MDEV-4702 - Reduce usage of LOCK_open

Following variables do not require LOCK_open protection anymore:
- table_def_cache (renamed to tdc_hash) is protected by rw-lock
  LOCK_tdc_hash;
- table_def_shutdown_in_progress doesn't need LOCK_open protection;
- last_table_id use atomics;
- TABLE_SHARE::ref_count (renamed to TABLE_SHARE::tdc.ref_count)
  is protected by TABLE_SHARE::tdc.LOCK_table_share;
- TABLE_SHARE::next, ::prev (renamed to tdc.next and tdc.prev),
  oldest_unused_share, end_of_unused_share are protected by
  LOCK_unused_shares;
- TABLE_SHARE::m_flush_tickets (renamed to tdc.m_flush_tickets)
  is protected by TABLE_SHARE::tdc.LOCK_table_share;
- refresh_version (renamed to tdc_version) use atomics.

1 files changed, 134 insertions, 0 deletions

diff --git a/sql/table_cache.h b/sql/table_cache.h
new file mode 100644
index 00000000000..91fa650d3b9
--- /dev/null
+++ b/sql/table_cache.h
@@ -0,0 +1,134 @@
+/* Copyright (c) 2000, 2012, Oracle and/or its affiliates.
+   Copyright (c) 2010, 2011 Monty Program Ab
+   Copyright (C) 2013 Sergey Vojtovich and MariaDB Foundation
+
+   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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+
+
+enum enum_tdc_remove_table_type
+{
+  TDC_RT_REMOVE_ALL,
+  TDC_RT_REMOVE_NOT_OWN,
+  TDC_RT_REMOVE_UNUSED,
+  TDC_RT_REMOVE_NOT_OWN_KEEP_SHARE
+};
+
+extern ulong tdc_size;
+extern ulong tc_size;
+extern TABLE *unused_tables;    /* FIXME: make private */
+extern mysql_mutex_t LOCK_open; /* FIXME: make private */
+
+extern int tdc_init(void);
+extern void tdc_start_shutdown(void);
+extern void tdc_deinit(void);
+extern ulong tdc_records(void);
+extern void tdc_purge(bool all);
+extern void tdc_init_share(TABLE_SHARE *share);
+extern void tdc_deinit_share(TABLE_SHARE *share);
+extern TABLE_SHARE *tdc_lock_share(const char *db, const char *table_name);
+extern void tdc_unlock_share(TABLE_SHARE *share);
+extern TABLE_SHARE *tdc_acquire_share(THD *thd, const char *db,
+                                      const char *table_name,
+                                      const char *key, uint key_length,
+                                      uint flags, TABLE **out_table);
+extern void tdc_release_share(TABLE_SHARE *share);
+extern bool tdc_remove_table(THD *thd, enum_tdc_remove_table_type remove_type,
+                             const char *db, const char *table_name,
+                             bool kill_delayed_threads);
+extern int tdc_wait_for_old_version(THD *thd, const char *db,
+                                    const char *table_name,
+                                    ulong wait_timeout, uint deadlock_weight);
+extern ulong tdc_refresh_version(void);
+extern void tdc_increment_refresh_version(void);
+extern void tdc_assign_new_table_id(TABLE_SHARE *share);
+
+extern uint tc_records(void);
+extern void tc_purge(void);
+extern void tc_add_table(THD *thd, TABLE *table);
+extern bool tc_release_table(TABLE *table);
+
+/**
+  Create a table cache key for non-temporary table.
+
+  @param key         Buffer for key (must be at least NAME_LEN*2+2 bytes).
+  @param db          Database name.
+  @param table_name  Table name.
+
+  @return Length of key.
+*/
+
+inline uint tdc_create_key(char *key, const char *db, const char *table_name)
+{
+  /*
+    In theory caller should ensure that both db and table_name are
+    not longer than NAME_LEN bytes. In practice we play safe to avoid
+    buffer overruns.
+  */
+  return (uint) (strmake(strmake(key, db, NAME_LEN) + 1, table_name,
+                         NAME_LEN) - key + 1);
+}
+
+/**
+  Convenience helper: call tdc_acquire_share() without out_table.
+*/
+
+static inline TABLE_SHARE *tdc_acquire_share(THD *thd, const char *db,
+                                             const char *table_name,
+                                             const char *key,
+                                             uint key_length, uint flags)
+{
+  return tdc_acquire_share(thd, db, table_name, key, key_length, flags, 0);
+}
+
+
+/**
+  Convenience helper: call tdc_acquire_share() without precomputed cache key.
+*/
+
+static inline TABLE_SHARE *tdc_acquire_share(THD *thd, const char *db,
+                                             const char *table_name, uint flags)
+{
+  char key[MAX_DBKEY_LENGTH];
+  uint key_length;
+  key_length= tdc_create_key(key, db, table_name);
+  return tdc_acquire_share(thd, db, table_name, key, key_length, flags);
+}
+
+
+/**
+  Convenience helper: call tdc_acquire_share() reusing the MDL cache key.
+
+  @note lifetime of the returned TABLE_SHARE is limited by the
+        lifetime of the TABLE_LIST object!!!
+*/
+
+uint get_table_def_key(const TABLE_LIST *table_list, const char **key);
+
+static inline TABLE_SHARE *tdc_acquire_share_shortlived(THD *thd, TABLE_LIST *tl,
+                                                        uint flags)
+{
+  const char *key;
+  uint        key_length= get_table_def_key(tl, &key);
+  return tdc_acquire_share(thd, tl->db, tl->table_name, key, key_length, flags);
+}
+
+
+class TDC_iterator
+{
+  ulong idx;
+public:
+  void init(void);
+  void deinit(void);
+  TABLE_SHARE *next(void);
+};