jndi/cosnaming/CNBindingEnumeration.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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package com.sun.jndi.cosnaming;

import javax.naming.*;
import javax.naming.spi.NamingManager;

import java.util.NoSuchElementException;
import java.util.Hashtable;

import org.omg.CosNaming.*;

/**
  * Implements the JNDI NamingEnumeration interface for COS
  * Naming. Gets hold of a list of bindings from the COS Naming Server
  * and allows the client to iterate through them.
  *
  * @author Raj Krishnamurthy
  * @author Rosanna Lee
  */

final class CNBindingEnumeration
        implements NamingEnumeration<javax.naming.Binding> {

    private static final int DEFAULT_BATCHSIZE = 100;
    private BindingListHolder _bindingList; // list of bindings
    private BindingIterator _bindingIter;   // iterator for getting list of bindings
    private int counter;                    // pointer in _bindingList
    private int batchsize = DEFAULT_BATCHSIZE;  // how many to ask for each time
    private CNCtx _ctx;                     // ctx to list
    private Hashtable<?,?> _env;            // environment for getObjectInstance
    private boolean more = false;           // iterator done?
    private boolean isLookedUpCtx = false;  // iterating on a context beneath this context ?

    /**
     * Creates a CNBindingEnumeration object.
     * @param ctx Context to enumerate
     */
    CNBindingEnumeration(CNCtx ctx, boolean isLookedUpCtx, Hashtable<?,?> env) {
        // Get batch size to use
        String batch = (env != null ?
            (String)env.get(javax.naming.Context.BATCHSIZE) : null);
        if (batch != null) {
            try {
                batchsize = Integer.parseInt(batch);
            } catch (NumberFormatException e) {
                throw new IllegalArgumentException("Batch size not numeric: " + batch);
            }
        }
        _ctx = ctx;
        _ctx.incEnumCount();
        this.isLookedUpCtx = isLookedUpCtx;
        _env = env;
        _bindingList = new BindingListHolder();
        BindingIteratorHolder _bindingIterH = new BindingIteratorHolder();

        // Perform listing and request that bindings be returned in _bindingIter
        // Upon return,_bindingList returns a zero length list
        _ctx._nc.list(0, _bindingList, _bindingIterH);

        _bindingIter = _bindingIterH.value;

        // Get first batch using _bindingIter
        if (_bindingIter != null) {
            more = _bindingIter.next_n(batchsize, _bindingList);
        } else {
            more = false;
        }
        counter = 0;
    }

    /**
     * Returns the next binding in the list.
     * @exception NamingException any naming exception.
     */

    public javax.naming.Binding next() throws NamingException {
        if (more && counter >= _bindingList.value.length) {
            getMore();
        }
        if (more && counter < _bindingList.value.length) {
            org.omg.CosNaming.Binding bndg = _bindingList.value[counter];
            counter++;
            return mapBinding(bndg);
        } else {
            throw new NoSuchElementException();
        }
    }


    /**
    * Returns true or false depending on whether there are more bindings.
    * @return boolean value
    */

    public boolean hasMore() throws NamingException {
        // If there's more, check whether current bindingList has been exhausted,
        // and if so, try to get more.
        // If no more, just say so.
        return more ? (counter < _bindingList.value.length || getMore()) : false;
    }

    /**
     * Returns true or false depending on whether there are more bindings.
     * Need to define this to satisfy the Enumeration api requirement.
     * @return boolean value
     */

    public boolean hasMoreElements() {
        try {
            return hasMore();
        } catch (NamingException e) {
            return false;
        }
    }

    /**
    * Returns the next binding in the list.
    * @exception NoSuchElementException Thrown when the end of the
    * list is reached.
    */

    public javax.naming.Binding nextElement() {
        try {
            return next();
        } catch (NamingException ne) {
            throw new NoSuchElementException();
        }
    }

    public void close() throws NamingException {
        more = false;
        if (_bindingIter != null) {
            _bindingIter.destroy();
            _bindingIter = null;
        }
        if (_ctx != null) {
            _ctx.decEnumCount();

            /**
             * context was obtained by CNCtx, the user doesn't have a handle to
             * it, close it as we are done enumerating through the context
             */
            if (isLookedUpCtx) {
                _ctx.close();
            }
            _ctx = null;
        }
    }

    protected void finalize() {
        try {
            close();
        } catch (NamingException e) {
            // ignore failures
        }
    }

    /**
     * Get the next batch using _bindingIter. Update the 'more' field.
     */
    private boolean getMore() throws NamingException {
        try {
            more = _bindingIter.next_n(batchsize, _bindingList);
            counter = 0; // reset
        } catch (Exception e) {
            more = false;
            NamingException ne = new NamingException(
                "Problem getting binding list");
            ne.setRootCause(e);
            throw ne;
        }
        return more;
    }

    /**
    * Constructs a JNDI Binding object from the COS Naming binding
    * object.
    * @exception NameNotFound No objects under the name.
    * @exception CannotProceed Unable to obtain a continuation context
    * @exception InvalidName Name not understood.
    * @exception NamingException One of the above.
    */

    private javax.naming.Binding mapBinding(org.omg.CosNaming.Binding bndg)
                throws NamingException {
        java.lang.Object obj = _ctx.callResolve(bndg.binding_name);

        Name cname = CNNameParser.cosNameToName(bndg.binding_name);

        try {
            obj = NamingManager.getObjectInstance(obj, cname, _ctx, _env);
        } catch (NamingException e) {
            throw e;
        } catch (Exception e) {
            NamingException ne = new NamingException(
                        "problem generating object using object factory");
            ne.setRootCause(e);
            throw ne;
        }

        // Use cname.toString() instead of bindingName because the name
        // in the binding should be a composite name
        String cnameStr = cname.toString();
        javax.naming.Binding jbndg = new javax.naming.Binding(cnameStr, obj);

        NameComponent[] comps = _ctx.makeFullName(bndg.binding_name);
        String fullName = CNNameParser.cosNameToInsString(comps);
        jbndg.setNameInNamespace(fullName);
        return jbndg;
    }
}