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client: Split ring_to_iovec() off ring_to_file()

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Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
This commit is contained in:
Markus Armbruster 2017-06-25 10:20:53 +02:00
parent 8301e0f144
commit 8fe2b949e6
1 changed files with 25 additions and 13 deletions
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38
src/client/ringbuf.c
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@ -27,7 +27,7 @@
* ringbuf.c: Simple ring buffer * ringbuf.c: Simple ring buffer
* *
* Known contributors to this file: * Known contributors to this file:
* Markus Armbruster, 2007-2015 * Markus Armbruster, 2007-2017
*/ */
#include <config.h> #include <config.h>
@ -215,19 +215,15 @@ ring_from_file(struct ring *r, int fd)
} }
/* /*
* Drain ring buffer to file referred by file descriptor @fd. * Set up @iov[] to describe complete contents of ring buffer.
* If ring buffer is already empty, do nothing and return 0. * @iov[] must have at least two elements.
* Else attempt to write complete contents with writev(), and return * Return number of elements used (zero for an empty ring buffer).
* its value.
*/ */
int static int
ring_to_file(struct ring *r, int fd) ring_to_iovec(struct ring *r, struct iovec iov[])
{ {
unsigned cons = r->cons % RING_SIZE; unsigned cons = r->cons % RING_SIZE;
unsigned prod = r->prod % RING_SIZE; unsigned prod = r->prod % RING_SIZE;
struct iovec iov[2];
int cnt;
ssize_t res;
if (r->cons == r->prod) if (r->cons == r->prod)
return 0; return 0;
@ -239,15 +235,31 @@ ring_to_file(struct ring *r, int fd)
/* r->buf[..prod-1] */ /* r->buf[..prod-1] */
iov[1].iov_base = r->buf; iov[1].iov_base = r->buf;
iov[1].iov_len = prod; iov[1].iov_len = prod;
cnt = 2; return 2;
} else { } else {
/* r->buf[cons..prod-1] */ /* r->buf[cons..prod-1] */
iov[0].iov_len = prod - cons; iov[0].iov_len = prod - cons;
cnt = 1; return 1;
} }
}
/*
* Drain ring buffer to file referred by file descriptor @fd.
* If ring buffer is already empty, do nothing and return 0.
* Else attempt to write complete contents with writev(), and return
* its value.
*/
int
ring_to_file(struct ring *r, int fd)
{
struct iovec iov[2];
int cnt;
ssize_t res;
cnt = ring_to_iovec(r, iov);
res = writev(fd, iov, cnt); res = writev(fd, iov, cnt);
if (res < 0) if (res < 0)
return res; return res;
r->cons += res; ring_discard(r, res);
return res; return res;
} }