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package ru.yandex.clickhouse.response;
import java.io.IOException;
import java.io.InputStream;
/**
* We have a stream of bytes and a separator as an input.
* We split the stream by the separator and pass the byte arrays to output.
*/
public class StreamSplitter {
private static final int buflen = 65536;
// initial parameters
private final InputStream delegate;
private final byte sep;
private byte[] buf;
// position until which the buf is filled with values read from delegate
private int posRead;
// position until which the values from buf already passed out through next()
private int posNext;
private int markedRead;
private int markedNext;
private boolean readOnce;
public StreamSplitter(ByteFragment bf, byte sep) {
this.delegate = bf.asStream();
this.sep = sep;
buf = new byte[bf.getLen()];
readOnce = true;
}
public StreamSplitter(InputStream delegate, byte sep, int buflen) {
this.delegate = delegate;
this.sep = sep;
buf = new byte[buflen];
}
public StreamSplitter(InputStream delegate, byte sep) {
this(delegate,sep, buflen);
}
public ByteFragment next() throws IOException {
// if sent out all that have read
if (posNext >= posRead) {
// need to read more from the stream
int readBytes = readFromStream();
if(readBytes <= 0) {
// if everything was sent out and there is nothing left in the stream
return null;
}
}
// looking for the separator
int positionSep;
while((positionSep = indexOf(buf, sep, posNext, posRead)) < posNext) {
// read from stream till we find the separator
int readBytes = readFromStream();
if(readBytes <= 0) {
// if there is nothing to read, return everything left as a result
positionSep = posRead;
break;
}
}
// if the separator is found, return the fragment
int fragmentStart = posNext;
posNext = positionSep+1;
return new ByteFragment(buf, fragmentStart, positionSep-fragmentStart);
}
// if there is no separator in read but not sent fragment - read more data
protected int readFromStream() throws IOException {
if (readOnce) {
if (posRead >= buf.length) {
return -1;
} else {
int read = delegate.read(buf, posRead, buf.length - posRead);
if(read > 0)
posRead += read;
return read;
}
} else {
if (posRead >= buf.length) { // buffer is filled
shiftOrResize();
}
int read = delegate.read(buf, posRead, buf.length - posRead);
if(read > 0)
posRead += read;
return read;
}
}
// if we have read till the end of buffer, we have to create a new buffer and move data by posNext (already send data position)
// if there is no sent data and buffer is still full - expand the buffer
private void shiftOrResize() {
if(posNext > 0) {
byte[] oldBuf = buf;
buf = new byte[buf.length];
System.arraycopy(oldBuf, posNext, buf, 0, oldBuf.length-posNext);
posRead -= posNext;
posNext = 0;
} else {
byte[] oldBuf = buf;
buf = new byte[buf.length*2];
System.arraycopy(oldBuf, 0, buf, 0, oldBuf.length);
}
}
private static int indexOf(byte[] array, byte target, int start, int end) {
for (int i = start; i < end; i++) {
if (array[i] == target) {
return i;
}
}
return -1;
}
public void close() throws IOException {
delegate.close();
}
@Override
public String toString() {
return "StreamSplitter{" +
"delegate=" + delegate +
", sep=" + sep +
", buf=" + new String(buf).trim() +
", posRead=" + posRead +
", posNext=" + posNext +
", readOnce=" + readOnce +
'}';
}
public void mark() {
markedRead = posRead;
markedNext = posNext;
}
public void reset() {
posRead = markedRead;
posNext = markedNext;
}
}
