MessageStream.java 11.3 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408
package org.onlab.nio;

import org.onlab.util.Counter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ByteChannel;
import java.nio.channels.SelectionKey;
import java.util.ArrayList;
import java.util.List;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static java.lang.System.currentTimeMillis;
import static java.nio.ByteBuffer.allocateDirect;

/**
 * Bi-directional message stream for transferring messages to & from the
 * network via two byte buffers.
 *
 * @param <M> message type
 */
public abstract class MessageStream<M extends Message> {

    protected Logger log = LoggerFactory.getLogger(getClass());

    private final IOLoop<M, ?> loop;
    private final ByteChannel channel;
    private final int maxIdleMillis;

    private final ByteBuffer inbound;
    private ByteBuffer outbound;
    private SelectionKey key;

    private volatile boolean closed = false;
    private volatile boolean writePending;
    private volatile boolean writeOccurred;

    private Exception ioError;
    private long lastActiveTime;

    private final Counter bytesIn = new Counter();
    private final Counter messagesIn = new Counter();
    private final Counter bytesOut = new Counter();
    private final Counter messagesOut = new Counter();

    /**
     * Creates a message stream associated with the specified IO loop and
     * backed by the given byte channel.
     *
     * @param loop          IO loop
     * @param byteChannel   backing byte channel
     * @param bufferSize    size of the backing byte buffers
     * @param maxIdleMillis maximum number of millis the stream can be idle
     *                      before it will be closed
     */
    protected MessageStream(IOLoop<M, ?> loop, ByteChannel byteChannel,
                            int bufferSize, int maxIdleMillis) {
        this.loop = checkNotNull(loop, "Loop cannot be null");
        this.channel = checkNotNull(byteChannel, "Byte channel cannot be null");

        checkArgument(maxIdleMillis > 0, "Idle time must be positive");
        this.maxIdleMillis = maxIdleMillis;

        inbound = allocateDirect(bufferSize);
        outbound = allocateDirect(bufferSize);
    }

    /**
     * Gets a single message from the specified byte buffer; this is
     * to be done without manipulating the buffer via flip, reset or clear.
     *
     * @param buffer byte buffer
     * @return read message or null if there are not enough bytes to read
     * a complete message
     */
    protected abstract M read(ByteBuffer buffer);

    /**
     * Puts the specified message into the specified byte buffer; this is
     * to be done without manipulating the buffer via flip, reset or clear.
     *
     * @param message message to be write into the buffer
     * @param buffer  byte buffer
     */
    protected abstract void write(M message, ByteBuffer buffer);

    /**
     * Closes the message buffer.
     */
    public void close() {
        synchronized (this) {
            if (closed) {
                return;
            }
            closed = true;
        }

        bytesIn.freeze();
        bytesOut.freeze();
        messagesIn.freeze();
        messagesOut.freeze();

        loop.removeStream(this);
        if (key != null) {
            try {
                key.cancel();
                key.channel().close();
            } catch (IOException e) {
                log.warn("Unable to close stream", e);
            }
        }
    }

    /**
     * Indicates whether this buffer has been closed.
     *
     * @return true if this stream has been closed
     */
    public synchronized boolean isClosed() {
        return closed;
    }

    /**
     * Returns the stream IO selection key.
     *
     * @return socket channel registration selection key
     */
    public SelectionKey key() {
        return key;
    }

    /**
     * Binds the selection key to be used for driving IO operations on the stream.
     *
     * @param key IO selection key
     */
    public void setKey(SelectionKey key) {
        this.key = key;
        this.lastActiveTime = currentTimeMillis();
    }

    /**
     * Returns the IO loop to which this stream is bound.
     *
     * @return I/O loop used to drive this stream
     */
    public IOLoop<M, ?> loop() {
        return loop;
    }

    /**
     * Indicates whether the any prior IO encountered an error.
     *
     * @return true if a write failed
     */
    public boolean hadError() {
        return ioError != null;
    }

    /**
     * Gets the prior IO error, if one occurred.
     *
     * @return IO error; null if none occurred
     */
    public Exception getError() {
        return ioError;
    }

    /**
     * Reads, without blocking, a list of messages from the stream.
     * The list will be empty if there were not messages pending.
     *
     * @return list of messages or null if backing channel has been closed
     * @throws IOException if messages could not be read
     */
    public List<M> read() throws IOException {
        try {
            int read = channel.read(inbound);
            if (read != -1) {
                // Read the messages one-by-one and add them to the list.
                List<M> messages = new ArrayList<>();
                M message;
                inbound.flip();
                while ((message = read(inbound)) != null) {
                    messages.add(message);
                    messagesIn.add(1);
                    bytesIn.add(message.length());
                }
                inbound.compact();

                // Mark the stream with current time to indicate liveness.
                lastActiveTime = currentTimeMillis();
                return messages;
            }
            return null;

        } catch (Exception e) {
            throw new IOException("Unable to read messages", e);
        }
    }

    /**
     * Writes the specified list of messages to the stream.
     *
     * @param messages list of messages to write
     * @throws IOException if error occurred while writing the data
     */
    public void write(List<M> messages) throws IOException {
        synchronized (this) {
            // First write all messages.
            for (M m : messages) {
                append(m);
            }
            flushUnlessAlreadyPlanningTo();
        }
    }

    /**
     * Writes the given message to the stream.
     *
     * @param message message to write
     * @throws IOException if error occurred while writing the data
     */
    public void write(M message) throws IOException {
        synchronized (this) {
            append(message);
            flushUnlessAlreadyPlanningTo();
        }
    }

    // Appends the specified message into the internal buffer, growing the
    // buffer if required.
    private void append(M message) {
        // If the buffer does not have sufficient length double it.
        while (outbound.remaining() < message.length()) {
            doubleSize();
        }
        write(message, outbound);
        messagesOut.add(1);
        bytesOut.add(message.length());
    }

    // Forces a flush, unless one is planned already.
    private void flushUnlessAlreadyPlanningTo() throws IOException {
        if (!writeOccurred && !writePending) {
            flush();
        }
    }

    /**
     * Flushes any pending writes.
     *
     * @throws IOException if flush failed
     */
    public void flush() throws IOException {
        synchronized (this) {
            if (!writeOccurred && !writePending) {
                outbound.flip();
                try {
                    channel.write(outbound);
                } catch (IOException e) {
                    if (!closed && !e.getMessage().equals("Broken pipe")) {
                        log.warn("Unable to write data", e);
                        ioError = e;
                    }
                }
                lastActiveTime = currentTimeMillis();
                writeOccurred = true;
                writePending = outbound.hasRemaining();
                outbound.compact();
            }
        }
    }

    /**
     * Indicates whether the stream has bytes to be written to the channel.
     *
     * @return true if there are bytes to be written
     */
    boolean isWritePending() {
        synchronized (this) {
            return writePending;
        }
    }


    /**
     * Indicates whether data has been written but not flushed yet.
     *
     * @return true if flush is required
     */
    boolean isFlushRequired() {
        synchronized (this) {
            return outbound.position() > 0;
        }
    }

    /**
     * Attempts to flush data, internal stream state and channel availability
     * permitting. Invoked by the driver I/O loop during handling of writable
     * selection key.
     * <p/>
     * Resets the internal state flags {@code writeOccurred} and
     * {@code writePending}.
     *
     * @throws IOException if implicit flush failed
     */
    void flushIfPossible() throws IOException {
        synchronized (this) {
            writePending = false;
            writeOccurred = false;
            if (outbound.position() > 0) {
                flush();
            }
        }
        key.interestOps(SelectionKey.OP_READ);
    }

    /**
     * Attempts to flush data, internal stream state and channel availability
     * permitting and if other writes are not pending. Invoked by the driver
     * I/O loop prior to entering select wait. Resets the internal
     * {@code writeOccurred} state flag.
     *
     * @throws IOException if implicit flush failed
     */
    void flushIfWriteNotPending() throws IOException {
        synchronized (this) {
            writeOccurred = false;
            if (!writePending && outbound.position() > 0) {
                flush();
            }
        }
        if (isWritePending()) {
            key.interestOps(key.interestOps() | SelectionKey.OP_WRITE);
        }
    }

    /**
     * Doubles the size of the outbound buffer.
     */
    private void doubleSize() {
        ByteBuffer newBuffer = allocateDirect(outbound.capacity() * 2);
        outbound.flip();
        newBuffer.put(outbound);
        outbound = newBuffer;
    }

    /**
     * Returns the maximum number of milliseconds the stream is allowed
     * without any read/write operations.
     *
     * @return number if millis of permissible idle time
     */
    protected int maxIdleMillis() {
        return maxIdleMillis;
    }


    /**
     * Returns true if the given stream has gone stale.
     *
     * @return true if the stream is stale
     */
    boolean isStale() {
        return currentTimeMillis() - lastActiveTime > maxIdleMillis() && key != null;
    }

    /**
     * Returns the inbound bytes counter.
     *
     * @return inbound bytes counter
     */
    public Counter bytesIn() {
        return bytesIn;
    }

    /**
     * Returns the outbound bytes counter.
     *
     * @return outbound bytes counter
     */
    public Counter bytesOut() {
        return bytesOut;
    }

    /**
     * Returns the inbound messages counter.
     *
     * @return inbound messages counter
     */
    public Counter messagesIn() {
        return messagesIn;
    }

    /**
     * Returns the outbound messages counter.
     *
     * @return outbound messages counter
     */
    public Counter messagesOut() {
        return messagesOut;
    }

}