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* This decoder is optimized to transfer data directly from the underlying * I/O session's channel to a {@link FileChannel}, whenever * possible avoiding intermediate buffering in the session buffer. * * @since 4.0 */ public class LengthDelimitedDecoder extends AbstractContentDecoder implements FileContentDecoder { private final long contentLength; private long len; public LengthDelimitedDecoder( final ReadableByteChannel channel, final SessionInputBuffer buffer, final BasicHttpTransportMetrics metrics, final long contentLength) { super(channel, buffer, metrics); Args.notNegative(contentLength, "Content length"); this.contentLength = contentLength; } @Override public int read(final ByteBuffer dst) throws IOException { Args.notNull(dst, "Byte buffer"); if (this.completed) { return -1; } final int chunk = (int) Math.min((this.contentLength - this.len), Integer.MAX_VALUE); final int bytesRead; if (this.buffer.hasData()) { final int maxLen = Math.min(chunk, this.buffer.length()); bytesRead = this.buffer.read(dst, maxLen); } else { bytesRead = readFromChannel(dst, chunk); } if (bytesRead == -1) { this.completed = true; if (this.len < this.contentLength) { throw new ConnectionClosedException( "Premature end of Content-Length delimited message body (expected: " + this.contentLength + "; received: " + this.len); } } this.len += bytesRead; if (this.len >= this.contentLength) { this.completed = true; } if (this.completed && bytesRead == 0) { return -1; } return bytesRead; } @Override public long transfer( final FileChannel dst, final long position, final long count) throws IOException { if (dst == null) { return 0; } if (this.completed) { return -1; } final int chunk = (int) Math.min((this.contentLength - this.len), Integer.MAX_VALUE); final long bytesRead; if (this.buffer.hasData()) { final int maxLen = Math.min(chunk, this.buffer.length()); dst.position(position); bytesRead = this.buffer.read(dst, maxLen); } else { if (this.channel.isOpen()) { if (position > dst.size()) { throw new IOException("Position past end of file [" + position + " > " + dst.size() + "]"); } bytesRead = dst.transferFrom(this.channel, position, count < chunk ? count : chunk); } else { bytesRead = -1; } if (bytesRead > 0) { this.metrics.incrementBytesTransferred(bytesRead); } } if (bytesRead == -1) { this.completed = true; if (this.len < this.contentLength) { throw new ConnectionClosedException( "Premature end of Content-Length delimited message body (expected: " + this.contentLength + "; received: " + this.len); } } this.len += bytesRead; if (this.len >= this.contentLength) { this.completed = true; } return bytesRead; } @Override public String toString() { final StringBuilder sb = new StringBuilder(); sb.append("[content length: "); sb.append(this.contentLength); sb.append("; pos: "); sb.append(this.len); sb.append("; completed: "); sb.append(this.completed); sb.append("]"); return sb.toString(); } }