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<div class="sub-title"><span class="package-label-in-type">Package</span>&nbsp;<a href="package-summary.html">org.apache.hadoop.hbase.wal</a></div>
<h1 title="Interface WALTailingReader" class="title">Interface WALTailingReader</h1>
</div>
<section class="class-description" id="class-description">
<dl class="notes">
<dt>All Superinterfaces:</dt>
<dd><code><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/AutoCloseable.html" title="class or interface in java.lang" class="external-link">AutoCloseable</a></code>, <code><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/io/Closeable.html" title="class or interface in java.io" class="external-link">Closeable</a></code></dd>
</dl>
<dl class="notes">
<dt>All Known Implementing Classes:</dt>
<dd><code><a href="../regionserver/wal/ProtobufWALTailingReader.html" title="class in org.apache.hadoop.hbase.regionserver.wal">ProtobufWALTailingReader</a></code></dd>
</dl>
<hr>
<div class="type-signature"><span class="annotations">@Private
</span><span class="modifiers">public interface </span><span class="element-name"><a href="../../../../../src-html/org/apache/hadoop/hbase/wal/WALTailingReader.html#line-29">WALTailingReader</a></span><span class="extends-implements">
extends <a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/io/Closeable.html" title="class or interface in java.io" class="external-link">Closeable</a></span></div>
<div class="block">A WAL reader which is designed for be able to tailing the WAL file which is currently being
written. It adds support</div>
</section>
<section class="summary">
<ul class="summary-list">
<!-- ======== NESTED CLASS SUMMARY ======== -->
<li>
<section class="nested-class-summary" id="nested-class-summary">
<h2>Nested Class Summary</h2>
<div class="caption"><span>Nested Classes</span></div>
<div class="summary-table three-column-summary">
<div class="table-header col-first">Modifier and Type</div>
<div class="table-header col-second">Interface</div>
<div class="table-header col-last">Description</div>
<div class="col-first even-row-color"><code>static final class&nbsp;</code></div>
<div class="col-second even-row-color"><code><a href="WALTailingReader.Result.html" class="type-name-link" title="class in org.apache.hadoop.hbase.wal">WALTailingReader.Result</a></code></div>
<div class="col-last even-row-color">&nbsp;</div>
<div class="col-first odd-row-color"><code>static enum&nbsp;</code></div>
<div class="col-second odd-row-color"><code><a href="WALTailingReader.State.html" class="type-name-link" title="enum class in org.apache.hadoop.hbase.wal">WALTailingReader.State</a></code></div>
<div class="col-last odd-row-color">&nbsp;</div>
</div>
</section>
</li>
<!-- ========== METHOD SUMMARY =========== -->
<li>
<section class="method-summary" id="method-summary">
<h2>Method Summary</h2>
<div id="method-summary-table">
<div class="table-tabs" role="tablist" aria-orientation="horizontal"><button id="method-summary-table-tab0" role="tab" aria-selected="true" aria-controls="method-summary-table.tabpanel" tabindex="0" onkeydown="switchTab(event)" onclick="show('method-summary-table', 'method-summary-table', 3)" class="active-table-tab">All Methods</button><button id="method-summary-table-tab2" role="tab" aria-selected="false" aria-controls="method-summary-table.tabpanel" tabindex="-1" onkeydown="switchTab(event)" onclick="show('method-summary-table', 'method-summary-table-tab2', 3)" class="table-tab">Instance Methods</button><button id="method-summary-table-tab3" role="tab" aria-selected="false" aria-controls="method-summary-table.tabpanel" tabindex="-1" onkeydown="switchTab(event)" onclick="show('method-summary-table', 'method-summary-table-tab3', 3)" class="table-tab">Abstract Methods</button></div>
<div id="method-summary-table.tabpanel" role="tabpanel">
<div class="summary-table three-column-summary" aria-labelledby="method-summary-table-tab0">
<div class="table-header col-first">Modifier and Type</div>
<div class="table-header col-second">Method</div>
<div class="table-header col-last">Description</div>
<div class="col-first even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code>void</code></div>
<div class="col-second even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code><a href="#close()" class="member-name-link">close</a>()</code></div>
<div class="col-last even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3">
<div class="block">Override to remove the 'throws IOException' as we are just a reader.</div>
</div>
<div class="col-first odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code>long</code></div>
<div class="col-second odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code><a href="#getPosition()" class="member-name-link">getPosition</a>()</code></div>
<div class="col-last odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3">
<div class="block">Get the current reading position.</div>
</div>
<div class="col-first even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code><a href="WALTailingReader.Result.html" title="class in org.apache.hadoop.hbase.wal">WALTailingReader.Result</a></code></div>
<div class="col-second even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code><a href="#next(long)" class="member-name-link">next</a><wbr>(long&nbsp;limit)</code></div>
<div class="col-last even-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3">
<div class="block">Read the next entry and make sure the position after reading does not go beyond the given
<code>limit</code>.</div>
</div>
<div class="col-first odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code>void</code></div>
<div class="col-second odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3"><code><a href="#resetTo(long,boolean)" class="member-name-link">resetTo</a><wbr>(long&nbsp;position,
boolean&nbsp;resetCompression)</code></div>
<div class="col-last odd-row-color method-summary-table method-summary-table-tab2 method-summary-table-tab3">
<div class="block">Reopen the reader to see if there is new data arrives, and also seek(or skip) to the given
position.</div>
</div>
</div>
</div>
</div>
</section>
</li>
</ul>
</section>
<section class="details">
<ul class="details-list">
<!-- ============ METHOD DETAIL ========== -->
<li>
<section class="method-details" id="method-detail">
<h2>Method Details</h2>
<ul class="member-list">
<li>
<section class="detail" id="next(long)">
<h3>next</h3>
<div class="member-signature"><span class="return-type"><a href="WALTailingReader.Result.html" title="class in org.apache.hadoop.hbase.wal">WALTailingReader.Result</a></span>&nbsp;<span class="element-name"><a href="../../../../../src-html/org/apache/hadoop/hbase/wal/WALTailingReader.html#line-121">next</a></span><wbr><span class="parameters">(long&nbsp;limit)</span></div>
<div class="block">Read the next entry and make sure the position after reading does not go beyond the given
<code>limit</code>.
<p/>
Notice that we will not throw any checked exception out, all the states are represented by the
return value. Of course we will log the exceptions out. The reason why we do this is that, for
tailing a WAL file which is currently being written, we will hit EOFException many times, so it
should not be considered as an 'exception' and also, creating an Exception is a bit expensive.</div>
<dl class="notes">
<dt>Parameters:</dt>
<dd><code>limit</code> - the position limit. See HBASE-14004 for more details about why we need this
limitation. -1 means no limit.</dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="getPosition()">
<h3>getPosition</h3>
<div class="member-signature"><span class="return-type">long</span>&nbsp;<span class="element-name"><a href="../../../../../src-html/org/apache/hadoop/hbase/wal/WALTailingReader.html#line-126">getPosition</a></span>()
throws <span class="exceptions"><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link">IOException</a></span></div>
<div class="block">Get the current reading position.</div>
<dl class="notes">
<dt>Throws:</dt>
<dd><code><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link">IOException</a></code></dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="resetTo(long,boolean)">
<h3>resetTo</h3>
<div class="member-signature"><span class="return-type">void</span>&nbsp;<span class="element-name"><a href="../../../../../src-html/org/apache/hadoop/hbase/wal/WALTailingReader.html#line-141">resetTo</a></span><wbr><span class="parameters">(long&nbsp;position,
boolean&nbsp;resetCompression)</span>
throws <span class="exceptions"><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link">IOException</a></span></div>
<div class="block">Reopen the reader to see if there is new data arrives, and also seek(or skip) to the given
position.
<p/>
If you want to read from the beginning instead of a given position, please pass -1 as
<code>position</code>, then the reader will locate to the first entry. Notice that, since we have a
magic header and a pb header, the first WAL entry is not located at position 0, so passing 0
will cause trouble.</div>
<dl class="notes">
<dt>Parameters:</dt>
<dd><code>position</code> - the position we want to start reading from after resetting, or -1 if
you want to start reading from the beginning.</dd>
<dd><code>resetCompression</code> - whether we also need to clear the compression context. If <code>true</code>,
we will use skip instead of seek after resetting.</dd>
<dt>Throws:</dt>
<dd><code><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link">IOException</a></code></dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="close()">
<h3>close</h3>
<div class="member-signature"><span class="return-type">void</span>&nbsp;<span class="element-name"><a href="../../../../../src-html/org/apache/hadoop/hbase/wal/WALTailingReader.html#line-146">close</a></span>()</div>
<div class="block">Override to remove the 'throws IOException' as we are just a reader.</div>
<dl class="notes">
<dt>Specified by:</dt>
<dd><code><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/AutoCloseable.html#close()" title="class or interface in java.lang" class="external-link">close</a></code>&nbsp;in interface&nbsp;<code><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/AutoCloseable.html" title="class or interface in java.lang" class="external-link">AutoCloseable</a></code></dd>
<dt>Specified by:</dt>
<dd><code><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/io/Closeable.html#close()" title="class or interface in java.io" class="external-link">close</a></code>&nbsp;in interface&nbsp;<code><a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/io/Closeable.html" title="class or interface in java.io" class="external-link">Closeable</a></code></dd>
</dl>
</section>
</li>
</ul>
</section>
</li>
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