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authorStephen Gallagher <sgallagh@redhat.com>2009-03-18 12:05:14 -0400
committerSimo Sorce <ssorce@redhat.com>2009-03-20 11:14:56 -0400
commit6a3ca34ec2ff7ecaa3b2ddac041ab49dd6a1b17c (patch)
tree456109d23c1b1e7497054061f4f6122af83d1f14
parent76c4a8cfaf29778423ac28d1088ca4e0a20e8b91 (diff)
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Add reconnection logic to the SBUS
Any client of the SBUS that wants to implement automatic reconnection may now call sbus_reconnect_init to set it up. The clients will need to set up a callback to handle the result of the reconnection and (in the case of a successful reconnection) readd the method handlers to the connection context.
-rw-r--r--server/sbus/sssd_dbus.h17
-rw-r--r--server/sbus/sssd_dbus_connection.c190
2 files changed, 206 insertions, 1 deletions
diff --git a/server/sbus/sssd_dbus.h b/server/sbus/sssd_dbus.h
index 2496ae89..b9c7a269 100644
--- a/server/sbus/sssd_dbus.h
+++ b/server/sbus/sssd_dbus.h
@@ -35,6 +35,8 @@ typedef int (*sbus_msg_handler_fn)(DBusMessage *, struct sbus_conn_ctx *);
*/
typedef int (*sbus_conn_destructor_fn)(void *);
+typedef void (*sbus_conn_reconn_callback_fn)(struct sbus_conn_ctx *, int, void *);
+
/*
* sbus_server_conn_init_fn
* Set up function for connection-specific activities
@@ -48,6 +50,12 @@ enum {
SBUS_CONN_TYPE_SHARED
};
+enum {
+ SBUS_RECONNECT_SUCCESS = 1,
+ SBUS_RECONNECT_EXCEEDED_RETRIES,
+ SBUS_RECONNECT_ERROR
+};
+
/* Special interface and method for D-BUS introspection */
#define DBUS_INTROSPECT_INTERFACE "org.freedesktop.DBus.Introspectable"
#define DBUS_INTROSPECT_METHOD "Introspect"
@@ -117,6 +125,15 @@ int sbus_conn_add_method_ctx(struct sbus_conn_ctx *conn_ctx,
struct sbus_method_ctx *method_ctx);
bool sbus_conn_disconnecting(struct sbus_conn_ctx *conn_ctx);
+/* max_retries < 0: retry forever
+ * max_retries = 0: never retry (why are you calling this function?)
+ * max_retries > 0: obvious
+ */
+void sbus_reconnect_init(struct sbus_conn_ctx *conn_ctx,
+ int max_retries,
+ sbus_conn_reconn_callback_fn callback,
+ void *pvt);
+
/* Default message handler
* Should be usable for most cases */
DBusHandlerResult sbus_message_handler(DBusConnection *conn,
diff --git a/server/sbus/sssd_dbus_connection.c b/server/sbus/sssd_dbus_connection.c
index 6dc3130b..3629957e 100644
--- a/server/sbus/sssd_dbus_connection.c
+++ b/server/sbus/sssd_dbus_connection.c
@@ -10,11 +10,18 @@ struct dbus_ctx_list;
struct sbus_conn_ctx {
DBusConnection *conn;
struct tevent_context *ev;
+ char *address;
int connection_type;
int disconnect;
struct sbus_method_ctx *method_ctx_list;
sbus_conn_destructor_fn destructor;
void *pvt_data; /* Private data for this connection */
+
+ int retries;
+ int max_retries;
+ sbus_conn_reconn_callback_fn reconnect_callback;
+ /* Private data needed to reinit after reconnection */
+ void *reconnect_pvt;
};
struct sbus_message_handler_ctx {
@@ -39,6 +46,8 @@ static int _method_list_contains_path(struct sbus_method_ctx *list,
struct sbus_method_ctx *method);
static void sbus_unreg_object_paths(struct sbus_conn_ctx *dct_ctx);
+static int sbus_auto_reconnect(struct sbus_conn_ctx *conn_ctx);
+
static void sbus_dispatch(struct tevent_context *ev,
struct tevent_timer *te,
struct timeval tv, void *data)
@@ -55,6 +64,32 @@ static void sbus_dispatch(struct tevent_context *ev,
conn = dct_ctx->conn;
DEBUG(6, ("conn: %lX\n", conn));
+ if (dct_ctx->retries > 0) {
+ DEBUG(6, ("SBUS is reconnecting. Deferring.\n"));
+ /* Currently trying to reconnect, defer dispatch */
+ new_event = tevent_add_timer(ev, dct_ctx, tv, sbus_dispatch, dct_ctx);
+ if (new_event == NULL) {
+ DEBUG(0,("Could not defer dispatch!\n"));
+ }
+ return;
+ }
+
+ if ((!dbus_connection_get_is_connected(conn)) &&
+ (dct_ctx->max_retries != 0)) {
+ /* Attempt to reconnect automatically */
+ ret = sbus_auto_reconnect(dct_ctx);
+ if (ret == EOK) {
+ DEBUG(1, ("Performing auto-reconnect\n"));
+ return;
+ }
+
+ DEBUG(0, ("Cannot start auto-reconnection.\n"));
+ dct_ctx->reconnect_callback(dct_ctx,
+ SBUS_RECONNECT_ERROR,
+ dct_ctx->reconnect_pvt);
+ return;
+ }
+
if((dct_ctx->disconnect) || (!dbus_connection_get_is_connected(conn))) {
DEBUG(3,("Connection is not open for dispatching.\n"));
/*
@@ -266,6 +301,8 @@ static void sbus_conn_wakeup_main(void *data)
}
}
+static int sbus_add_connection_int(struct sbus_conn_ctx **dct_ctx);
+
/*
* integrate_connection_with_event_loop
* Set up a D-BUS connection to use the libevents mainloop
@@ -277,18 +314,39 @@ int sbus_add_connection(TALLOC_CTX *ctx,
struct sbus_conn_ctx **dct_ctx,
int connection_type)
{
- dbus_bool_t dbret;
struct sbus_conn_ctx *dt_ctx;
+ int ret;
DEBUG(5,("Adding connection %lX\n", dbus_conn));
dt_ctx = talloc_zero(ctx, struct sbus_conn_ctx);
+
dt_ctx->ev = ev;
dt_ctx->conn = dbus_conn;
dt_ctx->connection_type = connection_type;
dt_ctx->disconnect = 0;
+
/* This will be replaced on the first call to sbus_conn_add_method_ctx() */
dt_ctx->method_ctx_list = NULL;
+ /* This can be overridden by a call to sbus_reconnect_init() */
+ dt_ctx->retries = 0;
+ dt_ctx->max_retries = 0;
+ dt_ctx->reconnect_callback = NULL;
+
+ ret = sbus_add_connection_int(&dt_ctx);
+ if (ret != EOK) {
+ talloc_free(dt_ctx);
+ return ret;
+ }
+ *dct_ctx = dt_ctx;
+ return EOK;
+}
+
+static int sbus_add_connection_int(struct sbus_conn_ctx **dct_ctx)
+{
+ dbus_bool_t dbret;
+ struct sbus_conn_ctx *dt_ctx = *dct_ctx;
+
/*
* Set the default destructor
* Connections can override this with
@@ -368,6 +426,9 @@ int sbus_new_connection(TALLOC_CTX *ctx, struct tevent_context *ev,
/* FIXME: release resources */
}
+ /* Store the address for later reconnection */
+ (*dct_ctx)->address = talloc_strdup((*dct_ctx), address);
+
dbus_connection_set_exit_on_disconnect((*dct_ctx)->conn, FALSE);
/* Set connection destructor */
@@ -659,6 +720,133 @@ void *sbus_conn_get_private_data(struct sbus_conn_ctx *conn_ctx)
return conn_ctx->pvt_data;
}
+static void sbus_reconnect(struct tevent_context *ev,
+ struct tevent_timer *te,
+ struct timeval tv, void *data)
+{
+ DBusConnection *dbus_conn;
+ DBusError dbus_error;
+ struct tevent_timer *event;
+ struct sbus_method_ctx *iter;
+ struct sbus_method_ctx *purge;
+ int ret;
+ struct sbus_conn_ctx *conn_ctx =
+ talloc_get_type(data, struct sbus_conn_ctx);
+
+ DEBUG(3, ("Making reconnection attempt %d to [%s]\n", conn_ctx->retries, conn_ctx->address));
+ /* Make a new connection to the D-BUS address */
+ dbus_error_init(&dbus_error);
+ dbus_conn = dbus_connection_open(conn_ctx->address, &dbus_error);
+ if (dbus_conn) {
+ /* We successfully reconnected. Set up mainloop
+ * integration.
+ */
+ DEBUG(3, ("Reconnected to [%s]\n", conn_ctx->address));
+ conn_ctx->conn = dbus_conn;
+ ret = sbus_add_connection_int(&conn_ctx);
+ if (ret != EOK) {
+ dbus_connection_unref(dbus_conn);
+ goto failed;
+ }
+
+ /* Remove object paths (the reconnection callback must re-add these */
+ iter = conn_ctx->method_ctx_list;
+ while (iter != NULL) {
+ DLIST_REMOVE(conn_ctx->method_ctx_list, iter);
+ purge = iter;
+ iter = iter->next;
+ talloc_unlink(conn_ctx, purge);
+ }
+
+ /* Reset retries to 0 to resume dispatch processing */
+ conn_ctx->retries = 0;
+
+ /* Notify the owner of this connection that the
+ * reconnection was successful
+ */
+ conn_ctx->reconnect_callback(conn_ctx,
+ SBUS_RECONNECT_SUCCESS,
+ conn_ctx->reconnect_pvt);
+ return;
+ }
+
+failed:
+ /* Reconnection failed, try again in a few seconds */
+ DEBUG(1, ("Failed to open connection: name=%s, message=%s\n",
+ dbus_error.name, dbus_error.message));
+ if (dbus_error_is_set(&dbus_error)) dbus_error_free(&dbus_error);
+
+ conn_ctx->retries++;
+
+ /* Check if we've passed our last chance or if we've lost track of
+ * our retry count somehow
+ */
+ if (((conn_ctx->max_retries > 0) &&
+ (conn_ctx->retries > conn_ctx->max_retries)) ||
+ conn_ctx->retries <= 0) {
+ conn_ctx->reconnect_callback(conn_ctx,
+ SBUS_RECONNECT_EXCEEDED_RETRIES,
+ conn_ctx->reconnect_pvt);
+ }
+
+ if (conn_ctx->retries == 2) {
+ tv.tv_sec += 3; /* Wait 3 seconds before the second reconnect attempt */
+ }
+ else if (conn_ctx->retries == 3) {
+ tv.tv_sec += 10; /* Wait 10 seconds before the third reconnect attempt */
+ }
+ else {
+ tv.tv_sec += 30; /* Wait 30 seconds before all subsequent reconnect attempts */
+ }
+ event = tevent_add_timer(conn_ctx->ev, conn_ctx, tv, sbus_reconnect, conn_ctx);
+ if (event == NULL) {
+ conn_ctx->reconnect_callback(conn_ctx,
+ SBUS_RECONNECT_ERROR,
+ conn_ctx->reconnect_pvt);
+ }
+}
+
+/* This function will free and recreate the sbus_conn_ctx,
+ * calling functions need to be aware of this (and whether
+ * they have attached a talloc destructor to the
+ * sbus_conn_ctx.
+ */
+static int sbus_auto_reconnect(struct sbus_conn_ctx *conn_ctx)
+{
+ struct tevent_timer *te = NULL;
+ struct timeval tv;
+
+ conn_ctx->retries++;
+ if ((conn_ctx->max_retries > 0) &&
+ (conn_ctx->retries >= conn_ctx->max_retries)) {
+ /* Return EAGAIN (to tell the calling process it
+ * needs to create a new connection from scratch
+ */
+ return EAGAIN;
+ }
+
+ gettimeofday(&tv, NULL);
+ tv.tv_sec += 1; /* Wait 1 second before the first reconnect attempt */
+ te = tevent_add_timer(conn_ctx->ev, conn_ctx, tv, sbus_reconnect, conn_ctx);
+ if (te == NULL) return EAGAIN;
+
+ return EOK;
+}
+
+/* Max retries */
+void sbus_reconnect_init(struct sbus_conn_ctx *conn_ctx,
+ int max_retries,
+ sbus_conn_reconn_callback_fn callback,
+ void *pvt)
+{
+ if(max_retries == 0 || callback == NULL) return;
+
+ conn_ctx->retries = 0;
+ conn_ctx->max_retries = max_retries;
+ conn_ctx->reconnect_callback = callback;
+ conn_ctx->reconnect_pvt = pvt;
+}
+
bool sbus_conn_disconnecting(struct sbus_conn_ctx *conn_ctx)
{
if (conn_ctx->disconnect == 1) return true;