| <!DOCTYPE html> |
| |
| |
| <html xmlns="http://www.w3.org/1999/xhtml"> |
| <head> |
| <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> |
| |
| <title>Introduction — DistributedLog 1.0 documentation</title> |
| |
| <link rel="stylesheet" href="../_static/override.css" type="text/css" /> |
| <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> |
| <link rel="stylesheet" href="../_static/bootstrap-3.1.0/css/bootstrap.min.css" type="text/css" /> |
| <link rel="stylesheet" href="../_static/bootstrap-3.1.0/css/bootstrap-theme.min.css" type="text/css" /> |
| <link rel="stylesheet" href="../_static/css/featherlight.min.css" type="text/css" /> |
| <link rel="stylesheet" href="../_static/css/docbird.css" type="text/css" /> |
| <link rel="stylesheet" href="../_static/css/docbird-xs.css" type="text/css" /> |
| <link rel="stylesheet" href="../_static/css/jquery.rateyo.min.css" type="text/css" /> |
| <link rel="stylesheet" href="../_static/css/selection-sharer.css" type="text/css" /> |
| |
| <script type="text/javascript"> |
| var DOCUMENTATION_OPTIONS = { |
| URL_ROOT: '../', |
| VERSION: '1.0', |
| COLLAPSE_INDEX: false, |
| FILE_SUFFIX: '.html', |
| HAS_SOURCE: true |
| }; |
| </script> |
| <script type="text/javascript" src="../_static/jquery.js"></script> |
| <script type="text/javascript" src="../_static/underscore.js"></script> |
| <script type="text/javascript" src="../_static/doctools.js"></script> |
| <script type="text/javascript" src="../_static/bootstrap-3.1.0/js/bootstrap.min.js"></script> |
| <script type="text/javascript" src="../_static/js/bootstrap-docbird.js"></script> |
| <script type="text/javascript" src="../_static/js/jquery-1.11.0.min.js"></script> |
| <script type="text/javascript" src="../_static/js/jquery-fix.js"></script> |
| <script type="text/javascript" src="../_static/js/featherlight.min.js"></script> |
| <script type="text/javascript" src="../_static/js/ifvisible.js"></script> |
| <script type="text/javascript" src="../_static/js/timeme.js"></script> |
| <script type="text/javascript" src="../_static/js/jquery.rateyo.min.js"></script> |
| <script type="text/javascript" src="../_static/js/js.cookie.js"></script> |
| <link rel="shortcut icon" href="../_static/docbird.ico"/> |
| <link rel="top" title="DistributedLog 1.0 documentation" href="../index.html" /> |
| <link rel="up" title="Getting Started" href="main.html" /> |
| <link rel="next" title="Quick Start" href="quickstart.html" /> |
| <link rel="prev" title="Getting Started" href="main.html" /> |
| <meta charset='utf-8'> |
| <meta http-equiv='X-UA-Compatible' content='IE=edge,chrome=1'> |
| <meta name='viewport' content='width=device-width, initial-scale=1.0, maximum-scale=1'> |
| <meta name="apple-mobile-web-app-capable" content="yes"> |
| |
| <meta property="docbird:project" content="DistributedLog" /> |
| |
| </head> |
| <body> |
| <div class="navbar navbar-default navbar-fixed-top" role="navigation"> |
| <div class="container-fluid"> |
| <div class="row db-header"> |
| <div class="col-sm-3 col-md-3 col-lg-3 hidden-xs db-header-controls"> |
| <a href="/" alt="Back to Docbird"> |
| <div class="db-home-button"> |
| <span class="glyphicon glyphicon-home"></span> |
| </div> |
| </a> |
| |
| <form action="../search.html" method="get" class="db-searchbox-form"> |
| <div class="form-group"> |
| <input type="text" name="q" class="form-control db-searchbox-input" placeholder="Search DistributedLog" /> |
| </div> |
| <input type="hidden" name="check_keywords" value="yes" /> |
| <input type="hidden" name="area" value="default" /> |
| </form> |
| |
| </div> |
| <div class="col-sm-7 col-md-7 col-lg-7 col-xs-12 db-header-info"> |
| <div class="visible-xs"> |
| <a href="/" alt="Back to Docbird"> |
| <div class="db-home-button"> |
| <span class="glyphicon glyphicon-home"></span> |
| </div> |
| </a> |
| </div> |
| <div class="visible-xs db-xs-menu-button"> |
| <div class="navbar-header"> |
| <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#db-xs-menu"> |
| <span class="sr-only">Toggle navigation</span> |
| <span class="icon-bar"></span> |
| <span class="icon-bar"></span> |
| <span class="icon-bar"></span> |
| </button> |
| </div> |
| </div> |
| <div class="db-header-projectname"> |
| <h1><a href="../index.html">DistributedLog</a></h1> |
| </div> |
| </div> |
| </div> |
| <div class="row db-xs-menu hidden-sm hidden-md hidden-lg |
| collapse" id="db-xs-menu"> |
| |
| <form action="../search.html" method="get" class="db-searchbox-form"> |
| <div class="form-group"> |
| <input type="text" name="q" class="form-control db-searchbox-input" placeholder="Search DistributedLog" /> |
| </div> |
| <input type="hidden" name="check_keywords" value="yes" /> |
| <input type="hidden" name="area" value="default" /> |
| </form> |
| |
| <div class="db-toc" role="complementary"> |
| <ul class="current"> |
| <li class="toctree-l1"><a class="reference internal" href="../download.html">Releases</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../download.html#rc1">0.3.51-RC1</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../download.html#rc0">0.3.51-RC0</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1 current"><a class="reference internal" href="main.html">Getting Started</a><ul class="current"> |
| <li class="toctree-l2 current"><a class="current reference internal" href="">Introduction</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="quickstart.html">Quick Start</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../api/main.html">API</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../api/core.html">Core Library API</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../api/proxy.html">Write Proxy Client API</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../api/practice.html">Best Practices</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../configuration/main.html">Configuration</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../configuration/core.html">Core Library Configuration</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../configuration/proxy.html">Write Proxy Configuration</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../configuration/client.html">Client Configuration</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../configuration/perlog.html">Per Stream Configuration</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../considerations/main.html">Considerations</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../considerations/main.html#consistency-durability-and-ordering">Consistency, Durability and Ordering</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../considerations/main.html#partitioning">Partitioning</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../considerations/main.html#processing-semantics">Processing Semantics</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../architecture/main.html">Architecture</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../architecture/main.html#data-model">Data Model</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../architecture/main.html#software-stack">Software Stack</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../architecture/main.html#lifecyle-of-records">Lifecyle of records</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../design/main.html">Detail Design</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../design/main.html#consistency">Consistency</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../design/main.html#streaming-reads">Streaming Reads</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../design/main.html#logsegment-lifecycle">LogSegment Lifecycle</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../globalreplicatedlog/main.html">Global Replicated Log</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../globalreplicatedlog/main.html#region-aware-data-placement-policy">Region Aware Data Placement Policy</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../globalreplicatedlog/main.html#cross-region-speculative-reads">Cross Region Speculative Reads</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../implementation/main.html">Implementation</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../implementation/storage.html">Storage</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../operations/main.html">Deployment & Administration</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/deployment.html">Cluster Setup & Deployment</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/operations.html">DistributedLog Operations</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/performance.html">Performance Tuning</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/hardware.html">Hardware</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/monitoring.html">Monitoring</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/zookeeper.html">ZooKeeper</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/bookkeeper.html">BookKeeper</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../performance/main.html">Performance</a></li> |
| <li class="toctree-l1"><a class="reference internal" href="../references/main.html">References</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../references/configuration.html">Configuration Settings</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../references/metrics.html">Metrics</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../references/features.html">Features</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../tutorials/main.html">Tutorials</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../tutorials/main.html#basic">Basic</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../tutorials/main.html#messaging">Messaging</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../tutorials/main.html#replicated-state-machines">Replicated State Machines</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../tutorials/main.html#analytics">Analytics</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../developer/main.html">Developer</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../developer/release.html">Release</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../faq.html">FAQ</a></li> |
| </ul> |
| |
| </div> |
| </div> |
| </div> |
| </div> |
| <div class="container"> |
| <div class="row"> |
| <div style="z-index: 1" class="col-xs-12 col-sm-12 col-md-12 col-lg-12"> |
| <style> |
| .overflow-container { |
| display: none; |
| } |
| .overflow-toggle { |
| text-decoration: none; |
| border-bottom: none; |
| border-radius: 4px; |
| border: 1px solid #eee; |
| padding: 1px 3px 3px; |
| color: #888; |
| font-weight: normal; |
| background-color: linen; |
| line-height: 1.85em; |
| cursor: pointer; |
| } |
| .overflow-toggle:hover { |
| color: #333; |
| border-color: #ccc; |
| background-color: beige; |
| } |
| </style> |
| <script> |
| $(function(){ |
| $('.overflow-toggle').on('click', function(){ |
| $(this).next().toggle(); |
| }); |
| }); |
| </script> |
| <div class="db-project-header-container"> |
| <div class="row"> |
| |
| <div class="db-project-info col-lg-12 col-md-12 col-sm-12 col-xs-12"> |
| <h1> |
| <a href="../index.html">DistributedLog</a> |
| |
| </h1> |
| |
| <div class="db-code-link"> |
| <a href="git@github.com:twitter/distributedlog.git/tree/master/" target="_blank">git@github.com:twitter/distributedlog.git/tree/master/</a> |
| </div> |
| |
| |
| </div> |
| </div> |
| |
| <div class="row db-project-links-row"> |
| <div class=" col-sm-3 col-md-3 col-lg-3 db-project-link-column"> |
| <div class="db-hashtag-container"> |
| |
| <span class="db-project-link-label">OWNERS</span> |
| |
| <em>None</em> |
| |
| |
| </div> |
| </div> |
| <div class="col-sm-3 col-md-3 col-lg-3 db-project-link-column"> |
| <div class="db-hashtag-container"> |
| |
| <span class="db-project-link-label">TAGS</span> |
| |
| <em><a class="db-hashtag" href="/?q=tags:%23uses_maven">#uses_maven</a></em> |
| |
| |
| </div> |
| </div> |
| <div class="col-sm-3 col-md-3 col-lg-3 db-project-link-column"> |
| <span class="db-project-link-label">HEALTH</span> |
| |
| <h3 style="margin-top: 0"> |
| <!-- <a href="/techdocs/checklist.html" class="label label-success">--> |
| <a href="/report/distributedlog" class=""> |
| 9.0 / 10 |
| <span style="margin-left: .25em" class="glyphicon glyphicon-ok"></span> |
| </a> |
| |
| </h3> |
| </div> |
| <div class="col-sm-3 col-md-3 col-lg-3 db-project-link-column"> |
| <span class="db-project-link-label">RATING</span> |
| <div id="rateYo"></div> |
| </div> |
| </div> |
| |
| </div> |
| </div> |
| <div class="col-xs-12 col-sm-8 col-md-8 col-lg-8"> |
| <div class="db-content-body"> |
| |
| <div class="section" id="introduction"> |
| <h1>Introduction<a class="headerlink" href="#introduction" title="Permalink to this headline">¶</a></h1> |
| <p>DistributedLog (DL) is a high performance replicated log service. |
| It offers durability, replication and strong consistency, which provides a fundamental building block |
| for building reliable distributed systems, e.g replicated-state-machines, general pub/sub systems, |
| distributed databases, distributed queues and etc.</p> |
| <p>DistributedLog maintains sequences of records in categories called <em>Logs</em> (aka <em>Log Streams</em>). |
| The processes that write records to a DL log are <em>writers</em>, while the processes that read |
| from logs and process the records are <em>readers</em>.</p> |
| <div class="figure align-center"> |
| <img alt="../_images/softwarestack1.png" src="../_images/softwarestack1.png" /> |
| <p class="caption">Figure 1. DistributedLog Software Stack</p> |
| </div> |
| <div class="section" id="logs"> |
| <h2>Logs<a class="headerlink" href="#logs" title="Permalink to this headline">¶</a></h2> |
| <p>A <strong>log</strong> is an ordered, immutable sequence of <em>log records</em>.</p> |
| <div class="figure align-center"> |
| <img alt="../_images/datamodel1.png" src="../_images/datamodel1.png" /> |
| <p class="caption">Figure 2. Anatomy of a log stream</p> |
| </div> |
| <div class="section" id="log-records"> |
| <h3>Log Records<a class="headerlink" href="#log-records" title="Permalink to this headline">¶</a></h3> |
| <p>Each <strong>log record</strong> is a sequence of bytes. |
| <strong>Log records</strong> are written sequentially into a <em>log stream</em>, and will be assigned with |
| a unique sequence number <em>called</em> <strong>DLSN</strong> (DistributedLog Sequence Number). Besides <em>DLSN</em>, |
| applications could assign its own sequence number while constructing log records. The |
| application defined sequence number is called <strong>TransactionID</strong> (<em>txid</em>). Either <em>DLSN</em> |
| or <em>TransactionID</em> could be used for positioning readers to start reading from a specific |
| <em>log record</em>.</p> |
| </div> |
| <div class="section" id="log-segments"> |
| <h3>Log Segments<a class="headerlink" href="#log-segments" title="Permalink to this headline">¶</a></h3> |
| <p>A <strong>log</strong> is broken down into <em>segments</em>, which each log segment contains its subset of |
| records. <strong>Log segments</strong> are distributed and stored in a log segment store (e.g Apache BookKeeper). |
| DistributedLog rolls the log segments based on configured rolling policy - either a configurable |
| period of time (e.g. every 2 hours) or a configurable maximum size (e.g. every 128MB). |
| So the data of logs will be divided into equal-sized <em>log segments</em> and distributed evenly |
| across log segment storage nodes. It allows the log to scale beyond a size that will fit on |
| a single server and also spread read traffic among the cluster.</p> |
| <p>The data of logs will either be kept forever until application <em>explicitly</em> truncates or be retained |
| for a configurable period of time. <strong>Explicit Truncation</strong> is useful for building replicated |
| state machines such as distributed databases. They usually require strong controls over when |
| the data could be truncated. <strong>Time-based Retention</strong> is useful for real-time analytics. They only |
| care about the data within a period of time.</p> |
| </div> |
| <div class="section" id="namespaces"> |
| <h3>Namespaces<a class="headerlink" href="#namespaces" title="Permalink to this headline">¶</a></h3> |
| <p>The <em>log streams</em> belong to same organization are usually categorized and managed under |
| a <strong>namespace</strong>. A DL <strong>namespace</strong> is basically for applications to locate where the |
| <em>log streams</em> are. Applications could <em>create</em> and <em>delete</em> streams under a namespace, |
| and also be able to <em>truncate</em> a stream to given sequence number (either <em>DLSN</em> or <em>TransactionID</em>).</p> |
| </div> |
| </div> |
| <div class="section" id="writers"> |
| <h2>Writers<a class="headerlink" href="#writers" title="Permalink to this headline">¶</a></h2> |
| <p>Writers write data into the logs of their choice. All the records are |
| appended into the logs in order. The sequencing is done by the writer, |
| which means there is only one active writer for a log at a given time. |
| DL guarantees correctness when two writers attempt writing to |
| to a same log when network partition happens - via fencing mechanism |
| in log segment store.</p> |
| <p>The log writers are served and managed in a service tier called <em>Write Proxy</em>. |
| The <em>Write Proxy</em> is used for accepting fan-in writes from large number |
| of clients. Details on <strong>Fan-in and Fan-out</strong> can be found further into this doc.</p> |
| </div> |
| <div class="section" id="readers"> |
| <h2>Readers<a class="headerlink" href="#readers" title="Permalink to this headline">¶</a></h2> |
| <p>Readers read records from the logs of their choice, starting from a provided |
| position. The provided position could be either <em>DLSN</em> or <em>TransactionID</em>. |
| The readers will read records in strict order from the logs. Different readers |
| could read records starting from different positions in a same log.</p> |
| <p>Unlike other pub/sub systems, DistributedLog doesn't record/manage readers' positions. |
| It leaves the tracking responsibility to applications, as different applications |
| might have different requirements on tracking and coordinating positions. It is hard |
| to get it right with a single approach. For example, distributed databases might store |
| the reader positions along with SSTables, so they would resume applying transactions |
| from the positions stored in SSTables. Tracking reader positions could easily be done |
| in application level using various stores (e.g. ZooKeeper, FileSystem, or Key/Value Stores).</p> |
| <p>The log records could be cached in a service tier called <em>Read Proxy</em>, to serve |
| large number of readers. Details on <strong>Fan-in and Fan-out</strong> can be found further into this doc.</p> |
| </div> |
| <div class="section" id="fan-in-and-fan-out"> |
| <h2>Fan-in and Fan-out<a class="headerlink" href="#fan-in-and-fan-out" title="Permalink to this headline">¶</a></h2> |
| <p>The core of DistributedLog supports single-writer, multiple-readers semantics. The service layer |
| built on top of the <em>DistributedLog Core</em> to support large scale of number of writers and readers. |
| The service layer includes <strong>Write Proxy</strong> and <strong>Read Proxy</strong>. <strong>Write Proxy</strong> manages |
| the writers of logs and fail over them when machines are failed. It allows supporting |
| which don't care about the log ownership by aggregating writes from many sources (aka <em>Fan-in</em>). |
| <strong>Read Proxy</strong> optimize reader path by caching log records in cases where hundreds or |
| thousands of readers are consuming a same log stream.</p> |
| </div> |
| <div class="section" id="guarantees"> |
| <h2>Guarantees<a class="headerlink" href="#guarantees" title="Permalink to this headline">¶</a></h2> |
| <p>At a high-level, DistributedLog gives the following guarantees:</p> |
| <ul class="simple"> |
| <li>Records written by a writer to a log will be appended in the order they are written. That is, if a record <em>R1</em> is written by same writer as a record <em>R2</em>, <em>R1</em> will have a smaller sequence number than <em>R2</em>.</li> |
| <li>Readers will see records in same order they were written to the log.</li> |
| <li>All records were persisted on disks before acknowledges, to gurantee durability.</li> |
| <li>For a log with replication factor of N, DistributedLog tolerates up to N-1 server failures without losing any records appended to the log.</li> |
| </ul> |
| <p>More details on these guarantees are given in the design section of this documentation.</p> |
| </div> |
| </div> |
| |
| |
| </div> |
| </div> |
| <div class="hidden-xs col-sm-3 col-md-3 col-md-offset-1 col-lg-3 db-sidebar"> |
| |
| <div class="db-toc" role="complementary"> |
| <ul class="current"> |
| <li class="toctree-l0 current"><a class="current reference internal" href="../index.html">DistributedLog</a></li> |
| </ul> |
| <ul class="current"> |
| <li class="toctree-l1"><a class="reference internal" href="../download.html">Releases</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../download.html#rc1">0.3.51-RC1</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../download.html#rc0">0.3.51-RC0</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1 current"><a class="reference internal" href="main.html">Getting Started</a><ul class="current"> |
| <li class="toctree-l2 current"><a class="current reference internal" href="">Introduction</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="quickstart.html">Quick Start</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../api/main.html">API</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../api/core.html">Core Library API</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../api/proxy.html">Write Proxy Client API</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../api/practice.html">Best Practices</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../configuration/main.html">Configuration</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../configuration/core.html">Core Library Configuration</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../configuration/proxy.html">Write Proxy Configuration</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../configuration/client.html">Client Configuration</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../configuration/perlog.html">Per Stream Configuration</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../considerations/main.html">Considerations</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../considerations/main.html#consistency-durability-and-ordering">Consistency, Durability and Ordering</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../considerations/main.html#partitioning">Partitioning</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../considerations/main.html#processing-semantics">Processing Semantics</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../architecture/main.html">Architecture</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../architecture/main.html#data-model">Data Model</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../architecture/main.html#software-stack">Software Stack</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../architecture/main.html#lifecyle-of-records">Lifecyle of records</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../design/main.html">Detail Design</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../design/main.html#consistency">Consistency</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../design/main.html#streaming-reads">Streaming Reads</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../design/main.html#logsegment-lifecycle">LogSegment Lifecycle</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../globalreplicatedlog/main.html">Global Replicated Log</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../globalreplicatedlog/main.html#region-aware-data-placement-policy">Region Aware Data Placement Policy</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../globalreplicatedlog/main.html#cross-region-speculative-reads">Cross Region Speculative Reads</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../implementation/main.html">Implementation</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../implementation/storage.html">Storage</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../operations/main.html">Deployment & Administration</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/deployment.html">Cluster Setup & Deployment</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/operations.html">DistributedLog Operations</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/performance.html">Performance Tuning</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/hardware.html">Hardware</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/monitoring.html">Monitoring</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/zookeeper.html">ZooKeeper</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../operations/bookkeeper.html">BookKeeper</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../performance/main.html">Performance</a></li> |
| <li class="toctree-l1"><a class="reference internal" href="../references/main.html">References</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../references/configuration.html">Configuration Settings</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../references/metrics.html">Metrics</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../references/features.html">Features</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../tutorials/main.html">Tutorials</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../tutorials/main.html#basic">Basic</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../tutorials/main.html#messaging">Messaging</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../tutorials/main.html#replicated-state-machines">Replicated State Machines</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../tutorials/main.html#analytics">Analytics</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../developer/main.html">Developer</a><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../developer/release.html">Release</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l1"><a class="reference internal" href="../faq.html">FAQ</a></li> |
| </ul> |
| |
| <span id="last"></span> |
| </div> |
| |
| </div> |
| <!-- <div id="slidebox"> --> |
| <!-- <button id="slidebox_close" type="button" class="close">×</button> --> |
| <!-- <p>Rate This Page</p> --> |
| <!-- <div id="rateYo"></div> --> |
| <!-- <p>Comment</p> |
| <input type="text" name="comment"></input> |
| <button>Submit</button> --> |
| <!-- </div> --> |
| </div> |
| </div> |
| <footer class="footer"> |
| <div class="container-fluid"> |
| <div class="row"> |
| <div class="col-md-10 col-md-offset-1"> |
| <p class="pull-right"> |
| <a href="#">Back to top</a> |
| |
| <br/> |
| |
| <div id="sourcelink"> |
| <a href="git@github.com:twitter/distributedlog.git/tree/master/docs/basics/introduction.rst" |
| rel="nofollow">Source</a> |
| |
| <a href="../_sources/basics/introduction.txt" |
| rel="nofollow">Raw</a> |
| <a href="../__docbird-build.log" |
| rel="nofollow">Build Log</a> |
| <a href="/report/stats/distributedlog:distributedlog" |
| rel="nofollow">Stats</a> |
| </div> |
| </p> |
| <p> |
| Built and hosted by <a href="/">DocBird</a>. |
| </p> |
| </div> |
| </div> |
| </div> |
| </footer> |
| <script type="text/javascript" src="../_static/js/docbird.js"></script> |
| <script type="text/javascript"> |
| var _gaq = _gaq || []; |
| _gaq.push(['_setAccount', 'UA-30775-8']); |
| _gaq.push(['_trackPageview']); |
| |
| (function() { |
| var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; |
| ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; |
| var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); |
| })(); |
| </script> |
| <!-- <script type="text/javascript" src="//s/d41d8cd98f00b204e9800998ecf8427e/en_US-tbnx1s-1988229788/6163/97/1.4.3/_/download/batch/com.atlassian.jira.collector.plugin.jira-issue-collector-plugin:issuecollector/com.atlassian.jira.collector.plugin.jira-issue-collector-plugin:issuecollector.js?collectorId=e62237fc"></script> |
| --> |
| |
| <script type="text/javascript"> |
| $(document).ready(function () { |
| // track user activity time (from https://github.com/jasonzissman/TimeMe.js) |
| TimeMe.setIdleDurationInSeconds(30); |
| TimeMe.setCurrentPageName("my-home-page"); |
| TimeMe.initialize(); |
| |
| // record page visit event when user leaves the page |
| window.onbeforeunload = function (event) { |
| xmlhttp=new XMLHttpRequest(); |
| xmlhttp.withCredentials = true; |
| xmlhttp.open("POST", "/event/distributedlog:distributedlog/visit", false); |
| xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); |
| var event_data = { |
| total_time_reading: TimeMe.getTimeOnCurrentPageInSeconds(), |
| page: window.location.href |
| }; |
| //alert("send: " + $.param(event_data)); |
| xmlhttp.send($.param(event_data)); |
| }; |
| |
| // ask user for page rating after 20 seconds |
| // setTimeout(function(){ |
| // alert("Rate this page!"); |
| // }, 20000); |
| }); |
| </script> |
| <!-- <style> |
| #slidebox{ |
| width: 250px; |
| height: 90px; |
| padding: 10px; |
| background-color: #fff; |
| border: 1px solid #ccc; |
| position: fixed; |
| bottom: 3px; |
| right: -280px; |
| z-index: 1; |
| } |
| #slidebox .close{ |
| margin-top: -5px; |
| opacity: 0.5; |
| } |
| #slidebox .close:hover{ |
| opacity: 0.7; |
| } |
| </style> --> |
| <script type="text/javascript"> |
| $(function() { |
| // $(window).scroll(function(){ |
| // var distanceTop = $('#last').offset().top - $(window).height(); |
| |
| // if ($(window).scrollTop() > distanceTop) |
| // $('#slidebox').animate({'right':'3px'},300); |
| // else |
| // $('#slidebox').stop(true).animate({'right':'-280px'},100); |
| // }); |
| |
| // $('#slidebox .close').bind('click',function(){ |
| // $(this).parent().remove(); |
| // }); |
| |
| $("#rateYo").rateYo({ |
| normalFill: "#A0A0A0", |
| halfStar: true, |
| rating: (Cookies.get('docbird.rating.distributedlog.distributedlog') || 0.0) |
| }).on("rateyo.set", function (e, data) { |
| var event_data = { |
| comment: '', // see todo note below |
| rating: data.rating, |
| page: window.location.href |
| }; |
| Cookies.get('docbird.rating.distributedlog.distributedlog', data.rating) |
| $.post('/event/distributedlog:distributedlog/rating', event_data) |
| // xmlhttp=new XMLHttpRequest(); |
| // xmlhttp.withCredentials = true; |
| // var event_data = { |
| // comment: '', // see todo note below |
| // rating: data.rating, |
| // page: window.location.href |
| // }; |
| // xmlhttp.open("GET", "/event/distributedlog/rating?" + $.param(event_data), false); |
| // xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); |
| // // todo: implement comment form in rating slide out, |
| // // and instead of hooking this event, include a submit button, |
| // // and read the rating with rating() method |
| |
| // // alert("send: " + $.param(event_data)); |
| // xmlhttp.send(); |
| |
| }); |
| |
| }); |
| </script> |
| <script src="_static/js/selection-sharer.js"></script> |
| <script> |
| $('.db-content-body').selectionSharer(); |
| </script> |
| </body> |
| </html> |
