Merge from merge-myrocks:

commit 445e518bc7
Author: Sergei Petrunia <psergey@askmonty.org>
Date:   Sat Jan 27 10:18:20 2018 +0000

    Copy of
    commit f8f364b47f2784f16b401f27658f1c16eaf348ec
    Author: Jay Edgar <jkedgar@fb.com>
    Date:   Tue Oct 17 15:19:31 2017 -0700

        Add a hashed, hierarchical, wheel timer implementation

        Summary:
        In order to implement idle timeouts on detached sessions we need something inside MySQL that is lightweight and can handle calling events in the future wi

        By default the timers are grouped into 10ms buckets (the 'hashed' part), though the size of the buckets is configurable at the creation of the timer.  Eac

        Reviewed By: djwatson

        Differential Revision: D6199806

        fbshipit-source-id: 5e1590f

storage/rocksdb/rdb_utils.cc

@@ -352,4 +352,30 @@ const char *get_rocksdb_supported_compression_types()
   return compression_methods_buf.c_str();
 }
 
+bool rdb_check_rocksdb_corruption() {
+  return !my_access(myrocks::rdb_corruption_marker_file_name().c_str(), F_OK);
+}
+
+void rdb_persist_corruption_marker() {
+  const std::string &fileName(myrocks::rdb_corruption_marker_file_name());
+  int fd = my_open(fileName.c_str(), O_CREAT | O_SYNC, MYF(MY_WME));
+  if (fd < 0) {
+    sql_print_error("RocksDB: Can't create file %s to mark rocksdb as "
+                    "corrupted.",
+                    fileName.c_str());
+  } else {
+    sql_print_information("RocksDB: Creating the file %s to abort mysqld "
+                          "restarts. Remove this file from the data directory "
+                          "after fixing the corruption to recover. ",
+                          fileName.c_str());
+  }
+
+  int ret = my_close(fd, MYF(MY_WME));
+  if (ret) {
+    // NO_LINT_DEBUG
+    sql_print_error("RocksDB: Error (%d) closing the file %s", ret,
+                    fileName.c_str());
+  }
+}
+
 } // namespace myrocks