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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/java/nio/channels/FileLock.java
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+/* FileLock.java --
+ Copyright (C) 2002, 2005 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+package java.nio.channels;
+
+import gnu.java.lang.CPStringBuilder;
+
+import java.io.IOException;
+
+/**
+ * @since 1.4
+ */
+public abstract class FileLock
+{
+ private final FileChannel channel;
+ private final long position;
+ private final long size;
+ private final boolean shared;
+
+ /**
+ * Initializes the file lock.
+ *
+ * @exception IllegalArgumentException If the preconditions on the parameters do not hold
+ */
+ protected FileLock(FileChannel channel, long position, long size,
+ boolean shared)
+ {
+ if (position < 0 || size < 0)
+ throw new IllegalArgumentException();
+
+ this.channel = channel;
+ this.position = position;
+ this.size = size;
+ this.shared = shared;
+ }
+
+ /**
+ * Tells whether or not this lock is valid.
+ */
+ public abstract boolean isValid();
+
+ /**
+ * Releases this lock.
+ *
+ * @exception IOException If an error occurs
+ * @exception ClosedChannelException If the locked channel is no longer open.
+ */
+ public abstract void release() throws IOException;
+
+ /**
+ * Returns the file channel upon whose file this lock is held.
+ */
+ public final FileChannel channel()
+ {
+ return channel;
+ }
+
+ /**
+ * Tells whether this lock is shared.
+ */
+ public final boolean isShared()
+ {
+ return shared;
+ }
+
+ /**
+ * Tells whether or not this lock overlaps the given lock range.
+ */
+ public final boolean overlaps(long position, long size)
+ {
+ if (position > this.position + this.size)
+ return false;
+
+ if (position + size < this.position)
+ return false;
+
+ return true;
+ }
+
+ /**
+ * Returns the position within the file of the first byte of the
+ * locked region.
+ */
+ public final long position()
+ {
+ return position;
+ }
+
+ /**
+ * Returns the size of the locked region in bytes.
+ */
+ public final long size()
+ {
+ return size;
+ }
+
+ /**
+ * Returns a string describing the range, type, and validity of this lock.
+ */
+ public final String toString()
+ {
+ CPStringBuilder buf = new CPStringBuilder(getClass().getName());
+ buf.append("[");
+ buf.append(position);
+ buf.append(":");
+ buf.append(size);
+ if (shared)
+ buf.append(" shared");
+ else
+ buf.append(" exclusive");
+ if (isValid())
+ buf.append(" valid]");
+ else
+ buf.append(" invalid]");
+ return buf.toString();
+ }
+}