~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2008 Sun Microsystems, 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 */

#ifndef DRIZZLED_SESSION_H

#define DRIZZLED_SESSION_H

#include "drizzled/plugin.h"

#include "drizzled/sql_locale.h"

#include "drizzled/resource_context.h"

#include "drizzled/cursor.h"

#include "drizzled/current_session.h"

#include "drizzled/sql_error.h"

#include "drizzled/file_exchange.h"

#include "drizzled/select_result_interceptor.h"

#include "drizzled/statistics_variables.h"

#include "drizzled/xid.h"

#include "drizzled/query_id.h"

#include "drizzled/named_savepoint.h"

#include "drizzled/transaction_context.h"

#include "drizzled/util/storable.h"

#include "drizzled/my_hash.h"

#include "drizzled/pthread_globals.h"

#include <netdb.h>

#include <sys/time.h>

#include <sys/resource.h>

#include <algorithm>

#include <bitset>

#include <deque>

#include <map>

#include <string>

#include "drizzled/identifier.h"

#include "drizzled/open_tables_state.h"

#include "drizzled/internal_error_handler.h"

#include "drizzled/diagnostics_area.h"

#include "drizzled/plugin/authorization.h"

#include <boost/unordered_map.hpp>

#include <boost/thread/thread.hpp>

#include <boost/thread/mutex.hpp>

#include <boost/thread/shared_mutex.hpp>

#include <boost/thread/condition_variable.hpp>

#include <boost/make_shared.hpp>

#define MIN_HANDSHAKE_SIZE      6

namespace drizzled

{

namespace plugin

{

class Client;

class Scheduler;

class EventObserverList;

}

namespace message

{

class Transaction;

class Statement;

class Resultset;

}

namespace internal

{

struct st_my_thread_var;

}

namespace table

{

class Placeholder;

}

class Lex_input_stream;

class user_var_entry;

class CopyField;

class Table_ident;

class TableShareInstance;

extern char internal_table_name[2];

extern char empty_c_string[1];

extern const char **errmesg;

#define TC_HEURISTIC_RECOVER_COMMIT   1

#define TC_HEURISTIC_RECOVER_ROLLBACK 2

extern uint32_t tc_heuristic_recover;

/**

  @brief

  Local storage for proto that are tmp table. This should be enlarged

  to hande the entire table-share for a local table. Once Hash is done,

  we should consider exchanging the map for it.

*/

typedef std::map <std::string, message::Table> ProtoCache;

/**

  The COPY_INFO structure is used by INSERT/REPLACE code.

  The schema of the row counting by the INSERT/INSERT ... ON DUPLICATE KEY

  UPDATE code:

    If a row is inserted then the copied variable is incremented.

    If a row is updated by the INSERT ... ON DUPLICATE KEY UPDATE and the

      new data differs from the old one then the copied and the updated

      variables are incremented.

    The touched variable is incremented if a row was touched by the update part

      of the INSERT ... ON DUPLICATE KEY UPDATE no matter whether the row

      was actually changed or not.

*/

class CopyInfo 

{

public:

  ha_rows records; /**< Number of processed records */

  ha_rows deleted; /**< Number of deleted records */

  ha_rows updated; /**< Number of updated records */

  ha_rows copied;  /**< Number of copied records */

  ha_rows error_count;

  ha_rows touched; /* Number of touched records */

  enum enum_duplicates handle_duplicates;

  int escape_char, last_errno;

  bool ignore;

  /* for INSERT ... UPDATE */

  List<Item> *update_fields;

  List<Item> *update_values;

  /* for VIEW ... WITH CHECK OPTION */

  CopyInfo() :

    records(0),

    deleted(0),

    updated(0),

    copied(0),

    error_count(0),

    touched(0),

    escape_char(0),

    last_errno(0),

    ignore(0),

    update_fields(0),

    update_values(0)

  { }

};

} /* namespace drizzled */

/** @TODO why is this in the middle of the file */

#include <drizzled/lex_column.h>

namespace drizzled

{

class select_result;

class Time_zone;

#define Session_SENTRY_MAGIC 0xfeedd1ff

#define Session_SENTRY_GONE  0xdeadbeef

struct drizzle_system_variables

{

  drizzle_system_variables()

  {}

  /*

    How dynamically allocated system variables are handled:

    The global_system_variables and max_system_variables are "authoritative"

    They both should have the same 'version' and 'size'.

    When attempting to access a dynamic variable, if the session version

    is out of date, then the session version is updated and realloced if

    neccessary and bytes copied from global to make up for missing data.

  */

  ulong dynamic_variables_version;

  char * dynamic_variables_ptr;

  uint32_t dynamic_variables_head;  /* largest valid variable offset */

  uint32_t dynamic_variables_size;  /* how many bytes are in use */

  uint64_t myisam_max_extra_sort_file_size;

  uint64_t max_heap_table_size;

  uint64_t tmp_table_size;

  ha_rows select_limit;

  ha_rows max_join_size;

  uint64_t auto_increment_increment;

  uint64_t auto_increment_offset;

  uint64_t bulk_insert_buff_size;

  uint64_t join_buff_size;

  uint32_t max_allowed_packet;

  uint64_t max_error_count;

  uint64_t max_length_for_sort_data;

  size_t max_sort_length;

  uint64_t min_examined_row_limit;

  bool optimizer_prune_level;

  bool log_warnings;

  uint32_t optimizer_search_depth;

  uint32_t div_precincrement;

  uint64_t preload_buff_size;

  uint32_t read_buff_size;

  uint32_t read_rnd_buff_size;

  bool replicate_query;

  size_t sortbuff_size;

  uint32_t thread_handling;

  uint32_t tx_isolation;

  size_t transaction_message_threshold;

  uint32_t completion_type;

  /* Determines which non-standard SQL behaviour should be enabled */

  uint32_t sql_mode;

  uint64_t max_seeks_for_key;

  size_t range_alloc_block_size;

  uint32_t query_alloc_block_size;

  uint32_t query_prealloc_size;

  uint64_t group_concat_max_len;

  uint64_t pseudo_thread_id;

  plugin::StorageEngine *storage_engine;

  /* Only charset part of these variables is sensible */

  const CHARSET_INFO  *character_set_filesystem;

  /* Both charset and collation parts of these variables are important */

  const CHARSET_INFO	*collation_server;

  inline const CHARSET_INFO  *getCollation(void) 

  {

    return collation_server;

  }

  /* Locale Support */

  MY_LOCALE *lc_time_names;

  Time_zone *time_zone;

};

extern struct drizzle_system_variables global_system_variables;

} /* namespace drizzled */

#include "drizzled/sql_lex.h"

namespace drizzled

{

void mark_transaction_to_rollback(Session *session, bool all);

/**

  Storage engine specific thread local data.

*/

struct Ha_data

{

  /**

    Storage engine specific thread local data.

    Lifetime: one user connection.

  */

  void *ha_ptr;

  /**

   * Resource contexts for both the "statement" and "normal"

   * transactions.

   *

   * Resource context at index 0:

   *

   * Life time: one statement within a transaction. If @@autocommit is

   * on, also represents the entire transaction.

   *

   * Resource context at index 1:

   *

   * Life time: one transaction within a connection. 

   *

   * @note

   *

   * If the storage engine does not participate in a transaction, 

   * there will not be a resource context.

   */

  drizzled::ResourceContext resource_context[2];

  Ha_data() :ha_ptr(NULL) {}

};

/**

 * Represents a client connection to the database server.

 *

 * Contains the client/server protocol object, the current statement

 * being executed, local-to-session variables and status counters, and

 * a host of other information.

 *

 * @todo

 *

 * The Session class should have a vector of Statement object pointers which

 * comprise the statements executed on the Session. Until this architectural

 * change is done, we can forget about parallel operations inside a session.

 *

 * @todo

 *

 * Make member variables private and have inlined accessors and setters.  Hide

 * all member variables that are not critical to non-internal operations of the

 * session object.

 */

typedef int64_t session_id_t;

class Session : public Open_tables_state

{

public:

  // Plugin storage in Session.

  typedef boost::unordered_map<std::string, util::Storable *, util::insensitive_hash, util::insensitive_equal_to> PropertyMap;

  typedef Session* Ptr;

  typedef boost::shared_ptr<Session> shared_ptr;

  typedef Session& reference;

  typedef const Session& const_reference;

  typedef const Session* const_pointer;

  typedef Session* pointer;

  /*

    MARK_COLUMNS_NONE:  Means mark_used_colums is not set and no indicator to

                        handler of fields used is set

    MARK_COLUMNS_READ:  Means a bit in read set is set to inform handler

	                that the field is to be read. If field list contains

                        duplicates, then session->dup_field is set to point

                        to the last found duplicate.

    MARK_COLUMNS_WRITE: Means a bit is set in write set to inform handler

			that it needs to update this field in write_row

                        and update_row.

  */

  enum enum_mark_columns mark_used_columns;

  inline void* alloc(size_t size)

  {

    return mem_root->alloc_root(size);

  }

  inline void* calloc(size_t size)

  {

    void *ptr;

    if ((ptr= mem_root->alloc_root(size)))

      memset(ptr, 0, size);

    return ptr;

  }

  inline char *strdup(const char *str)

  {

    return mem_root->strdup_root(str);

  }

  inline char *strmake(const char *str, size_t size)

  {

    return mem_root->strmake_root(str,size);

  }

  inline void *memdup(const void *str, size_t size)

  {

    return mem_root->memdup_root(str, size);

  }

  inline void *memdup_w_gap(const void *str, size_t size, uint32_t gap)

  {

    void *ptr;

    if ((ptr= mem_root->alloc_root(size + gap)))

      memcpy(ptr,str,size);

    return ptr;

  }

  /** Frees all items attached to this Statement */

  void free_items();

  /**

   * List of items created in the parser for this query. Every item puts

   * itself to the list on creation (see Item::Item() for details))

   */

  Item *free_list;

  memory::Root *mem_root; /**< Pointer to current memroot */

  memory::Root *getMemRoot()

  {

    return mem_root;

  }

  uint64_t xa_id;

  uint64_t getXaId()

  {

    return xa_id;

  }

  void setXaId(uint64_t in_xa_id)

  {

    xa_id= in_xa_id; 

  }

  /**

   * Uniquely identifies each statement object in thread scope; change during

   * statement lifetime.

   *

   * @todo should be const

   */

  uint32_t id;

  LEX *lex; /**< parse tree descriptor */

  LEX *getLex() 

  {

    return lex;

  }

  /** query associated with this statement */

  typedef boost::shared_ptr<const std::string> QueryString;

private:

  boost::shared_ptr<std::string> query;

  // Never allow for a modification of this outside of the class. c_str()

  // requires under some setup non const, you must copy the QueryString in

  // order to use it.

public:

  QueryString getQueryString() const

  {

    return query;

  }

  void resetQueryString()

  {

    query.reset();

    _state.reset();

  }

  /*

    We need to copy the lock on the string in order to make sure we have a stable string.

    Once this is done we can use it to build a const char* which can be handed off for

    a method to use (Innodb is currently the only engine using this).

  */

  const char *getQueryStringCopy(size_t &length)

  {

    QueryString tmp_string(getQueryString());

    if (not tmp_string)

    {

      length= 0;

      return NULL;

    }

    length= tmp_string->length();

    char *to_return= strmake(tmp_string->c_str(), tmp_string->length());

    return to_return;

  }

  class State {

    std::vector <char> _query;

  public:

    typedef boost::shared_ptr<State> const_shared_ptr;

    State(const char *in_packet, size_t in_packet_length)

    {

      if (in_packet_length)

      {

        size_t minimum= std::min(in_packet_length, static_cast<size_t>(PROCESS_LIST_WIDTH));

        _query.resize(minimum + 1);

        memcpy(&_query[0], in_packet, minimum);

      }

      else

      {

        _query.resize(0);

      }

    }

    const char *query() const

    {

      if (_query.size())

        return &_query[0];

      return "";

    }

    const char *query(size_t &size) const

    {

      if (_query.size())

      {

        size= _query.size() -1;

        return &_query[0];

      }

      size= 0;

      return "";

    }

  protected:

    friend class Session;

    typedef boost::shared_ptr<State> shared_ptr;

  };

private:

  State::shared_ptr  _state; 

public:

  State::const_shared_ptr state()

  {

    return _state;

  }

  /**

    Name of the current (default) database.

    If there is the current (default) database, "db" contains its name. If

    there is no current (default) database, "db" is NULL and "db_length" is

    0. In other words, "db", "db_length" must either be NULL, or contain a

    valid database name.

    @note this attribute is set and alloced by the slave SQL thread (for

    the Session of that thread); that thread is (and must remain, for now) the

    only responsible for freeing this member.

  */

private:

  util::string::shared_ptr _schema;

public:

  util::string::const_shared_ptr schema() const

  {

    if (_schema)

      return _schema;

    return util::string::const_shared_ptr(new std::string(""));

  }

  std::string catalog;

  /* current cache key */

  std::string query_cache_key;

  /**

    Constant for Session::where initialization in the beginning of every query.

    It's needed because we do not save/restore Session::where normally during

    primary (non subselect) query execution.

  */

  static const char * const DEFAULT_WHERE;

  memory::Root warn_root; /**< Allocation area for warnings and errors */

private:

  plugin::Client *client; /**< Pointer to client object */

public:

  void setClient(plugin::Client *client_arg);

  plugin::Client *getClient()

  {

    return client;

  }

  plugin::Scheduler *scheduler; /**< Pointer to scheduler object */

  void *scheduler_arg; /**< Pointer to the optional scheduler argument */

  typedef boost::unordered_map< std::string, user_var_entry *, util::insensitive_hash, util::insensitive_equal_to> UserVars;

private:

  typedef std::pair< UserVars::iterator, UserVars::iterator > UserVarsRange;

  UserVars user_vars; /**< Hash of user variables defined during the session's lifetime */

public:

  const UserVars &getUserVariables() const

  {

    return user_vars;

  }

  drizzle_system_variables variables; /**< Mutable local variables local to the session */

  struct system_status_var status_var; /**< Session-local status counters */

  THR_LOCK_INFO lock_info; /**< Locking information for this session */

  THR_LOCK_OWNER main_lock_id; /**< To use for conventional queries */

  THR_LOCK_OWNER *lock_id; /**< If not main_lock_id, points to the lock_id of a cursor. */

  /**

   * A pointer to the stack frame of the scheduler thread

   * which is called first in the thread for handling a client

   */

  char *thread_stack;

private:

  identifier::User::shared_ptr security_ctx;

  int32_t scoreboard_index;

  inline void checkSentry() const

  {

    assert(this->dbug_sentry == Session_SENTRY_MAGIC);

  }

public:

  identifier::User::const_shared_ptr user() const

  {

    if (security_ctx)

      return security_ctx;

    return identifier::User::const_shared_ptr();

  }

  void setUser(identifier::User::shared_ptr arg)

  {

    security_ctx= arg;

  }

  int32_t getScoreboardIndex()

  {

    return scoreboard_index;

  }

  void setScoreboardIndex(int32_t in_scoreboard_index)

  {

    scoreboard_index= in_scoreboard_index;

  }

  /**

   * Is this session viewable by the current user?

   */

  bool isViewable(identifier::User::const_reference) const;

  /**

    Used in error messages to tell user in what part of MySQL we found an

    error. E. g. when where= "having clause", if fix_fields() fails, user

    will know that the error was in having clause.

  */

  const char *where;

  /*

    One thread can hold up to one named user-level lock. This variable

    points to a lock object if the lock is present. See item_func.cc and

    chapter 'Miscellaneous functions', for functions GET_LOCK, RELEASE_LOCK.

  */

  uint32_t dbug_sentry; /**< watch for memory corruption */

private:

  boost::thread::id boost_thread_id;

  boost_thread_shared_ptr _thread;

  boost::this_thread::disable_interruption *interrupt;

  internal::st_my_thread_var *mysys_var;

public:

  boost_thread_shared_ptr &getThread()

  {

    return _thread;

  }

  void pushInterrupt(boost::this_thread::disable_interruption *interrupt_arg)

  {

    interrupt= interrupt_arg;

  }

  boost::this_thread::disable_interruption &getThreadInterupt()

  {

    assert(interrupt);

    return *interrupt;

  }

  internal::st_my_thread_var *getThreadVar()

  {

    return mysys_var;

  }

  /**

   * Type of current query: COM_STMT_PREPARE, COM_QUERY, etc. Set from

   * first byte of the packet in executeStatement()

   */

  enum enum_server_command command;

  uint32_t file_id;	/**< File ID for LOAD DATA INFILE */

  /* @note the following three members should likely move to Client */

  uint32_t max_client_packet_length; /**< Maximum number of bytes a client can send in a single packet */

private:

  boost::posix_time::ptime _epoch;

  boost::posix_time::ptime _connect_time;

  boost::posix_time::ptime _start_timer;

  boost::posix_time::ptime _end_timer;

  boost::posix_time::ptime _user_time;

public:

  uint64_t utime_after_lock; // This used by Innodb.

  void resetUserTime()

  {

    _user_time= boost::posix_time::not_a_date_time;

  }

  const boost::posix_time::ptime &start_timer() const

  {

    return _start_timer;

  }

  void getTimeDifference(boost::posix_time::time_duration &result_arg, const boost::posix_time::ptime &arg) const

  {

    result_arg=  arg - _start_timer;

  }

  thr_lock_type update_lock_default;

  /*

    Both of the following container points in session will be converted to an API.

  */

private:

  /* container for handler's private per-connection data */

  std::vector<Ha_data> ha_data;

  /*

    Id of current query. Statement can be reused to execute several queries

    query_id is global in context of the whole MySQL server.

    ID is automatically generated from an atomic counter.

    It's used in Cursor code for various purposes: to check which columns

    from table are necessary for this select, to check if it's necessary to

    update auto-updatable fields (like auto_increment and timestamp).

  */

  query_id_t query_id;

  query_id_t warn_query_id;

public:

  void **getEngineData(const plugin::MonitoredInTransaction *monitored);

  ResourceContext *getResourceContext(const plugin::MonitoredInTransaction *monitored,

                                      size_t index= 0);

  /**

   * Structure used to manage "statement transactions" and

   * "normal transactions". In autocommit mode, the normal transaction is

   * equivalent to the statement transaction.

   *

   * Storage engines will be registered here when they participate in

   * a transaction. No engine is registered more than once.

   */

  struct st_transactions {

    std::deque<NamedSavepoint> savepoints;

    /**

     * The normal transaction (since BEGIN WORK).

     *

     * Contains a list of all engines that have participated in any of the

     * statement transactions started within the context of the normal

     * transaction.

     *

     * @note In autocommit mode, this is empty.

     */

    TransactionContext all;

    /**

     * The statment transaction.

     *

     * Contains a list of all engines participating in the given statement.

     *

     * @note In autocommit mode, this will be used to commit/rollback the

     * normal transaction.

     */

    TransactionContext stmt;

    XID_STATE xid_state;

    void cleanup()

    {

      savepoints.clear();

    }

    st_transactions() :

      savepoints(),

      all(),

      stmt(),

      xid_state()

    { }

  } transaction;

  Field *dup_field;

  sigset_t signals;

  // As of right now we do not allow a concurrent execute to launch itself