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1 /* |
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2 * Copyright (c) 1996, 2016, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 |
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26 package java.io; |
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27 |
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28 |
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29 /** |
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30 * Piped character-output streams. |
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31 * |
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32 * @author Mark Reinhold |
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33 * @since 1.1 |
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34 */ |
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35 |
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36 public class PipedWriter extends Writer { |
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37 |
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38 /* REMIND: identification of the read and write sides needs to be |
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39 more sophisticated. Either using thread groups (but what about |
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40 pipes within a thread?) or using finalization (but it may be a |
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41 long time until the next GC). */ |
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42 private PipedReader sink; |
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43 |
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44 /* This flag records the open status of this particular writer. It |
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45 * is independent of the status flags defined in PipedReader. It is |
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46 * used to do a sanity check on connect. |
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47 */ |
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48 private boolean closed = false; |
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49 |
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50 /** |
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51 * Creates a piped writer connected to the specified piped |
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52 * reader. Data characters written to this stream will then be |
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53 * available as input from <code>snk</code>. |
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54 * |
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55 * @param snk The piped reader to connect to. |
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56 * @exception IOException if an I/O error occurs. |
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57 */ |
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58 public PipedWriter(PipedReader snk) throws IOException { |
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59 connect(snk); |
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60 } |
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61 |
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62 /** |
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63 * Creates a piped writer that is not yet connected to a |
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64 * piped reader. It must be connected to a piped reader, |
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65 * either by the receiver or the sender, before being used. |
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66 * |
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67 * @see java.io.PipedReader#connect(java.io.PipedWriter) |
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68 * @see java.io.PipedWriter#connect(java.io.PipedReader) |
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69 */ |
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70 public PipedWriter() { |
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71 } |
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72 |
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73 /** |
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74 * Connects this piped writer to a receiver. If this object |
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75 * is already connected to some other piped reader, an |
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76 * <code>IOException</code> is thrown. |
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77 * <p> |
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78 * If <code>snk</code> is an unconnected piped reader and |
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79 * <code>src</code> is an unconnected piped writer, they may |
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80 * be connected by either the call: |
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81 * <blockquote><pre> |
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82 * src.connect(snk)</pre></blockquote> |
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83 * or the call: |
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84 * <blockquote><pre> |
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85 * snk.connect(src)</pre></blockquote> |
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86 * The two calls have the same effect. |
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87 * |
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88 * @param snk the piped reader to connect to. |
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89 * @exception IOException if an I/O error occurs. |
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90 */ |
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91 public synchronized void connect(PipedReader snk) throws IOException { |
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92 if (snk == null) { |
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93 throw new NullPointerException(); |
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94 } else if (sink != null || snk.connected) { |
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95 throw new IOException("Already connected"); |
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96 } else if (snk.closedByReader || closed) { |
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97 throw new IOException("Pipe closed"); |
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98 } |
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99 |
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100 sink = snk; |
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101 snk.in = -1; |
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102 snk.out = 0; |
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103 snk.connected = true; |
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104 } |
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105 |
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106 /** |
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107 * Writes the specified <code>char</code> to the piped output stream. |
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108 * If a thread was reading data characters from the connected piped input |
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109 * stream, but the thread is no longer alive, then an |
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110 * <code>IOException</code> is thrown. |
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111 * <p> |
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112 * Implements the <code>write</code> method of <code>Writer</code>. |
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113 * |
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114 * @param c the <code>char</code> to be written. |
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115 * @exception IOException if the pipe is |
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116 * <a href=PipedOutputStream.html#BROKEN> <code>broken</code></a>, |
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117 * {@link #connect(java.io.PipedReader) unconnected}, closed |
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118 * or an I/O error occurs. |
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119 */ |
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120 public void write(int c) throws IOException { |
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121 if (sink == null) { |
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122 throw new IOException("Pipe not connected"); |
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123 } |
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124 sink.receive(c); |
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125 } |
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126 |
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127 /** |
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128 * Writes {@code len} characters from the specified character array |
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129 * starting at offset {@code off} to this piped output stream. |
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130 * This method blocks until all the characters are written to the output |
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131 * stream. |
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132 * If a thread was reading data characters from the connected piped input |
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133 * stream, but the thread is no longer alive, then an |
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134 * {@code IOException} is thrown. |
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135 * |
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136 * @param cbuf the data. |
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137 * @param off the start offset in the data. |
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138 * @param len the number of characters to write. |
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139 * |
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140 * @throws IndexOutOfBoundsException |
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141 * If {@code off} is negative, or {@code len} is negative, |
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142 * or {@code off + len} is negative or greater than the length |
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143 * of the given array |
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144 * |
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145 * @throws IOException if the pipe is |
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146 * <a href=PipedOutputStream.html#BROKEN><code>broken</code></a>, |
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147 * {@link #connect(java.io.PipedReader) unconnected}, closed |
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148 * or an I/O error occurs. |
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149 */ |
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150 public void write(char cbuf[], int off, int len) throws IOException { |
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151 if (sink == null) { |
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152 throw new IOException("Pipe not connected"); |
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153 } else if ((off | len | (off + len) | (cbuf.length - (off + len))) < 0) { |
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154 throw new IndexOutOfBoundsException(); |
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155 } |
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156 sink.receive(cbuf, off, len); |
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157 } |
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158 |
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159 /** |
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160 * Flushes this output stream and forces any buffered output characters |
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161 * to be written out. |
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162 * This will notify any readers that characters are waiting in the pipe. |
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163 * |
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164 * @exception IOException if the pipe is closed, or an I/O error occurs. |
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165 */ |
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166 public synchronized void flush() throws IOException { |
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167 if (sink != null) { |
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168 if (sink.closedByReader || closed) { |
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169 throw new IOException("Pipe closed"); |
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170 } |
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171 synchronized (sink) { |
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172 sink.notifyAll(); |
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173 } |
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174 } |
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175 } |
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176 |
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177 /** |
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178 * Closes this piped output stream and releases any system resources |
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179 * associated with this stream. This stream may no longer be used for |
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180 * writing characters. |
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181 * |
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182 * @exception IOException if an I/O error occurs. |
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183 */ |
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184 public void close() throws IOException { |
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185 closed = true; |
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186 if (sink != null) { |
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187 sink.receivedLast(); |
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188 } |
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189 } |
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190 } |