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| <h1>Source code for apache_beam.io.gcp.datastore.v1new.adaptive_throttler</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 "License"); 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 "AS IS" 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="c1"># Utility functions & classes that are _not_ specific to the datastore client.</span> |
| <span class="c1">#</span> |
| <span class="c1"># For internal use only; no backwards-compatibility guarantees.</span> |
| |
| <span class="c1"># pytype: skip-file</span> |
| |
| <span class="kn">import</span> <span class="nn">random</span> |
| |
| <span class="kn">from</span> <span class="nn">apache_beam.io.gcp.datastore.v1new</span> <span class="kn">import</span> <span class="n">util</span> |
| |
| |
| <div class="viewcode-block" id="AdaptiveThrottler"><a class="viewcode-back" href="../../../../../../apache_beam.io.gcp.datastore.v1new.adaptive_throttler.html#apache_beam.io.gcp.datastore.v1new.adaptive_throttler.AdaptiveThrottler">[docs]</a><span class="k">class</span> <span class="nc">AdaptiveThrottler</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span> |
| <span class="w"> </span><span class="sd">"""Implements adaptive throttling.</span> |
| |
| <span class="sd"> See</span> |
| <span class="sd"> https://landing.google.com/sre/book/chapters/handling-overload.html#client-side-throttling-a7sYUg</span> |
| <span class="sd"> for a full discussion of the use case and algorithm applied.</span> |
| <span class="sd"> """</span> |
| |
| <span class="c1"># The target minimum number of requests per samplePeriodMs, even if no</span> |
| <span class="c1"># requests succeed. Must be greater than 0, else we could throttle to zero.</span> |
| <span class="c1"># Because every decision is probabilistic, there is no guarantee that the</span> |
| <span class="c1"># request rate in any given interval will not be zero. (This is the +1 from</span> |
| <span class="c1"># the formula in</span> |
| <span class="c1"># https://landing.google.com/sre/book/chapters/handling-overload.html )</span> |
| <span class="n">MIN_REQUESTS</span> <span class="o">=</span> <span class="mi">1</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">window_ms</span><span class="p">,</span> <span class="n">bucket_ms</span><span class="p">,</span> <span class="n">overload_ratio</span><span class="p">):</span> |
| <span class="w"> </span><span class="sd">"""Initializes AdaptiveThrottler.</span> |
| |
| <span class="sd"> Args:</span> |
| <span class="sd"> window_ms: int, length of history to consider, in ms, to set</span> |
| <span class="sd"> throttling.</span> |
| <span class="sd"> bucket_ms: int, granularity of time buckets that we store data in, in</span> |
| <span class="sd"> ms.</span> |
| <span class="sd"> overload_ratio: float, the target ratio between requests sent and</span> |
| <span class="sd"> successful requests. This is "K" in the formula in</span> |
| <span class="sd"> https://landing.google.com/sre/book/chapters/handling-overload.html.</span> |
| <span class="sd"> """</span> |
| <span class="bp">self</span><span class="o">.</span><span class="n">_all_requests</span> <span class="o">=</span> <span class="n">util</span><span class="o">.</span><span class="n">MovingSum</span><span class="p">(</span><span class="n">window_ms</span><span class="p">,</span> <span class="n">bucket_ms</span><span class="p">)</span> |
| <span class="bp">self</span><span class="o">.</span><span class="n">_successful_requests</span> <span class="o">=</span> <span class="n">util</span><span class="o">.</span><span class="n">MovingSum</span><span class="p">(</span><span class="n">window_ms</span><span class="p">,</span> <span class="n">bucket_ms</span><span class="p">)</span> |
| <span class="bp">self</span><span class="o">.</span><span class="n">_overload_ratio</span> <span class="o">=</span> <span class="nb">float</span><span class="p">(</span><span class="n">overload_ratio</span><span class="p">)</span> |
| <span class="bp">self</span><span class="o">.</span><span class="n">_random</span> <span class="o">=</span> <span class="n">random</span><span class="o">.</span><span class="n">Random</span><span class="p">()</span> |
| |
| <span class="k">def</span> <span class="nf">_throttling_probability</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">now</span><span class="p">):</span> |
| <span class="k">if</span> <span class="ow">not</span> <span class="bp">self</span><span class="o">.</span><span class="n">_all_requests</span><span class="o">.</span><span class="n">has_data</span><span class="p">(</span><span class="n">now</span><span class="p">):</span> |
| <span class="k">return</span> <span class="mi">0</span> |
| <span class="n">all_requests</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_all_requests</span><span class="o">.</span><span class="n">sum</span><span class="p">(</span><span class="n">now</span><span class="p">)</span> |
| <span class="n">successful_requests</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_successful_requests</span><span class="o">.</span><span class="n">sum</span><span class="p">(</span><span class="n">now</span><span class="p">)</span> |
| <span class="k">return</span> <span class="nb">max</span><span class="p">(</span> |
| <span class="mi">0</span><span class="p">,</span> <span class="p">(</span><span class="n">all_requests</span> <span class="o">-</span> <span class="bp">self</span><span class="o">.</span><span class="n">_overload_ratio</span> <span class="o">*</span> <span class="n">successful_requests</span><span class="p">)</span> <span class="o">/</span> |
| <span class="p">(</span><span class="n">all_requests</span> <span class="o">+</span> <span class="n">AdaptiveThrottler</span><span class="o">.</span><span class="n">MIN_REQUESTS</span><span class="p">))</span> |
| |
| <div class="viewcode-block" id="AdaptiveThrottler.throttle_request"><a class="viewcode-back" href="../../../../../../apache_beam.io.gcp.datastore.v1new.adaptive_throttler.html#apache_beam.io.gcp.datastore.v1new.adaptive_throttler.AdaptiveThrottler.throttle_request">[docs]</a> <span class="k">def</span> <span class="nf">throttle_request</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">now</span><span class="p">):</span> |
| <span class="w"> </span><span class="sd">"""Determines whether one RPC attempt should be throttled.</span> |
| |
| <span class="sd"> This should be called once each time the caller intends to send an RPC; if</span> |
| <span class="sd"> it returns true, drop or delay that request (calling this function again</span> |
| <span class="sd"> after the delay).</span> |
| |
| <span class="sd"> Args:</span> |
| <span class="sd"> now: int, time in ms since the epoch</span> |
| <span class="sd"> Returns:</span> |
| <span class="sd"> bool, True if the caller should throttle or delay the request.</span> |
| <span class="sd"> """</span> |
| <span class="n">throttling_probability</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_throttling_probability</span><span class="p">(</span><span class="n">now</span><span class="p">)</span> |
| <span class="bp">self</span><span class="o">.</span><span class="n">_all_requests</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="n">now</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span> |
| <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_random</span><span class="o">.</span><span class="n">uniform</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span> <span class="o"><</span> <span class="n">throttling_probability</span></div> |
| |
| <div class="viewcode-block" id="AdaptiveThrottler.successful_request"><a class="viewcode-back" href="../../../../../../apache_beam.io.gcp.datastore.v1new.adaptive_throttler.html#apache_beam.io.gcp.datastore.v1new.adaptive_throttler.AdaptiveThrottler.successful_request">[docs]</a> <span class="k">def</span> <span class="nf">successful_request</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">now</span><span class="p">):</span> |
| <span class="w"> </span><span class="sd">"""Notifies the throttler of a successful request.</span> |
| |
| <span class="sd"> Must be called once for each request (for which throttle_request was</span> |
| <span class="sd"> previously called) that succeeded.</span> |
| |
| <span class="sd"> Args:</span> |
| <span class="sd"> now: int, time in ms since the epoch</span> |
| <span class="sd"> """</span> |
| <span class="bp">self</span><span class="o">.</span><span class="n">_successful_requests</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="n">now</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span></div></div> |
| </pre></div> |
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