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| <div class="subTitle">org.apache.beam.sdk.io</div> |
| <h2 title="Class UnboundedSource.UnboundedReader" class="title">Class UnboundedSource.UnboundedReader<OutputT></h2> |
| </div> |
| <div class="contentContainer"> |
| <ul class="inheritance"> |
| <li>java.lang.Object</li> |
| <li> |
| <ul class="inheritance"> |
| <li><a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html" title="class in org.apache.beam.sdk.io">org.apache.beam.sdk.io.Source.Reader</a><OutputT></li> |
| <li> |
| <ul class="inheritance"> |
| <li>org.apache.beam.sdk.io.UnboundedSource.UnboundedReader<OutputT></li> |
| </ul> |
| </li> |
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| <dd>java.lang.AutoCloseable</dd> |
| </dl> |
| <dl> |
| <dt>Enclosing class:</dt> |
| <dd><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.html" title="class in org.apache.beam.sdk.io">UnboundedSource</a><<a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.html" title="type parameter in UnboundedSource">OutputT</a>,<a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.html" title="type parameter in UnboundedSource">CheckpointMarkT</a> extends <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.CheckpointMark.html" title="interface in org.apache.beam.sdk.io">UnboundedSource.CheckpointMark</a>></dd> |
| </dl> |
| <hr> |
| <br> |
| <pre><a href="../../../../../org/apache/beam/sdk/annotations/Experimental.html" title="annotation in org.apache.beam.sdk.annotations">@Experimental</a>(<a href="../../../../../org/apache/beam/sdk/annotations/Experimental.html#value--">value</a>=<a href="../../../../../org/apache/beam/sdk/annotations/Experimental.Kind.html#SOURCE_SINK">SOURCE_SINK</a>) |
| public abstract static class <span class="typeNameLabel">UnboundedSource.UnboundedReader<OutputT></span> |
| extends <a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html" title="class in org.apache.beam.sdk.io">Source.Reader</a><OutputT></pre> |
| <div class="block">A <code>Reader</code> that reads an unbounded amount of input. |
| |
| <p>A given <code>UnboundedReader</code> object will only be accessed by a single thread at once.</div> |
| </li> |
| </ul> |
| </div> |
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| <h3>Field Summary</h3> |
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| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Field and Description</th> |
| </tr> |
| <tr class="altColor"> |
| <td class="colFirst"><code>static long</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#BACKLOG_UNKNOWN">BACKLOG_UNKNOWN</a></span></code> |
| <div class="block">Constant representing an unknown amount of backlog.</div> |
| </td> |
| </tr> |
| </table> |
| </li> |
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| <tr> |
| <th class="colOne" scope="col">Constructor and Description</th> |
| </tr> |
| <tr class="altColor"> |
| <td class="colOne"><code><span class="memberNameLink"><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#UnboundedReader--">UnboundedReader</a></span>()</code> </td> |
| </tr> |
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| <h3>Method Summary</h3> |
| <table class="memberSummary" border="0" cellpadding="3" cellspacing="0" summary="Method Summary table, listing methods, and an explanation"> |
| <caption><span id="t0" class="activeTableTab"><span>All Methods</span><span class="tabEnd"> </span></span><span id="t2" class="tableTab"><span><a href="javascript:show(2);">Instance Methods</a></span><span class="tabEnd"> </span></span><span id="t3" class="tableTab"><span><a href="javascript:show(4);">Abstract Methods</a></span><span class="tabEnd"> </span></span><span id="t4" class="tableTab"><span><a href="javascript:show(8);">Concrete Methods</a></span><span class="tabEnd"> </span></span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Method and Description</th> |
| </tr> |
| <tr id="i0" class="altColor"> |
| <td class="colFirst"><code>abstract boolean</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#advance--">advance</a></span>()</code> |
| <div class="block">Advances the reader to the next valid record.</div> |
| </td> |
| </tr> |
| <tr id="i1" class="rowColor"> |
| <td class="colFirst"><code>abstract <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.CheckpointMark.html" title="interface in org.apache.beam.sdk.io">UnboundedSource.CheckpointMark</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#getCheckpointMark--">getCheckpointMark</a></span>()</code> |
| <div class="block">Returns a <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.CheckpointMark.html" title="interface in org.apache.beam.sdk.io"><code>UnboundedSource.CheckpointMark</code></a> representing the progress of this <code>UnboundedReader</code>.</div> |
| </td> |
| </tr> |
| <tr id="i2" class="altColor"> |
| <td class="colFirst"><code>byte[]</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#getCurrentRecordId--">getCurrentRecordId</a></span>()</code> |
| <div class="block">Returns a unique identifier for the current record.</div> |
| </td> |
| </tr> |
| <tr id="i3" class="rowColor"> |
| <td class="colFirst"><code>abstract <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.html" title="class in org.apache.beam.sdk.io">UnboundedSource</a><<a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html" title="type parameter in UnboundedSource.UnboundedReader">OutputT</a>,?></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#getCurrentSource--">getCurrentSource</a></span>()</code> |
| <div class="block">Returns the <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.html" title="class in org.apache.beam.sdk.io"><code>UnboundedSource</code></a> that created this reader.</div> |
| </td> |
| </tr> |
| <tr id="i4" class="altColor"> |
| <td class="colFirst"><code>long</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#getSplitBacklogBytes--">getSplitBacklogBytes</a></span>()</code> |
| <div class="block">Returns the size of the backlog of unread data in the underlying data source represented by |
| this split of this source.</div> |
| </td> |
| </tr> |
| <tr id="i5" class="rowColor"> |
| <td class="colFirst"><code>long</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#getTotalBacklogBytes--">getTotalBacklogBytes</a></span>()</code> |
| <div class="block">Returns the size of the backlog of unread data in the underlying data source represented by |
| all splits of this source.</div> |
| </td> |
| </tr> |
| <tr id="i6" class="altColor"> |
| <td class="colFirst"><code>abstract <a href="https://static.javadoc.io/joda-time/joda-time/2.10.1/org/joda/time/Instant.html?is-external=true" title="class or interface in org.joda.time">Instant</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#getWatermark--">getWatermark</a></span>()</code> |
| <div class="block">Returns a timestamp before or at the timestamps of all future elements read by this reader.</div> |
| </td> |
| </tr> |
| <tr id="i7" class="rowColor"> |
| <td class="colFirst"><code>abstract boolean</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#start--">start</a></span>()</code> |
| <div class="block">Initializes the reader and advances the reader to the first record.</div> |
| </td> |
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| </a> |
| <h3>Methods inherited from class org.apache.beam.sdk.io.<a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html" title="class in org.apache.beam.sdk.io">Source.Reader</a></h3> |
| <code><a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html#close--">close</a>, <a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html#getCurrent--">getCurrent</a>, <a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html#getCurrentTimestamp--">getCurrentTimestamp</a></code></li> |
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| <h3>Methods inherited from class java.lang.Object</h3> |
| <code>clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait</code></li> |
| </ul> |
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| <h4>BACKLOG_UNKNOWN</h4> |
| <pre>public static final long BACKLOG_UNKNOWN</pre> |
| <div class="block">Constant representing an unknown amount of backlog.</div> |
| <dl> |
| <dt><span class="seeLabel">See Also:</span></dt> |
| <dd><a href="../../../../../constant-values.html#org.apache.beam.sdk.io.UnboundedSource.UnboundedReader.BACKLOG_UNKNOWN">Constant Field Values</a></dd> |
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| <h4>UnboundedReader</h4> |
| <pre>public UnboundedReader()</pre> |
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| <h4>start</h4> |
| <pre>public abstract boolean start() |
| throws java.io.IOException</pre> |
| <div class="block">Initializes the reader and advances the reader to the first record. If the reader has been |
| restored from a checkpoint then it should advance to the next unread record at the point the |
| checkpoint was taken. |
| |
| <p>This method will be called exactly once. The invocation will occur prior to calling <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#advance--"><code>advance()</code></a> or <a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html#getCurrent--"><code>Source.Reader.getCurrent()</code></a>. This method may perform expensive operations that are |
| needed to initialize the reader. |
| |
| <p>Returns <code>true</code> if a record was read, <code>false</code> if there is no more input |
| currently available. Future calls to <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#advance--"><code>advance()</code></a> may return <code>true</code> once more data |
| is available. Regardless of the return value of <code>start</code>, <code>start</code> will not be |
| called again on the same <code>UnboundedReader</code> object; it will only be called again when a |
| new reader object is constructed for the same source, e.g. on recovery.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html#start--">start</a></code> in class <code><a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html" title="class in org.apache.beam.sdk.io">Source.Reader</a><<a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html" title="type parameter in UnboundedSource.UnboundedReader">OutputT</a>></code></dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd><code>true</code> if a record was read, <code>false</code> if there is no more input available.</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.io.IOException</code></dd> |
| </dl> |
| </li> |
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| <a name="advance--"> |
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| <h4>advance</h4> |
| <pre>public abstract boolean advance() |
| throws java.io.IOException</pre> |
| <div class="block">Advances the reader to the next valid record. |
| |
| <p>Returns <code>true</code> if a record was read, <code>false</code> if there is no more input |
| available. Future calls to <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#advance--"><code>advance()</code></a> may return <code>true</code> once more data is |
| available.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html#advance--">advance</a></code> in class <code><a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html" title="class in org.apache.beam.sdk.io">Source.Reader</a><<a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html" title="type parameter in UnboundedSource.UnboundedReader">OutputT</a>></code></dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd><code>true</code> if a record was read, <code>false</code> if there is no more input available.</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.io.IOException</code></dd> |
| </dl> |
| </li> |
| </ul> |
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| <h4>getCurrentRecordId</h4> |
| <pre>public byte[] getCurrentRecordId() |
| throws java.util.NoSuchElementException</pre> |
| <div class="block">Returns a unique identifier for the current record. This should be the same for each instance |
| of the same logical record read from the underlying data source. |
| |
| <p>It is only necessary to override this if <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.html#requiresDeduping--"><code>UnboundedSource.requiresDeduping()</code></a> has been overridden to |
| return true. |
| |
| <p>For example, this could be a hash of the record contents, or a logical ID present in the |
| record. If this is generated as a hash of the record contents, it should be at least 16 bytes |
| (128 bits) to avoid collisions. |
| |
| <p>This method has the same restrictions on when it can be called as <a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html#getCurrent--"><code>Source.Reader.getCurrent()</code></a> and |
| <a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html#getCurrentTimestamp--"><code>Source.Reader.getCurrentTimestamp()</code></a>.</div> |
| <dl> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.util.NoSuchElementException</code> - if the reader is at the beginning of the input and <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#start--"><code>start()</code></a> or <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#advance--"><code>advance()</code></a> wasn't called, or if the last <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#start--"><code>start()</code></a> or <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#advance--"><code>advance()</code></a> returned <code>false</code>.</dd> |
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| </li> |
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| <h4>getWatermark</h4> |
| <pre>public abstract <a href="https://static.javadoc.io/joda-time/joda-time/2.10.1/org/joda/time/Instant.html?is-external=true" title="class or interface in org.joda.time">Instant</a> getWatermark()</pre> |
| <div class="block">Returns a timestamp before or at the timestamps of all future elements read by this reader. |
| |
| <p>This can be approximate. If records are read that violate this guarantee, they will be |
| considered late, which will affect how they will be processed. See <a href="../../../../../org/apache/beam/sdk/transforms/windowing/Window.html" title="class in org.apache.beam.sdk.transforms.windowing"><code>Window</code></a> for more information on late data and how to |
| handle it. |
| |
| <p>However, this value should be as late as possible. Downstream windows may not be able to |
| close until this watermark passes their end. |
| |
| <p>For example, a source may know that the records it reads will be in timestamp order. In |
| this case, the watermark can be the timestamp of the last record read. For a source that does |
| not have natural timestamps, timestamps can be set to the time of reading, in which case the |
| watermark is the current clock time. |
| |
| <p>See <a href="../../../../../org/apache/beam/sdk/transforms/windowing/Window.html" title="class in org.apache.beam.sdk.transforms.windowing"><code>Window</code></a> and <a href="../../../../../org/apache/beam/sdk/transforms/windowing/Trigger.html" title="class in org.apache.beam.sdk.transforms.windowing"><code>Trigger</code></a> for more information on timestamps and |
| watermarks. |
| |
| <p>May be called after <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#advance--"><code>advance()</code></a> or <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#start--"><code>start()</code></a> has returned false, but not before |
| <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#start--"><code>start()</code></a> has been called.</div> |
| </li> |
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| <h4>getCheckpointMark</h4> |
| <pre>public abstract <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.CheckpointMark.html" title="interface in org.apache.beam.sdk.io">UnboundedSource.CheckpointMark</a> getCheckpointMark()</pre> |
| <div class="block">Returns a <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.CheckpointMark.html" title="interface in org.apache.beam.sdk.io"><code>UnboundedSource.CheckpointMark</code></a> representing the progress of this <code>UnboundedReader</code>. |
| |
| <p>If this <code>UnboundedReader</code> does not support checkpoints, it may return a |
| CheckpointMark which does nothing, like: |
| |
| <pre><code> |
| public UnboundedSource.CheckpointMark getCheckpointMark() { |
| return new UnboundedSource.CheckpointMark() { |
| public void finalizeCheckpoint() throws IOException { |
| // nothing to do |
| } |
| }; |
| } |
| </code></pre> |
| |
| <p>All elements read between the last time this method was called (or since this reader was |
| created, if this method has not been called on this reader) until this method is called will |
| be processed together as a bundle. (An element is considered 'read' if it could be returned |
| by a call to <a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html#getCurrent--"><code>Source.Reader.getCurrent()</code></a>.) |
| |
| <p>Once the result of processing those elements and the returned checkpoint have been durably |
| committed, <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.CheckpointMark.html#finalizeCheckpoint--"><code>UnboundedSource.CheckpointMark.finalizeCheckpoint()</code></a> will be called at most once at some |
| later point on the returned <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.CheckpointMark.html" title="interface in org.apache.beam.sdk.io"><code>UnboundedSource.CheckpointMark</code></a> object. Checkpoint finalization is |
| best-effort, and checkpoints may not be finalized. If duplicate elements may be produced if |
| checkpoints are not finalized in a timely manner, <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.html#requiresDeduping--"><code>UnboundedSource.requiresDeduping()</code></a> |
| should be overridden to return true, and <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#getCurrentRecordId--"><code>getCurrentRecordId()</code></a> should |
| be overridden to return unique record IDs. |
| |
| <p>A checkpoint will be committed to durable storage only if all all previous checkpoints |
| produced by the same reader have also been committed. |
| |
| <p>The returned object should not be modified. |
| |
| <p>May not be called before <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#start--"><code>start()</code></a> has been called.</div> |
| </li> |
| </ul> |
| <a name="getSplitBacklogBytes--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>getSplitBacklogBytes</h4> |
| <pre>public long getSplitBacklogBytes()</pre> |
| <div class="block">Returns the size of the backlog of unread data in the underlying data source represented by |
| this split of this source. |
| |
| <p>One of this or <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#getTotalBacklogBytes--"><code>getTotalBacklogBytes()</code></a> should be overridden in order to allow the |
| runner to scale the amount of resources allocated to the pipeline.</div> |
| </li> |
| </ul> |
| <a name="getTotalBacklogBytes--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>getTotalBacklogBytes</h4> |
| <pre>public long getTotalBacklogBytes()</pre> |
| <div class="block">Returns the size of the backlog of unread data in the underlying data source represented by |
| all splits of this source. |
| |
| <p>One of this or <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html#getSplitBacklogBytes--"><code>getSplitBacklogBytes()</code></a> should be overridden in order to allow the |
| runner to scale the amount of resources allocated to the pipeline.</div> |
| </li> |
| </ul> |
| <a name="getCurrentSource--"> |
| <!-- --> |
| </a> |
| <ul class="blockListLast"> |
| <li class="blockList"> |
| <h4>getCurrentSource</h4> |
| <pre>public abstract <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.html" title="class in org.apache.beam.sdk.io">UnboundedSource</a><<a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html" title="type parameter in UnboundedSource.UnboundedReader">OutputT</a>,?> getCurrentSource()</pre> |
| <div class="block">Returns the <a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.html" title="class in org.apache.beam.sdk.io"><code>UnboundedSource</code></a> that created this reader. This will not change over the |
| life of the reader.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html#getCurrentSource--">getCurrentSource</a></code> in class <code><a href="../../../../../org/apache/beam/sdk/io/Source.Reader.html" title="class in org.apache.beam.sdk.io">Source.Reader</a><<a href="../../../../../org/apache/beam/sdk/io/UnboundedSource.UnboundedReader.html" title="type parameter in UnboundedSource.UnboundedReader">OutputT</a>></code></dd> |
| </dl> |
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