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   <h1>Source code for apache_beam.transforms.periodicsequence</h1><div class="highlight"><pre>
 <span></span><span class="c1">#</span>
 <span class="c1"># Licensed to the Apache Software Foundation (ASF) under one or more</span>
 <span class="c1"># contributor license agreements.  See the NOTICE file distributed with</span>
 <span class="c1"># this work for additional information regarding copyright ownership.</span>
 <span class="c1"># The ASF licenses this file to You under the Apache License, Version 2.0</span>
 <span class="c1"># (the &quot;License&quot;); you may not use this file except in compliance with</span>
 <span class="c1"># the License.  You may obtain a copy of the License at</span>
 <span class="c1">#</span>
 <span class="c1">#    http://www.apache.org/licenses/LICENSE-2.0</span>
 <span class="c1">#</span>
 <span class="c1"># Unless required by applicable law or agreed to in writing, software</span>
 <span class="c1"># distributed under the License is distributed on an &quot;AS IS&quot; BASIS,</span>
 <span class="c1"># WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span>
 <span class="c1"># See the License for the specific language governing permissions and</span>
 <span class="c1"># limitations under the License.</span>
 <span class="c1">#</span>

 <span class="kn">import</span> <span class="nn">math</span>
 <span class="kn">import</span> <span class="nn">time</span>

 <span class="kn">import</span> <span class="nn">apache_beam</span> <span class="k">as</span> <span class="nn">beam</span>
 <span class="kn">from</span> <span class="nn">apache_beam.io.restriction_trackers</span> <span class="kn">import</span> <span class="n">OffsetRange</span>
 <span class="kn">from</span> <span class="nn">apache_beam.io.restriction_trackers</span> <span class="kn">import</span> <span class="n">OffsetRestrictionTracker</span>
 <span class="kn">from</span> <span class="nn">apache_beam.io.watermark_estimators</span> <span class="kn">import</span> <span class="n">ManualWatermarkEstimator</span>
 <span class="kn">from</span> <span class="nn">apache_beam.runners</span> <span class="kn">import</span> <span class="n">sdf_utils</span>
 <span class="kn">from</span> <span class="nn">apache_beam.transforms</span> <span class="kn">import</span> <span class="n">core</span>
 <span class="kn">from</span> <span class="nn">apache_beam.transforms</span> <span class="kn">import</span> <span class="n">window</span>
 <span class="kn">from</span> <span class="nn">apache_beam.transforms.ptransform</span> <span class="kn">import</span> <span class="n">PTransform</span>
 <span class="kn">from</span> <span class="nn">apache_beam.transforms.window</span> <span class="kn">import</span> <span class="n">TimestampedValue</span>
 <span class="kn">from</span> <span class="nn">apache_beam.utils</span> <span class="kn">import</span> <span class="n">timestamp</span>
 <span class="kn">from</span> <span class="nn">apache_beam.utils.timestamp</span> <span class="kn">import</span> <span class="n">MAX_TIMESTAMP</span>
 <span class="kn">from</span> <span class="nn">apache_beam.utils.timestamp</span> <span class="kn">import</span> <span class="n">Timestamp</span>


 <div class="viewcode-block" id="ImpulseSeqGenRestrictionProvider"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.ImpulseSeqGenRestrictionProvider">[docs]</a><span class="k">class</span> <span class="nc">ImpulseSeqGenRestrictionProvider</span><span class="p">(</span><span class="n">core</span><span class="o">.</span><span class="n">RestrictionProvider</span><span class="p">):</span>
 <div class="viewcode-block" id="ImpulseSeqGenRestrictionProvider.initial_restriction"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.ImpulseSeqGenRestrictionProvider.initial_restriction">[docs]</a>  <span class="k">def</span> <span class="nf">initial_restriction</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">element</span><span class="p">):</span>
     <span class="n">start</span><span class="p">,</span> <span class="n">end</span><span class="p">,</span> <span class="n">interval</span> <span class="o">=</span> <span class="n">element</span>
     <span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">start</span><span class="p">,</span> <span class="n">Timestamp</span><span class="p">):</span>
       <span class="n">start</span> <span class="o">=</span> <span class="n">start</span><span class="o">.</span><span class="n">micros</span> <span class="o">/</span> <span class="mi">1000000</span>
     <span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">end</span><span class="p">,</span> <span class="n">Timestamp</span><span class="p">):</span>
       <span class="n">end</span> <span class="o">=</span> <span class="n">end</span><span class="o">.</span><span class="n">micros</span> <span class="o">/</span> <span class="mi">1000000</span>

     <span class="k">assert</span> <span class="n">start</span> <span class="o">&lt;=</span> <span class="n">end</span>
     <span class="k">assert</span> <span class="n">interval</span> <span class="o">&gt;</span> <span class="mi">0</span>
     <span class="n">total_outputs</span> <span class="o">=</span> <span class="n">math</span><span class="o">.</span><span class="n">ceil</span><span class="p">((</span><span class="n">end</span> <span class="o">-</span> <span class="n">start</span><span class="p">)</span> <span class="o">/</span> <span class="n">interval</span><span class="p">)</span>
     <span class="k">return</span> <span class="n">OffsetRange</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="n">total_outputs</span><span class="p">)</span></div>

 <div class="viewcode-block" id="ImpulseSeqGenRestrictionProvider.create_tracker"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.ImpulseSeqGenRestrictionProvider.create_tracker">[docs]</a>  <span class="k">def</span> <span class="nf">create_tracker</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">restriction</span><span class="p">):</span>
     <span class="k">return</span> <span class="n">OffsetRestrictionTracker</span><span class="p">(</span><span class="n">restriction</span><span class="p">)</span></div>

 <div class="viewcode-block" id="ImpulseSeqGenRestrictionProvider.restriction_size"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.ImpulseSeqGenRestrictionProvider.restriction_size">[docs]</a>  <span class="k">def</span> <span class="nf">restriction_size</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">unused_element</span><span class="p">,</span> <span class="n">restriction</span><span class="p">):</span>
     <span class="k">return</span> <span class="n">restriction</span><span class="o">.</span><span class="n">size</span><span class="p">()</span></div>

   <span class="c1"># On drain, immediately stop emitting new elements</span>
 <div class="viewcode-block" id="ImpulseSeqGenRestrictionProvider.truncate"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.ImpulseSeqGenRestrictionProvider.truncate">[docs]</a>  <span class="k">def</span> <span class="nf">truncate</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">unused_element</span><span class="p">,</span> <span class="n">unused_restriction</span><span class="p">):</span>
     <span class="k">return</span> <span class="kc">None</span></div></div>


 <div class="viewcode-block" id="ImpulseSeqGenDoFn"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.ImpulseSeqGenDoFn">[docs]</a><span class="k">class</span> <span class="nc">ImpulseSeqGenDoFn</span><span class="p">(</span><span class="n">beam</span><span class="o">.</span><span class="n">DoFn</span><span class="p">):</span>
 <span class="w">  </span><span class="sd">&#39;&#39;&#39;</span>
 <span class="sd">  ImpulseSeqGenDoFn fn receives tuple elements with three parts:</span>

 <span class="sd">  * first_timestamp = first timestamp to output element for.</span>
 <span class="sd">  * last_timestamp = last timestamp/time to output element for.</span>
 <span class="sd">  * fire_interval = how often to fire an element.</span>

 <span class="sd">  For each input element received, ImpulseSeqGenDoFn fn will start</span>
 <span class="sd">  generating output elements in following pattern:</span>

 <span class="sd">  * if element timestamp is less than current runtime then output element.</span>
 <span class="sd">  * if element timestamp is greater than current runtime, wait until next</span>
 <span class="sd">    element timestamp.</span>

 <span class="sd">  ImpulseSeqGenDoFn can&#39;t guarantee that each element is output at exact time.</span>
 <span class="sd">  ImpulseSeqGenDoFn guarantees that elements would not be output prior to</span>
 <span class="sd">  given runtime timestamp.</span>
 <span class="sd">  &#39;&#39;&#39;</span>
 <div class="viewcode-block" id="ImpulseSeqGenDoFn.process"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.ImpulseSeqGenDoFn.process">[docs]</a>  <span class="nd">@beam</span><span class="o">.</span><span class="n">DoFn</span><span class="o">.</span><span class="n">unbounded_per_element</span><span class="p">()</span>
   <span class="k">def</span> <span class="nf">process</span><span class="p">(</span>
       <span class="bp">self</span><span class="p">,</span>
       <span class="n">element</span><span class="p">,</span>
       <span class="n">restriction_tracker</span><span class="o">=</span><span class="n">beam</span><span class="o">.</span><span class="n">DoFn</span><span class="o">.</span><span class="n">RestrictionParam</span><span class="p">(</span>
           <span class="n">ImpulseSeqGenRestrictionProvider</span><span class="p">()),</span>
       <span class="n">watermark_estimator</span><span class="o">=</span><span class="n">beam</span><span class="o">.</span><span class="n">DoFn</span><span class="o">.</span><span class="n">WatermarkEstimatorParam</span><span class="p">(</span>
           <span class="n">ManualWatermarkEstimator</span><span class="o">.</span><span class="n">default_provider</span><span class="p">())):</span>
 <span class="w">    </span><span class="sd">&#39;&#39;&#39;</span>
 <span class="sd">    :param element: (start_timestamp, end_timestamp, interval)</span>
 <span class="sd">    :param restriction_tracker:</span>
 <span class="sd">    :return: yields elements at processing real-time intervals with value of</span>
 <span class="sd">      target output timestamp for the element.</span>
 <span class="sd">    &#39;&#39;&#39;</span>
     <span class="n">start</span><span class="p">,</span> <span class="n">_</span><span class="p">,</span> <span class="n">interval</span> <span class="o">=</span> <span class="n">element</span>

     <span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">start</span><span class="p">,</span> <span class="n">Timestamp</span><span class="p">):</span>
       <span class="n">start</span> <span class="o">=</span> <span class="n">start</span><span class="o">.</span><span class="n">micros</span> <span class="o">/</span> <span class="mi">1000000</span>

     <span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">restriction_tracker</span><span class="p">,</span> <span class="n">sdf_utils</span><span class="o">.</span><span class="n">RestrictionTrackerView</span><span class="p">)</span>

     <span class="n">current_output_index</span> <span class="o">=</span> <span class="n">restriction_tracker</span><span class="o">.</span><span class="n">current_restriction</span><span class="p">()</span><span class="o">.</span><span class="n">start</span>
     <span class="n">current_output_timestamp</span> <span class="o">=</span> <span class="n">start</span> <span class="o">+</span> <span class="n">interval</span> <span class="o">*</span> <span class="n">current_output_index</span>
     <span class="n">current_time</span> <span class="o">=</span> <span class="n">time</span><span class="o">.</span><span class="n">time</span><span class="p">()</span>
     <span class="n">watermark_estimator</span><span class="o">.</span><span class="n">set_watermark</span><span class="p">(</span>
         <span class="n">timestamp</span><span class="o">.</span><span class="n">Timestamp</span><span class="p">(</span><span class="n">current_output_timestamp</span><span class="p">))</span>

     <span class="k">while</span> <span class="n">current_output_timestamp</span> <span class="o">&lt;=</span> <span class="n">current_time</span><span class="p">:</span>
       <span class="k">if</span> <span class="n">restriction_tracker</span><span class="o">.</span><span class="n">try_claim</span><span class="p">(</span><span class="n">current_output_index</span><span class="p">):</span>
         <span class="k">yield</span> <span class="n">current_output_timestamp</span>
         <span class="n">current_output_index</span> <span class="o">+=</span> <span class="mi">1</span>
         <span class="n">current_output_timestamp</span> <span class="o">=</span> <span class="n">start</span> <span class="o">+</span> <span class="n">interval</span> <span class="o">*</span> <span class="n">current_output_index</span>
         <span class="n">current_time</span> <span class="o">=</span> <span class="n">time</span><span class="o">.</span><span class="n">time</span><span class="p">()</span>
         <span class="n">watermark_estimator</span><span class="o">.</span><span class="n">set_watermark</span><span class="p">(</span>
             <span class="n">timestamp</span><span class="o">.</span><span class="n">Timestamp</span><span class="p">(</span><span class="n">current_output_timestamp</span><span class="p">))</span>
       <span class="k">else</span><span class="p">:</span>
         <span class="k">return</span>

     <span class="n">restriction_tracker</span><span class="o">.</span><span class="n">defer_remainder</span><span class="p">(</span>
         <span class="n">timestamp</span><span class="o">.</span><span class="n">Timestamp</span><span class="p">(</span><span class="n">current_output_timestamp</span><span class="p">))</span></div></div>


 <div class="viewcode-block" id="PeriodicSequence"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.PeriodicSequence">[docs]</a><span class="k">class</span> <span class="nc">PeriodicSequence</span><span class="p">(</span><span class="n">PTransform</span><span class="p">):</span>
 <span class="w">  </span><span class="sd">&#39;&#39;&#39;</span>
 <span class="sd">  PeriodicSequence transform receives tuple elements with three parts:</span>

 <span class="sd">  * first_timestamp = first timestamp to output element for.</span>
 <span class="sd">  * last_timestamp = last timestamp/time to output element for.</span>
 <span class="sd">  * fire_interval = how often to fire an element.</span>

 <span class="sd">  For each input element received, PeriodicSequence transform will start</span>
 <span class="sd">  generating output elements in following pattern:</span>

 <span class="sd">  * if element timestamp is less than current runtime then output element.</span>
 <span class="sd">  * if element timestamp is greater than current runtime, wait until next</span>
 <span class="sd">    element timestamp.</span>

 <span class="sd">  PeriodicSequence can&#39;t guarantee that each element is output at exact time.</span>
 <span class="sd">  PeriodicSequence guarantees that elements would not be output prior to given</span>
 <span class="sd">  runtime timestamp.</span>
 <span class="sd">  The PCollection generated by PeriodicSequence is unbounded.</span>
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="k">def</span> <span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
     <span class="k">pass</span>

 <div class="viewcode-block" id="PeriodicSequence.expand"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.PeriodicSequence.expand">[docs]</a>  <span class="k">def</span> <span class="nf">expand</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">pcoll</span><span class="p">):</span>
     <span class="k">return</span> <span class="p">(</span>
         <span class="n">pcoll</span>
         <span class="o">|</span> <span class="s1">&#39;GenSequence&#39;</span> <span class="o">&gt;&gt;</span> <span class="n">beam</span><span class="o">.</span><span class="n">ParDo</span><span class="p">(</span><span class="n">ImpulseSeqGenDoFn</span><span class="p">())</span>
         <span class="o">|</span> <span class="s1">&#39;MapToTimestamped&#39;</span> <span class="o">&gt;&gt;</span> <span class="n">beam</span><span class="o">.</span><span class="n">Map</span><span class="p">(</span><span class="k">lambda</span> <span class="n">tt</span><span class="p">:</span> <span class="n">TimestampedValue</span><span class="p">(</span><span class="n">tt</span><span class="p">,</span> <span class="n">tt</span><span class="p">)))</span></div></div>


 <div class="viewcode-block" id="PeriodicImpulse"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.PeriodicImpulse">[docs]</a><span class="k">class</span> <span class="nc">PeriodicImpulse</span><span class="p">(</span><span class="n">PTransform</span><span class="p">):</span>
 <span class="w">  </span><span class="sd">&#39;&#39;&#39;</span>
 <span class="sd">  PeriodicImpulse transform generates an infinite sequence of elements with</span>
 <span class="sd">  given runtime interval.</span>

 <span class="sd">  PeriodicImpulse transform behaves same as {@link PeriodicSequence} transform,</span>
 <span class="sd">  but can be used as first transform in pipeline.</span>
 <span class="sd">  The PCollection generated by PeriodicImpulse is unbounded.</span>
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="k">def</span> <span class="fm">__init__</span><span class="p">(</span>
       <span class="bp">self</span><span class="p">,</span>
       <span class="n">start_timestamp</span><span class="o">=</span><span class="n">Timestamp</span><span class="o">.</span><span class="n">now</span><span class="p">(),</span>
       <span class="n">stop_timestamp</span><span class="o">=</span><span class="n">MAX_TIMESTAMP</span><span class="p">,</span>
       <span class="n">fire_interval</span><span class="o">=</span><span class="mf">360.0</span><span class="p">,</span>
       <span class="n">apply_windowing</span><span class="o">=</span><span class="kc">False</span><span class="p">):</span>
 <span class="w">    </span><span class="sd">&#39;&#39;&#39;</span>
 <span class="sd">    :param start_timestamp: Timestamp for first element.</span>
 <span class="sd">    :param stop_timestamp: Timestamp after which no elements will be output.</span>
 <span class="sd">    :param fire_interval: Interval at which to output elements.</span>
 <span class="sd">    :param apply_windowing: Whether each element should be assigned to</span>
 <span class="sd">      individual window. If false, all elements will reside in global window.</span>
 <span class="sd">    &#39;&#39;&#39;</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">start_ts</span> <span class="o">=</span> <span class="n">start_timestamp</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">stop_ts</span> <span class="o">=</span> <span class="n">stop_timestamp</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">interval</span> <span class="o">=</span> <span class="n">fire_interval</span>
     <span class="bp">self</span><span class="o">.</span><span class="n">apply_windowing</span> <span class="o">=</span> <span class="n">apply_windowing</span>

 <div class="viewcode-block" id="PeriodicImpulse.expand"><a class="viewcode-back" href="../../../apache_beam.transforms.periodicsequence.html#apache_beam.transforms.periodicsequence.PeriodicImpulse.expand">[docs]</a>  <span class="k">def</span> <span class="nf">expand</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">pbegin</span><span class="p">):</span>
     <span class="n">result</span> <span class="o">=</span> <span class="p">(</span>
         <span class="n">pbegin</span>
         <span class="o">|</span> <span class="s1">&#39;ImpulseElement&#39;</span> <span class="o">&gt;&gt;</span> <span class="n">beam</span><span class="o">.</span><span class="n">Create</span><span class="p">(</span>
             <span class="p">[(</span><span class="bp">self</span><span class="o">.</span><span class="n">start_ts</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">stop_ts</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">interval</span><span class="p">)])</span>
         <span class="o">|</span> <span class="s1">&#39;GenSequence&#39;</span> <span class="o">&gt;&gt;</span> <span class="n">beam</span><span class="o">.</span><span class="n">ParDo</span><span class="p">(</span><span class="n">ImpulseSeqGenDoFn</span><span class="p">())</span>
         <span class="o">|</span> <span class="s1">&#39;MapToTimestamped&#39;</span> <span class="o">&gt;&gt;</span> <span class="n">beam</span><span class="o">.</span><span class="n">Map</span><span class="p">(</span><span class="k">lambda</span> <span class="n">tt</span><span class="p">:</span> <span class="n">TimestampedValue</span><span class="p">(</span><span class="n">tt</span><span class="p">,</span> <span class="n">tt</span><span class="p">)))</span>
     <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">apply_windowing</span><span class="p">:</span>
       <span class="n">result</span> <span class="o">=</span> <span class="n">result</span> <span class="o">|</span> <span class="s1">&#39;ApplyWindowing&#39;</span> <span class="o">&gt;&gt;</span> <span class="n">beam</span><span class="o">.</span><span class="n">WindowInto</span><span class="p">(</span>
           <span class="n">window</span><span class="o">.</span><span class="n">FixedWindows</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">interval</span><span class="p">))</span>
     <span class="k">return</span> <span class="n">result</span></div></div>
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