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.TH "el_flush" "3" "10 June 2019 (v9999)" "bofc.pl"
.SH NAME
.PP
.BR el_flush ,\ el_oflush
- flush logs from all buffers to underlying devices.
.SH SYNOPSIS
.PP
.BI "#include <embedlog.h>"
.PP
.BI "int el_flush(void)"
.br
.BI "int el_oflush(struct el *" el ")"
.SH DESCRIPTION
.PP
.B embedlog
(and underlying drivers, operating systems, libraries etc) to improve
performance, may buffer message before commiting changes to actual device.
And it's ok, there is really no need to waste resources every time you want to
log 50 bytes of debug print on commiting message physically to the drive - or
send via network.
It's much more common to buffer messages in RAM until certain ammount of bytes
are ready to send - and then send a bunch of data in one quick burst.
But that behaviour is not always desired, like in situation in which we know we
won't be printing logs for long time.
For such situation explicit flush may in order.
.PP
.BR el_flush (3)
flushes logs from all buffers to underlying device.
For example, when logs are printed to file, logs are written through buffered
.B stdio
functions, which may result in some logs never being actually put into block
device in case of abnormal application crash - that of course depends on
settings like
.BR EL_FSYNC_EVERY .
This function will do everything what is in its power to make sure logs landed
on underlying device.
This applies to files, but also to logs with network output.
.PP
.BR el_oflush (3)
works just the same, but accepts custom
.I el
object as argument.
.SH RETURN VALUE
.PP
Functions return 0 upon successful flush or -1 on errors.
When -1 was returned there is no guarantee that data has landed on underlying
device.
.SH ERRORS
.PP
.BR el_flush (3)
and
.BR el_oflush (3)
may return errors from functions like:
.BR fflush (),\ fileno (),\ fsync (),\ fseek (),\ ftell (),\ fopen ()
and/or
.BR fclose ().
.PP
.BR el_oflush (3)
may additionally return:
.TP
.B EINVAL
Passed el object is not valid
.SH SEE ALSO
.PP
.BR el_overview (7),
.BR el_cleanup (3),
.BR el_destroy (3),
.BR el_init (3),
.BR el_new (3),
.BR el_ocleanup (3),
.BR el_oinit (3),
.BR el_ooption (3),
.BR el_operror (3),
.BR el_opmemory (3),
.BR el_opmemory_table (3),
.BR el_oprint (3),
.BR el_option (3),
.BR el_oputs (3),
.BR el_ovprint (3),
.BR el_perror (3),
.BR el_pmemory (3),
.BR el_pmemory_table (3),
.BR el_print (3),
.BR el_puts (3),
.BR el_vprint (3).
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