public static InputStream markSupportedInputStream()

in dubbo-common/src/main/java/org/apache/dubbo/common/io/StreamUtils.java [122:229]
84 lines of code
13 McCabe index (conditional complexity)

    public static InputStream markSupportedInputStream(final InputStream is, final int markBufferSize) {
        if (is.markSupported()) {
            return is;
        }

        return new InputStream() {
            byte[] mMarkBuffer;

            boolean mInMarked = false;
            boolean mInReset = false;
            boolean mDry = false;
            private int mPosition = 0;
            private int mCount = 0;

            @Override
            public int read() throws IOException {
                if (!mInMarked) {
                    return is.read();
                } else {
                    if (mPosition < mCount) {
                        byte b = mMarkBuffer[mPosition++];
                        return b & 0xFF;
                    }

                    if (!mInReset) {
                        if (mDry) {
                            return -1;
                        }

                        if (null == mMarkBuffer) {
                            mMarkBuffer = new byte[markBufferSize];
                        }
                        if (mPosition >= markBufferSize) {
                            throw new IOException("Mark buffer is full!");
                        }

                        int read = is.read();
                        if (-1 == read) {
                            mDry = true;
                            return -1;
                        }

                        mMarkBuffer[mPosition++] = (byte) read;
                        mCount++;

                        return read;
                    } else {
                        // mark buffer is used, exit mark status!
                        mInMarked = false;
                        mInReset = false;
                        mPosition = 0;
                        mCount = 0;

                        return is.read();
                    }
                }
            }

            /**
             * NOTE: the <code>readlimit</code> argument for this class
             *  has no meaning.
             */
            @Override
            public synchronized void mark(int readlimit) {
                mInMarked = true;
                mInReset = false;

                // mark buffer is not empty
                int count = mCount - mPosition;
                if (count > 0) {
                    System.arraycopy(mMarkBuffer, mPosition, mMarkBuffer, 0, count);
                    mCount = count;
                    mPosition = 0;
                }
            }

            @Override
            public synchronized void reset() throws IOException {
                if (!mInMarked) {
                    throw new IOException("should mark before reset!");
                }

                mInReset = true;
                mPosition = 0;
            }

            @Override
            public boolean markSupported() {
                return true;
            }

            @Override
            public int available() throws IOException {
                int available = is.available();

                if (mInMarked && mInReset) {
                    available += mCount - mPosition;
                }

                return available;
            }

            @Override
            public void close() throws IOException {
                is.close();
            }
        };
    }