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transaction_base.hxx

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00001 /*-------------------------------------------------------------------------
00002  *
00003  *   FILE
00004  *      pqxx/transaction_base.hxx
00005  *
00006  *   DESCRIPTION
00007  *      common code and definitions for the transaction classes.
00008  *   pqxx::transaction_base defines the interface for any abstract class that
00009  *   represents a database transaction
00010  *   DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/transaction_base instead.
00011  *
00012  * Copyright (c) 2001-2004, Jeroen T. Vermeulen <jtv@xs4all.nl>
00013  *
00014  * See COPYING for copyright license.  If you did not receive a file called
00015  * COPYING with this source code, please notify the distributor of this mistake,
00016  * or contact the author.
00017  *
00018  *-------------------------------------------------------------------------
00019  */
00020 
00021 /* End-user programs need not include this file, unless they define their own
00022  * transaction classes.  This is not something the typical program should want
00023  * to do.
00024  *
00025  * However, reading this file is worthwhile because it defines the public
00026  * interface for the available transaction classes such as transaction and 
00027  * nontransaction.
00028  */
00029 
00030 #include "pqxx/connection_base"
00031 #include "pqxx/isolation"
00032 #include "pqxx/result"
00033 
00034 /* Methods tested in eg. self-test program test001 are marked with "//[t1]"
00035  */
00036 
00037 
00038 namespace pqxx
00039 {
00040 class connection_base;
00041 class transaction_base;
00042 
00043 
00044 namespace internal
00045 {
00046 class PQXX_LIBEXPORT transactionfocus : public namedclass
00047 {
00048 public:
00049   transactionfocus(transaction_base &t, 
00050       const PGSTD::string &Name,
00051       const PGSTD::string &Classname) :
00052     namedclass(Name, Classname),
00053     m_Trans(t),
00054     m_registered(false)
00055   {
00056   }
00057 
00058 protected:
00059   void register_me();
00060   void unregister_me() throw ();
00061   void reg_pending_error(const PGSTD::string &) throw ();
00062   bool registered() const throw () { return m_registered; }
00063 
00064   transaction_base &m_Trans;
00065 
00066 private:
00067   bool m_registered;
00068 
00070   transactionfocus();
00072   transactionfocus(const transactionfocus &);
00074   transactionfocus &operator=(const transactionfocus &);
00075 };
00076 } // namespace internal
00077 
00078 
00079 
00081 
00089 class PQXX_LIBEXPORT transaction_base : public internal::namedclass
00090 {
00091   // TODO: Retry non-serializable transaction w/update only on broken_connection
00092 public:
00094   typedef isolation_traits<read_committed> isolation_tag;
00095 
00096   virtual ~transaction_base() =0;                                       //[t1]
00097 
00099 
00111   void commit();                                                        //[t1]
00112 
00114 
00117   void abort();                                                         //[t10]
00118 
00120 
00124   result exec(const char Query[], 
00125               const PGSTD::string &Desc=PGSTD::string());               //[t1]
00126 
00128 
00135   result exec(const PGSTD::string &Query,
00136               const PGSTD::string &Desc=PGSTD::string())                //[t2]
00137         { return exec(Query.c_str(), Desc); }
00138 
00139   result exec(const PGSTD::stringstream &Query,
00140               const PGSTD::string &Desc=PGSTD::string())                //[t9]
00141         { return exec(Query.str(), Desc); }
00142 
00144   void process_notice(const char Msg[]) const                           //[t14]
00145         { m_Conn.process_notice(Msg); }
00147   void process_notice(const PGSTD::string &Msg) const                   //[t14]
00148         { m_Conn.process_notice(Msg); }
00149 
00151   connection_base &conn() const { return m_Conn; }                      //[t4]
00152 
00154 
00162   void set_variable(const PGSTD::string &Var, const PGSTD::string &Val);//[t61]
00163 
00165 
00171   PGSTD::string get_variable(const PGSTD::string &) const;              //[t61]
00172 
00173 #ifdef PQXX_DEPRECATED_HEADERS
00174 
00175   void Commit() { commit(); }
00177   void Abort() { abort(); }
00179   result Exec(const char Q[], const PGSTD::string &D=PGSTD::string())
00180         { return exec(Q,D); }
00182   result Exec(const PGSTD::string &Q, const PGSTD::string &D=PGSTD::string())
00183         { return exec(Q,D); }
00185   void ProcessNotice(const char M[]) const { return process_notice(M); }
00187   void ProcessNotice(const PGSTD::string &M) const { return process_notice(M); }
00189   PGSTD::string Name() const { return name(); }
00191   connection_base &Conn() const { return conn(); }
00193   void SetVariable(const PGSTD::string &Var, const PGSTD::string &Val)
00194         { set_variable(Var,Val); }
00195 #endif
00196 
00197 protected:
00199 
00202   explicit transaction_base(connection_base &, 
00203                           const PGSTD::string &TName,
00204                           const PGSTD::string &CName);
00205 
00207 
00209   void Begin();
00210 
00212   void End() throw ();
00213 
00215   virtual void do_begin() =0;
00217   virtual result do_exec(const char Query[]) =0;
00219   virtual void do_commit() =0;
00221   virtual void do_abort() =0;
00222 
00223   // For use by implementing class:
00224 
00226 
00234   result DirectExec(const char C[], int Retries=0);
00235  
00236 private:
00237   /* A transaction goes through the following stages in its lifecycle:
00238    *  - nascent: the transaction hasn't actually begun yet.  If our connection 
00239    *    fails at this stage, it may recover and the transaction can attempt to
00240    *    establish itself again.
00241    *  - active: the transaction has begun.  Since no commit command has been 
00242    *    issued, abortion is implicit if the connection fails now.
00243    *  - aborted: an abort has been issued; the transaction is terminated and 
00244    *    its changes to the database rolled back.  It will accept no further 
00245    *    commands.
00246    *  - committed: the transaction has completed successfully, meaning that a 
00247    *    commit has been issued.  No further commands are accepted.
00248    *  - in_doubt: the connection was lost at the exact wrong time, and there is
00249    *    no way of telling whether the transaction was committed or aborted.
00250    *
00251    * Checking and maintaining state machine logic is the responsibility of the 
00252    * base class (ie., this one).
00253    */
00254   enum Status 
00255   { 
00256     st_nascent, 
00257     st_active, 
00258     st_aborted, 
00259     st_committed,
00260     st_in_doubt
00261   };
00262 
00263 
00264   void CheckPendingError();
00265 
00266   friend class Cursor;
00267   friend class cursor_base;
00268   int GetUniqueCursorNum() { return m_UniqueCursorNum++; }
00269   void MakeEmpty(result &R) const { m_Conn.MakeEmpty(R); }
00270 
00271   friend class internal::transactionfocus;
00272   void RegisterFocus(internal::transactionfocus *);
00273   void UnregisterFocus(internal::transactionfocus *) throw ();
00274   void RegisterPendingError(const PGSTD::string &) throw ();
00275   friend class tablereader;
00276   void BeginCopyRead(const PGSTD::string &Table, const PGSTD::string &Columns);
00277   bool ReadCopyLine(PGSTD::string &L) { return m_Conn.ReadCopyLine(L); }
00278   friend class tablewriter;
00279   void BeginCopyWrite(const PGSTD::string &Table, 
00280         const PGSTD::string &Columns = PGSTD::string());
00281   void WriteCopyLine(const PGSTD::string &L) { m_Conn.WriteCopyLine(L); }
00282   void EndCopyWrite() { m_Conn.EndCopyWrite(); }
00283 
00284   friend class pipeline;
00285   void start_exec(const PGSTD::string &Q) { m_Conn.start_exec(Q); }
00286   internal::pq::PGresult *get_result() { return m_Conn.get_result(); }
00287   void consume_input() throw () { m_Conn.consume_input(); }
00288   bool is_busy() const throw () { return m_Conn.is_busy(); }
00289 
00290   connection_base &m_Conn;
00291 
00292   int m_UniqueCursorNum;
00293   internal::unique<internal::transactionfocus> m_Focus;
00294   Status m_Status;
00295   bool m_Registered;
00296   mutable PGSTD::map<PGSTD::string, PGSTD::string> m_Vars;
00297   PGSTD::string m_PendingError;
00298 
00300   transaction_base();
00302   transaction_base(const transaction_base &);
00304   transaction_base &operator=(const transaction_base &);
00305 };
00306 
00307 } // namespace pqxx
00308 
00309 

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