monc: let users specify a callback when they reopen their monitor session

Then the callback is triggered when a new session is established, and the
daemon can do whatever it likes. There are no guarantees about how long it
might take to trigger, though. In particular we call the provided callback
while not holding our own lock in order to avoid deadlock. This could lead
to some funny ordering from the user's perspective if they call
reopen_session() again before getting the callback, but there's no way around
that, so they just have to use it appropriately.

Signed-off-by: Greg Farnum <greg@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
(cherry picked from commit 1a8c43474bf36bfcf2a94bf9b7e756a2a99f33fd)

diff --git a/src/mon/MonClient.cc b/src/mon/MonClient.cc
index 5c8ad4ee788b0b6cdf812a13bc7f1bae9a725286..1da030e218361a686d5bf3e9ce09582863514caa 100644 (file)
--- a/src/mon/MonClient.cc
+++ b/src/mon/MonClient.cc
@@ -65,6 +65,7 @@ MonClient::MonClient(CephContext *cct_) :
   want_monmap(true),
   want_keys(0), global_id(0),
   authenticate_err(0),
+  session_established_context(NULL),
   auth(NULL),
   keyring(NULL),
   rotating_secrets(NULL),
@@ -76,6 +77,7 @@ MonClient::MonClient(CephContext *cct_) :
 MonClient::~MonClient()
 {
   delete auth_supported;
+  delete session_established_context;
   delete auth;
   delete keyring;
   delete rotating_secrets;
@@ -390,6 +392,7 @@ int MonClient::authenticate(double timeout)
 
 void MonClient::handle_auth(MAuthReply *m)
 {
+  Context *cb = NULL;
   bufferlist::iterator p = m->result_bl.begin();
   if (state == MC_STATE_NEGOTIATING) {
     if (!auth || (int)m->protocol != auth->get_protocol()) {
@@ -449,11 +452,20 @@ void MonClient::handle_auth(MAuthReply *m)
        log_client->reset_session();
        send_log();
       }
+      if (session_established_context) {
+        cb = session_established_context;
+        session_established_context = NULL;
+      }
     }
   
     _check_auth_tickets();
   }
   auth_cond.SignalAll();
+  if (cb) {
+    monc_lock.Unlock();
+    cb->complete(0);
+    monc_lock.Lock();
+  }
 }
 
 

diff --git a/src/mon/MonClient.h b/src/mon/MonClient.h
index dcd39775a8571d84a959a29c03d16a06d7c6324f..3b4897c9beceae324d0d4136a537224a2e99c3e9 100644 (file)
--- a/src/mon/MonClient.h
+++ b/src/mon/MonClient.h
@@ -126,6 +126,7 @@ private:
   int authenticate_err;
 
   list<Message*> waiting_for_session;
+  Context *session_established_context;
 
   string _pick_random_mon();
   void _finish_hunting();
@@ -216,8 +217,19 @@ public:
     Mutex::Locker l(monc_lock);
     _send_mon_message(m);
   }
-  void reopen_session() {
+  /**
+   * If you specify a callback, you should not call
+   * reopen_session() again until it has been triggered. The MonClient
+   * will behave, but the first callback could be triggered after
+   * the session has been killed and the MonClient has started trying
+   * to reconnect to another monitor.
+   */
+  void reopen_session(Context *cb=NULL) {
     Mutex::Locker l(monc_lock);
+    if (cb) {
+      delete session_established_context;
+      session_established_context = cb;
+    }
     _reopen_session();
   }