Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.ignite.internal.processors.hadoop.igfs; import org.apache.commons.logging.*; import org.apache.hadoop.fs.*; import org.apache.ignite.*; import org.apache.ignite.internal.*; import org.apache.ignite.internal.igfs.common.*; import org.apache.ignite.internal.util.typedef.internal.*; import org.jetbrains.annotations.*; import java.io.*; /** * IGFS input stream wrapper for hadoop interfaces. */ @SuppressWarnings("FieldAccessedSynchronizedAndUnsynchronized") public final class HadoopIgfsInputStream extends InputStream implements Seekable, PositionedReadable, HadoopIgfsStreamEventListener { /** Minimum buffer size. */ private static final int MIN_BUF_SIZE = 4 * 1024; /** Server stream delegate. */ private HadoopIgfsStreamDelegate delegate; /** Stream ID used by logger. */ private long logStreamId; /** Stream position. */ private long pos; /** Stream read limit. */ private long limit; /** Mark position. */ private long markPos = -1; /** Prefetch buffer. */ private DoubleFetchBuffer buf = new DoubleFetchBuffer(); /** Buffer half size for double-buffering. */ private int bufHalfSize; /** Closed flag. */ private volatile boolean closed; /** Flag set if stream was closed due to connection breakage. */ private boolean connBroken; /** Logger. */ private Log log; /** Client logger. */ private IgfsLogger clientLog; /** Read time. */ private long readTime; /** User time. */ private long userTime; /** Last timestamp. */ private long lastTs; /** Amount of read bytes. */ private long total; /** * Creates input stream. * * @param delegate Server stream delegate. * @param limit Read limit. * @param bufSize Buffer size. * @param log Log. * @param clientLog Client logger. */ public HadoopIgfsInputStream(HadoopIgfsStreamDelegate delegate, long limit, int bufSize, Log log, IgfsLogger clientLog, long logStreamId) { assert limit >= 0; this.delegate = delegate; this.limit = limit; this.log = log; this.clientLog = clientLog; this.logStreamId = logStreamId; bufHalfSize = Math.max(bufSize, MIN_BUF_SIZE); lastTs = System.nanoTime(); delegate.hadoop().addEventListener(delegate, this); } /** * Read start. */ private void readStart() { long now = System.nanoTime(); userTime += now - lastTs; lastTs = now; } /** * Read end. */ private void readEnd() { long now = System.nanoTime(); readTime += now - lastTs; lastTs = now; } /** {@inheritDoc} */ @Override public synchronized int read() throws IOException { checkClosed(); readStart(); try { if (eof()) return -1; buf.refreshAhead(pos); int res = buf.atPosition(pos); pos++; total++; buf.refreshAhead(pos); return res; } catch (IgniteCheckedException e) { throw HadoopIgfsUtils.cast(e); } finally { readEnd(); } } /** {@inheritDoc} */ @Override public synchronized int read(@NotNull byte[] b, int off, int len) throws IOException { checkClosed(); if (eof()) return -1; readStart(); try { long remaining = limit - pos; int read = buf.flatten(b, pos, off, len); pos += read; total += read; remaining -= read; if (remaining > 0 && read != len) { int readAmt = (int) Math.min(remaining, len - read); delegate.hadoop().readData(delegate, pos, readAmt, b, off + read, len - read).get(); read += readAmt; pos += readAmt; total += readAmt; } buf.refreshAhead(pos); return read; } catch (IgniteCheckedException e) { throw HadoopIgfsUtils.cast(e); } finally { readEnd(); } } /** {@inheritDoc} */ @Override public synchronized long skip(long n) throws IOException { checkClosed(); if (clientLog.isLogEnabled()) clientLog.logSkip(logStreamId, n); long oldPos = pos; if (pos + n <= limit) pos += n; else pos = limit; buf.refreshAhead(pos); return pos - oldPos; } /** {@inheritDoc} */ @Override public synchronized int available() throws IOException { checkClosed(); int available = buf.available(pos); assert available >= 0; return available; } /** {@inheritDoc} */ @Override public synchronized void close() throws IOException { if (!closed) { readStart(); if (log.isDebugEnabled()) log.debug("Closing input stream: " + delegate); delegate.hadoop().closeStream(delegate); readEnd(); if (clientLog.isLogEnabled()) clientLog.logCloseIn(logStreamId, userTime, readTime, total); markClosed(false); if (log.isDebugEnabled()) log.debug("Closed stream [delegate=" + delegate + ", readTime=" + readTime + ", userTime=" + userTime + ']'); } } /** {@inheritDoc} */ @Override public synchronized void mark(int readLimit) { markPos = pos; if (clientLog.isLogEnabled()) clientLog.logMark(logStreamId, readLimit); } /** {@inheritDoc} */ @Override public synchronized void reset() throws IOException { checkClosed(); if (clientLog.isLogEnabled()) clientLog.logReset(logStreamId); if (markPos == -1) throw new IOException("Stream was not marked."); pos = markPos; buf.refreshAhead(pos); } /** {@inheritDoc} */ @Override public boolean markSupported() { return true; } /** {@inheritDoc} */ @Override public synchronized int read(long position, byte[] buf, int off, int len) throws IOException { long remaining = limit - position; int read = (int) Math.min(len, remaining); // Return -1 at EOF. if (read == 0) return -1; readFully(position, buf, off, read); return read; } /** {@inheritDoc} */ @Override public synchronized void readFully(long position, byte[] buf, int off, int len) throws IOException { long remaining = limit - position; checkClosed(); if (len > remaining) throw new EOFException("End of stream reached before data was fully read."); readStart(); try { int read = this.buf.flatten(buf, position, off, len); total += read; if (read != len) { int readAmt = len - read; delegate.hadoop().readData(delegate, position + read, readAmt, buf, off + read, readAmt).get(); total += readAmt; } if (clientLog.isLogEnabled()) clientLog.logRandomRead(logStreamId, position, len); } catch (IgniteCheckedException e) { throw HadoopIgfsUtils.cast(e); } finally { readEnd(); } } /** {@inheritDoc} */ @Override public void readFully(long position, byte[] buf) throws IOException { readFully(position, buf, 0, buf.length); } /** {@inheritDoc} */ @Override public synchronized void seek(long pos) throws IOException { A.ensure(pos >= 0, "position must be non-negative"); checkClosed(); if (clientLog.isLogEnabled()) clientLog.logSeek(logStreamId, pos); if (pos > limit) pos = limit; if (log.isDebugEnabled()) log.debug("Seek to position [delegate=" + delegate + ", pos=" + pos + ", oldPos=" + this.pos + ']'); this.pos = pos; buf.refreshAhead(pos); } /** {@inheritDoc} */ @Override public synchronized long getPos() { return pos; } /** {@inheritDoc} */ @Override public synchronized boolean seekToNewSource(long targetPos) { return false; } /** {@inheritDoc} */ @Override public void onClose() { markClosed(true); } /** {@inheritDoc} */ @Override public void onError(String errMsg) { // No-op. } /** * Marks stream as closed. * * @param connBroken {@code True} if connection with server was lost. */ private void markClosed(boolean connBroken) { // It is ok to have race here. if (!closed) { closed = true; this.connBroken = connBroken; delegate.hadoop().removeEventListener(delegate); } } /** * @throws IOException If check failed. */ private void checkClosed() throws IOException { if (closed) { if (connBroken) throw new IOException("Server connection was lost."); else throw new IOException("Stream is closed."); } } /** * @return {@code True} if end of stream reached. */ private boolean eof() { return limit == pos; } /** * Asynchronous prefetch buffer. */ private static class FetchBufferPart { /** Read future. */ private IgniteInternalFuture<byte[]> readFut; /** Position of cached chunk in file. */ private long pos; /** Prefetch length. Need to store as read future result might be not available yet. */ private int len; /** * Creates fetch buffer part. * * @param readFut Read future for this buffer. * @param pos Read position. * @param len Chunk length. */ private FetchBufferPart(IgniteInternalFuture<byte[]> readFut, long pos, int len) { this.readFut = readFut; this.pos = pos; this.len = len; } /** * Copies cached data if specified position matches cached region. * * @param dst Destination buffer. * @param pos Read position in file. * @param dstOff Offset in destination buffer from which start writing. * @param len Maximum number of bytes to copy. * @return Number of bytes copied. * @throws IgniteCheckedException If read future failed. */ public int flatten(byte[] dst, long pos, int dstOff, int len) throws IgniteCheckedException { // If read start position is within cached boundaries. if (contains(pos)) { byte[] data = readFut.get(); int srcPos = (int) (pos - this.pos); int cpLen = Math.min(len, data.length - srcPos); U.arrayCopy(data, srcPos, dst, dstOff, cpLen); return cpLen; } return 0; } /** * @return {@code True} if data is ready to be read. */ public boolean ready() { return readFut.isDone(); } /** * Checks if current buffer part contains given position. * * @param pos Position to check. * @return {@code True} if position matches buffer region. */ public boolean contains(long pos) { return this.pos <= pos && this.pos + len > pos; } } private class DoubleFetchBuffer { /** */ private FetchBufferPart first; /** */ private FetchBufferPart second; /** * Copies fetched data from both buffers to destination array if cached region matched read position. * * @param dst Destination buffer. * @param pos Read position in file. * @param dstOff Destination buffer offset. * @param len Maximum number of bytes to copy. * @return Number of bytes copied. * @throws IgniteCheckedException If any read operation failed. */ public int flatten(byte[] dst, long pos, int dstOff, int len) throws IgniteCheckedException { assert dstOff >= 0; assert dstOff + len <= dst.length : "Invalid indices [dst.length=" + dst.length + ", dstOff=" + dstOff + ", len=" + len + ']'; int bytesCopied = 0; if (first != null) { bytesCopied += first.flatten(dst, pos, dstOff, len); if (bytesCopied != len && second != null) { assert second.pos == first.pos + first.len; bytesCopied += second.flatten(dst, pos + bytesCopied, dstOff + bytesCopied, len - bytesCopied); } } return bytesCopied; } /** * Gets byte at specified position in buffer. * * @param pos Stream position. * @return Read byte. * @throws IgniteCheckedException If read failed. */ public int atPosition(long pos) throws IgniteCheckedException { // Should not reach here if stream contains no data. assert first != null; if (first.contains(pos)) { byte[] bytes = first.readFut.get(); return bytes[((int) (pos - first.pos))] & 0xFF; } else { assert second != null; assert second.contains(pos); byte[] bytes = second.readFut.get(); return bytes[((int) (pos - second.pos))] & 0xFF; } } /** * Starts asynchronous buffer refresh if needed, depending on current position. * * @param pos Current stream position. */ public void refreshAhead(long pos) { if (fullPrefetch(pos)) { first = fetch(pos, bufHalfSize); second = fetch(pos + bufHalfSize, bufHalfSize); } else if (needFlip(pos)) { first = second; second = fetch(first.pos + first.len, bufHalfSize); } } /** * @param pos Position from which read is expected. * @return Number of bytes available to be read without blocking. */ public int available(long pos) { int available = 0; if (first != null) { if (first.contains(pos)) { if (first.ready()) { available += (pos - first.pos); if (second != null && second.ready()) available += second.len; } } else { if (second != null && second.contains(pos) && second.ready()) available += (pos - second.pos); } } return available; } /** * Checks if position shifted enough to forget previous buffer. * * @param pos Current position. * @return {@code True} if need flip buffers. */ private boolean needFlip(long pos) { // Return true if we read more then half of second buffer. return second != null && second.contains(pos); } /** * Determines if all cached bytes should be discarded and new region should be * prefetched. * * @param curPos Current stream position. * @return {@code True} if need to refresh both blocks. */ private boolean fullPrefetch(long curPos) { // If no data was prefetched yet, return true. return first == null || curPos < first.pos || (second != null && curPos >= second.pos + second.len); } /** * Starts asynchronous fetch for given region. * * @param pos Position to read from. * @param size Number of bytes to read. * @return Fetch buffer part. */ private FetchBufferPart fetch(long pos, int size) { long remaining = limit - pos; size = (int) Math.min(size, remaining); return size <= 0 ? null : new FetchBufferPart(delegate.hadoop().readData(delegate, pos, size, null, 0, 0), pos, size); } } }