.\" Automatically generated by Pandoc 2.10.1
.\"
.TH "PMEMLOG_APPEND" "3" "2020-10-28" "PMDK - pmemlog API version 1.1" "PMDK Programmer's Manual"
.hy
.\" SPDX-License-Identifier: BSD-3-Clause
.\" Copyright 2017-2018, Intel Corporation
.SH NAME
.PP
\f[B]pmemlog_append\f[R](), \f[B]pmemlog_appendv\f[R]() - append bytes
to the persistent memory resident log file
.SH SYNOPSIS
.IP
.nf
\f[C]
#include <libpmemlog.h>

int pmemlog_append(PMEMlogpool *plp, const void *buf, size_t count);
int pmemlog_appendv(PMEMlogpool *plp, const struct iovec *iov, int iovcnt);
\f[R]
.fi
.SH DESCRIPTION
.PP
The \f[B]pmemlog_append\f[R]() function appends \f[I]count\f[R] bytes
from \f[I]buf\f[R] to the current write offset in the log memory pool
\f[I]plp\f[R].
Calling this function is analogous to appending to a file.
The append is atomic and cannot be torn by a program failure or system
crash.
.PP
The \f[B]pmemlog_appendv\f[R]() function appends to the log memory pool
\f[I]plp\f[R] from the scatter/gather list \f[I]iov\f[R] in a manner
similar to \f[B]writev\f[R](2).
The entire list of buffers is appended atomically, as if the buffers in
\f[I]iov\f[R] were concatenated in order.
The append is atomic and cannot be torn by a program failure or system
crash.
.SH RETURN VALUE
.PP
On success, \f[B]pmemlog_append\f[R]() and \f[B]pmemlog_appendv\f[R]()
return 0.
On error, they return -1 and set \f[I]errno\f[R] appropriately.
.SH ERRORS
.PP
\f[B]EINVAL\f[R] The vector count \f[I]iovcnt\f[R] is less than zero.
.PP
\f[B]ENOSPC\f[R] There is no room for the data in the log file.
.PP
\f[B]EROFS\f[R] The log file is open in read-only mode.
.SH NOTES
.PP
Since \f[B]libpmemlog\f[R](7) is designed as a low-latency code path,
many of the checks routinely done by the operating system for
\f[B]writev\f[R](2) are not practical in the library\[cq]s
implementation of \f[B]pmemlog_appendv\f[R]().
No attempt is made to detect NULL or incorrect pointers, for example.
.SH SEE ALSO
.PP
\f[B]writev\f[R](2), \f[B]libpmemlog\f[R](7) and
\f[B]<https://pmem.io>\f[R]