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Improve connection cleanup to avoid many error messages with ioc exit on some operating systems #200

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merged 6 commits into from
Feb 5, 2024
Merged

Improve connection cleanup to avoid many error messages with ioc exit on some operating systems #200

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f13e70e
Invalid socket, but still prone to race conditions
FreddieAkeroyd Dec 20, 2023
0138904
Add sleeep
FreddieAkeroyd Dec 20, 2023
1256604
Add select() call
FreddieAkeroyd Dec 21, 2023
b2cf380
Merge remote-tracking branch 'upstream/master' into server_clean_hack…
FreddieAkeroyd Dec 21, 2023
7f89753
shutdown socket prior to close
FreddieAkeroyd Dec 22, 2023
19db7d3
Do not print accept error on connection close
FreddieAkeroyd Dec 24, 2023
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16 changes: 14 additions & 2 deletions asyn/drvAsynSerial/drvAsynIPServerPort.c
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Original file line number Diff line number Diff line change
Expand Up @@ -305,7 +305,7 @@ static void connectionListener(void *drvPvt)
asynPrint(pasynUser, ASYN_TRACE_FLOW,
"drvAsynIPServerPort: %s started listening for connections on %s\n",
tty->portName, tty->serverInfo);
while (1) {
while (tty->fd != INVALID_SOCKET) {
if (tty->socketType == SOCK_DGRAM) {
if ((tty->UDPbufferPos == 0) && (tty->UDPbufferSize == 0)) {
tty->UDPbufferSize = recvfrom(tty->fd, tty->UDPbuffer, THEORETICAL_UDP_MAX_SIZE , 0, NULL, NULL);
Expand All @@ -324,6 +324,12 @@ static void connectionListener(void *drvPvt)

} else {
clientFd = epicsSocketAccept(tty->fd, (struct sockaddr *) &clientAddr, &clientLen);
if (tty->fd == INVALID_SOCKET) {
asynPrint(pasynUser, ASYN_TRACE_FLOW,
"drvAsynIPServerPort: terminating connection thread for %s\n",
tty->serverInfo);
break; /* we must be in ioc shutdown and ttyCleanup has been called */
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... or maybe the file descriptor limit was reached and accept() has returned with errno==EMFILE.

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Do we need to add a separate test for this condition when we check clientFd at https://github.com/FreddieAkeroyd/asyn/blob/19db7d33e5576393f99feeb196f88b7d321e5a95/asyn/drvAsynSerial/drvAsynIPServerPort.c#L336 or would this situation also affect tty->fd ?

}
asynPrint(pasynUser, ASYN_TRACE_FLOW,
"drvAsynIPServerPort: new connection, socket=%d on %s\n",
clientFd, tty->serverInfo);
Expand Down Expand Up @@ -497,7 +503,13 @@ static void ttyCleanup(void *pPvt)
if (!tty) return;
if (tty->fd >= 0) {
asynPrint(tty->pasynUser, ASYN_TRACE_FLOW, "drvAsynIPServerPort:ttyCleanup %s: shutdown socket %d\n", tty->portName, tty->fd);
epicsSocketDestroy(tty->fd);
SOCKET fd_save = tty->fd;
tty->fd = INVALID_SOCKET;
/* shutdown then close the socket so accept thread will terminate */
shutdown(fd_save, SHUT_RDWR);
epicsThreadSleep(0.01); /* give time for shutdown to be noticed prior to close */
epicsSocketDestroy(fd_save);
epicsThreadSleep(0.1);
}
free(tty->portName);
free(tty->serverInfo);
Expand Down