Re: [Qemu-devel] Socket reconnection.

[Ian Molton <ian.molton@collabora.co.uk>]

Krumme, Chris wrote:
> Hello Ian,

Hello!

> Qemu_malloc will never return 0, so sched function can return void.

Gah! nasty. Check removed.

> This is a mixture of tabs and spaces, for new code pick one.

I've been sticking with spaces generally. I can't find 'CodingStyle' so
I copied. I think spaces suck for this though. What is acceptable?
linux kernel style ?
 
> The if(prev) can just be this = prev;  if prev is NULL you want NULL
> anyway.

Quite. Fixed.

> Thanks

Likewise.

Fresh patch attached. Anthony, if this is ok, I can rebase this and its
prerequisite.

>From 05581c5badd693b7537fe57f85a2ff5ddcb7972d Mon Sep 17 00:00:00 2001
From: Ian Molton <ian.molton@collabora.co.uk>
Date: Tue, 1 Dec 2009 11:18:41 +0000
Subject: [PATCH 2/4] socket: Add a reconnect option.

	Add a reconnect option that allows sockets to reconnect (after a
specified delay) to the specified server. This makes the virtio-rng driver
useful in production environments where the EGD server may need to be restarted.

Signed-off-by: Ian Molton <ian.molton@collabora.co.uk>
---
 qemu-char.c   |  169 ++++++++++++++++++++++++++++++++++++++++++++-------------
 qemu-char.h   |    2 +
 qemu-config.c |    3 +
 vl.c          |    4 ++
 4 files changed, 139 insertions(+), 39 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index e202585..f20d697 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -1870,8 +1870,12 @@ typedef struct {
     int max_size;
     int do_telnetopt;
     int do_nodelay;
+    int reconnect;
     int is_unix;
     int msgfd;
+    QemuOpts *opts;
+    CharDriverState *chr;
+    int (*setup)(QemuOpts *opts);
 } TCPCharDriver;
 
 static void tcp_chr_accept(void *opaque);
@@ -2011,6 +2015,61 @@ static ssize_t tcp_chr_recv(CharDriverState *chr, char *buf, size_t len)
 }
 #endif
 
+struct reconnect_list {
+    TCPCharDriver *s;
+    uint64_t when;
+    struct reconnect_list *next;
+};
+
+static struct reconnect_list *rc_list;
+
+static void qemu_chr_sched_reconnect(TCPCharDriver *s)
+{
+    struct reconnect_list *new = qemu_malloc(sizeof(*new));
+    struct timeval tv;
+
+    gettimeofday(&tv, NULL);
+    new->s = s;
+    new->when = (s->reconnect + tv.tv_sec) * 1000000 + tv.tv_usec;
+    new->next = rc_list;
+    rc_list = new;
+}
+
+static int qemu_chr_connect_socket(TCPCharDriver *s);
+
+void qemu_chr_reconnect(void)
+{
+    struct reconnect_list *this = rc_list, *prev = NULL;
+    struct timeval tv;
+    uint64_t now;
+
+    if (!this)
+        return;
+
+    gettimeofday(&tv, NULL);
+    now = tv.tv_sec * 1000000 + tv.tv_usec;
+
+    while (this) {
+        if (this->when <= now) {
+            if (qemu_chr_connect_socket(this->s)) {
+                if (prev)
+                    prev->next = this->next;
+                else
+                    rc_list = NULL;
+                qemu_chr_event(this->s->chr, CHR_EVENT_RECONNECTED);
+                free(this);
+                this = prev;
+            }
+            else {
+                this->when += this->s->reconnect * 1000000;
+            }
+        }
+        prev = this;
+	if (this)
+            this = this->next;
+    }
+}
+
 static void tcp_chr_read(void *opaque)
 {
     CharDriverState *chr = opaque;
@@ -2030,10 +2089,16 @@ static void tcp_chr_read(void *opaque)
         if (s->listen_fd >= 0) {
             qemu_set_fd_handler(s->listen_fd, tcp_chr_accept, NULL, chr);
         }
-        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
+        if (!s->reconnect) {
+            qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
+        }
         closesocket(s->fd);
         s->fd = -1;
-        qemu_chr_event(chr, CHR_EVENT_CLOSED);
+        if (s->reconnect) {
+            qemu_chr_sched_reconnect(s);
+        } else {
+            qemu_chr_event(chr, CHR_EVENT_CLOSED);
+        }
     } else if (size > 0) {
         if (s->do_telnetopt)
             tcp_chr_process_IAC_bytes(chr, s, buf, &size);
@@ -2137,7 +2202,6 @@ static CharDriverState *qemu_chr_open_socket(QemuOpts *opts)
 {
     CharDriverState *chr = NULL;
     TCPCharDriver *s = NULL;
-    int fd = -1;
     int is_listen;
     int is_waitconnect;
     int do_nodelay;
@@ -2145,34 +2209,40 @@ static CharDriverState *qemu_chr_open_socket(QemuOpts *opts)
     int is_telnet;
 
     is_listen      = qemu_opt_get_bool(opts, "server", 0);
+    is_unix        = qemu_opt_get(opts, "path") != NULL;
+
     is_waitconnect = qemu_opt_get_bool(opts, "wait", 1);
     is_telnet      = qemu_opt_get_bool(opts, "telnet", 0);
     do_nodelay     = !qemu_opt_get_bool(opts, "delay", 1);
-    is_unix        = qemu_opt_get(opts, "path") != NULL;
-    if (!is_listen)
+
+    if (!is_listen) {
         is_waitconnect = 0;
+    } else {
+        if (is_telnet)
+            s->do_telnetopt = 1;
+    }
+
 
-    chr = qemu_mallocz(sizeof(CharDriverState));
     s = qemu_mallocz(sizeof(TCPCharDriver));
+    chr = qemu_mallocz(sizeof(CharDriverState));
+    s->opts = opts;
+
+    if (!is_listen && !is_telnet)
+        s->reconnect = qemu_opt_get_number(opts, "reconnect", 0);
 
     if (is_unix) {
         if (is_listen) {
-            fd = unix_listen_opts(opts);
+            s->setup = unix_listen_opts;
         } else {
-            fd = unix_connect_opts(opts);
+            s->setup = unix_connect_opts;
         }
     } else {
         if (is_listen) {
-            fd = inet_listen_opts(opts, 0);
+            s->setup = inet_listen_opts;
         } else {
-            fd = inet_connect_opts(opts);
+            s->setup = inet_connect_opts;
         }
     }
-    if (fd < 0)
-        goto fail;
-
-    if (!is_waitconnect)
-        socket_set_nonblock(fd);
 
     s->connected = 0;
     s->fd = -1;
@@ -2186,19 +2256,6 @@ static CharDriverState *qemu_chr_open_socket(QemuOpts *opts)
     chr->chr_close = tcp_chr_close;
     chr->get_msgfd = tcp_get_msgfd;
 
-    if (is_listen) {
-        s->listen_fd = fd;
-        qemu_set_fd_handler(s->listen_fd, tcp_chr_accept, NULL, chr);
-        if (is_telnet)
-            s->do_telnetopt = 1;
-
-    } else {
-        s->connected = 1;
-        s->fd = fd;
-        socket_set_nodelay(fd);
-        tcp_chr_connect(chr);
-    }
-
     /* for "info chardev" monitor command */
     chr->filename = qemu_malloc(256);
     if (is_unix) {
@@ -2215,22 +2272,56 @@ static CharDriverState *qemu_chr_open_socket(QemuOpts *opts)
                  qemu_opt_get_bool(opts, "server", 0) ? ",server" : "");
     }
 
-    if (is_listen && is_waitconnect) {
-        printf("QEMU waiting for connection on: %s\n",
-               chr->filename);
-        tcp_chr_accept(chr);
-        socket_set_nonblock(s->listen_fd);
-    }
-    return chr;
+    s->chr = chr;
+
+    if(qemu_chr_connect_socket(s))
+        return chr;
 
- fail:
-    if (fd >= 0)
-        closesocket(fd);
-    qemu_free(s);
     qemu_free(chr);
+    qemu_free(s);
+
     return NULL;
 }
 
+
+static int qemu_chr_connect_socket(TCPCharDriver *s)
+{
+    QemuOpts *opts = s->opts;
+    int is_listen;
+    int fd;
+    int is_waitconnect;
+    int do_nodelay;
+
+    is_waitconnect = qemu_opt_get_bool(opts, "wait", 1);
+    is_listen      = qemu_opt_get_bool(opts, "server", 0);
+    do_nodelay     = !qemu_opt_get_bool(opts, "delay", 1);
+
+
+    fd = s->setup(s->opts);
+    if (fd < 0)
+        return 0;
+
+    if (!is_waitconnect)
+        socket_set_nonblock(fd);
+
+    if (is_listen) {
+        s->listen_fd = fd;
+        qemu_set_fd_handler(s->listen_fd, tcp_chr_accept, NULL, s->chr);
+        if (is_waitconnect) {
+            printf("QEMU waiting for connection on: %s\n",
+                   s->chr->filename);
+            tcp_chr_accept(s->chr);
+            socket_set_nonblock(s->listen_fd);
+        }
+    } else {
+        s->fd = fd;
+        socket_set_nodelay(fd);
+        tcp_chr_connect(s->chr);
+    }
+
+    return 1;
+}
+
 static QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename)
 {
     char host[65], port[33], width[8], height[8];
diff --git a/qemu-char.h b/qemu-char.h
index 9957db1..dc954e2 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -14,6 +14,7 @@
 #define CHR_EVENT_MUX_IN  3 /* mux-focus was set to this terminal */
 #define CHR_EVENT_MUX_OUT 4 /* mux-focus will move on */
 #define CHR_EVENT_CLOSED  5 /* connection closed */
+#define CHR_EVENT_RECONNECTED  6 /* reconnect event */
 
 
 #define CHR_IOCTL_SERIAL_SET_PARAMS   1
@@ -73,6 +74,7 @@ CharDriverState *qemu_chr_open_opts(QemuOpts *opts,
                                     void (*init)(struct CharDriverState *s));
 CharDriverState *qemu_chr_open(const char *label, const char *filename, void (*init)(struct CharDriverState *s));
 void qemu_chr_close(CharDriverState *chr);
+void qemu_chr_reconnect(void);
 void qemu_chr_printf(CharDriverState *s, const char *fmt, ...);
 int qemu_chr_write(CharDriverState *s, const uint8_t *buf, int len);
 void qemu_chr_send_event(CharDriverState *s, int event);
diff --git a/qemu-config.c b/qemu-config.c
index 590fc05..ff8b06e 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -140,6 +140,9 @@ QemuOptsList qemu_chardev_opts = {
         },{
             .name = "signal",
             .type = QEMU_OPT_BOOL,
+        },{
+            .name = "reconnect",
+            .type = QEMU_OPT_NUMBER,
         },
         { /* end if list */ }
     },
diff --git a/vl.c b/vl.c
index 44763af..5876c3e 100644
--- a/vl.c
+++ b/vl.c
@@ -3795,6 +3795,10 @@ void main_loop_wait(int timeout)
 
     host_main_loop_wait(&timeout);
 
+    /* Reconnect any disconnected sockets, if necessary */
+
+    qemu_chr_reconnect();
+
     /* poll any events */
     /* XXX: separate device handlers from system ones */
     nfds = -1;
-- 
1.6.5