Add callback when the ID provider switches from offline to online

Allow backends to set a callback in the be_ctx that should be
invoked when the ID provider goes online.

This can be used to perform regular maintenance tasks that are
valid only when going online.

1 files changed, 138 insertions, 0 deletions

diff --git a/src/providers/data_provider_be.c b/src/providers/data_provider_be.c
index e5a5ff7b0..27a4571a7 100644
--- a/src/providers/data_provider_be.c
+++ b/src/providers/data_provider_be.c
@@ -166,8 +166,146 @@ void be_mark_offline(struct be_ctx *ctx)
 
     ctx->offstat.went_offline = time(NULL);
     ctx->offstat.offline = true;
+    ctx->run_online_cb = true;
 }
 
+
+struct be_conn_online_cb {
+    struct be_conn_online_cb *prev;
+    struct be_conn_online_cb *next;
+
+    be_conn_online_callback_t cb;
+    void *pvt;
+
+    struct be_ctx *be;
+};
+
+static int online_cb_destructor(TALLOC_CTX *ptr);
+int be_add_online_cb(TALLOC_CTX *mem_ctx,
+                     struct be_ctx *ctx,
+                     be_conn_online_callback_t cb,
+                     void *pvt,
+                     struct be_conn_online_cb **online_cb)
+{
+    struct be_conn_online_cb *on_cb;
+
+    if (!ctx || !cb) {
+        return EINVAL;
+    }
+
+    on_cb = talloc(mem_ctx, struct be_conn_online_cb);
+    if (!on_cb) {
+        return ENOMEM;
+    }
+
+    on_cb->cb = cb;
+    on_cb->pvt = pvt;
+    on_cb->be = ctx;
+
+    DLIST_ADD(ctx->online_cb_list, on_cb);
+
+    talloc_set_destructor((TALLOC_CTX *)on_cb, online_cb_destructor);
+
+    /* Make sure we run the callback for the first
+     * connection after startup.
+     */
+    ctx->run_online_cb = true;
+
+    if (online_cb) {
+        *online_cb = on_cb;
+    }
+
+    return EOK;
+}
+
+static int online_cb_destructor(TALLOC_CTX *ptr)
+{
+    struct be_conn_online_cb *cb =
+            talloc_get_type(ptr, struct be_conn_online_cb);
+    DLIST_REMOVE(cb->be->online_cb_list, cb);
+    return 0;
+}
+
+
+struct be_online_cb_ctx {
+    struct be_ctx *be;
+    struct be_conn_online_cb *callback;
+};
+
+static void be_run_online_cb_step(struct tevent_context *ev,
+                                  struct tevent_timer *te,
+                                  struct timeval current_time,
+                                  void *pvt);
+void be_run_online_cb(struct be_ctx *be) {
+    struct timeval soon;
+    struct tevent_timer *te;
+    struct be_online_cb_ctx *cb_ctx;
+
+    if (be->run_online_cb && be->online_cb_list) {
+        /* Reset the flag. We only want to run these
+         * callbacks when transitioning to online
+         */
+        be->run_online_cb = false;
+
+        DEBUG(3, ("Going online. Running callbacks.\n"));
+
+        cb_ctx = talloc(be, struct be_online_cb_ctx);
+        if (!cb_ctx) {
+            DEBUG(0, ("Out of memory. Could not invoke callbacks\n"));
+            return;
+        }
+        cb_ctx->be = be;
+        cb_ctx->callback = be->online_cb_list;
+
+        /* Delay 30ms so we don't block any other events */
+        soon = tevent_timeval_current_ofs(0, 30000);
+        te = tevent_add_timer(be->ev, cb_ctx, soon,
+                              be_run_online_cb_step,
+                              cb_ctx);
+        if (!te) {
+            DEBUG(0, ("Out of memory. Could not invoke callbacks\n"));
+            talloc_free(cb_ctx);
+        }
+    }
+}
+
+static void be_run_online_cb_step(struct tevent_context *ev,
+                                  struct tevent_timer *te,
+                                  struct timeval current_time,
+                                  void *pvt)
+{
+    struct be_online_cb_ctx *cb_ctx =
+            talloc_get_type(pvt, struct be_online_cb_ctx);
+    struct tevent_timer *tev;
+    struct timeval soon;
+
+    /* Call the callback */
+    cb_ctx->callback->cb(cb_ctx->callback->pvt);
+
+    if (cb_ctx->callback->next) {
+        cb_ctx->callback = cb_ctx->callback->next;
+
+        /* Delay 30ms so we don't block any other events */
+        soon = tevent_timeval_current_ofs(0, 30000);
+        tev = tevent_add_timer(cb_ctx->be->ev, cb_ctx, soon,
+                               be_run_online_cb_step,
+                               cb_ctx);
+        if (!te) {
+            DEBUG(0, ("Out of memory. Could not invoke callbacks\n"));
+            goto final;
+        }
+        return;
+    }
+
+final:
+    /* Steal the timer event onto the be_ctx so it doesn't
+     * get freed with the cb_ctx
+     */
+    talloc_steal(cb_ctx->be, te);
+    talloc_free(cb_ctx);
+}
+
+
 static int be_check_online(DBusMessage *message, struct sbus_connection *conn)
 {
     struct be_client *becli;