Re: [PATCHES] Attempt to clean up ExecSql() in JDBC

I looked at the patch and it looks fine. As for what fqp and hfr stand
for I don't have a clue. I was looking through the fe/be protocol
documentation and think I might have a clue about what they are being
used for.

thanks,
--Barry

Anders Bengtsson wrote:
> Hi,
>
> Attached is my attempt to clean up the horrors of the ExecSQL() method in
> the JDBC driver.
>
> I've done this by extracting it into a new method object called
> QueryExecutor (should go into org/postgresql/core/) and then taking it
> apart into different methods in that class.
>
> A short summary:
>
> * Extracted ExecSQL() from Connection into a method object called
> QueryExecutor.
>
> * Moved ReceiveFields() from Connection to QueryExecutor.
>
> * Extracted parts of the original ExecSQL() method body into smaller
> methods on QueryExecutor.
>
> * Bug fix: The instance variable "pid" in Connection was used in two
> places with different meaning. Both were probably in dead code, but it's
> fixed anyway.
>
> /Anders
>
>
> PS.: If anyone has any idea what the variable names "fqp" and "hfr" stand
> for, please tell me! :)
>
> _____________________________________________________________________
> A n d e r s B e n g t s s o n ndrsbngtssn(at)yahoo(dot)se
> Stockholm, Sweden
>
>
> ------------------------------------------------------------------------
>
> Index: src/interfaces/jdbc/org/postgresql/Connection.java
> ===================================================================
> RCS file: /home/projects/pgsql/cvsroot/pgsql/src/interfaces/jdbc/org/postgresql/Connection.java,v
> retrieving revision 1.26
> diff -c -r1.26 Connection.java
> *** src/interfaces/jdbc/org/postgresql/Connection.java 2001/08/24 16:50:12 1.26
> --- src/interfaces/jdbc/org/postgresql/Connection.java 2001/08/26 18:33:48
> ***************
> *** 8,14 ****
> import org.postgresql.fastpath.*;
> import org.postgresql.largeobject.*;
> import org.postgresql.util.*;
> ! import org.postgresql.core.Encoding;
>
> /**
> * $Id: Connection.java,v 1.26 2001/08/24 16:50:12 momjian Exp $
> --- 8,14 ----
> import org.postgresql.fastpath.*;
> import org.postgresql.largeobject.*;
> import org.postgresql.util.*;
> ! import org.postgresql.core.*;
>
> /**
> * $Id: Connection.java,v 1.26 2001/08/24 16:50:12 momjian Exp $
> ***************
> *** 348,513 ****
> * @return a ResultSet holding the results
> * @exception SQLException if a database error occurs
> */
> ! public java.sql.ResultSet ExecSQL(String sql,java.sql.Statement stat) throws SQLException
> {
> ! // added Jan 30 2001 to correct maxrows per statement
> ! int maxrows=0;
> ! if(stat!=null)
> ! maxrows=stat.getMaxRows();
> !
> ! // added Oct 7 1998 to give us thread safety.
> ! synchronized(pg_stream) {
> ! // Deallocate all resources in the stream associated
> ! // with a previous request.
> ! // This will let the driver reuse byte arrays that has already
> ! // been allocated instead of allocating new ones in order
> ! // to gain performance improvements.
> ! // PM 17/01/01: Commented out due to race bug. See comments in
> ! // PG_Stream
> ! //pg_stream.deallocate();
> !
> ! Field[] fields = null;
> ! Vector tuples = new Vector();
> ! byte[] buf = null;
> ! int fqp = 0;
> ! boolean hfr = false;
> ! String recv_status = null, msg;
> ! int update_count = 1;
> ! int insert_oid = 0;
> ! SQLException final_error = null;
> !
> ! buf = encoding.encode(sql);
> ! try
> ! {
> ! pg_stream.SendChar('Q');
> ! pg_stream.Send(buf);
> ! pg_stream.SendChar(0);
> ! pg_stream.flush();
> ! } catch (IOException e) {
> ! throw new PSQLException("postgresql.con.ioerror",e);
> ! }
> !
> ! while (!hfr || fqp > 0)
> ! {
> ! Object tup=null; // holds rows as they are recieved
> !
> ! int c = pg_stream.ReceiveChar();
> !
> ! switch (c)
> ! {
> ! case 'A': // Asynchronous Notify
> ! pid = pg_stream.ReceiveInteger(4);
> ! msg = pg_stream.ReceiveString(encoding);
> ! break;
> ! case 'B': // Binary Data Transfer
> ! if (fields == null)
> ! throw new PSQLException("postgresql.con.tuple");
> ! tup = pg_stream.ReceiveTuple(fields.length, true);
> ! // This implements Statement.setMaxRows()
> ! if(maxrows==0 || tuples.size()<maxrows)
> ! tuples.addElement(tup);
> ! break;
> ! case 'C': // Command Status
> ! recv_status = pg_stream.ReceiveString(encoding);
> !
> ! // Now handle the update count correctly.
> ! if(recv_status.startsWith("INSERT") || recv_status.startsWith("UPDATE") || recv_status.startsWith("DELETE") || recv_status.startsWith("MOVE")) {
> ! try {
> ! update_count = Integer.parseInt(recv_status.substring(1+recv_status.lastIndexOf(' ')));
> ! } catch(NumberFormatException nfe) {
> ! throw new PSQLException("postgresql.con.fathom",recv_status);
> ! }
> ! if(recv_status.startsWith("INSERT")) {
> ! try {
> ! insert_oid = Integer.parseInt(recv_status.substring(1+recv_status.indexOf(' '),recv_status.lastIndexOf(' ')));
> ! } catch(NumberFormatException nfe) {
> ! throw new PSQLException("postgresql.con.fathom",recv_status);
> ! }
> ! }
> ! }
> ! if (fields != null)
> ! hfr = true;
> ! else
> ! {
> ! try
> ! {
> ! pg_stream.SendChar('Q');
> ! pg_stream.SendChar(' ');
> ! pg_stream.SendChar(0);
> ! pg_stream.flush();
> ! } catch (IOException e) {
> ! throw new PSQLException("postgresql.con.ioerror",e);
> ! }
> ! fqp++;
> ! }
> ! break;
> ! case 'D': // Text Data Transfer
> ! if (fields == null)
> ! throw new PSQLException("postgresql.con.tuple");
> ! tup = pg_stream.ReceiveTuple(fields.length, false);
> ! // This implements Statement.setMaxRows()
> ! if(maxrows==0 || tuples.size()<maxrows)
> ! tuples.addElement(tup);
> ! break;
> ! case 'E': // Error Message
> ! msg = pg_stream.ReceiveString(encoding);
> ! final_error = new SQLException(msg);
> ! hfr = true;
> ! break;
> ! case 'I': // Empty Query
> ! int t = pg_stream.ReceiveChar();
> !
> ! if (t != 0)
> ! throw new PSQLException("postgresql.con.garbled");
> ! if (fqp > 0)
> ! fqp--;
> ! if (fqp == 0)
> ! hfr = true;
> ! break;
> ! case 'N': // Error Notification
> ! addWarning(pg_stream.ReceiveString(encoding));
> ! break;
> ! case 'P': // Portal Name
> ! String pname = pg_stream.ReceiveString(encoding);
> ! break;
> ! case 'T': // MetaData Field Description
> ! if (fields != null)
> ! throw new PSQLException("postgresql.con.multres");
> ! fields = ReceiveFields();
> ! break;
> ! case 'Z': // backend ready for query, ignore for now :-)
> ! break;
> ! default:
> ! throw new PSQLException("postgresql.con.type",new Character((char)c));
> ! }
> ! }
> ! if (final_error != null)
> ! throw final_error;
> !
> ! return getResultSet(this, stat, fields, tuples, recv_status, update_count, insert_oid);
> ! }
> ! }
> !
> ! /**
> ! * Receive the field descriptions from the back end
> ! *
> ! * @return an array of the Field object describing the fields
> ! * @exception SQLException if a database error occurs
> ! */
> ! private Field[] ReceiveFields() throws SQLException
> ! {
> ! int nf = pg_stream.ReceiveIntegerR(2), i;
> ! Field[] fields = new Field[nf];
> !
> ! for (i = 0 ; i < nf ; ++i)
> ! {
> ! String typname = pg_stream.ReceiveString(encoding);
> ! int typid = pg_stream.ReceiveIntegerR(4);
> ! int typlen = pg_stream.ReceiveIntegerR(2);
> ! int typmod = pg_stream.ReceiveIntegerR(4);
> ! fields[i] = new Field(this, typname, typid, typlen, typmod);
> ! }
> ! return fields;
> }
>
> /**
> --- 348,356 ----
> * @return a ResultSet holding the results
> * @exception SQLException if a database error occurs
> */
> ! public java.sql.ResultSet ExecSQL(String sql, java.sql.Statement stat) throws SQLException
> {
> ! return new QueryExecutor(sql, stat, pg_stream, this).execute();
> }
>
> /**
> ***************
> *** 793,799 ****
> * This returns a resultset. It must be overridden, so that the correct
> * version (from jdbc1 or jdbc2) are returned.
> */
> ! protected abstract java.sql.ResultSet getResultSet(org.postgresql.Connection conn,java.sql.Statement stat, Field[] fields, Vector tuples, String status, int updateCount,int insertOID) throws SQLException;
>
> /**
> * In some cases, it is desirable to immediately release a Connection's
> --- 636,642 ----
> * This returns a resultset. It must be overridden, so that the correct
> * version (from jdbc1 or jdbc2) are returned.
> */
> ! public abstract java.sql.ResultSet getResultSet(org.postgresql.Connection conn,java.sql.Statement stat, Field[] fields, Vector tuples, String status, int updateCount,int insertOID) throws SQLException;
>
> /**
> * In some cases, it is desirable to immediately release a Connection's
> Index: src/interfaces/jdbc/org/postgresql/jdbc1/Connection.java
> ===================================================================
> RCS file: /home/projects/pgsql/cvsroot/pgsql/src/interfaces/jdbc/org/postgresql/jdbc1/Connection.java,v
> retrieving revision 1.8
> diff -c -r1.8 Connection.java
> *** src/interfaces/jdbc/org/postgresql/jdbc1/Connection.java 2001/08/24 16:50:15 1.8
> --- src/interfaces/jdbc/org/postgresql/jdbc1/Connection.java 2001/08/26 18:33:48
> ***************
> *** 131,137 ****
> * This overides the method in org.postgresql.Connection and returns a
> * ResultSet.
> */
> ! protected java.sql.ResultSet getResultSet(org.postgresql.Connection conn,java.sql.Statement stat, Field[] fields, Vector tuples, String status, int updateCount,int insertOID) throws SQLException
> {
> // in jdbc1 stat is ignored.
> return new org.postgresql.jdbc1.ResultSet((org.postgresql.jdbc1.Connection)conn,fields,tuples,status,updateCount,insertOID);
> --- 131,137 ----
> * This overides the method in org.postgresql.Connection and returns a
> * ResultSet.
> */
> ! public java.sql.ResultSet getResultSet(org.postgresql.Connection conn,java.sql.Statement stat, Field[] fields, Vector tuples, String status, int updateCount,int insertOID) throws SQLException
> {
> // in jdbc1 stat is ignored.
> return new org.postgresql.jdbc1.ResultSet((org.postgresql.jdbc1.Connection)conn,fields,tuples,status,updateCount,insertOID);
> Index: src/interfaces/jdbc/org/postgresql/jdbc2/Connection.java
> ===================================================================
> RCS file: /home/projects/pgsql/cvsroot/pgsql/src/interfaces/jdbc/org/postgresql/jdbc2/Connection.java,v
> retrieving revision 1.10
> diff -c -r1.10 Connection.java
> *** src/interfaces/jdbc/org/postgresql/jdbc2/Connection.java 2001/08/24 16:50:16 1.10
> --- src/interfaces/jdbc/org/postgresql/jdbc2/Connection.java 2001/08/26 18:33:49
> ***************
> *** 204,210 ****
> * This overides the method in org.postgresql.Connection and returns a
> * ResultSet.
> */
> ! protected java.sql.ResultSet getResultSet(org.postgresql.Connection conn, java.sql.Statement stat,Field[] fields, Vector tuples, String status, int updateCount, int insertOID) throws SQLException
> {
> // In 7.1 we now test concurrency to see which class to return. If we are not working with a
> // Statement then default to a normal ResultSet object.
> --- 204,210 ----
> * This overides the method in org.postgresql.Connection and returns a
> * ResultSet.
> */
> ! public java.sql.ResultSet getResultSet(org.postgresql.Connection conn, java.sql.Statement stat,Field[] fields, Vector tuples, String status, int updateCount, int insertOID) throws SQLException
> {
> // In 7.1 we now test concurrency to see which class to return. If we are not working with a
> // Statement then default to a normal ResultSet object.
>
>
> ------------------------------------------------------------------------
>
>
> package org.postgresql.core;
>
> import java.util.Vector;
> import java.io.IOException;
> import java.sql.*;
> import org.postgresql.*;
> import org.postgresql.util.PSQLException;
>
> /**
> * Executes a query on the backend.
> *
> * <p>The lifetime of a QueryExecutor object is from sending the query
> * until the response has been received from the backend.
> *
> * $Id$
> */
>
> public class QueryExecutor {
>
> private final String sql;
> private final java.sql.Statement statement;
> private final PG_Stream pg_stream;
> private final org.postgresql.Connection connection;
>
> public QueryExecutor(String sql,
> java.sql.Statement statement,
> PG_Stream pg_stream,
> org.postgresql.Connection connection)
> throws SQLException
> {
> this.sql = sql;
> this.statement = statement;
> this.pg_stream = pg_stream;
> this.connection = connection;
>
> if (statement != null)
> maxRows = statement.getMaxRows();
> else
> maxRows = 0;
> }
>
> private Field[] fields = null;
> private Vector tuples = new Vector();
> private String status = null;
> private int update_count = 1;
> private int insert_oid = 0;
> private int maxRows;
>
> /**
> * Execute a query on the backend.
> */
> public java.sql.ResultSet execute() throws SQLException {
>
> int fqp = 0;
> boolean hfr = false;
>
> synchronized(pg_stream) {
>
> sendQuery(sql);
>
> while (!hfr || fqp > 0) {
> int c = pg_stream.ReceiveChar();
>
> switch (c)
> {
> case 'A': // Asynchronous Notify
> int pid = pg_stream.ReceiveInteger(4);
> String msg = pg_stream.ReceiveString(connection.getEncoding());
> break;
> case 'B': // Binary Data Transfer
> receiveTuple(true);
> break;
> case 'C': // Command Status
> receiveCommandStatus();
>
> if (fields != null)
> hfr = true;
> else {
> sendQuery(" ");
> fqp++;
> }
> break;
> case 'D': // Text Data Transfer
> receiveTuple(false);
> break;
> case 'E': // Error Message
> throw new SQLException(pg_stream.ReceiveString(connection.getEncoding()));
> case 'I': // Empty Query
> int t = pg_stream.ReceiveChar();
> if (t != 0)
> throw new PSQLException("postgresql.con.garbled");
>
> if (fqp > 0)
> fqp--;
> if (fqp == 0)
> hfr = true;
> break;
> case 'N': // Error Notification
> connection.addWarning(pg_stream.ReceiveString(connection.getEncoding()));
> break;
> case 'P': // Portal Name
> String pname = pg_stream.ReceiveString(connection.getEncoding());
> break;
> case 'T': // MetaData Field Description
> receiveFields();
> break;
> case 'Z': // backend ready for query, ignore for now :-)
> break;
> default:
> throw new PSQLException("postgresql.con.type",
> new Character((char) c));
> }
> }
>
> return connection.getResultSet(connection, statement, fields, tuples, status, update_count, insert_oid);
> }
> }
>
> /**
> * Send a query to the backend.
> */
> private void sendQuery(String query) throws SQLException {
> try {
> pg_stream.SendChar('Q');
> pg_stream.Send(connection.getEncoding().encode(query));
> pg_stream.SendChar(0);
> pg_stream.flush();
>
> } catch (IOException e) {
> throw new PSQLException("postgresql.con.ioerror", e);
> }
> }
>
> /**
> * Receive a tuple from the backend.
> *
> * @param isBinary set if the tuple should be treated as binary data
> */
> private void receiveTuple(boolean isBinary) throws SQLException {
> if (fields == null)
> throw new PSQLException("postgresql.con.tuple");
> Object tuple = pg_stream.ReceiveTuple(fields.length, isBinary);
> if (maxRows == 0 || tuples.size() < maxRows)
> tuples.addElement(tuple);
> }
>
> /**
> * Receive command status from the backend.
> */
> private void receiveCommandStatus() throws SQLException {
>
> status = pg_stream.ReceiveString(connection.getEncoding());
>
> try {
> // Now handle the update count correctly.
> if (status.startsWith("INSERT") || status.startsWith("UPDATE") || status.startsWith("DELETE") || status.startsWith("MOVE")) {
> update_count = Integer.parseInt(status.substring(1 + status.lastIndexOf(' ')));
> }
> if (status.startsWith("INSERT")) {
> insert_oid = Integer.parseInt(status.substring(1 + status.indexOf(' '),
> status.lastIndexOf(' ')));
> }
> } catch (NumberFormatException nfe) {
> throw new PSQLException("postgresql.con.fathom", status);
> }
> }
>
> /**
> * Receive the field descriptions from the back end.
> */
> private void receiveFields() throws SQLException {
> if (fields != null)
> throw new PSQLException("postgresql.con.multres");
>
> int size = pg_stream.ReceiveIntegerR(2);
> fields = new Field[size];
>
> for (int i = 0; i < fields.length; i++) {
> String typeName = pg_stream.ReceiveString(connection.getEncoding());
> int typeOid = pg_stream.ReceiveIntegerR(4);
> int typeLength = pg_stream.ReceiveIntegerR(2);
> int typeModifier = pg_stream.ReceiveIntegerR(4);
> fields[i] = new Field(connection, typeName, typeOid, typeLength, typeModifier);
> }
> }
> }
>
>
> ------------------------------------------------------------------------
>
>
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>
> execsql.patch
>
> Content-Type:
>
> TEXT/PLAIN
> Content-Encoding:
>
> BASE64
>
>
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> QueryExecutor.java
>
> Content-Type:
>
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> Content-Encoding:
>
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>
>
> ------------------------------------------------------------------------
> Part 1.4
>
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>
>