librados: add wait_for_latest_map()

There are times when we need to make sure the client has the latest osdmap,
for example after sending a mon command modifying pool properties.

Signed-off-by: Sage Weil <sage@inktank.com>

7 files changed, 71 insertions, 0 deletions

diff --git a/src/include/rados/librados.hpp b/src/include/rados/librados.hpp
index 436c9a60418..58a64996705 100644
--- a/src/include/rados/librados.hpp
+++ b/src/include/rados/librados.hpp
@@ -811,6 +811,9 @@ namespace librados
     int cluster_stat(cluster_stat_t& result);
     int cluster_fsid(std::string *fsid);
 
+    /// get/wait for the most recent osdmap
+    int wait_for_latest_map();
+
     /*
      * pool aio
      *
diff --git a/src/librados/RadosClient.cc b/src/librados/RadosClient.cc
index 4614108c981..61d6aebc70f 100644
--- a/src/librados/RadosClient.cc
+++ b/src/librados/RadosClient.cc
@@ -368,6 +368,24 @@ void librados::RadosClient::wait_for_osdmap()
   }
 }
 
+int librados::RadosClient::wait_for_latest_osdmap()
+{
+  Mutex mylock("RadosClient::wait_for_latest_osdmap");
+  Cond cond;
+  bool done;
+
+  lock.Lock();
+  objecter->wait_for_latest_osd_map(new C_SafeCond(&mylock, &cond, &done));
+  lock.Unlock();
+
+  mylock.Lock();
+  while (!done)
+    cond.Wait(mylock);
+  mylock.Unlock();
+
+  return 0;
+}
+
 int librados::RadosClient::pool_list(std::list<std::string>& v)
 {
   Mutex::Locker l(lock);
diff --git a/src/librados/RadosClient.h b/src/librados/RadosClient.h
index 9f795498089..80f26794985 100644
--- a/src/librados/RadosClient.h
+++ b/src/librados/RadosClient.h
@@ -82,6 +82,8 @@ public:
 
   uint64_t get_instance_id();
 
+  int wait_for_latest_osdmap();
+
   int create_ioctx(const char *name, IoCtxImpl **io);
 
   int get_fsid(std::string *s);
diff --git a/src/librados/librados.cc b/src/librados/librados.cc
index 738c3224afe..a9f317f06cc 100644
--- a/src/librados/librados.cc
+++ b/src/librados/librados.cc
@@ -1619,6 +1619,11 @@ int librados::Rados::cluster_fsid(string *fsid)
   return client->get_fsid(fsid);
 }
 
+int librados::Rados::wait_for_latest_map()
+{
+  return client->wait_for_latest_osdmap();
+}
+
 librados::PoolAsyncCompletion *librados::Rados::pool_async_create_completion()
 {
   PoolAsyncCompletionImpl *c = new PoolAsyncCompletionImpl;
diff --git a/src/osdc/Objecter.cc b/src/osdc/Objecter.cc
index 9ad49b0715b..3b39a7d987c 100644
--- a/src/osdc/Objecter.cc
+++ b/src/osdc/Objecter.cc
@@ -969,6 +969,37 @@ void Objecter::wait_for_osd_map()
   lock.Unlock();
 }
 
+struct C_Objecter_GetVersion : public Context {
+  Objecter *objecter;
+  uint64_t oldest, newest;
+  Context *fin;
+  C_Objecter_GetVersion(Objecter *o, Context *c)
+    : objecter(o), oldest(0), newest(0), fin(c) {}
+  void finish(int r) {
+    if (r >= 0)
+      objecter->_get_latest_version(oldest, newest, fin);
+  }
+};
+
+void Objecter::wait_for_latest_osd_map(Context *fin)
+{
+  ldout(cct, 10) << __func__ << dendl;
+  C_Objecter_GetVersion *c = new C_Objecter_GetVersion(this, fin);
+  monc->get_version("osdmap", &c->newest, &c->oldest, c);
+}
+
+void Objecter::_get_latest_version(epoch_t oldest, epoch_t newest, Context *fin)
+{
+  if (osdmap->get_epoch() >= newest) {
+  ldout(cct, 10) << __func__ << " latest " << newest << ", have it" << dendl;
+    if (fin)
+      fin->complete(0);
+    return;
+  }
+
+  ldout(cct, 10) << __func__ << " latest " << newest << ", waiting" << dendl;
+  wait_for_new_map(fin, newest, 0);
+}
 
 void Objecter::maybe_request_map()
 {
diff --git a/src/osdc/Objecter.h b/src/osdc/Objecter.h
index f42d07415cc..b24349499a1 100644
--- a/src/osdc/Objecter.h
+++ b/src/osdc/Objecter.h
@@ -1389,6 +1389,8 @@ private:
   void set_client_incarnation(int inc) { client_inc = inc; }
 
   void wait_for_new_map(Context *c, epoch_t epoch, int err=0);
+  void wait_for_latest_osd_map(Context *fin);
+  void _get_latest_version(epoch_t oldest, epoch_t neweset, Context *fin);
 
   /** Get the current set of global op flags */
   int get_global_op_flags() { return global_op_flags; }
diff --git a/src/test/librados/misc.cc b/src/test/librados/misc.cc
index 64358df23d9..a753521798c 100644
--- a/src/test/librados/misc.cc
+++ b/src/test/librados/misc.cc
@@ -48,6 +48,16 @@ TEST(LibRadosMisc, ClusterFSID) {
   ASSERT_EQ(0, destroy_one_pool(pool_name, &cluster));
 }
 
+TEST(LibRadosMisc, WaitOSDMapPP) {
+  Rados cluster;
+  std::string pool_name = get_temp_pool_name();
+  ASSERT_EQ("", create_one_pool_pp(pool_name, cluster));
+
+  ASSERT_EQ(0, cluster.wait_for_latest_map());
+
+  ASSERT_EQ(0, destroy_one_pool_pp(pool_name, cluster));
+}
+
 static std::string read_key_from_tmap(IoCtx& ioctx, const std::string &obj,
 				      const std::string &key)
 {