NativeTypeArray.java
/*
** Module : NativeTypeArray.java
** Abstract : an array of descriptors passed as a single argument to a native function
**
** Copyright (c) 2013-2017, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------Description---------------------------------
** 001 GES 20131211 First version.
** 002 GES 20140130 Even arrays need to be passed as a pointer to a pointer (one more level of
** indirection than we were providing).
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** 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 Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
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** Affero GPL version 3 and may not be removed by you.
**
** 0. Attribution Requirement.
**
** You must preserve all legal notices or author attributions in the covered
** work or Appropriate Legal Notices displayed by works containing the covered
** work. You may not remove from the covered work any author or developer
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*/
package com.goldencode.p2j.library;
import java.io.*;
import com.goldencode.p2j.util.*;
/**
* An array of descriptors passed as a single argument to a native function. 4GL RETURN
* parameters cannot have an extent, so this can only be used for INPUT, INPUT-OUTPUT and
* OUTPUT parameters. This class hides the complexity of rendering/restoring arrays to
* native memory.
*/
public class NativeTypeArray
extends BaseNativeType
{
/** Stores the contained elements for the array. */
private BaseNativeType[] elements = new BaseNativeType[0];
/**
* Default constructor.
*/
public NativeTypeArray()
{
super();
setPassByPointer(true);
type = LibraryManager.TYPE_POINTER;
}
/**
* Constructor that takes a list of elements.
*
* @param elements
* The elements for this array.
*/
public NativeTypeArray(BaseNativeType[] elements)
{
this();
this.elements = elements;
}
/**
* Access the array of data elements.
*
* @return The array of elements.
*/
public BaseNativeType[] getElements()
{
return elements;
}
/**
* Assign the array of data elements.
*
* @param elements
* The array of elements.
*/
public void setElements(BaseNativeType[] elements)
{
this.elements = elements;
}
/**
* Report the size (in bytes) of the native memory needed to store this instance.
* <p>
* This should never be called on the server, only on the client side.
*
* @return The number of bytes needed.
*/
public int size()
{
return (elements.length > 0) ? elements.length * elements[0].size() : 0;
}
/**
* Render the data into native memory, which will be allocated if the address is not
* given.
* <p>
* This should never be called on the server, only on the client side.
* <p>
* Arrays are rendered as a pointer to a block of memory in which each element is
* written contiguously from lowest address to highest address and the size of the
* block is the number of elements multiplied by the size of each element (which
* must be the same for all elements). This is consistent with how native code ('C'
* language) handles arrays.
*
* @param addr
* The memory address to which the data should be rendered, if the caller
* is supplying a buffer or 0 if the buffer should be allocated.
*
* @return The memory address of the rendered data or 0 if there is no data to
* output.
*/
public long render(long addr)
{
if (elements.length > 0)
{
// all elements of the array must have the same size
int sz = elements[0].size();
memptr local = new memptr();
if (addr == 0)
{
// save off for restore use later
ref = local;
// allocate the block which must be big enough to store the array
local.setLength(elements.length * sz);
addr = local.getPointerValue().longValue();
}
else
{
local.setPointerValue(addr);
}
if (copyIn || elements[0].isPassByPointer())
{
for (int i = 0; i < elements.length; i++)
{
// calculate the address at which to write our next element
long idx = addr + (i * sz);
// give each element a chance to render itself
elements[i].render(idx);
}
}
}
else
{
addr = 0;
}
return addr;
}
/**
* Copy back (if necessary) data from the native memory and deallocate the memory
* if this instance allocated it in the first place.
* <p>
* This should never be called on the server, only on the client side.
*
* @param addr
* The memory address from which the data should be restored, if the caller
* is supplying a buffer or 0 if the buffer should already exist.
*/
public void restore(long addr)
{
memptr local = ref;
if (local == null && addr != 0)
{
local = new memptr();
local.setPointerValue(addr);
}
if (copyOut && local != null && elements.length > 0)
{
addr = local.getPointerValue().longValue();
// all elements of the array must have the same size
int sz = elements[0].size();
// each element must have a chance to restore and deallocate the native resources
for (int i = 0; i < elements.length; i++)
{
// calculate the address at which to read our next element
long idx = addr + (i * sz);
elements[i].restore(idx);
}
}
// deallocate memory if we allocated it
if (ref != null)
ref.setLength(0);
}
/**
* Replacement for the default object reading method. The latest
* state is read from the input source. The parent's state is
* read first.
*
* @param in
* The input source from which fields will be restored.
*
* @throws IOException
* In case of I/O errors.
* @throws ClassNotFoundException
* If payload can't be instantiated.
*/
public void readExternal(ObjectInput in)
throws IOException,
ClassNotFoundException
{
super.readExternal(in);
int len = in.readInt();
elements = new BaseNativeType[len];
for (int i = 0; i < len; i++)
{
elements[i] = (BaseNativeType) in.readObject();
}
}
/**
* Replacement for the default object writing method. The latest
* state is written to the output destination. The parent's state is
* written first.
*
* @param out
* The output destination to which fields will be saved.
*
* @throws IOException
* In case of I/O errors.
*/
public void writeExternal(ObjectOutput out)
throws IOException
{
super.writeExternal(out);
out.writeInt(elements.length);
for (int i = 0; i < elements.length; i++)
{
out.writeObject(elements[i]);
}
}
}