Initial commit,

copy of
commit 86587affafe77ef555f7c3839839de44f0f203f3
Author: Tian Xia <tianx@fb.com>
Date:   Tue Oct 4 10:01:52 2016 -0700

    Allow filtering of show commands through admission control

storage/rocksdb/rdb_utils.h

@@ -0,0 +1,206 @@
+/*
+   Copyright (c) 2016, Facebook, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+#pragma once
+
+/* C++ standard header files */
+#include <string>
+
+/* MySQL header files */
+#include "./sql_string.h"
+
+/* RocksDB header files */
+#include "rocksdb/slice.h"
+
+#ifdef HAVE_JEMALLOC
+  #include <jemalloc/jemalloc.h>
+#endif
+
+namespace myrocks {
+
+/*
+  Guess what?
+  An interface is a class where all members are public by default.
+*/
+
+#ifndef interface
+#define interface struct
+#endif  // interface
+
+/*
+  Introduce C-style pseudo-namespaces, a handy way to make code more readble
+  when calling into a legacy API, which does not have any namespace defined.
+  Since we cannot or don't want to change the API in any way, we can use this
+  mechanism to define readability tokens that look like C++ namespaces, but are
+  not enforced in any way by the compiler, since the pre-compiler strips them
+  out. However, on the calling side, code looks like my_core::thd_ha_data()
+  rather than plain a thd_ha_data() call. This technique adds an immediate
+  visible cue on what type of API we are calling into.
+*/
+
+#ifndef my_core
+// C-style pseudo-namespace for MySQL Core API, to be used in decorating calls
+// to non-obvious MySQL functions, like the ones that do not start with well
+// known prefixes: "my_", "sql_", and "mysql_".
+#define my_core
+#endif  // my_core
+
+/*
+  The intent behind a SHIP_ASSERT() macro is to have a mechanism for validating
+  invariants in retail builds. Traditionally assertions (such as macros defined
+  in <cassert>) are evaluated for performance reasons only in debug builds and
+  become NOOP in retail builds when NDEBUG is defined.
+
+  This macro is intended to validate the invariants which are critical for
+  making sure that data corruption and data loss won't take place. Proper
+  intended usage can be described as "If a particular condition is not true then
+  stop everything what's going on and terminate the process because continued
+  execution will cause really bad things to happen".
+
+  Use the power of SHIP_ASSERT() wisely.
+*/
+
+#ifndef SHIP_ASSERT
+#define SHIP_ASSERT(expr)                                               \
+  do {                                                                  \
+    if (!(expr)) {                                                      \
+      my_safe_printf_stderr("\nShip assert failure: \'%s\'\n", #expr);  \
+      abort_with_stack_traces();                                        \
+    }                                                                   \
+  } while (0)
+#endif  // SHIP_ASSERT
+
+/*
+  Assert a implies b.
+  If a is true, then b must be true.
+  If a is false, then the value is b does not matter.
+*/
+#ifndef DBUG_ASSERT_IMP
+#define DBUG_ASSERT_IMP(a, b) DBUG_ASSERT(!(a) || (b))
+#endif
+
+/*
+  Assert a if and only if b.
+  a and b must be both true or both false.
+*/
+#ifndef DBUG_ASSERT_IFF
+#define DBUG_ASSERT_IFF(a, b) \
+  DBUG_ASSERT(static_cast<bool>(a) == static_cast<bool>(b))
+#endif
+
+/*
+  Helper function to get an NULL terminated uchar* out of a given MySQL String.
+*/
+
+inline uchar* rdb_mysql_str_to_uchar_str(my_core::String *str)
+{
+  DBUG_ASSERT(str != nullptr);
+  return reinterpret_cast<uchar*>(str->c_ptr());
+}
+
+/*
+  Helper function to get plain (not necessary NULL terminated) uchar* out of a
+  given STL string.
+*/
+
+inline const uchar* rdb_std_str_to_uchar_ptr(const std::string &str)
+{
+  return reinterpret_cast<const uchar*>(str.data());
+}
+
+/*
+  Helper function to get plain (not necessary NULL terminated) uchar* out of a
+  given RocksDB item.
+*/
+
+inline const uchar* rdb_slice_to_uchar_ptr(const rocksdb::Slice *item)
+{
+  DBUG_ASSERT(item != nullptr);
+  return reinterpret_cast<const uchar*>(item->data());
+}
+
+/*
+  Call this function in cases when you can't rely on garbage collector and need
+  to explicitly purge all unused dirty pages. This should be a relatively rare
+  scenario for cases where it has been verified that this intervention has
+  noticeable benefits.
+*/
+inline int purge_all_jemalloc_arenas()
+{
+#ifdef HAVE_JEMALLOC
+  unsigned narenas = 0;
+  size_t sz = sizeof(unsigned);
+  char name[25] = { 0 };
+
+  // Get the number of arenas first. Please see `jemalloc` documentation for
+  // all the various options.
+  int result = mallctl("arenas.narenas", &narenas, &sz, nullptr, 0);
+
+  // `mallctl` returns 0 on success and we really want caller to know if all the
+  // trickery actually works.
+  if (result) {
+    return result;
+  }
+
+  // Form the command to be passed to `mallctl` and purge all the unused dirty
+  // pages.
+  snprintf(name, sizeof(name) / sizeof(char), "arena.%d.purge", narenas);
+  result = mallctl(name, nullptr, nullptr, nullptr, 0);
+
+  return result;
+#else
+  return EXIT_SUCCESS;
+#endif
+}
+
+/*
+  Helper functions to parse strings.
+*/
+
+const char* rdb_skip_spaces(struct charset_info_st* cs, const char *str)
+  __attribute__((__nonnull__, __warn_unused_result__));
+
+bool rdb_compare_strings_ic(const char *str1, const char *str2)
+  __attribute__((__nonnull__, __warn_unused_result__));
+
+const char* rdb_find_in_string(const char *str, const char *pattern,
+                               bool *succeeded)
+  __attribute__((__nonnull__, __warn_unused_result__));
+
+const char* rdb_check_next_token(struct charset_info_st* cs, const char *str,
+                                 const char *pattern, bool *succeeded)
+  __attribute__((__nonnull__, __warn_unused_result__));
+
+const char* rdb_parse_id(struct charset_info_st* cs, const char *str,
+                         std::string *id)
+  __attribute__((__nonnull__(1, 2), __warn_unused_result__));
+
+const char* rdb_skip_id(struct charset_info_st* cs, const char *str)
+  __attribute__((__nonnull__, __warn_unused_result__));
+
+/*
+  Helper functions to populate strings.
+*/
+
+std::string rdb_hexdump(const char *data, std::size_t data_len,
+                        std::size_t maxsize = 0)
+  __attribute__((__nonnull__));
+
+/*
+  Helper function to see if a database exists
+ */
+bool rdb_database_exists(const std::string& db_name);
+
+}  // namespace myrocks