1 /*

     2  * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package java.net.http.internal;

    27 

    28 import java.nio.ByteBuffer;

    29 import java.nio.CharBuffer;

    30 import java.nio.charset.CharacterCodingException;

    31 import java.nio.charset.Charset;

    32 import java.nio.charset.CharsetDecoder;

    33 import java.nio.charset.CoderResult;

    34 import java.nio.charset.CodingErrorAction;

    35 import java.util.List;

    36 import java.util.Objects;

    37 import java.util.concurrent.CompletableFuture;

    38 import java.util.concurrent.CompletionStage;

    39 import java.util.concurrent.ConcurrentLinkedDeque;

    40 import java.util.concurrent.Flow;

    41 import java.util.concurrent.Flow.Subscriber;

    42 import java.util.concurrent.Flow.Subscription;

    43 import java.util.concurrent.atomic.AtomicLong;

    44 import java.util.concurrent.atomic.AtomicReference;

    45 import java.util.function.Function;

    46 import java.net.http.internal.common.Demand;

    47 import java.net.http.HttpResponse.BodySubscriber;

    48 import java.net.http.internal.common.MinimalFuture;

    49 import java.net.http.internal.common.SequentialScheduler;

    50 

    51 /** An adapter between {@code BodySubscriber} and {@code Flow.Subscriber<String>}. */

    52 public final class LineSubscriberAdapter<S extends Subscriber<? super String>,R>

    53         implements BodySubscriber<R> {

    54     private final CompletableFuture<R> cf = new MinimalFuture<>();

    55     private final S subscriber;

    56     private final Function<S, R> finisher;

    57     private final Charset charset;

    58     private final String eol;

    59     private volatile LineSubscription downstream;

    60 

    61     private LineSubscriberAdapter(S subscriber,

    62                                   Function<S, R> finisher,

    63                                   Charset charset,

    64                                   String eol) {

    65         if (eol != null && eol.isEmpty())

    66             throw new IllegalArgumentException("empty line separator");

    67         this.subscriber = Objects.requireNonNull(subscriber);

    68         this.finisher = Objects.requireNonNull(finisher);

    69         this.charset = Objects.requireNonNull(charset);

    70         this.eol = eol;

    71     }

    72 

    73     @Override

    74     public void onSubscribe(Subscription subscription) {

    75         downstream = LineSubscription.create(subscription,

    76                                              charset,

    77                                              eol,

    78                                              subscriber,

    79                                              cf);

    80         subscriber.onSubscribe(downstream);

    81     }

    82 

    83     @Override

    84     public void onNext(List<ByteBuffer> item) {

    85         try {

    86             downstream.submit(item);

    87         } catch (Throwable t) {

    88             onError(t);

    89         }

    90     }

    91 

    92     @Override

    93     public void onError(Throwable throwable) {

    94         try {

    95             downstream.signalError(throwable);

    96         } finally {

    97             cf.completeExceptionally(throwable);

    98         }

    99     }

   100 

   101     @Override

   102     public void onComplete() {

   103         try {

   104             downstream.signalComplete();

   105         } finally {

   106             cf.complete(finisher.apply(subscriber));

   107         }

   108     }

   109 

   110     @Override

   111     public CompletionStage<R> getBody() {

   112         return cf;

   113     }

   114 

   115     public static <S extends Subscriber<? super String>, R> LineSubscriberAdapter<S, R>

   116     create(S subscriber, Function<S, R> finisher, Charset charset, String eol)

   117     {

   118         if (eol != null && eol.isEmpty())

   119             throw new IllegalArgumentException("empty line separator");

   120         return new LineSubscriberAdapter<>(Objects.requireNonNull(subscriber),

   121                 Objects.requireNonNull(finisher),

   122                 Objects.requireNonNull(charset),

   123                 eol);

   124     }

   125 

   126     static final class LineSubscription implements Flow.Subscription {

   127         final Flow.Subscription upstreamSubscription;

   128         final CharsetDecoder decoder;

   129         final String newline;

   130         final Demand downstreamDemand;

   131         final ConcurrentLinkedDeque<ByteBuffer> queue;

   132         final SequentialScheduler scheduler;

   133         final Flow.Subscriber<? super String> upstream;

   134         final CompletableFuture<?> cf;

   135         private final AtomicReference<Throwable> errorRef = new AtomicReference<>();

   136         private final AtomicLong demanded = new AtomicLong();

   137         private volatile boolean completed;

   138         private volatile boolean cancelled;

   139 

   140         private final char[] chars = new char[1024];

   141         private final ByteBuffer leftover = ByteBuffer.wrap(new byte[64]);

   142         private final CharBuffer buffer = CharBuffer.wrap(chars);

   143         private final StringBuilder builder = new StringBuilder();

   144         private int lineCount;

   145         private String nextLine;

   146 

   147         private LineSubscription(Flow.Subscription s,

   148                                  CharsetDecoder dec,

   149                                  String separator,

   150                                  Flow.Subscriber<? super String> subscriber,

   151                                  CompletableFuture<?> completion) {

   152             downstreamDemand = new Demand();

   153             queue = new ConcurrentLinkedDeque<>();

   154             upstreamSubscription = Objects.requireNonNull(s);

   155             decoder = Objects.requireNonNull(dec);

   156             newline = separator;

   157             upstream = Objects.requireNonNull(subscriber);

   158             cf = Objects.requireNonNull(completion);

   159             scheduler = SequentialScheduler.synchronizedScheduler(this::loop);

   160         }

   161 

   162         @Override

   163         public void request(long n) {

   164             if (cancelled) return;

   165             if (downstreamDemand.increase(n)) {

   166                 scheduler.runOrSchedule();

   167             }

   168         }

   169 

   170         @Override

   171         public void cancel() {

   172             cancelled = true;

   173             upstreamSubscription.cancel();

   174         }

   175 

   176         public void submit(List<ByteBuffer> list) {

   177             queue.addAll(list);

   178             demanded.decrementAndGet();

   179             scheduler.runOrSchedule();

   180         }

   181 

   182         public void signalComplete() {

   183             completed = true;

   184             scheduler.runOrSchedule();

   185         }

   186 

   187         public void signalError(Throwable error) {

   188             if (errorRef.compareAndSet(null,

   189                     Objects.requireNonNull(error))) {

   190                 scheduler.runOrSchedule();

   191             }

   192         }

   193 

   194         // This method looks at whether some bytes where left over (in leftover)

   195         // from decoding the previous buffer when the previous buffer was in

   196         // underflow. If so, it takes bytes one by one from the new buffer 'in'

   197         // and combines them with the leftover bytes until 'in' is exhausted or a

   198         // character was produced in 'out', resolving the previous underflow.

   199         // Returns true if the buffer is still in underflow, false otherwise.

   200         // However, in both situation some chars might have been produced in 'out'.

   201         private boolean isUnderFlow(ByteBuffer in, CharBuffer out, boolean endOfInput)

   202                 throws CharacterCodingException {

   203             int limit = leftover.position();

   204             if (limit == 0) {

   205                 // no leftover

   206                 return false;

   207             } else {

   208                 CoderResult res = null;

   209                 while (in.hasRemaining()) {

   210                     leftover.position(limit);

   211                     leftover.limit(++limit);

   212                     leftover.put(in.get());

   213                     leftover.position(0);

   214                     res = decoder.decode(leftover, out,

   215                             endOfInput && !in.hasRemaining());

   216                     int remaining = leftover.remaining();

   217                     if (remaining > 0) {

   218                         assert leftover.position() == 0;

   219                         leftover.position(remaining);

   220                     } else {

   221                         leftover.position(0);

   222                     }

   223                     leftover.limit(leftover.capacity());

   224                     if (res.isUnderflow() && remaining > 0 && in.hasRemaining()) {

   225                         continue;

   226                     }

   227                     if (res.isError()) {

   228                         res.throwException();

   229                     }

   230                     assert !res.isOverflow();

   231                     return false;

   232                 }

   233                 return !endOfInput;

   234             }

   235         }

   236 

   237         // extract characters from start to end and remove them from

   238         // the StringBuilder

   239         private static String take(StringBuilder b, int start, int end) {

   240             assert start == 0;

   241             String line;

   242             if (end == start) return "";

   243             line = b.substring(start, end);

   244             b.delete(start, end);

   245             return line;

   246         }

   247 

   248         // finds end of line, returns -1 if not found, or the position after

   249         // the line delimiter if found, removing the delimiter in the process.

   250         private static int endOfLine(StringBuilder b, String eol, boolean endOfInput) {

   251             int len = b.length();

   252             if (eol != null) { // delimiter explicitly specified

   253                 int i = b.indexOf(eol);

   254                 if (i >= 0) {

   255                     // remove the delimiter and returns the position

   256                     // of the char after it.

   257                     b.delete(i, i + eol.length());

   258                     return i;

   259                 }

   260             } else { // no delimiter specified, behaves as BufferedReader::readLine

   261                 boolean crfound = false;

   262                 for (int i = 0; i < len; i++) {

   263                     char c = b.charAt(i);

   264                     if (c == '\n') {

   265                         // '\n' or '\r\n' found.

   266                         // remove the delimiter and returns the position

   267                         // of the char after it.

   268                         b.delete(crfound ? i - 1 : i, i + 1);

   269                         return crfound ? i - 1 : i;

   270                     } else if (crfound) {

   271                         // previous char was '\r', c != '\n'

   272                         assert i != 0;

   273                         // remove the delimiter and returns the position

   274                         // of the char after it.

   275                         b.delete(i - 1, i);

   276                         return i - 1;

   277                     }

   278                     crfound = c == '\r';

   279                 }

   280                 if (crfound && endOfInput) {

   281                     // remove the delimiter and returns the position

   282                     // of the char after it.

   283                     b.delete(len - 1, len);

   284                     return len - 1;

   285                 }

   286             }

   287             return endOfInput && len > 0 ? len : -1;

   288         }

   289 

   290         // Looks at whether the StringBuilder contains a line.

   291         // Returns null if more character are needed.

   292         private static String nextLine(StringBuilder b, String eol, boolean endOfInput) {

   293             int next = endOfLine(b, eol, endOfInput);

   294             return (next > -1) ? take(b, 0, next) : null;

   295         }

   296 

   297         // Attempts to read the next line. Returns the next line if

   298         // the delimiter was found, null otherwise. The delimiters are

   299         // consumed.

   300         private String nextLine()

   301                 throws CharacterCodingException {

   302             assert nextLine == null;

   303             LINES:

   304             while (nextLine == null) {

   305                 boolean endOfInput = completed && queue.isEmpty();

   306                 nextLine = nextLine(builder, newline,

   307                         endOfInput && leftover.position() == 0);

   308                 if (nextLine != null) return nextLine;

   309                 ByteBuffer b;

   310                 BUFFERS:

   311                 while ((b = queue.peek()) != null) {

   312                     if (!b.hasRemaining()) {

   313                         queue.poll();

   314                         continue BUFFERS;

   315                     }

   316                     BYTES:

   317                     while (b.hasRemaining()) {

   318                         buffer.position(0);

   319                         buffer.limit(buffer.capacity());

   320                         boolean endofInput = completed && queue.size() <= 1;

   321                         if (isUnderFlow(b, buffer, endofInput)) {

   322                             assert !b.hasRemaining();

   323                             if (buffer.position() > 0) {

   324                                 buffer.flip();

   325                                 builder.append(buffer);

   326                             }

   327                             continue BUFFERS;

   328                         }

   329                         CoderResult res = decoder.decode(b, buffer, endofInput);

   330                         if (res.isError()) res.throwException();

   331                         if (buffer.position() > 0) {

   332                             buffer.flip();

   333                             builder.append(buffer);

   334                             continue LINES;

   335                         }

   336                         if (res.isUnderflow() && b.hasRemaining()) {

   337                             //System.out.println("underflow: adding " + b.remaining() + " bytes");

   338                             leftover.put(b);

   339                             assert !b.hasRemaining();

   340                             continue BUFFERS;

   341                         }

   342                     }

   343                 }

   344 

   345                 assert queue.isEmpty();

   346                 if (endOfInput) {

   347                     // Time to cleanup: there may be some undecoded leftover bytes

   348                     // We need to flush them out.

   349                     // The decoder has been configured to replace malformed/unmappable

   350                     // chars with some replacement, in order to behave like

   351                     // InputStreamReader.

   352                     leftover.flip();

   353                     buffer.position(0);

   354                     buffer.limit(buffer.capacity());

   355 

   356                     // decode() must be called just before flush, even if there

   357                     // is nothing to decode. We must do this even if leftover

   358                     // has no remaining bytes.

   359                     CoderResult res = decoder.decode(leftover, buffer, endOfInput);

   360                     if (buffer.position() > 0) {

   361                         buffer.flip();

   362                         builder.append(buffer);

   363                     }

   364                     if (res.isError()) res.throwException();

   365 

   366                     // Now call decoder.flush()

   367                     buffer.position(0);

   368                     buffer.limit(buffer.capacity());

   369                     res = decoder.flush(buffer);

   370                     if (buffer.position() > 0) {

   371                         buffer.flip();

   372                         builder.append(buffer);

   373                     }

   374                     if (res.isError()) res.throwException();

   375 

   376                     // It's possible that we reach here twice - just for the

   377                     // purpose of checking that no bytes were left over, so

   378                     // we reset leftover/decoder to make the function reentrant.

   379                     leftover.position(0);

   380                     leftover.limit(leftover.capacity());

   381                     decoder.reset();

   382 

   383                     // if some chars were produced then this call will

   384                     // return them.

   385                     return nextLine = nextLine(builder, newline, endOfInput);

   386                 }

   387                 return null;

   388             }

   389             return null;

   390         }

   391 

   392         // The main sequential scheduler loop.

   393         private void loop() {

   394             try {

   395                 while (!cancelled) {

   396                     Throwable error = errorRef.get();

   397                     if (error != null) {

   398                         cancelled = true;

   399                         scheduler.stop();

   400                         upstream.onError(error);

   401                         cf.completeExceptionally(error);

   402                         return;

   403                     }

   404                     if (nextLine == null) nextLine = nextLine();

   405                     if (nextLine == null) {

   406                         if (completed) {

   407                             scheduler.stop();

   408                             if (leftover.position() != 0) {

   409                                 // Underflow: not all bytes could be

   410                                 // decoded, but no more bytes will be coming.

   411                                 // This should not happen as we should already

   412                                 // have got a MalformedInputException, or

   413                                 // replaced the unmappable chars.

   414                                 errorRef.compareAndSet(null,

   415                                         new IllegalStateException(

   416                                                 "premature end of input ("

   417                                                         + leftover.position()

   418                                                         + " undecoded bytes)"));

   419                                 continue;

   420                             } else {

   421                                 upstream.onComplete();

   422                             }

   423                             return;

   424                         } else if (demanded.get() == 0

   425                                 && !downstreamDemand.isFulfilled()) {

   426                             long incr = Math.max(1, downstreamDemand.get());

   427                             demanded.addAndGet(incr);

   428                             upstreamSubscription.request(incr);

   429                             continue;

   430                         } else return;

   431                     }

   432                     assert nextLine != null;

   433                     assert newline != null && !nextLine.endsWith(newline)

   434                             || !nextLine.endsWith("\n") || !nextLine.endsWith("\r");

   435                     if (downstreamDemand.tryDecrement()) {

   436                         String forward = nextLine;

   437                         nextLine = null;

   438                         upstream.onNext(forward);

   439                     } else return; // no demand: come back later

   440                 }

   441             } catch (Throwable t) {

   442                 try {

   443                     upstreamSubscription.cancel();

   444                 } finally {

   445                     signalError(t);

   446                 }

   447             }

   448         }

   449 

   450         static LineSubscription create(Flow.Subscription s,

   451                                        Charset charset,

   452                                        String lineSeparator,

   453                                        Flow.Subscriber<? super String> upstream,

   454                                        CompletableFuture<?> cf) {

   455             return new LineSubscription(Objects.requireNonNull(s),

   456                     Objects.requireNonNull(charset).newDecoder()

   457                             // use the same decoder configuration than

   458                             // java.io.InputStreamReader

   459                             .onMalformedInput(CodingErrorAction.REPLACE)

   460                             .onUnmappableCharacter(CodingErrorAction.REPLACE),

   461                     lineSeparator,

   462                     Objects.requireNonNull(upstream),

   463                     Objects.requireNonNull(cf));

   464         }

   465     }

   466 }

   467