1 files changed, 116 insertions, 0 deletions
diff --git a/src/librbd/ConfigWatcher.cc b/src/librbd/ConfigWatcher.cc
new file mode 100644
index 000000000..0e4127804
--- /dev/null
+++ b/src/librbd/ConfigWatcher.cc
@@ -0,0 +1,116 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "librbd/ConfigWatcher.h"
+#include "common/config_obs.h"
+#include "common/dout.h"
+#include "common/errno.h"
+#include "librbd/ImageCtx.h"
+#include "librbd/ImageState.h"
+#include "librbd/api/Config.h"
+#include <deque>
+#include <string>
+#include <vector>
+#include <boost/algorithm/string/predicate.hpp>
+
+#define dout_subsys ceph_subsys_rbd
+#undef dout_prefix
+#define dout_prefix *_dout << "librbd::ConfigWatcher: " \
+                           << __func__ << ": "
+
+namespace librbd {
+
+template <typename I>
+struct ConfigWatcher<I>::Observer : public md_config_obs_t {
+  ConfigWatcher<I>* m_config_watcher;
+
+  std::deque<std::string> m_config_key_strs;
+  mutable std::vector<const char*> m_config_keys;
+
+  Observer(CephContext* cct, ConfigWatcher<I>* config_watcher)
+    : m_config_watcher(config_watcher) {
+    const std::string rbd_key_prefix("rbd_");
+    auto& schema = cct->_conf.get_schema();
+    for (auto& pair : schema) {
+      // watch all "rbd_" keys for simplicity
+      if (!boost::starts_with(pair.first, rbd_key_prefix)) {
+        continue;
+      }
+
+      m_config_key_strs.emplace_back(pair.first);
+    }
+
+    m_config_keys.reserve(m_config_key_strs.size());
+    for (auto& key : m_config_key_strs) {
+      m_config_keys.emplace_back(key.c_str());
+    }
+    m_config_keys.emplace_back(nullptr);
+  }
+
+  const char** get_tracked_conf_keys() const override {
+    ceph_assert(!m_config_keys.empty());
+    return &m_config_keys[0];
+  }
+
+  void handle_conf_change(const ConfigProxy& conf,
+                          const std::set <std::string> &changed) override {
+    m_config_watcher->handle_global_config_change(changed);
+  }
+};
+
+template <typename I>
+ConfigWatcher<I>::ConfigWatcher(I& image_ctx)
+  : m_image_ctx(image_ctx) {
+}
+
+template <typename I>
+ConfigWatcher<I>::~ConfigWatcher() {
+  ceph_assert(m_observer == nullptr);
+}
+
+template <typename I>
+void ConfigWatcher<I>::init() {
+  auto cct = m_image_ctx.cct;
+  ldout(cct, 10) << dendl;
+
+  m_observer = new Observer(cct, this);
+  cct->_conf.add_observer(m_observer);
+}
+
+template <typename I>
+void ConfigWatcher<I>::shut_down() {
+  auto cct = m_image_ctx.cct;
+  ldout(cct, 10) << dendl;
+
+  ceph_assert(m_observer != nullptr);
+  cct->_conf.remove_observer(m_observer);
+
+  delete m_observer;
+  m_observer = nullptr;
+}
+
+template <typename I>
+void ConfigWatcher<I>::handle_global_config_change(
+    std::set<std::string> changed_keys) {
+
+  {
+    // ignore any global changes that are being overridden
+    std::shared_lock image_locker{m_image_ctx.image_lock};
+    for (auto& key : m_image_ctx.config_overrides) {
+      changed_keys.erase(key);
+    }
+  }
+  if (changed_keys.empty()) {
+    return;
+  }
+
+  auto cct = m_image_ctx.cct;
+  ldout(cct, 10) << "changed_keys=" << changed_keys << dendl;
+
+  // refresh the image to pick up any global config overrides
+  m_image_ctx.state->handle_update_notification();
+}
+
+} // namespace librbd
+
+template class librbd::ConfigWatcher<librbd::ImageCtx>;