1 files changed, 137 insertions, 0 deletions
diff --git a/src/mds/Mantle.cc b/src/mds/Mantle.cc
new file mode 100644
index 000000000..653d47d66
--- /dev/null
+++ b/src/mds/Mantle.cc
@@ -0,0 +1,137 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2016 Michael Sevilla <mikesevilla3@gmail.com>
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#include "mdstypes.h"
+#include "MDSRank.h"
+#include "Mantle.h"
+#include "msg/Messenger.h"
+#include "common/Clock.h"
+#include "CInode.h"
+
+#define dout_context g_ceph_context
+#undef dout_prefix
+#define dout_prefix *_dout << "mds.mantle "
+#define mantle_dout(lvl) \
+  do {\
+    auto subsys = ceph_subsys_mds;\
+    if ((dout_context)->_conf->subsys.should_gather(ceph_subsys_mds_balancer, lvl)) {\
+      subsys = ceph_subsys_mds_balancer;\
+    }\
+    dout_impl(dout_context, ceph::dout::need_dynamic(subsys), lvl) dout_prefix
+
+#define mantle_dendl dendl; } while (0)
+
+
+static int dout_wrapper(lua_State *L)
+{
+  int level = luaL_checkinteger(L, 1);
+  lua_concat(L, lua_gettop(L)-1);
+  mantle_dout(ceph::dout::need_dynamic(level)) << lua_tostring(L, 2)
+					       << mantle_dendl;
+  return 0;
+}
+
+int Mantle::balance(std::string_view script,
+                    mds_rank_t whoami,
+                    const std::vector<std::map<std::string, double>> &metrics,
+                    std::map<mds_rank_t, double> &my_targets)
+{
+  lua_settop(L, 0); /* clear the stack */
+
+  /* load the balancer */
+  if (luaL_loadstring(L, script.data())) {
+    mantle_dout(0) << "WARNING: mantle could not load balancer: "
+            << lua_tostring(L, -1) << mantle_dendl;
+    return -CEPHFS_EINVAL;
+  }
+
+  /* tell the balancer which mds is making the decision */
+  lua_pushinteger(L, (lua_Integer)whoami);
+  lua_setglobal(L, "whoami");
+
+  /* global mds metrics to hold all dictionaries */
+  lua_newtable(L);
+
+  /* push name of mds (i) and its metrics onto Lua stack */
+  for (size_t i=0; i < metrics.size(); i++) {
+    lua_newtable(L);
+
+    /* push values into this mds's table; setfield assigns key/pops val */
+    for (const auto &it : metrics[i]) {
+      lua_pushnumber(L, it.second);
+      lua_setfield(L, -2, it.first.c_str());
+    }
+
+    /* in global mds table at stack[-3], set k=stack[-1] to v=stack[-2] */
+    lua_seti(L, -2, i);
+  }
+
+  /* set the name of the global mds table */
+  lua_setglobal(L, "mds");
+
+  ceph_assert(lua_gettop(L) == 1);
+  if (lua_pcall(L, 0, 1, 0) != LUA_OK) {
+    mantle_dout(0) << "WARNING: mantle could not execute script: "
+            << lua_tostring(L, -1) << mantle_dendl;
+    return -CEPHFS_EINVAL;
+  }
+
+  /* parse response by iterating over Lua stack */
+  if (lua_istable(L, -1) == 0) {
+    mantle_dout(0) << "WARNING: mantle script returned a malformed response" << mantle_dendl;
+    return -CEPHFS_EINVAL;
+  }
+
+  /* fill in return value */
+  for (lua_pushnil(L); lua_next(L, -2); lua_pop(L, 1)) {
+    if (!lua_isinteger(L, -2) || !lua_isnumber(L, -1)) {
+      mantle_dout(0) << "WARNING: mantle script returned a malformed response" << mantle_dendl;
+      return -CEPHFS_EINVAL;
+    }
+    mds_rank_t rank(lua_tointeger(L, -2));
+    my_targets[rank] = lua_tonumber(L, -1);
+  }
+
+  return 0;
+}
+
+Mantle::Mantle (void)
+{
+  /* build lua vm state */
+  L = luaL_newstate();
+  if (!L) {
+    mantle_dout(0) << "WARNING: mantle could not load Lua state" << mantle_dendl;
+    throw std::bad_alloc();
+  }
+
+  /* balancer policies can use basic Lua functions */
+  static const luaL_Reg loadedlibs[] = {
+    {"_G", luaopen_base},
+    {LUA_COLIBNAME, luaopen_coroutine},
+    {LUA_STRLIBNAME, luaopen_string},
+    {LUA_MATHLIBNAME, luaopen_math},
+    {LUA_TABLIBNAME, luaopen_table},
+    {LUA_UTF8LIBNAME, luaopen_utf8},
+    {NULL, NULL}
+  };
+
+  const luaL_Reg *lib;
+  for (lib = loadedlibs; lib->func; lib++) {
+      luaL_requiref(L, lib->name, lib->func, 1);
+      lua_pop(L, 1);  /* remove lib */
+  }
+
+  /* setup debugging */
+  lua_register(L, "BAL_LOG", dout_wrapper);
+}