software.amazon.nio.spi.s3.S3SeekableByteChannel Maven / Gradle / Ivy
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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0
*/
package software.amazon.nio.spi.s3;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.NonReadableChannelException;
import java.nio.channels.NonWritableChannelException;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.SeekableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.nio.file.OpenOption;
import java.nio.file.StandardOpenOption;
import java.time.Duration;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import software.amazon.awssdk.services.s3.S3AsyncClient;
import software.amazon.nio.spi.s3.util.TimeOutUtils;
class S3SeekableByteChannel implements SeekableByteChannel {
private static final Logger LOGGER = LoggerFactory.getLogger(S3SeekableByteChannel.class);
private long position;
private final S3Path path;
private final ReadableByteChannel readDelegate;
private final S3WritableByteChannel writeDelegate;
private boolean closed;
private long size = -1L;
S3SeekableByteChannel(S3Path s3Path, S3AsyncClient s3Client, Set options) throws IOException {
this(s3Path, s3Client, 0L, options, null, null);
}
private S3SeekableByteChannel(S3Path s3Path, S3AsyncClient s3Client, long startAt, Set options,
Long timeout, TimeUnit timeUnit) throws IOException {
position = startAt;
path = s3Path;
closed = false;
s3Path.getFileSystem().registerOpenChannel(this);
if (options.contains(StandardOpenOption.WRITE) && options.contains(StandardOpenOption.READ)) {
throw new IOException("This channel does not support read and write access simultaneously");
}
if (options.contains(StandardOpenOption.SYNC) || options.contains(StandardOpenOption.DSYNC)) {
throw new IOException("The SYNC/DSYNC options is not supported");
}
var config = s3Path.getFileSystem().configuration();
if (options.contains(StandardOpenOption.WRITE)) {
LOGGER.debug("using S3WritableByteChannel as write delegate for path '{}'", s3Path.toUri());
readDelegate = null;
var transferUtil = new S3TransferUtil(s3Client, timeout, timeUnit);
writeDelegate = new S3WritableByteChannel(s3Path, s3Client, transferUtil, options);
position = 0L;
} else if (options.contains(StandardOpenOption.READ) || options.isEmpty()) {
LOGGER.debug("using S3ReadAheadByteChannel as read delegate for path '{}'", s3Path.toUri());
readDelegate =
new S3ReadAheadByteChannel(s3Path, config.getMaxFragmentSize(), config.getMaxFragmentNumber(), s3Client, this,
timeout, timeUnit);
writeDelegate = null;
} else {
throw new IOException("Invalid channel mode");
}
}
/**
* Reads a sequence of bytes from this channel into the given buffer.
*
* Bytes are read starting at this channel's current position, and
* then the position is updated with the number of bytes actually read.
* Otherwise, this method behaves exactly as specified in the {@link
* ReadableByteChannel} interface.
*
* @param dst the destination buffer
* @return the number of bytes read or -1 if no more bytes can be read.
*/
@Override
public int read(ByteBuffer dst) throws IOException {
validateOpen();
if (readDelegate == null) {
throw new NonReadableChannelException();
}
return readDelegate.read(dst);
}
/**
* Writes a sequence of bytes to this channel from the given buffer.
*
*
Bytes are written starting at this channel's current position, unless
* the channel is connected to an entity such as a file that is opened with
* the {@link StandardOpenOption#APPEND APPEND} option, in
* which case the position is first advanced to the end. The entity to which
* the channel is connected will grow to accommodate the
* written bytes, and the position updates with the number of bytes
* actually written. Otherwise, this method behaves exactly as specified by
* the {@link WritableByteChannel} interface.
*
* @param src the src of the bytes to write to this channel
*/
@Override
public int write(ByteBuffer src) throws IOException {
validateOpen();
if (writeDelegate == null) {
throw new NonWritableChannelException();
}
var length = src.remaining();
this.position += length;
return writeDelegate.write(src);
}
/**
* Returns this channel's position.
*
* @return This channel's position,
* a non-negative integer counting the number of bytes
* from the beginning of the entity to the current position
*/
@Override
public long position() throws IOException {
validateOpen();
synchronized (this) {
return position;
}
}
/**
* Sets this channel's position.
*
*
Setting the position to a value that is greater than the current size
* is legal but does not change the size of the entity. A later attempt to
* read bytes at such a position will immediately return an end-of-file
* indication. A later attempt to write bytes at such a position will cause
* the entity to grow to accommodate the new bytes; the values of any bytes
* between the previous end-of-file and the newly-written bytes are
* unspecified.
*
*
Setting the channel's position is not recommended when connected to
* an entity, typically a file, that is opened with the {@link
* StandardOpenOption#APPEND APPEND} option. When opened for
* append, the position is first advanced to the end before writing.
*
* @param newPosition The new position, a non-negative integer counting
* the number of bytes from the beginning of the entity
* @return This channel
* @throws ClosedChannelException If this channel is closed
* @throws IllegalArgumentException If the new position is negative
* @throws IOException If some other I/O error occurs
*/
@Override
public SeekableByteChannel position(long newPosition) throws IOException {
if (newPosition < 0) {
throw new IllegalArgumentException("newPosition cannot be < 0");
}
if (!isOpen()) {
throw new ClosedChannelException();
}
// this is only valid to read channels
if (readDelegate == null) {
throw new NonReadableChannelException();
}
synchronized (this) {
position = newPosition;
return this;
}
}
/**
* Returns the current size of entity to which this channel is connected.
*
* @return The current size, measured in bytes
* @throws IOException If some other I/O error occurs
*/
@Override
public long size() throws IOException {
validateOpen();
if (size < 0) {
fetchSize();
}
return this.size;
}
private void fetchSize() throws IOException {
synchronized (this) {
this.size = S3BasicFileAttributes.get(path, Duration.ofMinutes(TimeOutUtils.TIMEOUT_TIME_LENGTH_1)).size();
LOGGER.debug("size of '{}' is '{}'", path.toUri(), this.size);
}
}
/**
* Truncates the entity, to which this channel is connected, to the given
* size.
*
*
If the given size is less than the current size then the entity is
* truncated, discarding any bytes beyond the new end. If the given size is
* greater than or equal to the current size then the entity is not modified.
* In either case, if the current position is greater than the given size
* then it is set to that size.
*
*
An implementation of this interface may prohibit truncation when
* connected to an entity, typically a file, opened with the {@link
* StandardOpenOption#APPEND APPEND} option.
*
* @param size The new size, a non-negative byte count
* @return This channel
*/
@Override
public SeekableByteChannel truncate(long size) {
throw new UnsupportedOperationException("Currently not supported");
}
/**
* Tells whether this channel is open.
*
* @return {@code true} if, and only if, this channels delegate is open
*/
@Override
public boolean isOpen() {
synchronized (this) {
return !this.closed;
}
}
/**
* Closes this channel.
*
*
After a channel is closed, any further attempt to invoke I/O
* operations upon it will cause a {@link ClosedChannelException} to be
* thrown.
*
*
If this channel is already closed then invoking this method has no
* effect.
*
*
This method may be invoked at any time. If some other thread has
* already invoked it, however, then another invocation will block until
* the first invocation is complete, after which it will return without
* effect.
*/
@Override
public void close() throws IOException {
synchronized (this) {
if (readDelegate != null) {
readDelegate.close();
}
if (writeDelegate != null) {
writeDelegate.close();
}
closed = true;
path.getFileSystem().deregisterClosedChannel(this);
}
}
private void validateOpen() throws ClosedChannelException {
if (this.closed) {
throw new ClosedChannelException();
}
}
/**
* Access the underlying {@code ReadableByteChannel} used for reading
*
* @return the channel. May be null if opened for writing only
*/
ReadableByteChannel getReadDelegate() {
return this.readDelegate;
}
/**
* Access the underlying {@code WritableByteChannel} used for writing
*
* @return the channel. May be null if opened for reading only
*/
WritableByteChannel getWriteDelegate() {
return this.writeDelegate;
}
}