop_reload_config (MainLoop *self)
void	main_loop_verify_config (GString *result, MainLoop *self)
gboolean	main_loop_is_terminating (MainLoop *self)
void	main_loop_exit (MainLoop *self)
int	main_loop_read_and_init_config (MainLoop *self)
gboolean	main_loop_was_last_reload_successful (MainLoop *self)
void	main_loop_run (MainLoop *self)
MainLoop *	main_loop_get_instance (void)
GlobalConfig *	main_loop_get_current_config (MainLoop *self)
GlobalConfig *	main_loop_get_pending_new_config (MainLoop *self)
void	main_loop_init (MainLoop *self, MainLoopOptions *options)
void	main_loop_deinit (MainLoop *self)
void	main_loop_add_options (GOptionContext *ctx)
gboolean	main_loop_is_server_mode (MainLoop *self)
void	main_loop_set_server_mode (MainLoop *self, gboolean server_mode)
gboolean	main_loop_initialize_state (GlobalConfig *cfg, const gchar *persist_filename)
void	main_loop_thread_resource_init (void)
void	main_loop_thread_resource_deinit (void)
gboolean	main_loop_is_control_server_running (MainLoop *self)
GQuark	main_loop_error_quark (void)

Variables
volatile gint	main_loop_workers_running
ThreadId	main_thread_handle
GCond	thread_halt_cond
GMutex	workers_running_lock

Macro Definition Documentation

MAIN_LOOP_ERROR

#define MAIN_LOOP_ERROR   main_loop_error_quark()

Typedef Documentation

MainLoopTaskFunc

typedef gpointer(* MainLoopTaskFunc) (gpointer user_data)

Enumeration Type Documentation

MainLoopError

enum MainLoopError

Enumerator
MAIN_LOOP_ERROR_FAILED
MAIN_LOOP_ERROR_RELOAD_FAILED

Function Documentation

main_loop_add_options()

void main_loop_add_options

(

GOptionContext *

ctx

)

main_loop_deinit()

void main_loop_deinit

(

MainLoop *

self

)

main_loop_error_quark()

GQuark main_loop_error_quark

(

void

)

main_loop_exit()

void main_loop_exit

(

MainLoop *

self

)

main_loop_get_current_config()

GlobalConfig* main_loop_get_current_config

(

MainLoop *

self

)

main_loop_get_instance()

MainLoop* main_loop_get_instance

(

void

)

main_loop_get_pending_new_config()

GlobalConfig* main_loop_get_pending_new_config

(

MainLoop *

self

)

main_loop_init()

void main_loop_init	(	MainLoop *	self,
		MainLoopOptions *	options
	)

main_loop_initialize_state()

gboolean main_loop_initialize_state	(	GlobalConfig *	cfg,
		const gchar *	persist_filename
	)

main_loop_is_control_server_running()

gboolean main_loop_is_control_server_running

(

MainLoop *

self

)

main_loop_is_server_mode()

gboolean main_loop_is_server_mode

(

MainLoop *

self

)

main_loop_is_terminating()

gboolean main_loop_is_terminating

(

MainLoop *

self

)

main_loop_read_and_init_config()

int main_loop_read_and_init_config

(

MainLoop *

self

)

main_loop_reload_config()

void main_loop_reload_config

(

MainLoop *

self

)

main_loop_reload_config_commence()

void main_loop_reload_config_commence

(

MainLoop *

self

)

main_loop_reload_config_prepare()

gboolean main_loop_reload_config_prepare	(	MainLoop *	self,
		GError **	error
	)

main_loop_run()

void main_loop_run

(

MainLoop *

self

)

main_loop_set_server_mode()

void main_loop_set_server_mode	(	MainLoop *	self,
		gboolean	server_mode
	)

main_loop_thread_resource_deinit()

void main_loop_thread_resource_deinit

(

void

)

main_loop_thread_resource_init()

void main_loop_thread_resource_init

(

void

)

main_loop_verify_config()

void main_loop_verify_config	(	GString *	result,
		MainLoop *	self
	)

main_loop_was_last_reload_successful()

gboolean main_loop_was_last_reload_successful

(

MainLoop *

self

)

Variable Documentation

main_loop_workers_running

volatile gint main_loop_workers_running

extern

main_thread_handle

ThreadId main_thread_handle

extern

Processing model

This comment documents how the work performed by syslog-ng is partitioned between threads. First of all it is useful to know that the configuration is translated to a tree of LogPipe instances, as described in a comment in logpipe.h.

The basic assumptions for threading:

• configuration file is parsed in the main thread
• the log pipe tree is built in the main thread
• processing of messages is stalled while the configuration is reloaded
• the _queue() operation for LogPipe instances can happen in multiple threads
• notifications across LogPipe instances happen in the main thread

This boils down to:

• If not otherwise specified LogPipe derived classes can only be instantiated (e.g. new()) or initialized/deinitialized (_init/deinit) in the main thread. Exceptions to this rule are documented below.
• All queue operations finish before either deinit is called.
• Locking is only needed between multiple invocations of _queue() in parallel threads, and any other main thread activity.

Threading model

• the main thread manages the configuration and polls for I/O using epoll
• whenever an I/O event happens, work may be delegated to worker threads. Currently only the LogReader/LogWriter classes make use of worker threads, everything else remains in the main thread (internal messages, incoming connections, etc).
• all I/O polling must be registered in the main thread (update_watches and friends)

thread_halt_cond

GCond thread_halt_cond

extern

workers_running_lock

GMutex workers_running_lock

extern