Cronet API Refactoring

components/cronet/android/api/src/org/chromium/net/InputStreamChannel.java

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package org.chromium.net;
-
-import java.io.FileInputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.nio.ByteBuffer;
-import java.nio.channels.ReadableByteChannel;
-import java.util.concurrent.atomic.AtomicBoolean;
-
-/**
- * Adapts an {@link InputStream} into a {@link ReadableByteChannel}, exactly like
- * {@link java.nio.channels.Channels#newChannel(InputStream)} does, but more efficiently, since it
- * does not allocate a temporary buffer if it doesn't have to, and it freely takes advantage of
- * {@link FileInputStream}'s trivial conversion to {@link java.nio.channels.FileChannel}.
- */
-final class InputStreamChannel implements ReadableByteChannel {
-    private static final int MAX_TMP_BUFFER_SIZE = 16384;
-    private static final int MIN_TMP_BUFFER_SIZE = 4096;
-    private final InputStream mInputStream;
-    private final AtomicBoolean mIsOpen = new AtomicBoolean(true);
-
-    private InputStreamChannel(InputStream inputStream) {
-        mInputStream = inputStream;
-    }
-
-    static ReadableByteChannel wrap(InputStream inputStream) {
-        if (inputStream instanceof FileInputStream) {
-            return ((FileInputStream) inputStream).getChannel();
-        }
-        return new InputStreamChannel(inputStream);
-    }
-
-    @Override
-    public int read(ByteBuffer dst) throws IOException {
-        final int read;
-        if (dst.hasArray()) {
-            read = mInputStream.read(
-                    dst.array(), dst.arrayOffset() + dst.position(), dst.remaining());
-            if (read > 0) {
-                dst.position(dst.position() + read);
-            }
-        } else {
-            // Since we're allocating a buffer for every read, we want to choose a good size - on
-            // Android, the only case where a ByteBuffer won't have a backing byte[] is if it was
-            // created wrapping a void * in native code, or if it represents a memory-mapped file.
-            // Especially in the latter case, we want to avoid allocating a buffer that could be
-            // very large.
-            final int possibleToRead = Math.min(
-                    Math.max(mInputStream.available(), MIN_TMP_BUFFER_SIZE), dst.remaining());
-            final int reasonableToRead = Math.min(MAX_TMP_BUFFER_SIZE, possibleToRead);
-            byte[] tmpBuf = new byte[reasonableToRead];
-            read = mInputStream.read(tmpBuf);
-            if (read > 0) {
-                dst.put(tmpBuf, 0, read);
-            }
-        }
-        return read;
-    }
-
-    @Override
-    public boolean isOpen() {
-        return mIsOpen.get();
-    }
-
-    @Override
-    public void close() throws IOException {
-        if (mIsOpen.compareAndSet(true, false)) {
-            mInputStream.close();
-        }
-    }
-}