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Since the socket is non-blocking, it is necessary to use select(2) even

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when there is no timeout, because read(2) will return immediately if there
is no data waiting in the TCP buffer, causing fetch_read() to busy-loop on
slow connections.

MFC after:	3 weeks
Noticed by:	Yanhui Shen <shen.elf@gmail.com>
This commit is contained in:
Dag-Erling Smørgrav 2012-04-30 12:11:45 +00:00
parent 671c033623
commit 30787285b5
1 changed files with 13 additions and 17 deletions
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30
lib/libfetch/common.c
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@ -455,11 +455,9 @@ fetch_read(conn_t *conn, char *buf, size_t len)
struct timeval now, timeout, delta;
fd_set readfds;
ssize_t rlen, total;
int r;
char *start;
if (fetchTimeout) {
FD_ZERO(&readfds);
if (fetchTimeout > 0) {
gettimeofday(&timeout, NULL);
timeout.tv_sec += fetchTimeout;
}
@ -523,23 +521,21 @@ fetch_read(conn_t *conn, char *buf, size_t len)
return (-1);
}
// assert(rlen == FETCH_READ_WAIT);
while (fetchTimeout && !FD_ISSET(conn->sd, &readfds)) {
FD_ZERO(&readfds);
while (!FD_ISSET(conn->sd, &readfds)) {
FD_SET(conn->sd, &readfds);
gettimeofday(&now, NULL);
delta.tv_sec = timeout.tv_sec - now.tv_sec;
delta.tv_usec = timeout.tv_usec - now.tv_usec;
if (delta.tv_usec < 0) {
delta.tv_usec += 1000000;
delta.tv_sec--;
}
if (delta.tv_sec < 0) {
errno = ETIMEDOUT;
fetch_syserr();
return (-1);
if (fetchTimeout > 0) {
gettimeofday(&now, NULL);
if (!timercmp(&timeout, &now, >)) {
errno = ETIMEDOUT;
fetch_syserr();
return (-1);
}
timersub(&timeout, &now, &delta);
}
errno = 0;
r = select(conn->sd + 1, &readfds, NULL, NULL, &delta);
if (r == -1) {
if (select(conn->sd + 1, &readfds, NULL, NULL,
fetchTimeout > 0 ? &delta : NULL) < 0) {
if (errno == EINTR) {
if (fetchRestartCalls)
continue;