com.bigdata.service.ResourceService Maven / Gradle / Ivy
/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Feb 18, 2009
*/
package com.bigdata.service;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.nio.channels.OverlappingFileLockException;
import java.nio.channels.SocketChannel;
import java.util.UUID;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.zip.Adler32;
import java.util.zip.CheckedInputStream;
import org.apache.log4j.Logger;
import com.bigdata.btree.IndexSegmentStore;
import com.bigdata.counters.CAT;
import com.bigdata.counters.CounterSet;
import com.bigdata.counters.Instrument;
import com.bigdata.io.ByteBufferInputStream;
import com.bigdata.io.ByteBufferOutputStream;
import com.bigdata.util.Bytes;
import com.bigdata.util.DaemonThreadFactory;
import com.bigdata.util.concurrent.ShutdownHelper;
/**
* A service which permits resources (managed files or buffers) identified by a
* {@link UUID} to be read by a remote service. This class runs one thread to
* accept connections and thread pool to send data.
*
* @author Bryan Thompson
* @version $Id$
*
* @todo This class was derived from the {@link ResourceService} in the HA
* branch. The NIO pieces of this class should be based on the work in the
* HA branch on the write replication pipeline. The main structure of this
* class is based on the {@link ResourceService} since it allows
* concurrent connections, which the write pipeline does not support
* (because it is designed specifically for a node to node streaming
* replication protocol), however the class as originally implemented does
* not allow us to keep connections open.
*
* @todo Nodes should hold open connections for buffer transfers to avoid
* overhead with establishing those connections and problems with
* immediate reconnect under heavy load.
*
* @todo Should have start() method to defer initialization of thread pools and
* the {@link ServerSocket} until outside of the constructor. Either
* handle visibility appropriately for those fields or move them and the
* shutdown protocol into an inner class which is only initialized when
* the service is running.
*
* @todo Verify that multiple transfers may proceed in parallel to the from the
* same source to the same receiver. This is important in order for low
* latency queries to remain lively when we are moving a shard from one
* node to another. This also suggests that we may want to have different
* pools for servicing buffer requests for low latency queries versus
* requests for high latency queries and shards.
*
* @todo If we had an {@link Adler32} native implementation then we could
* checksum the nio {@link ByteBuffer}s without copying the data into the
* Java heap. The {@link Adler32} implementation is based on zlib, which
* is an acceptable license. So we might create a JNI component for that.
* Also, there may be direct JNI calls available into the underlying zlib
* library from Java.
*
* This could be created in a fairly straightforward manner by bundling
* zlib, bundling a Make file for our JNI components, and using
* GetDirectByteBufferAddress to access the data on the C
* heap. See JNI Spec, JNI FAQ,
* and ZLib project.
*
* @todo The change log for this class is as follows:
*
* - hold open connections in order to avoid problems with socket
* reconnects;
*
* - exchange buffers using NIO transfers rather than sending files using
* standard file IO and streams.
*
* - done. make the counter updates thread safe using {@link CAT}s.
*
* - added generics to the base class used to fetch files or buffers.
*
* - added a {@link ResourceTypeEnum} byte in the request protocol (breaks
* compatibility for earlier versions of this service).
*/
public abstract class ResourceService {
protected static final Logger log = Logger.getLogger(ResourceService.class);
/**
* The Internet socket address at which the service is accepting
* connections.
*/
private final InetSocketAddress addr;
// /**
// * The port on which the service is accepting connections.
// */
// public final int port;
/**
* The server socket.
*/
private final ServerSocket ss;
/**
* true once running and until closed.
*/
private volatile boolean open = false;
/**
* Performance counters for this service.
*/
public final Counters counters = new Counters();
/**
* Return the address at which this service is accepting connections.
*/
public InetSocketAddress getAddr() {
return addr;
}
// /**
// * Constructor uses the default nic, any free port, and the default request
// * service pool size.
// *
// * @throws IOException
// */
// public ResourceService() throws IOException {
//
// this(0/* port */, 0/* requestServicePoolSize */);
//
// }
//
// /**
// * Constructor uses the default nic and request service pool size.
// *
// * @param port
// * The port on which to start the service or ZERO (0) to use any
// * open port.
// *
// * @throws IOException
// */
// public ResourceService(final int port) throws IOException {
//
// this(port, 0/* requestServicePoolSize */);
//
// }
//
// /**
// * Constructor uses a non-loopback address on the default nic.
// *
// * @param port
// * The port on which to start the service or ZERO (0) to use any
// * open port.
// * @param requestServicePoolSize
// * The size of the thread pool that will handle requests. When
// * ZERO (0) a cached thread pool will be used with no specific
// * size limit.
// *
// * @throws IOException
// *
// * @see {@link NicUtil#getIpAddress(String, String, boolean)}
// */
// public ResourceService(final int port, final int requestServicePoolSize)
// throws IOException {
//
// this(new InetSocketAddress(InetAddress.getByName(NicUtil.getIpAddress(
// "default.nic"/* systemPropertyName */,
// "default"/* defaultNicName */, false/* loopbackOk */)), port),
// requestServicePoolSize);
//
// }
/**
* Create and start the service.
*
* @param addr
* The IP address and port at which the service will accept
* connections. The port MAY be zero to use an ephemeral port.
* @param requestServicePoolSize
* The size of the thread pool that will handle requests. When
* ZERO (0) a cached thread pool will be used with no specific
* size limit.
*
* @throws IOException
*/
public ResourceService(final InetSocketAddress addr,
final int requestServicePoolSize) throws IOException {
if (addr == null)
throw new IllegalArgumentException();
if (requestServicePoolSize < 0)
throw new IllegalArgumentException();
/*
* Create the ServerSocket using the specified port (which may be ZERO),
* the default backlog, and the specified IP address.
*/
ss = new ServerSocket(addr.getPort(), 0/* default backlog */, addr
.getAddress());
/*
* Save off a version of [addr] in which the actual port which reflects
* the actual port at which service is running.
*/
this.addr = new InetSocketAddress(addr.getAddress(), ss.getLocalPort());
if (log.isInfoEnabled())
log.info("Running on addr=" + this.addr);
if (requestServicePoolSize == 0) {
requestService = (ThreadPoolExecutor) Executors
.newCachedThreadPool(new DaemonThreadFactory(getClass()
.getName()
+ ".requestService"));
} else {
requestService = (ThreadPoolExecutor) Executors.newFixedThreadPool(
requestServicePoolSize, new DaemonThreadFactory(getClass()
.getName()
+ ".requestService"));
}
// Begin accepting connections.
acceptService.submit(new AcceptTask());
}
// /**
// * Return an unused port.
// *
// * @param suggestedPort
// * The suggested port.
// *
// * @return The suggested port, unless it is zero or already in use, in which
// * case an unused port is returned.
// *
// * @throws IOException
// */
// static protected int getPort(int suggestedPort) throws IOException {
// ServerSocket openSocket;
// try {
// openSocket = new ServerSocket(suggestedPort);
// } catch (BindException ex) {
// // the port is busy, so look for a random open port
// openSocket = new ServerSocket(0);
// }
// final int port = openSocket.getLocalPort();
// openSocket.close();
// return port;
// }
/**
* Overridden to ensure that the service is always shutdown.
*/
@Override
protected void finalize() throws Throwable {
shutdownNow();
super.finalize();
}
/**
* Wait until the service is running.
*
* @param timeout
* The timeout.
* @param unit
* The unit for the timeout.
* @throws InterruptedException
* if interrupted while waiting.
* @throws TimeoutException
* if the timeout expired before the service was running.
*/
public void awaitRunning(final long timeout, final TimeUnit unit)
throws InterruptedException, TimeoutException {
// the start time in nanoseconds.
final long begin = System.nanoTime();
// the timeout in nanoseconds.
final long nanos = unit.toNanos(timeout);
// the time remaining in nanoseconds.
long remaining = nanos;
if (lock.tryLock(remaining, TimeUnit.NANOSECONDS)) {
try {
while (!open) {
remaining = nanos - (System.nanoTime() - begin);
if (!running.await(remaining, TimeUnit.NANOSECONDS)) {
// timeout
break;
}
}
if (open)
return;
} finally {
lock.unlock();
}
}
throw new TimeoutException();
}
private final Lock lock = new ReentrantLock();
private final Condition running = lock.newCondition();
/**
* Class handles the accept of new connections. Only a single instance of
* this task will be executed over the life of the service. Each connection
* runs a {@link RequestTask}. The connection requests a resource using its
* {@link UUID}. If the resource is available, etc., then it is shipped back
* over the socket.
*/
private class AcceptTask implements Runnable {
public void run() {
lock.lock();
try {
open = true;
running.signal();
} finally {
lock.unlock();
}
try {
while (open) {
/*
* Hand off request to a pool of worker threads.
*
* Note: The Future of this task is ignored. If there is a
* problem a message is logged, the client socket is closed,
* the execution of the task is aborted.
*
* @todo this thread per accepted connection pattern does
* not allow us to keep the connections open for a given
* node.
*/
requestService.submit(new RequestTask(ss.accept()));
}
} catch (IOException ex) {
if (!open) {
if (log.isInfoEnabled())
log.info("closed.");
return;
}
log.error(ex);
}
}
}
/**
* Runs a single thread which accepts connections.
*/
private final ExecutorService acceptService = Executors
.newSingleThreadExecutor(new DaemonThreadFactory(getClass()
.getName()
+ ".acceptService"));
/**
* Runs a pool of threads for handling requests.
*/
private final ExecutorService requestService;
public boolean isOpen() {
return open;
}
/**
* @todo Is there a possible lock ordering problem with synchronized
* {@link #shutdown()} and {@link #shutdownNow()} methods and the
* internal {@link #lock}?
*/
synchronized public void shutdown() {
if (!isOpen()) {
log.warn("Not running");
}
if (log.isInfoEnabled())
log.info("");
/*
* Immediate shutdown of the accept thread. No new requests will be
* accepted or will start.
*/
acceptService.shutdownNow();
try {
new ShutdownHelper(requestService, 10/* logTimeout */, TimeUnit.SECONDS) {
public void logTimeout() {
log.warn("Awaiting request service termination: elapsed="
+ TimeUnit.NANOSECONDS.toMillis(elapsed()) + "ms");
}
};
} catch (InterruptedException ex) {
log.warn("Interrupted awaiting request service termination.");
}
// Note: Runnable will terminate when open == false.
open = false;
try {
ss.close();
} catch (IOException e) {
log.warn(e);
}
}
synchronized public void shutdownNow() {
if (!isOpen()) {
return;
}
if (log.isInfoEnabled())
log.info("");
// cancel the single AcceptTask.
acceptService.shutdownNow();
requestService.shutdownNow();
// Note: Runnable will terminate when open == false.
open = false;
try {
ss.close();
} catch (IOException e) {
log.warn(e);
}
}
/**
* Known status codes.
*/
public enum StatusEnum {
OK(0), DENY(1), NOT_FOUND(2), INTERNAL_ERROR(3), ;
private final byte b;
private StatusEnum(final int b) {
this.b = (byte) b;
}
public byte get() {
return b;
}
public static StatusEnum valueOf(final byte b) {
switch (b) {
case 0:
return OK;
case 1:
return NOT_FOUND;
case 2:
return INTERNAL_ERROR;
default:
throw new IllegalArgumentException("Invalid byte: " + b);
}
}
}
/**
* Type safe enumeration of the kinds of resources which can be served.
*/
public static enum ResourceTypeEnum {
FILE(0), BUFFER(1);
private final byte b;
private ResourceTypeEnum(final int b) {
this.b = (byte) b;
}
public byte get() {
return b;
}
public static ResourceTypeEnum valueOf(final byte b) {
switch (b) {
case 0:
return FILE;
case 1:
return BUFFER;
default:
throw new IllegalArgumentException("Invalid byte: " + b);
}
}
}
/**
* Handles a request and is run (by the caller) on a worker thread pool.
*
* The request consists of the following fields:
*
* - resource type
* - The {@link ResourceTypeEnum}, represented as a single byte.
* - resource identifier
* - The {@link UUID} of the resource to be read.
*
*
* The response consists for the following fields:
*
* - status
* - A single byte. 0 is Ok. Anything else is an error. The defined status
* codes are:
*
* - 0
* - Ok. The data will be sent.
* - 1
* - Resource not found (there is no managed resource for that UUID).
*
*
*
*
*
* The rest of the fields only apply for normal operation.
* - length
* - A 64-bit integer in network byte order specifying the length of the
* file.
* - data
* - the data bytes.
* - checksum
* - A 64-bit long in network byte order specifying the {@link Adler32}
* checksum of the data bytes as computed by the service. The receiver
* should compute the checksum on its end and verify that they agree.
*
* If anything goes wrong then the socket will be asynchronously closed by
* the service.
*/
private class RequestTask implements Runnable {
/**
* The client socket.
*/
final private Socket s;
/**
* Set true once we sent the status code and any associated data in the
* header.
*
* Note: Once we send the status and the header (file length) we flush
* the output stream and are committed to the response. At that point we
* can no longer send an error code instead. All we can do is log the
* error and close the client socket.
*/
private boolean sentStatus = false;
/**
*
* @param s
* The client socket.
*/
public RequestTask(final Socket s) {
this.s = s;
counters.requestCount.increment();
}
/**
* Note: {@link OverlappingFileLockException}s can arise when there are
* concurrent requests to obtain a shared lock on the same file.
* Personally, I think that this is a bug since the lock requests are
* shared and should be processed without deadlock. However, the code
* handles this case by proceeding without the lock - exactly as it
* would handle the case where a shared lock was not available. This is
* still somewhat fragile since it someone does not test the
* {@link FileLock} and was in fact granted an exclusive lock when they
* requested a shared lock then this code will be unwilling to send the
* resource. There are two ways to make that work out - either we DO NOT
* use {@link FileLock} for read-only files (index segments) or we
* ALWAYS discard the {@link FileLock} if it is not shared when we
* requested a shared lock and proceed without a lock. For this reason,
* the behavior of this class and {@link IndexSegmentStore} MUST match.
*
* @see IndexSegmentStore
* @see http://blogs.sun.com/DaveB/entry/new_improved_in_java_se1
* @see http://forums.sun.com/thread.jspa?threadID=5324314.
*/
public void run() {
if (log.isInfoEnabled())
log.info("localPort=" + s.getLocalPort());
InputStream is = null;
try {
is = s.getInputStream();
// the buffer size is limited to the size of a UUID.
final DataInputStream in = new DataInputStream(
new BufferedInputStream(is, Bytes.SIZEOF_UUID));
final ResourceTypeEnum resourceType = ResourceTypeEnum.valueOf(in.readByte());
final long mostSigBits = in.readLong();
final long leastSigBits = in.readLong();
final UUID uuid = new UUID(mostSigBits, leastSigBits);
if (log.isInfoEnabled())
log.info("Requested: uuid=" + uuid);
switch (resourceType) {
case FILE: {
final File file = getResource(uuid);
if (file == null) {
sendError(StatusEnum.NOT_FOUND);
return;
}
sendFile(uuid, file);
break;
}
case BUFFER: {
final ByteBuffer buffer = getBuffer(uuid);
if (buffer == null) {
sendError(StatusEnum.NOT_FOUND);
return;
}
sendBuffer(uuid, buffer);
break;
}
default:
sendError(StatusEnum.NOT_FOUND);
return;
}
} catch (SentErrorException ex) {
/*
* This exception is thrown by sendError(). We don't have to do
* anything since an error response was already sent.
*/
} catch (Throwable t) {
/*
* Something unexpected. If possible we will send an error
* response. Otherwise we just close the client socket.
*/
try {
log.error("Unknown error: " + t, t);
sendError(StatusEnum.INTERNAL_ERROR);
return;
} catch (Throwable t2) {
// ignore.
}
} finally {
if (is != null) {
try {
// close the request input stream.
is.close();
} catch (IOException ex) {
/* ignore */
} finally {
is = null;
}
}
try {
// close the client socket.
s.close();
} catch (IOException ex) {
/* ignore */
}
}
}
/**
* Send an error response.
*
* @param e
* The error code.
* @throws SentErrorException
* normally.
* @throws IOException
* if we can't write on the client socket.
*/
private void sendError(final StatusEnum e) throws SentErrorException, IOException {
assert e != null;
assert e != StatusEnum.OK;
switch (e) {
case OK:
throw new AssertionError();
case DENY:
counters.denyCount.increment();
break;
case NOT_FOUND:
counters.notFoundCount.increment();
break;
case INTERNAL_ERROR:
counters.internalErrorCount.increment();
break;
default:
throw new AssertionError();
}
if (!sentStatus) {
final OutputStream os = s.getOutputStream();
try {
os.write(new byte[] { e.get() });
os.flush();
} finally {
sentStatus = true;
os.close();
}
}
throw new SentErrorException();
}
/**
* Prepare and send a file.
*
* @param uuid
* The identifier for the file resource.
* @param file
* The corresponding file in the file system.
*
* @throws SentErrorException
* @throws IOException
*/
private final void sendFile(final UUID uuid, final File file)
throws SentErrorException, IOException {
final long length = file.length();
if (log.isInfoEnabled())
log.info("Sending " + file + ", length=" + length + ", uuid=" + uuid);
// Open the file to be sent.
final FileInputStream fis;
try {
fis = new FileInputStream(file);
} catch (IOException ex) {
log.error("Sending " + file + ", length=" + length + ", uuid=" + uuid, ex);
sendError(StatusEnum.INTERNAL_ERROR);
return;
}
// try block used to ensure that we close [fis] in finally{}.
final FileLock fileLock;
try {
/*
* Seek a shared lock on the file. This will prevent it from
* being deleted while we are sending its data and it will also
* prevent us from sending a file on which someone else has a
* write lock. If we can't get a shared lock then no worries.
*
* Note: The FileLock will be released when we close the
* FileChannel on which it depends.
*/
try {
fileLock = fis.getChannel().tryLock(0, Long.MAX_VALUE, true/* shared */);
if (fileLock == null) {
throw new IOException("Resource is locked: " + file);
}
if (!fileLock.isShared()) {
/*
* Do NOT hold the file lock if it is exclusive
* (shared lock requests convert to exclusive lock
* requests on some platforms). We do not want to
* prevent others from accessing this resource,
* especially not the StoreManager itself.
*/
fileLock.release();
}
} catch (OverlappingFileLockException ex) {
/*
* Note: OverlappingFileLockException can be thrown when
* there are concurrent requests to obtain the same
* shared lock. I consider this a JDK bug. It should be
* possible to service both requests without deadlock.
*/
if (log.isInfoEnabled())
log.info("Will proceed without lock: file=" + file + " : " + ex);
} catch (IOException ex) {
log.error("Sending " + file + ", length=" + length + ", uuid=" + uuid, ex);
sendError(StatusEnum.INTERNAL_ERROR);
return;
}
// Send the file.
sendResource(uuid, file, length, fis);
counters.nwrites.increment();
} catch (Exception ex) {
counters.writeErrorCount.increment();
// could be client death here.
log.warn(ex, ex);
return;
} finally {
try {
/*
* Close the FileChannel.
*
* Note: This will release the FileLock if one was acquired.
*/
fis.close();
} catch (Throwable t) {
/* ignore */
}
}
}
/**
* Prepare and send a {@link ByteBuffer}. The bytes from the
* {@link ByteBuffer#position()} to the {@link ByteBuffer#limit()} will
* be send. The position and limit are not modified.
*
* @param uuid
* The identifier for the buffer resource.
* @param buffer
* The corresponding buffer object.
*
* @throws SentErrorException
* @throws IOException
*/
private final void sendBuffer(final UUID uuid, final ByteBuffer buffer)
throws SentErrorException, IOException {
/*
* Get a read-only view to avoid problems with concurrent
* modification of the buffer's position, limit, etc.
*/
final ByteBuffer b = buffer.asReadOnlyBuffer();
// The #of bytes to be transferred.
final int remaining = buffer.remaining();
if (log.isInfoEnabled())
log.info("Sending " + b + ", length=" + remaining + ", uuid=" + uuid);
// Open input stream reading from the buffer to be sent.
final InputStream fis = new ByteBufferInputStream(b);
// try block used to ensure that we close [fis] in finally{}.
try {
// Send the file.
sendResource(uuid, b, (long) remaining, fis);
counters.nwrites.increment();
} catch (Exception ex) {
counters.writeErrorCount.increment();
// could be client death here.
log.warn(ex, ex);
return;
} finally {
try {
fis.close();
} catch (Throwable t) {
/* ignore */
}
}
}
/**
* Sends given resource to the socket.
*
* @param uuid
* The {@link UUID} which identifies the resource (from the
* request).
* @param resource
* The {@link File} or {@link ByteBuffer} which is to be sent
* (logging purposes only).
* @param length
* The length of that file in bytes.
* @param is
* The {@link InputStream} reading on that file.
* @throws IOException
*
* @todo use NIO reads on {@link FileChannel} with direct
* {@link ByteBuffer} and transfer to {@link SocketChannel}. This
* might make it more difficult to compute the checksum so who
* knows if it is worth it. Note that this approach will also add
* {@link InterruptedException} to our throws list.
*/
private void sendResource(final UUID uuid, final Object resource, final long length, final InputStream is)
throws IOException {
assert uuid != null;
assert resource != null;
assert length >= 0;
assert is != null;
assert !sentStatus;
long bytesWritten = 0L;
final long begin = System.nanoTime();
final OutputStream os = s.getOutputStream();
try {
// send the header.
{
final DataOutputStream dos = new DataOutputStream(os);
// status byte.
dos.write(new byte[] { StatusEnum.OK.get() });
// file length.
dos.writeLong(length);
// flush the data output stream.
dos.flush();
bytesWritten += 1 + Bytes.SIZEOF_LONG;
// Note: Don't have to flush here but can't sendError
// anymore.
// os.flush();
// presume status has been sent.
sentStatus = true;
}
// send the data
final long checksum;
{
// the size for the writes on the socket.
final int BUFSIZE = Bytes.kilobyte32 * 2;
// input stream computes checksum as it reads the data.
final CheckedInputStream cis = new CheckedInputStream(
// buffered input stream for reading from the file.
new BufferedInputStream(is),
// checksum impl.
new Adler32());
final byte[] buff = new byte[BUFSIZE];
while (true) {
// #of bytes read into the buffer.
final int read = cis.read(buff, 0, BUFSIZE);
if (read <= 0)
break;
// write on the socket.
os.write(buff, 0, read);
bytesWritten += read;
}
// the checksum of the bytes read from the file.
checksum = cis.getChecksum().getValue();
}
// write the checksum on the socket.
{
final DataOutputStream dos = new DataOutputStream(os);
// checksum.
dos.writeLong(checksum);
bytesWritten += Bytes.SIZEOF_LONG;
// flush the data output stream.
dos.flush();
}
// all done.
os.flush();
if (log.isInfoEnabled())
log.info("Sent: uuid=" + uuid + ", resource=" + resource + ", length=" + length + ", checksum=" + checksum
+ ", elapsed=" + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - begin) + "ms");
} finally {
try {
os.close();
} catch (Throwable t) {
// Ignore.
}
counters.bytesWritten.add(bytesWritten);
counters.elapsedWriteNanos.add(System.nanoTime() - begin);
synchronized (counters.maxWriteSizeLock) {
counters.maxWriteSize = Math.max(counters.maxWriteSize,
bytesWritten);
}
}
}
}
/**
* An instance of this exception is thrown internally if an error response
* is sent. The exception is trapped and ignored. The purpose of the
* exception is to recognize that the error response has already been
* handled.
*/
private static class SentErrorException extends RuntimeException {
/**
*
*/
private static final long serialVersionUID = 0L;
}
/**
* Return file identified by the {@link UUID}.
*
* @param uuid
*
* @return The file -or- null if there is no file associated
* with that {@link UUID}.
*
* @throws Exception
* if the resource may not be served.
*/
abstract protected File getResource(final UUID uuid) throws Exception;
/**
* Return {@link ByteBuffer} identified by the {@link UUID}.
*
* @param uuid
*
* @return The {@link ByteBuffer} -or- null if there is no
* buffer associated with that {@link UUID}.
*
* @throws Exception
* if the resource may not be served.
*/
abstract protected ByteBuffer getBuffer(final UUID uuid) throws Exception;
/**
* Client for a {@link BufferService} reads a single resource from the
* specified service, writing it into the local file system.
*
* @param
* The generic type of the resource identifier.
* @param
* The generic type of the resource object.
*
* @todo should use a configurable socket factory whose configuration is
* shared by the {@link BufferService}. This would allow SSL
* connections, etc.
*/
public static abstract class FetchResourceTask implements Callable {
final InetSocketAddress addr;
protected FetchResourceTask(final InetSocketAddress addr) {
if (addr == null)
throw new IllegalArgumentException();
this.addr = addr;
}
/**
* The logical identifier for the resource.
*/
abstract S logId();
/**
* The resource.
*/
abstract T logResource();
/*
* @todo use NIO transfers for buffers and files.
*/
public void transfer(final InputStream is, final OutputStream os)
throws Exception {
final long begin = System.nanoTime();
// read the response header.
final long length;
{
final DataInputStream dis = new DataInputStream(is);
final StatusEnum e = StatusEnum.valueOf(dis.readByte());
switch (e) {
case OK:
length = dis.readLong();
break;
default:
throw new IOException(e.toString() + ", id:" + logId());
}
}
// read the data.
long nread = 0L;
final long checksum;
{
// the size for the reads on the socket.
final int BUFSIZE = Bytes.kilobyte32 * 2;
// input stream computes checksum as it reads the data.
final CheckedInputStream cis = new CheckedInputStream(is, new Adler32());
final BufferedOutputStream bos = new BufferedOutputStream(os);
final byte[] buff = new byte[BUFSIZE];
while (nread < length) {
final long remaining = length - nread;
final int len = remaining > BUFSIZE ? BUFSIZE : (int) remaining;
// #of bytes read into the buffer.
final int read = cis.read(buff, 0, len);
if (read <= 0) {
// we have run out of data early.
throw new IOException("EOF? #read=" + nread
+ ", length=" + length + ",id=" + logId());
}
nread += read;
if (nread > length) {
// we have too much data.
throw new IOException("EOF? #read=" + nread
+ ", length=" + length + ",id=" + logId());
}
// write on the file.
bos.write(buff, 0, read);
}
// flush buffered writes to the file.
bos.flush();
// the checksum of the bytes read from the socket.
checksum = cis.getChecksum().getValue();
}
// read checksum from the socket and verify.
{
final DataInputStream dis = new DataInputStream(is);
final long expected = dis.readLong();
if (expected != checksum) {
throw new IOException("checksum error: id=" + logId());
}
}
if (log.isInfoEnabled()) {
log.info("read "
+ nread
+ " bytes, resource="
+ logResource()
+ ", checksum="
+ checksum
+ ", id="
+ logId()
+ ", elapsed="
+ TimeUnit.NANOSECONDS.toMillis(System.nanoTime()
- begin) + "ms");
}
}
}
/**
* Task sends a request for a file's data and then receives the data onto a
* local file.
*
* @todo Receive file's data using NIO to transfer from a
* {@link FileChannel} to the caller using a {@link SocketChannel}.
*/
public static class ReadResourceTask extends FetchResourceTask {
protected static final Logger log = Logger.getLogger(ReadResourceTask.class);
final UUID uuid;
final File file;
/**
* @param addr
* The Internet address and port at which the service from
* which the resource will be read is accepting connections.
* @param port
* The port at which to connect to the service from which the
* resource will be read.
* @param uuid
* The UUID which identifies the desired resource.
* @param file
* The local file on which the received data will be written.
* The file may exist but if it exists then it must be empty.
*/
public ReadResourceTask(final InetSocketAddress addr,
final UUID uuid, final File file) {
super(addr);
if (uuid == null)
throw new IllegalArgumentException();
if (file == null)
throw new IllegalArgumentException();
this.uuid = uuid;
this.file = file;
}
public UUID logId() {
return uuid;
}
public File logResource() {
return file;
}
/**
* Return the {@link File} on which the resource was written. If the
* operation fails, then the caller is responsible deciding whether or
* not the {@link File} specified to the constructor needs to be
* deleted.
*
* @throws IOException
* if the file exists and is not empty.
* @throws IOException
* if another process has a lock on the file.
*/
public File call() throws Exception {
Socket s = null;
final FileOutputStream os = new FileOutputStream(file);
try {
if (log.isInfoEnabled())
log.info("uuid=" + uuid + ", localFile=" + file);
final FileLock fileLock = os.getChannel().tryLock();
if (fileLock == null) {
throw new IOException("File is already locked: " + file);
}
if (os.getChannel().size() != 0L) {
throw new IOException("File not empty: " + file);
}
s = new Socket(addr.getAddress(), addr.getPort());
// send the UUID of the resource that we want.
{
final DataOutputStream dos = new DataOutputStream(s.getOutputStream());
dos.writeByte(ResourceTypeEnum.FILE.get());
dos.writeLong(uuid.getMostSignificantBits());
dos.writeLong(uuid.getLeastSignificantBits());
// flush the request.
dos.flush();
}
// buffered input stream for reading from the socket.
final InputStream is = new BufferedInputStream(s.getInputStream());
transfer(is, os);
return file;
} finally {
// close the socket (if open).
try {
if (s != null)
s.close();
} catch (Throwable t) {/* ignore */
}
// release the file lock (if acquired).
try {
os.close();
} catch (Throwable t) {/* ignore */
}
}
}
}
/**
* Class sends a request for a remote {@link ByteBuffer} and then receives
* the data into a local {@link ByteBuffer}.
*
* @todo Use NIO, not streams.
* @todo Checksum the buffer and validate the checksum at the receiver.
*/
public static class ReadBufferTask extends
FetchResourceTask {
protected static final Logger log = Logger
.getLogger(ReadResourceTask.class);
final UUID id;
final ByteBuffer outbuf;
/**
* @param addr
* The Internet address and port at which to connect the
* service from which the resource will be read.
* @param id
* The id that identifies the source ByteBuffer.
* @param outbuf
* The {@link ByteBuffer} to which the data from the remote
* source {@link ByteBuffer} will be transferred.
*/
public ReadBufferTask(final InetSocketAddress addr,
final UUID id, final ByteBuffer outbuf) {
super(addr);
if (id == null)
throw new IllegalArgumentException();
if (outbuf == null)
throw new IllegalArgumentException();
this.id = id;
this.outbuf = outbuf;
}
public UUID logId() {
return id;
}
public ByteBuffer logResource() {
return outbuf;
}
/**
* Issue a request to the remote service for the {@link ByteBuffer} on
* that service which was identified to the constructor and then accept
* the data into the local {@link ByteBuffer} provided to the
* constructor.
*
* @return A mutable view onto the received data within the caller's
* {@link ByteBuffer}. The data read from the remote service are
* available for reading from {@link ByteBuffer#position()} to
* {@link ByteBuffer#limit()} in the returned buffer.
*
* @throws Exception
* if something goes wrong (buffer does not exist, IO error,
* overflow in the local buffer when receiving the data from
* the remote service, etc.).
*/
public ByteBuffer call() throws Exception {
Socket s = null;
// duplicate to avoid side effects on the caller's position and limit.
final ByteBuffer b = outbuf.duplicate();
final OutputStream os = new ByteBufferOutputStream(b);
try {
s = new Socket(addr.getAddress(), addr.getPort());
// send the UUID of the resource that we want.
{
final DataOutputStream dos = new DataOutputStream(s.getOutputStream());
dos.writeByte(ResourceTypeEnum.BUFFER.get());
dos.writeLong(id.getMostSignificantBits());
dos.writeLong(id.getLeastSignificantBits());
// flush the request.
dos.flush();
}
// buffered input stream for reading from the socket.
final InputStream is = new BufferedInputStream(s.getInputStream());
transfer(is, os);
// flip the view to prepare it for reading.
b.flip();
// return the writable view.
return b;
} finally {
// close the socket (if open).
try {
if (s != null)
s.close();
} catch (Throwable t) {/* ignore */
}
// release the file lock (if acquired).
try {
os.close();
} catch (Throwable t) {/* ignore */
}
}
}
} // class ReadBufferTask
/**
* Performance counters for the {@link ResourceService}.
*
* @todo could also monitor the accept and request thread pools. The latter
* is the more interesting from a workload perspective.
*/
static public class Counters {
/**
* #of requests.
*/
public final CAT requestCount = new CAT();
/**
* #of requests which are denied.
*/
public final CAT denyCount = new CAT();
/**
* #of requests for which the resource was not found.
*/
public final CAT notFoundCount = new CAT();
/**
* #of requests which end in an internal error.
*/
public final CAT internalErrorCount = new CAT();
/**
* #of errors for responses where we attempt to write the requested data
* on the socket.
*/
public final CAT writeErrorCount = new CAT();
/**
* #of responses where we attempt to write the data on the socket.
*/
public final CAT nwrites = new CAT();
/**
* #of data bytes sent.
*/
public final CAT bytesWritten = new CAT();
/**
* The largest response written so far.
*/
public long maxWriteSize;
/**
* A lock used to make updates to {@link #maxWriteSize} atomic.
*/
final private Object maxWriteSizeLock = new Object();
/**
* #of nanoseconds sending data (this will double count time for data
* that are served concurrently to different receivers).
*/
public final CAT elapsedWriteNanos = new CAT();
synchronized public CounterSet getCounters() {
if (root == null) {
root = new CounterSet();
/*
* #of requests and their status outcome counters.
*/
{
final CounterSet tmp = root.makePath("status");
tmp.addCounter("Request Count", new Instrument() {
public void sample() {
setValue(requestCount.get());
}
});
tmp.addCounter("Deny Count", new Instrument() {
public void sample() {
setValue(denyCount.get());
}
});
tmp.addCounter("Not Found Count", new Instrument() {
public void sample() {
setValue(notFoundCount.get());
}
});
tmp.addCounter("Internal Error Count", new Instrument() {
public void sample() {
setValue(internalErrorCount.get());
}
});
}
/*
* writes (A write is a response where we try to write the file
* on the socket).
*/
{
final CounterSet tmp = root.makePath("writes");
tmp.addCounter("nwrites", new Instrument() {
public void sample() {
setValue(nwrites.get());
}
});
tmp.addCounter("bytesWritten", new Instrument() {
public void sample() {
setValue(bytesWritten.get());
}
});
tmp.addCounter("writeSecs", new Instrument() {
public void sample() {
final double writeSecs = (elapsedWriteNanos.get() / 1000000000.);
setValue(writeSecs);
}
});
tmp.addCounter("bytesWrittenPerSec", new Instrument() {
public void sample() {
final double writeSecs = (elapsedWriteNanos.get() / 1000000000.);
final double bytesWrittenPerSec = (writeSecs == 0L ? 0d : (bytesWritten.get() / writeSecs));
setValue(bytesWrittenPerSec);
}
});
tmp.addCounter("maxWriteSize", new Instrument() {
public void sample() {
setValue(maxWriteSize);
}
});
}
}
return root;
}
private CounterSet root = null;
}
}