/*
 * Copyright (c) 2008, 2019, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.nio.ch;

import java.nio.channels.*;
import java.util.*;
import jdk.internal.misc.Unsafe;

Maintains a mapping of pending I/O requests (identified by the address of an OVERLAPPED structure) to Futures.
/** * Maintains a mapping of pending I/O requests (identified by the address of * an OVERLAPPED structure) to Futures. */
class PendingIoCache { private static final Unsafe unsafe = Unsafe.getUnsafe(); private static final int addressSize = unsafe.addressSize(); private static int dependsArch(int value32, int value64) { return (addressSize == 4) ? value32 : value64; } /* * typedef struct _OVERLAPPED { * DWORD Internal; * DWORD InternalHigh; * DWORD Offset; * DWORD OffsetHigh; * HANDLE hEvent; * } OVERLAPPED; */ private static final int SIZEOF_OVERLAPPED = dependsArch(20, 32); // set to true when closed private boolean closed; // set to true when thread is waiting for all I/O operations to complete private boolean closePending; // maps OVERLAPPED to PendingFuture @SuppressWarnings("rawtypes") private final Map<Long,PendingFuture> pendingIoMap = new HashMap<Long,PendingFuture>(); // per-channel cache of OVERLAPPED structures private long[] overlappedCache = new long[4]; private int overlappedCacheCount = 0; PendingIoCache() { } long add(PendingFuture<?,?> result) { synchronized (this) { if (closed) throw new AssertionError("Should not get here"); long ov; if (overlappedCacheCount > 0) { ov = overlappedCache[--overlappedCacheCount]; } else { ov = unsafe.allocateMemory(SIZEOF_OVERLAPPED); } pendingIoMap.put(ov, result); return ov; } } @SuppressWarnings("unchecked") <V,A> PendingFuture<V,A> remove(long overlapped) { synchronized (this) { PendingFuture<V,A> res = pendingIoMap.remove(overlapped); if (res != null) { if (overlappedCacheCount < overlappedCache.length) { overlappedCache[overlappedCacheCount++] = overlapped; } else { // cache full or channel closing unsafe.freeMemory(overlapped); } // notify closing thread. if (closePending) { this.notifyAll(); } } return res; } } void close() { synchronized (this) { if (closed) return; // handle case where I/O operations that have not completed. if (!pendingIoMap.isEmpty()) clearPendingIoMap(); // release memory for any cached OVERLAPPED structures while (overlappedCacheCount > 0) { unsafe.freeMemory( overlappedCache[--overlappedCacheCount] ); } // done closed = true; } } private void clearPendingIoMap() { assert Thread.holdsLock(this); // wait up to 50ms for the I/O operations to complete closePending = true; try { this.wait(50); } catch (InterruptedException x) { Thread.currentThread().interrupt(); } closePending = false; if (pendingIoMap.isEmpty()) return; // cause all pending I/O operations to fail // simulate the failure of all pending I/O operations. for (Long ov: pendingIoMap.keySet()) { PendingFuture<?,?> result = pendingIoMap.get(ov); // make I/O port aware of the stale OVERLAPPED structure Iocp iocp = (Iocp)((Groupable)result.channel()).group(); iocp.makeStale(ov); // execute a task that invokes the result handler's failed method final Iocp.ResultHandler rh = (Iocp.ResultHandler)result.getContext(); Runnable task = new Runnable() { public void run() { rh.failed(-1, new AsynchronousCloseException()); } }; iocp.executeOnPooledThread(task); } pendingIoMap.clear(); } }