8187443: Forest Consolidation: Move files to unified layout

Reviewed-by: darcy, ihse

src/java.base/share/classes/sun/nio/fs/NativeBuffers.java

@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2008, 2009, 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.fs;
+
+import jdk.internal.misc.Unsafe;
+
+/**
+ * Factory for native buffers.
+ */
+
+class NativeBuffers {
+    private NativeBuffers() { }
+
+    private static final Unsafe unsafe = Unsafe.getUnsafe();
+
+    private static final int TEMP_BUF_POOL_SIZE = 3;
+    private static ThreadLocal<NativeBuffer[]> threadLocal =
+        new ThreadLocal<NativeBuffer[]>();
+
+    /**
+     * Allocates a native buffer, of at least the given size, from the heap.
+     */
+    static NativeBuffer allocNativeBuffer(int size) {
+        // Make a new one of at least 2k
+        if (size < 2048) size = 2048;
+        return new NativeBuffer(size);
+    }
+
+    /**
+     * Returns a native buffer, of at least the given size, from the thread
+     * local cache.
+     */
+    static NativeBuffer getNativeBufferFromCache(int size) {
+        // return from cache if possible
+        NativeBuffer[] buffers = threadLocal.get();
+        if (buffers != null) {
+            for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
+                NativeBuffer buffer = buffers[i];
+                if (buffer != null && buffer.size() >= size) {
+                    buffers[i] = null;
+                    return buffer;
+                }
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Returns a native buffer, of at least the given size. The native buffer
+     * is taken from the thread local cache if possible; otherwise it is
+     * allocated from the heap.
+     */
+    static NativeBuffer getNativeBuffer(int size) {
+        NativeBuffer buffer = getNativeBufferFromCache(size);
+        if (buffer != null) {
+            buffer.setOwner(null);
+            return buffer;
+        } else {
+            return allocNativeBuffer(size);
+        }
+    }
+
+    /**
+     * Releases the given buffer. If there is space in the thread local cache
+     * then the buffer goes into the cache; otherwise the memory is deallocated.
+     */
+    static void releaseNativeBuffer(NativeBuffer buffer) {
+        // create cache if it doesn't exist
+        NativeBuffer[] buffers = threadLocal.get();
+        if (buffers == null) {
+            buffers = new NativeBuffer[TEMP_BUF_POOL_SIZE];
+            buffers[0] = buffer;
+            threadLocal.set(buffers);
+            return;
+        }
+        // Put it in an empty slot if such exists
+        for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
+            if (buffers[i] == null) {
+                buffers[i] = buffer;
+                return;
+            }
+        }
+        // Otherwise replace a smaller one in the cache if such exists
+        for (int i=0; i<TEMP_BUF_POOL_SIZE; i++) {
+            NativeBuffer existing = buffers[i];
+            if (existing.size() < buffer.size()) {
+                existing.free();
+                buffers[i] = buffer;
+                return;
+            }
+        }
+
+        // free it
+        buffer.free();
+    }
+
+    /**
+     * Copies a byte array and zero terminator into a given native buffer.
+     */
+    static void copyCStringToNativeBuffer(byte[] cstr, NativeBuffer buffer) {
+        long offset = Unsafe.ARRAY_BYTE_BASE_OFFSET;
+        long len = cstr.length;
+        assert buffer.size() >= (len + 1);
+        unsafe.copyMemory(cstr, offset, null, buffer.address(), len);
+        unsafe.putByte(buffer.address() + len, (byte)0);
+    }
+
+    /**
+     * Copies a byte array and zero terminator into a native buffer, returning
+     * the buffer.
+     */
+    static NativeBuffer asNativeBuffer(byte[] cstr) {
+        NativeBuffer buffer = getNativeBuffer(cstr.length+1);
+        copyCStringToNativeBuffer(cstr, buffer);
+        return buffer;
+    }
+}