mirror of
https://github.com/postgres/postgres.git
synced 2025-05-03 22:24:49 +03:00
289 lines
9.0 KiB
Java
289 lines
9.0 KiB
Java
package org.postgresql.fastpath;
|
|
|
|
import java.io.*;
|
|
import java.lang.*;
|
|
import java.net.*;
|
|
import java.util.*;
|
|
import java.sql.*;
|
|
import org.postgresql.util.*;
|
|
|
|
// Important: There are a lot of debug code commented out. Please do not
|
|
// delete these.
|
|
|
|
/**
|
|
* This class implements the Fastpath api.
|
|
*
|
|
* <p>This is a means of executing functions imbeded in the org.postgresql backend
|
|
* from within a java application.
|
|
*
|
|
* <p>It is based around the file src/interfaces/libpq/fe-exec.c
|
|
*
|
|
* @see org.postgresql.FastpathFastpathArg
|
|
* @see org.postgresql.LargeObject
|
|
*/
|
|
public class Fastpath
|
|
{
|
|
// This maps the functions names to their id's (possible unique just
|
|
// to a connection).
|
|
protected Hashtable func = new Hashtable();
|
|
|
|
protected org.postgresql.Connection conn; // our connection
|
|
protected org.postgresql.PG_Stream stream; // the network stream
|
|
|
|
/**
|
|
* Initialises the fastpath system
|
|
*
|
|
* <p><b>Important Notice</b>
|
|
* <br>This is called from org.postgresql.Connection, and should not be called
|
|
* from client code.
|
|
*
|
|
* @param conn org.postgresql.Connection to attach to
|
|
* @param stream The network stream to the backend
|
|
*/
|
|
public Fastpath(org.postgresql.Connection conn,org.postgresql.PG_Stream stream)
|
|
{
|
|
this.conn=conn;
|
|
this.stream=stream;
|
|
//DriverManager.println("Fastpath initialised");
|
|
}
|
|
|
|
/**
|
|
* Send a function call to the PostgreSQL backend
|
|
*
|
|
* @param fnid Function id
|
|
* @param resulttype True if the result is an integer, false for other results
|
|
* @param args FastpathArguments to pass to fastpath
|
|
* @return null if no data, Integer if an integer result, or byte[] otherwise
|
|
* @exception SQLException if a database-access error occurs.
|
|
*/
|
|
public Object fastpath(int fnid,boolean resulttype,FastpathArg[] args) throws SQLException
|
|
{
|
|
// added Oct 7 1998 to give us thread safety
|
|
synchronized(stream) {
|
|
|
|
// send the function call
|
|
try {
|
|
// 70 is 'F' in ASCII. Note: don't use SendChar() here as it adds padding
|
|
// that confuses the backend. The 0 terminates the command line.
|
|
stream.SendInteger(70,1);
|
|
stream.SendInteger(0,1);
|
|
|
|
stream.SendInteger(fnid,4);
|
|
stream.SendInteger(args.length,4);
|
|
|
|
for(int i=0;i<args.length;i++)
|
|
args[i].send(stream);
|
|
|
|
// This is needed, otherwise data can be lost
|
|
stream.flush();
|
|
|
|
} catch(IOException ioe) {
|
|
throw new PSQLException("postgresql.fp.send",new Integer(fnid),ioe);
|
|
}
|
|
|
|
// Now handle the result
|
|
|
|
// We should get 'V' on sucess or 'E' on error. Anything else is treated
|
|
// as an error.
|
|
//int in = stream.ReceiveChar();
|
|
//DriverManager.println("ReceiveChar() = "+in+" '"+((char)in)+"'");
|
|
//if(in!='V') {
|
|
//if(in=='E')
|
|
//throw new SQLException(stream.ReceiveString(4096));
|
|
//throw new SQLException("Fastpath: expected 'V' from backend, got "+((char)in));
|
|
//}
|
|
|
|
// Now loop, reading the results
|
|
Object result = null; // our result
|
|
while(true) {
|
|
int in = stream.ReceiveChar();
|
|
//DriverManager.println("ReceiveChar() = "+in+" '"+((char)in)+"'");
|
|
switch(in)
|
|
{
|
|
case 'V':
|
|
break;
|
|
|
|
//------------------------------
|
|
// Function returned properly
|
|
//
|
|
case 'G':
|
|
int sz = stream.ReceiveIntegerR(4);
|
|
//DriverManager.println("G: size="+sz); //debug
|
|
|
|
// Return an Integer if
|
|
if(resulttype)
|
|
result = new Integer(stream.ReceiveIntegerR(sz));
|
|
else {
|
|
byte buf[] = new byte[sz];
|
|
stream.Receive(buf,0,sz);
|
|
result = buf;
|
|
}
|
|
break;
|
|
|
|
//------------------------------
|
|
// Error message returned
|
|
case 'E':
|
|
throw new PSQLException("postgresql.fp.error",stream.ReceiveString(4096));
|
|
|
|
//------------------------------
|
|
// Notice from backend
|
|
case 'N':
|
|
conn.addWarning(stream.ReceiveString(4096));
|
|
break;
|
|
|
|
//------------------------------
|
|
// End of results
|
|
//
|
|
// Here we simply return res, which would contain the result
|
|
// processed earlier. If no result, this already contains null
|
|
case '0':
|
|
//DriverManager.println("returning "+result);
|
|
return result;
|
|
|
|
case 'Z':
|
|
break;
|
|
|
|
default:
|
|
throw new PSQLException("postgresql.fp.protocol",new Character((char)in));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Send a function call to the PostgreSQL backend by name.
|
|
*
|
|
* Note: the mapping for the procedure name to function id needs to exist,
|
|
* usually to an earlier call to addfunction().
|
|
*
|
|
* This is the prefered method to call, as function id's can/may change
|
|
* between versions of the backend.
|
|
*
|
|
* For an example of how this works, refer to org.postgresql.LargeObject
|
|
*
|
|
* @param name Function name
|
|
* @param resulttype True if the result is an integer, false for other
|
|
* results
|
|
* @param args FastpathArguments to pass to fastpath
|
|
* @return null if no data, Integer if an integer result, or byte[] otherwise
|
|
* @exception SQLException if name is unknown or if a database-access error
|
|
* occurs.
|
|
* @see org.postgresql.LargeObject
|
|
*/
|
|
public Object fastpath(String name,boolean resulttype,FastpathArg[] args) throws SQLException
|
|
{
|
|
//DriverManager.println("Fastpath: calling "+name);
|
|
return fastpath(getID(name),resulttype,args);
|
|
}
|
|
|
|
/**
|
|
* This convenience method assumes that the return value is an Integer
|
|
* @param name Function name
|
|
* @param args Function arguments
|
|
* @return integer result
|
|
* @exception SQLException if a database-access error occurs or no result
|
|
*/
|
|
public int getInteger(String name,FastpathArg[] args) throws SQLException
|
|
{
|
|
Integer i = (Integer)fastpath(name,true,args);
|
|
if(i==null)
|
|
throw new PSQLException("postgresql.fp.expint",name);
|
|
return i.intValue();
|
|
}
|
|
|
|
/**
|
|
* This convenience method assumes that the return value is an Integer
|
|
* @param name Function name
|
|
* @param args Function arguments
|
|
* @return byte[] array containing result
|
|
* @exception SQLException if a database-access error occurs or no result
|
|
*/
|
|
public byte[] getData(String name,FastpathArg[] args) throws SQLException
|
|
{
|
|
return (byte[])fastpath(name,false,args);
|
|
}
|
|
|
|
/**
|
|
* This adds a function to our lookup table.
|
|
*
|
|
* <p>User code should use the addFunctions method, which is based upon a
|
|
* query, rather than hard coding the oid. The oid for a function is not
|
|
* guaranteed to remain static, even on different servers of the same
|
|
* version.
|
|
*
|
|
* @param name Function name
|
|
* @param fnid Function id
|
|
*/
|
|
public void addFunction(String name,int fnid)
|
|
{
|
|
func.put(name,new Integer(fnid));
|
|
}
|
|
|
|
/**
|
|
* This takes a ResultSet containing two columns. Column 1 contains the
|
|
* function name, Column 2 the oid.
|
|
*
|
|
* <p>It reads the entire ResultSet, loading the values into the function
|
|
* table.
|
|
*
|
|
* <p><b>REMEMBER</b> to close() the resultset after calling this!!
|
|
*
|
|
* <p><b><em>Implementation note about function name lookups:</em></b>
|
|
*
|
|
* <p>PostgreSQL stores the function id's and their corresponding names in
|
|
* the pg_proc table. To speed things up locally, instead of querying each
|
|
* function from that table when required, a Hashtable is used. Also, only
|
|
* the function's required are entered into this table, keeping connection
|
|
* times as fast as possible.
|
|
*
|
|
* <p>The org.postgresql.LargeObject class performs a query upon it's startup,
|
|
* and passes the returned ResultSet to the addFunctions() method here.
|
|
*
|
|
* <p>Once this has been done, the LargeObject api refers to the functions by
|
|
* name.
|
|
*
|
|
* <p>Dont think that manually converting them to the oid's will work. Ok,
|
|
* they will for now, but they can change during development (there was some
|
|
* discussion about this for V7.0), so this is implemented to prevent any
|
|
* unwarranted headaches in the future.
|
|
*
|
|
* @param rs ResultSet
|
|
* @exception SQLException if a database-access error occurs.
|
|
* @see org.postgresql.LargeObjectManager
|
|
*/
|
|
public void addFunctions(ResultSet rs) throws SQLException
|
|
{
|
|
while(rs.next()) {
|
|
func.put(rs.getString(1),new Integer(rs.getInt(2)));
|
|
}
|
|
}
|
|
|
|
/**
|
|
* This returns the function id associated by its name
|
|
*
|
|
* <p>If addFunction() or addFunctions() have not been called for this name,
|
|
* then an SQLException is thrown.
|
|
*
|
|
* @param name Function name to lookup
|
|
* @return Function ID for fastpath call
|
|
* @exception SQLException is function is unknown.
|
|
*/
|
|
public int getID(String name) throws SQLException
|
|
{
|
|
Integer id = (Integer)func.get(name);
|
|
|
|
// may be we could add a lookup to the database here, and store the result
|
|
// in our lookup table, throwing the exception if that fails.
|
|
// We must, however, ensure that if we do, any existing ResultSet is
|
|
// unaffected, otherwise we could break user code.
|
|
//
|
|
// so, until we know we can do this (needs testing, on the TODO list)
|
|
// for now, we throw the exception and do no lookups.
|
|
if(id==null)
|
|
throw new PSQLException("postgresql.fp.unknown",name);
|
|
|
|
return id.intValue();
|
|
}
|
|
}
|
|
|