sd_bus_close, sd_bus_flush, sd_bus_default_flush_close — Close and flush a bus connection
#include <systemd/sd-bus.h>
void sd_bus_close( | sd_bus *bus); |
int sd_bus_flush( | sd_bus *bus); |
void sd_bus_default_flush_close( | void); |
sd_bus_close() disconnects the specified bus connection. When this
call is invoked and the specified bus object refers to an active connection it is immediately
terminated. No further messages may be sent or received on it. Any messages queued in the bus
object (both incoming and outgoing) are released. If invoked on NULL bus
object or when the bus connection is already closed this function executes no operation. This
call does not free or unreference the bus object itself. Use
sd_bus_unref(3)
for that.
sd_bus_flush() synchronously writes out all outgoing queued message
on a bus connection if there are any. This function call may block if the peer is not processing
bus messages quickly.
Before a program exits it is usually a good idea to flush any pending messages with
sd_bus_flush() and then close connections with
sd_bus_close() to ensure that no unwritten messages are lost, no further
messages may be queued and all incoming but unprocessed messages are released. After both
operations have been done, it is a good idea to also drop any remaining references to the bus
object so that it may be freed. Since these three operations are frequently done together a
helper call
sd_bus_flush_close_unref(3)
is provided that combines them into one.
sd_bus_default_flush_close() is similar to
sd_bus_flush_close_unref(), but does not take a bus pointer argument and
instead iterates over any of the "default" buses opened by
sd_bus_default(3),
sd_bus_default_user(3),
sd_bus_default_system(3),
and similar calls. sd_bus_default_flush_close() is particularly useful to
clean up any buses opened using those calls before the program exits.
On success, sd_bus_flush() returns a non-negative integer. On
failure, it returns a negative errno-style error code.
Functions described here are available as a shared
library, which can be compiled against and linked to with the
libsystemd pkg-config(1)
file.
The code described here uses
getenv(3),
which is declared to be not multi-thread-safe. This means that the code calling the functions described
here must not call
setenv(3)
from a parallel thread. It is recommended to only do calls to setenv()
from an early phase of the program when no other threads have been started.
sd_bus_close() and
sd_bus_flush() were added in version 221.
sd_bus_default_flush_close() was added in version 227.