Merged in code-style-guide (pull request #13)

Code style guide

docs/build/html/_sources/codestyle.txt

@@ -0,0 +1,162 @@
+Code style guide
+================
+
+This document explains the coding style used in the R3 prototyping repository. You will be expected to follow these
+recommendations when submitting patches for review. Please take the time to read them and internalise them, to save
+time during code review.
+
+What follows are *recommendations* and not *rules*. They are in places intentionally vague, so use your good judgement
+when interpreting them.
+
+.. note:: Parts of the codebase may not follow this style guide yet. If you see a place that doesn't, please fix it!
+
+1. General style
+################
+
+We use the standard Java coding style from Sun, adapted for Kotlin in ways that should be fairly intuitive.
+
+We aim for line widths of no more than 120 characters. That is wide enough to avoid lots of pointless wrapping but
+narrow enough that with a widescreen monitor and a 12 point fixed width font (like Menlo) you can fit two files
+next to each other. This is not a rigidly enforced rule and if wrapping a line would be excessively awkward, let it
+overflow. Overflow of a few characters here and there isn't a big deal: the goal is general convenience.
+
+Code is vertically dense, blank lines in methods are used sparingly. This is so more code can fit on screen at once.
+
+Each file has a copyright notice at the top. Copy it from the existing files if you create a new one. We do not mark
+classes with @author Javadoc annotations.
+
+In Kotlin code, KDoc is used rather than JavaDoc. It's very similar except it uses Markdown for formatting instead
+of HTML tags.
+
+We target Java 8 and use the latest Java APIs whenever convenient. We use ``java.time.Instant`` to represent timestamps
+and ``java.nio.file.Path`` to represent file paths.
+
+We use spaces and not tabs.
+
+Never apply any design pattern religiously. There are no silver bullets in programming and if something is fashionable,
+that doesn't mean it's always better. In particular:
+
+* Use functional programming patterns like map, filter, fold only where it's genuinely more convenient. Never be afraid
+  to use a simple imperative construct like a for loop or a mutable counter if that results in more direct, English-like
+  code.
+* Use immutability when you don't anticipate very rapid or complex changes to the content. Immutability can help avoid
+  bugs, but over-used it can make code that has to adjust fields of an immutable object (in a clone) hard to read and
+  stress the garbage collector. When such code becomes a widespread pattern it can lead to code that is just generically
+  slow but without hotspots.
+* The tradeoffs between various thread safety techniques are complex, subtle, and no technique is always superior to
+  the others. Our code uses a mix of locks, worker threads and messaging depending on the situation.
+
+2. Comments
+###########
+
+We like them as long as they add detail that is missing from the code. Comments that simply repeat the story already
+told by the code are best deleted. Comments should:
+
+* Explain what the code is doing at a higher level than is obtainable from just examining the statement and
+  surrounding code.
+* Explain why certain choices were made and the tradeoffs considered.
+* Explain how things can go wrong, which is a detail often not easily seen just by reading the code.
+* Use good grammar with capital letters and full stops. This gets us in the right frame of mind for writing real
+  explanations of things.
+
+When writing code, imagine that you have an intelligent colleague looking over your shoulder asking you questions
+as you go. Think about what they might ask, and then put your answers in the code.
+
+Don’t be afraid of redundancy, many people will start reading your code in the middle with little or no idea of what
+it’s about, eg, due to a bug or a need to introduce a new feature. It’s OK to repeat basic facts or descriptions in
+different places if that increases the chance developers will see something important.
+
+API docs: all public methods, constants and classes should have doc comments in either JavaDoc or KDoc. API docs should:
+
+* Explain what the method does in words different to how the code describes it.
+* Always have some text, annotation-only JavaDocs don’t render well. Write “Returns a blah blah blah” rather
+  than “@returns blah blah blah” if that's the only content (or leave it out if you have nothing more to say than the
+  code already says).
+* Illustrate with examples when you might want to use the method or class. Point the user at alternatives if this code
+  is not always right.
+* Make good use of {@link} annotations.
+
+Bad JavaDocs look like this:
+
+.. sourcecode:: java
+
+   /** @return the size of the Bloom filter. */
+   public int getBloomFilterSize() {
+       return block;
+   }
+
+Good JavaDocs look like this:
+
+.. sourcecode:: java
+
+   /**
+    * Returns the size of the current {@link BloomFilter} in bytes. Larger filters have
+    * lower false positive rates for the same number of inserted keys and thus lower privacy,
+    * but bandwidth usage is also correspondingly reduced.
+    */
+   public int getBloomFilterSize() { ... }
+
+We use C-style (``/** */``) comments for API docs and we use C++ style comments (``//``) for explanations that are
+only intended to be viewed by people who read the code.
+
+3. Threading
+############
+
+Classes that are thread safe should be annotated with the ``@ThreadSafe`` annotation. The class or method comments
+should describe how threads are expected to interact with your code, unless it's obvious because the class is
+(for example) a simple immutable data holder.
+
+Code that supports callbacks or event listeners should always accept an ``Executor`` argument that defaults to
+``MoreExecutors.directThreadExecutor()`` (i.e. the calling thread) when registering the callback. This makes it easy
+to integrate the callbacks with whatever threading environment the calling code expects, e.g. serialised onto a single
+worker thread if necessary, or run directly on the background threads used by the class if the callback is thread safe
+and doesn't care in what context it's invoked.
+
+In the prototyping code it's OK to use synchronised methods i.e. with an exposed lock when the use of locking is quite
+trivial. If the synchronisation in your code is getting more complex, consider the following:
+
+1. Is the complexity necessary? At this early stage, don't worry too much about performance or scalability, as we're
+   exploring the design space rather than making an optimal implementation of a design that's already nailed down.
+2. Could you simplify it by making the data be owned by a dedicated, encapsulated worker thread? If so, remember to
+   think about flow control and what happens if a work queue fills up: the actor model can often be useful but be aware
+   of the downsides and try to avoid explicitly defining messages, prefer to send closures onto the worker thread
+   instead.
+3. If you use an explicit lock and the locking gets complex, and *always* if the class supports callbacks, use the
+   cycle detecting locks from the Guava library.
+4. Can you simplify some things by using thread-safe collections like ``CopyOnWriteArrayList`` or ``ConcurrentHashMap``?
+   These data structures are more expensive than their non-thread-safe equivalents but can be worth it if it lets us
+   simplify the code.
+
+Immutable data structures can be very useful for making it easier to reason about multi-threaded code. Kotlin makes it
+easy to define these via the "data" attribute, which auto-generates a copy() method. That lets you create clones of
+an immutable object with arbitrary fields adjusted in the clone. But if you can't use the data attribute for some
+reason, for instance, you are working in Java or because you need an inheritance heirarchy, then consider that making
+a class fully immutable may result in very awkward code if there's ever a need to make complex changes to it. If in
+doubt, ask. Remember, never apply any design pattern religiously.
+
+4. Assertions and errors
+########################
+
+We use them liberally and we use them at runtime, in production. That means we avoid the "assert" keyword in Java,
+and instead prefer to use the ``check()`` or ``require()`` functions in Kotlin (for an ``IllegalStateException`` or
+``IllegalArgumentException`` respectively), or the Guava ``Preconditions.check`` method from Java.
+
+We define new exception types liberally. We prefer not to provide English language error messages in exceptions at
+the throw site, instead we define new types with any useful information as fields, with a toString() method if
+really necessary. In other words, don't do this:
+
+.. sourcecode:: java
+
+   throw new Exception("The foo broke")
+
+instead do this
+
+.. sourcecode:: java
+
+   class FooBrokenException extends Exception {}
+   throw new FooBrokenException()
+
+The latter is easier to catch and handle if later necessary, and the type name should explain what went wrong.
+
+Note that Kotlin does not require exception types to be declared in method prototypes like Java does.
+

docs/build/html/_sources/index.txt

@@ -41,4 +41,5 @@ Read on to learn:
 
    visualiser
    roadmap
+   codestyle
 

docs/build/html/_sources/protocol-state-machines.txt

@@ -146,8 +146,8 @@ each side.
           )
 
 
-          private class UnacceptablePriceException(val givenPrice: Amount) : Exception()
+          class UnacceptablePriceException(val givenPrice: Amount) : Exception()
-          private class AssetMismatchException(val expectedTypeName: String, val typeName: String) : Exception() {
+          class AssetMismatchException(val expectedTypeName: String, val typeName: String) : Exception() {
               override fun toString() = "The submitted asset didn't match the expected type: $expectedTypeName vs $typeName"
           }
 

docs/build/html/_static/basic.css

@@ -4,7 +4,7 @@
  *
  * Sphinx stylesheet -- basic theme.
  *
- * :copyright: Copyright 2007-2015 by the Sphinx team, see AUTHORS.
+ * :copyright: Copyright 2007-2016 by the Sphinx team, see AUTHORS.
  * :license: BSD, see LICENSE for details.
  *
  */

docs/build/html/_static/doctools.js

@@ -4,7 +4,7 @@
  *
  * Sphinx JavaScript utilities for all documentation.
  *
- * :copyright: Copyright 2007-2015 by the Sphinx team, see AUTHORS.
+ * :copyright: Copyright 2007-2016 by the Sphinx team, see AUTHORS.
  * :license: BSD, see LICENSE for details.
  *
  */

docs/build/html/_static/pygments.css

@@ -4,8 +4,10 @@
 .highlight .err { border: 1px solid #FF0000 } /* Error */
 .highlight .k { color: #007020; font-weight: bold } /* Keyword */
 .highlight .o { color: #666666 } /* Operator */
+.highlight .ch { color: #408090; font-style: italic } /* Comment.Hashbang */
 .highlight .cm { color: #408090; font-style: italic } /* Comment.Multiline */
 .highlight .cp { color: #007020 } /* Comment.Preproc */
+.highlight .cpf { color: #408090; font-style: italic } /* Comment.PreprocFile */
 .highlight .c1 { color: #408090; font-style: italic } /* Comment.Single */
 .highlight .cs { color: #408090; background-color: #fff0f0 } /* Comment.Special */
 .highlight .gd { color: #A00000 } /* Generic.Deleted */

docs/build/html/_static/searchtools.js

@@ -4,12 +4,13 @@
  *
  * Sphinx JavaScript utilties for the full-text search.
  *
- * :copyright: Copyright 2007-2015 by the Sphinx team, see AUTHORS.
+ * :copyright: Copyright 2007-2016 by the Sphinx team, see AUTHORS.
  * :license: BSD, see LICENSE for details.
  *
  */
 
 
+/* Non-minified version JS is _stemmer.js if file is provided */ 
 /**
  * Porter Stemmer
  */
@@ -373,8 +374,7 @@ var Search = {
     }
 
     // lookup as search terms in fulltext
-    results = results.concat(this.performTermsSearch(searchterms, excluded, terms, Scorer.term))
+    results = results.concat(this.performTermsSearch(searchterms, excluded, terms, titleterms));
-                     .concat(this.performTermsSearch(searchterms, excluded, titleterms, Scorer.title));
 
     // let the scorer override scores with a custom scoring function
     if (Scorer.score) {
@@ -538,23 +538,47 @@ var Search = {
   /**
    * search for full-text terms in the index
    */
-  performTermsSearch : function(searchterms, excluded, terms, score) {
+  performTermsSearch : function(searchterms, excluded, terms, titleterms) {
     var filenames = this._index.filenames;
     var titles = this._index.titles;
 
-    var i, j, file, files;
+    var i, j, file;
     var fileMap = {};
+    var scoreMap = {};
     var results = [];
 
     // perform the search on the required terms
     for (i = 0; i < searchterms.length; i++) {
       var word = searchterms[i];
+      var files = [];
+      var _o = [
+        {files: terms[word], score: Scorer.term},
+        {files: titleterms[word], score: Scorer.title}
+      ];
+
       // no match but word was a required one
-      if ((files = terms[word]) === undefined)
+      if ($u.every(_o, function(o){return o.files === undefined;})) {
         break;
-      if (files.length === undefined) {
-        files = [files];
       }
+      // found search word in contents
+      $u.each(_o, function(o) {
+        var _files = o.files;
+        if (_files === undefined)
+          return
+
+        if (_files.length === undefined)
+          _files = [_files];
+        files = files.concat(_files);
+
+        // set score for the word in each file to Scorer.term
+        for (j = 0; j < _files.length; j++) {
+          file = _files[j];
+          if (!(file in scoreMap))
+            scoreMap[file] = {}
+          scoreMap[file][word] = o.score;
+        }
+      });
+
       // create the mapping
       for (j = 0; j < files.length; j++) {
         file = files[j];
@@ -576,7 +600,9 @@ var Search = {
       // ensure that none of the excluded terms is in the search result
       for (i = 0; i < excluded.length; i++) {
         if (terms[excluded[i]] == file ||
-          $u.contains(terms[excluded[i]] || [], file)) {
+            titleterms[excluded[i]] == file ||
+            $u.contains(terms[excluded[i]] || [], file) ||
+            $u.contains(titleterms[excluded[i]] || [], file)) {
           valid = false;
           break;
         }
@@ -584,6 +610,9 @@ var Search = {
 
       // if we have still a valid result we can add it to the result list
       if (valid) {
+        // select one (max) score for the file.
+        // for better ranking, we should calculate ranking by using words statistics like basic tf-idf...
+        var score = $u.max($u.map(fileMap[file], function(w){return scoreMap[file][w]}));
         results.push([filenames[file], titles[file], '', null, score]);
       }
     }

docs/build/html/_static/websupport.js

@@ -4,7 +4,7 @@
  *
  * sphinx.websupport utilties for all documentation.
  *
- * :copyright: Copyright 2007-2015 by the Sphinx team, see AUTHORS.
+ * :copyright: Copyright 2007-2016 by the Sphinx team, see AUTHORS.
  * :license: BSD, see LICENSE for details.
  *
  */

docs/build/html/codestyle.html

@@ -0,0 +1,355 @@
+
+
+<!DOCTYPE html>
+<!--[if IE 8]><html class="no-js lt-ie9" lang="en" > <![endif]-->
+<!--[if gt IE 8]><!--> <html class="no-js" lang="en" > <!--<![endif]-->
+<head>
+  <meta charset="utf-8">
+  
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  
+  <title>Code style guide &mdash; R3 Prototyping 0.1 documentation</title>
+  
+
+  
+  
+
+  
+
+  
+  
+    
+
+  
+
+  
+  
+    <link rel="stylesheet" href="_static/css/custom.css" type="text/css" />
+  
+
+  
+
+  
+    <link rel="top" title="R3 Prototyping 0.1 documentation" href="index.html"/>
+        <link rel="prev" title="Roadmap" href="roadmap.html"/> 
+
+  
+  <script src="_static/js/modernizr.min.js"></script>
+
+</head>
+
+<body class="wy-body-for-nav" role="document">
+
+  <div class="wy-grid-for-nav">
+
+    
+    <nav data-toggle="wy-nav-shift" class="wy-nav-side">
+      <div class="wy-side-scroll">
+        <div class="wy-side-nav-search">
+          
+
+          
+            <a href="index.html" class="icon icon-home"> R3 Prototyping
+          
+
+          
+          </a>
+
+          
+            
+            
+              <div class="version">
+                0.1
+              </div>
+            
+          
+
+          
+<div role="search">
+  <form id="rtd-search-form" class="wy-form" action="search.html" method="get">
+    <input type="text" name="q" placeholder="Search docs" />
+    <input type="hidden" name="check_keywords" value="yes" />
+    <input type="hidden" name="area" value="default" />
+  </form>
+</div>
+
+          
+        </div>
+
+        <div class="wy-menu wy-menu-vertical" data-spy="affix" role="navigation" aria-label="main navigation">
+          
+            
+            
+                <p class="caption"><span class="caption-text">Overview</span></p>
+<ul>
+<li class="toctree-l1"><a class="reference internal" href="inthebox.html">What&#8217;s included?</a></li>
+<li class="toctree-l1"><a class="reference internal" href="getting-set-up.html">Getting set up</a></li>
+<li class="toctree-l1"><a class="reference internal" href="data-model.html">Data model</a></li>
+<li class="toctree-l1"><a class="reference internal" href="messaging.html">Networking and messaging</a></li>
+</ul>
+<p class="caption"><span class="caption-text">Tutorials</span></p>
+<ul>
+<li class="toctree-l1"><a class="reference internal" href="tutorial.html">Writing a contract</a></li>
+<li class="toctree-l1"><a class="reference internal" href="protocol-state-machines.html">Protocol state machines</a></li>
+</ul>
+<p class="caption"><span class="caption-text">Appendix</span></p>
+<ul class="current">
+<li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
+<li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1 current"><a class="current reference internal" href="">Code style guide</a><ul>
+<li class="toctree-l2"><a class="reference internal" href="#general-style">1. General style</a></li>
+<li class="toctree-l2"><a class="reference internal" href="#comments">2. Comments</a></li>
+<li class="toctree-l2"><a class="reference internal" href="#threading">3. Threading</a></li>
+<li class="toctree-l2"><a class="reference internal" href="#assertions-and-errors">4. Assertions and errors</a></li>
+</ul>
+</li>
+</ul>
+
+            
+          
+        </div>
+      </div>
+    </nav>
+
+    <section data-toggle="wy-nav-shift" class="wy-nav-content-wrap">
+
+      
+      <nav class="wy-nav-top" role="navigation" aria-label="top navigation">
+        <i data-toggle="wy-nav-top" class="fa fa-bars"></i>
+        <a href="index.html">R3 Prototyping</a>
+      </nav>
+
+
+      
+      <div class="wy-nav-content">
+        <div class="rst-content">
+          
+
+
+
+
+
+<div role="navigation" aria-label="breadcrumbs navigation">
+  <ul class="wy-breadcrumbs">
+    <li><a href="index.html">Docs</a> &raquo;</li>
+      
+    <li>Code style guide</li>
+      <li class="wy-breadcrumbs-aside">
+        
+          
+            <a href="_sources/codestyle.txt" rel="nofollow"> View page source</a>
+          
+        
+      </li>
+  </ul>
+  <hr/>
+</div>
+          <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
+           <div itemprop="articleBody">
+            
+  <div class="section" id="code-style-guide">
+<h1>Code style guide<a class="headerlink" href="#code-style-guide" title="Permalink to this headline">¶</a></h1>
+<p>This document explains the coding style used in the R3 prototyping repository. You will be expected to follow these
+recommendations when submitting patches for review. Please take the time to read them and internalise them, to save
+time during code review.</p>
+<p>What follows are <em>recommendations</em> and not <em>rules</em>. They are in places intentionally vague, so use your good judgement
+when interpreting them.</p>
+<div class="admonition note">
+<p class="first admonition-title">Note</p>
+<p class="last">Parts of the codebase may not follow this style guide yet. If you see a place that doesn&#8217;t, please fix it!</p>
+</div>
+<div class="section" id="general-style">
+<h2>1. General style<a class="headerlink" href="#general-style" title="Permalink to this headline">¶</a></h2>
+<p>We use the standard Java coding style from Sun, adapted for Kotlin in ways that should be fairly intuitive.</p>
+<p>We aim for line widths of no more than 120 characters. That is wide enough to avoid lots of pointless wrapping but
+narrow enough that with a widescreen monitor and a 12 point fixed width font (like Menlo) you can fit two files
+next to each other. This is not a rigidly enforced rule and if wrapping a line would be excessively awkward, let it
+overflow. Overflow of a few characters here and there isn&#8217;t a big deal: the goal is general convenience.</p>
+<p>Code is vertically dense, blank lines in methods are used sparingly. This is so more code can fit on screen at once.</p>
+<p>Each file has a copyright notice at the top. Copy it from the existing files if you create a new one. We do not mark
+classes with &#64;author Javadoc annotations.</p>
+<p>In Kotlin code, KDoc is used rather than JavaDoc. It&#8217;s very similar except it uses Markdown for formatting instead
+of HTML tags.</p>
+<p>We target Java 8 and use the latest Java APIs whenever convenient. We use <code class="docutils literal"><span class="pre">java.time.Instant</span></code> to represent timestamps
+and <code class="docutils literal"><span class="pre">java.nio.file.Path</span></code> to represent file paths.</p>
+<p>We use spaces and not tabs.</p>
+<p>Never apply any design pattern religiously. There are no silver bullets in programming and if something is fashionable,
+that doesn&#8217;t mean it&#8217;s always better. In particular:</p>
+<ul class="simple">
+<li>Use functional programming patterns like map, filter, fold only where it&#8217;s genuinely more convenient. Never be afraid
+to use a simple imperative construct like a for loop or a mutable counter if that results in more direct, English-like
+code.</li>
+<li>Use immutability when you don&#8217;t anticipate very rapid or complex changes to the content. Immutability can help avoid
+bugs, but over-used it can make code that has to adjust fields of an immutable object (in a clone) hard to read and
+stress the garbage collector. When such code becomes a widespread pattern it can lead to code that is just generically
+slow but without hotspots.</li>
+<li>The tradeoffs between various thread safety techniques are complex, subtle, and no technique is always superior to
+the others. Our code uses a mix of locks, worker threads and messaging depending on the situation.</li>
+</ul>
+</div>
+<div class="section" id="comments">
+<h2>2. Comments<a class="headerlink" href="#comments" title="Permalink to this headline">¶</a></h2>
+<p>We like them as long as they add detail that is missing from the code. Comments that simply repeat the story already
+told by the code are best deleted. Comments should:</p>
+<ul class="simple">
+<li>Explain what the code is doing at a higher level than is obtainable from just examining the statement and
+surrounding code.</li>
+<li>Explain why certain choices were made and the tradeoffs considered.</li>
+<li>Explain how things can go wrong, which is a detail often not easily seen just by reading the code.</li>
+<li>Use good grammar with capital letters and full stops. This gets us in the right frame of mind for writing real
+explanations of things.</li>
+</ul>
+<p>When writing code, imagine that you have an intelligent colleague looking over your shoulder asking you questions
+as you go. Think about what they might ask, and then put your answers in the code.</p>
+<p>Don’t be afraid of redundancy, many people will start reading your code in the middle with little or no idea of what
+it’s about, eg, due to a bug or a need to introduce a new feature. It’s OK to repeat basic facts or descriptions in
+different places if that increases the chance developers will see something important.</p>
+<p>API docs: all public methods, constants and classes should have doc comments in either JavaDoc or KDoc. API docs should:</p>
+<ul class="simple">
+<li>Explain what the method does in words different to how the code describes it.</li>
+<li>Always have some text, annotation-only JavaDocs don’t render well. Write “Returns a blah blah blah” rather
+than “&#64;returns blah blah blah” if that&#8217;s the only content (or leave it out if you have nothing more to say than the
+code already says).</li>
+<li>Illustrate with examples when you might want to use the method or class. Point the user at alternatives if this code
+is not always right.</li>
+<li>Make good use of <a class="reference external" href="mailto:{&#37;&#52;&#48;link">{<span>&#64;</span>link</a>} annotations.</li>
+</ul>
+<p>Bad JavaDocs look like this:</p>
+<div class="highlight-java"><div class="highlight"><pre><span class="cm">/** @return the size of the Bloom filter. */</span>
+<span class="kd">public</span> <span class="kt">int</span> <span class="nf">getBloomFilterSize</span><span class="o">()</span> <span class="o">{</span>
+    <span class="k">return</span> <span class="n">block</span><span class="o">;</span>
+<span class="o">}</span>
+</pre></div>
+</div>
+<p>Good JavaDocs look like this:</p>
+<div class="highlight-java"><div class="highlight"><pre><span class="cm">/**</span>
+<span class="cm"> * Returns the size of the current {@link BloomFilter} in bytes. Larger filters have</span>
+<span class="cm"> * lower false positive rates for the same number of inserted keys and thus lower privacy,</span>
+<span class="cm"> * but bandwidth usage is also correspondingly reduced.</span>
+<span class="cm"> */</span>
+<span class="kd">public</span> <span class="kt">int</span> <span class="nf">getBloomFilterSize</span><span class="o">()</span> <span class="o">{</span> <span class="o">...</span> <span class="o">}</span>
+</pre></div>
+</div>
+<p>We use C-style (<code class="docutils literal"><span class="pre">/**</span> <span class="pre">*/</span></code>) comments for API docs and we use C++ style comments (<code class="docutils literal"><span class="pre">//</span></code>) for explanations that are
+only intended to be viewed by people who read the code.</p>
+</div>
+<div class="section" id="threading">
+<h2>3. Threading<a class="headerlink" href="#threading" title="Permalink to this headline">¶</a></h2>
+<p>Classes that are thread safe should be annotated with the <code class="docutils literal"><span class="pre">&#64;ThreadSafe</span></code> annotation. The class or method comments
+should describe how threads are expected to interact with your code, unless it&#8217;s obvious because the class is
+(for example) a simple immutable data holder.</p>
+<p>Code that supports callbacks or event listeners should always accept an <code class="docutils literal"><span class="pre">Executor</span></code> argument that defaults to
+<code class="docutils literal"><span class="pre">MoreExecutors.directThreadExecutor()</span></code> (i.e. the calling thread) when registering the callback. This makes it easy
+to integrate the callbacks with whatever threading environment the calling code expects, e.g. serialised onto a single
+worker thread if necessary, or run directly on the background threads used by the class if the callback is thread safe
+and doesn&#8217;t care in what context it&#8217;s invoked.</p>
+<p>In the prototyping code it&#8217;s OK to use synchronised methods i.e. with an exposed lock when the use of locking is quite
+trivial. If the synchronisation in your code is getting more complex, consider the following:</p>
+<ol class="arabic simple">
+<li>Is the complexity necessary? At this early stage, don&#8217;t worry too much about performance or scalability, as we&#8217;re
+exploring the design space rather than making an optimal implementation of a design that&#8217;s already nailed down.</li>
+<li>Could you simplify it by making the data be owned by a dedicated, encapsulated worker thread? If so, remember to
+think about flow control and what happens if a work queue fills up: the actor model can often be useful but be aware
+of the downsides and try to avoid explicitly defining messages, prefer to send closures onto the worker thread
+instead.</li>
+<li>If you use an explicit lock and the locking gets complex, and <em>always</em> if the class supports callbacks, use the
+cycle detecting locks from the Guava library.</li>
+<li>Can you simplify some things by using thread-safe collections like <code class="docutils literal"><span class="pre">CopyOnWriteArrayList</span></code> or <code class="docutils literal"><span class="pre">ConcurrentHashMap</span></code>?
+These data structures are more expensive than their non-thread-safe equivalents but can be worth it if it lets us
+simplify the code.</li>
+</ol>
+<p>Immutable data structures can be very useful for making it easier to reason about multi-threaded code. Kotlin makes it
+easy to define these via the &#8220;data&#8221; attribute, which auto-generates a copy() method. That lets you create clones of
+an immutable object with arbitrary fields adjusted in the clone. But if you can&#8217;t use the data attribute for some
+reason, for instance, you are working in Java or because you need an inheritance heirarchy, then consider that making
+a class fully immutable may result in very awkward code if there&#8217;s ever a need to make complex changes to it. If in
+doubt, ask. Remember, never apply any design pattern religiously.</p>
+</div>
+<div class="section" id="assertions-and-errors">
+<h2>4. Assertions and errors<a class="headerlink" href="#assertions-and-errors" title="Permalink to this headline">¶</a></h2>
+<p>We use them liberally and we use them at runtime, in production. That means we avoid the &#8220;assert&#8221; keyword in Java,
+and instead prefer to use the <code class="docutils literal"><span class="pre">check()</span></code> or <code class="docutils literal"><span class="pre">require()</span></code> functions in Kotlin (for an <code class="docutils literal"><span class="pre">IllegalStateException</span></code> or
+<code class="docutils literal"><span class="pre">IllegalArgumentException</span></code> respectively), or the Guava <code class="docutils literal"><span class="pre">Preconditions.check</span></code> method from Java.</p>
+<p>We define new exception types liberally. We prefer not to provide English language error messages in exceptions at
+the throw site, instead we define new types with any useful information as fields, with a toString() method if
+really necessary. In other words, don&#8217;t do this:</p>
+<div class="highlight-java"><div class="highlight"><pre><span class="k">throw</span> <span class="k">new</span> <span class="n">Exception</span><span class="o">(</span><span class="s">&quot;The foo broke&quot;</span><span class="o">)</span>
+</pre></div>
+</div>
+<p>instead do this</p>
+<div class="highlight-java"><div class="highlight"><pre><span class="kd">class</span> <span class="nc">FooBrokenException</span> <span class="kd">extends</span> <span class="n">Exception</span> <span class="o">{}</span>
+<span class="k">throw</span> <span class="k">new</span> <span class="n">FooBrokenException</span><span class="o">()</span>
+</pre></div>
+</div>
+<p>The latter is easier to catch and handle if later necessary, and the type name should explain what went wrong.</p>
+<p>Note that Kotlin does not require exception types to be declared in method prototypes like Java does.</p>
+</div>
+</div>
+
+
+           </div>
+          </div>
+          <footer>
+  
+    <div class="rst-footer-buttons" role="navigation" aria-label="footer navigation">
+      
+      
+        <a href="roadmap.html" class="btn btn-neutral" title="Roadmap" accesskey="p"><span class="fa fa-arrow-circle-left"></span> Previous</a>
+      
+    </div>
+  
+
+  <hr/>
+
+  <div role="contentinfo">
+    <p>
+        &copy; Copyright 2015, R3 CEV.
+
+    </p>
+  </div>
+  Built with <a href="http://sphinx-doc.org/">Sphinx</a> using a <a href="https://github.com/snide/sphinx_rtd_theme">theme</a> provided by <a href="https://readthedocs.org">Read the Docs</a>. 
+
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+      </div>
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+    </section>
+
+  </div>
+  
+
+
+  
+
+    <script type="text/javascript">
+        var DOCUMENTATION_OPTIONS = {
+            URL_ROOT:'./',
+            VERSION:'0.1',
+            COLLAPSE_INDEX:false,
+            FILE_SUFFIX:'.html',
+            HAS_SOURCE:  true
+        };
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+      <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>
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+    <script type="text/javascript" src="_static/js/theme.js"></script>
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+      jQuery(function () {
+          SphinxRtdTheme.StickyNav.enable();
+      });
+  </script>
+   
+
+</body>
+</html>

docs/build/html/data-model.html

@@ -102,6 +102,7 @@
 <ul>
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             

docs/build/html/genindex.html

@@ -96,6 +96,7 @@
 <ul>
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             

docs/build/html/getting-set-up.html

@@ -101,6 +101,7 @@
 <ul>
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             

docs/build/html/index.html

@@ -96,6 +96,7 @@
 <ul>
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             
@@ -214,6 +215,13 @@ prove or disprove the following hypothesis:</p>
 <ul>
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a><ul>
+<li class="toctree-l2"><a class="reference internal" href="codestyle.html#general-style">1. General style</a></li>
+<li class="toctree-l2"><a class="reference internal" href="codestyle.html#comments">2. Comments</a></li>
+<li class="toctree-l2"><a class="reference internal" href="codestyle.html#threading">3. Threading</a></li>
+<li class="toctree-l2"><a class="reference internal" href="codestyle.html#assertions-and-errors">4. Assertions and errors</a></li>
+</ul>
+</li>
 </ul>
 </div>
 </div>

docs/build/html/inthebox.html

@@ -101,6 +101,7 @@
 <ul>
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             

docs/build/html/messaging.html

@@ -102,6 +102,7 @@
 <ul>
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             

docs/build/html/protocol-state-machines.html

@@ -106,6 +106,7 @@
 <ul>
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             
@@ -275,8 +276,8 @@ each side.</p>
     <span class="p">)</span>
 
 
-    <span class="k">private</span> <span class="k">class</span> <span class="nc">UnacceptablePriceException</span><span class="p">(</span><span class="k">val</span> <span class="py">givenPrice</span><span class="p">:</span> <span class="n">Amount</span><span class="p">)</span> <span class="p">:</span> <span class="n">Exception</span><span class="p">()</span>
+    <span class="k">class</span> <span class="nc">UnacceptablePriceException</span><span class="p">(</span><span class="k">val</span> <span class="py">givenPrice</span><span class="p">:</span> <span class="n">Amount</span><span class="p">)</span> <span class="p">:</span> <span class="n">Exception</span><span class="p">()</span>
-    <span class="k">private</span> <span class="k">class</span> <span class="nc">AssetMismatchException</span><span class="p">(</span><span class="k">val</span> <span class="py">expectedTypeName</span><span class="p">:</span> <span class="n">String</span><span class="p">,</span> <span class="k">val</span> <span class="py">typeName</span><span class="p">:</span> <span class="n">String</span><span class="p">)</span> <span class="p">:</span> <span class="n">Exception</span><span class="p">()</span> <span class="p">{</span>
+    <span class="k">class</span> <span class="nc">AssetMismatchException</span><span class="p">(</span><span class="k">val</span> <span class="py">expectedTypeName</span><span class="p">:</span> <span class="n">String</span><span class="p">,</span> <span class="k">val</span> <span class="py">typeName</span><span class="p">:</span> <span class="n">String</span><span class="p">)</span> <span class="p">:</span> <span class="n">Exception</span><span class="p">()</span> <span class="p">{</span>
         <span class="k">override</span> <span class="k">fun</span> <span class="nf">toString</span><span class="p">()</span> <span class="p">=</span> <span class="s">&quot;The submitted asset didn&#39;t match the expected type: $expectedTypeName vs $typeName&quot;</span>
     <span class="p">}</span>
 

docs/build/html/roadmap.html

@@ -31,6 +31,7 @@
 
   
     <link rel="top" title="R3 Prototyping 0.1 documentation" href="index.html"/>
+        <link rel="next" title="Code style guide" href="codestyle.html"/>
         <link rel="prev" title="Using the visualiser" href="visualiser.html"/> 
 
   
@@ -96,6 +97,7 @@
 <ul class="current">
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1 current"><a class="current reference internal" href="">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             
@@ -184,6 +186,8 @@ Thread.stop() unsafe to use), and to measure and enforce runtime limits to handl
   
     <div class="rst-footer-buttons" role="navigation" aria-label="footer navigation">
       
+        <a href="codestyle.html" class="btn btn-neutral float-right" title="Code style guide" accesskey="n">Next <span class="fa fa-arrow-circle-right"></span></a>
+      
       
         <a href="visualiser.html" class="btn btn-neutral" title="Using the visualiser" accesskey="p"><span class="fa fa-arrow-circle-left"></span> Previous</a>
       

docs/build/html/search.html

@@ -95,6 +95,7 @@
 <ul>
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             

docs/build/html/tutorial.html

@@ -108,6 +108,7 @@
 <ul>
 <li class="toctree-l1"><a class="reference internal" href="visualiser.html">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             
@@ -202,7 +203,7 @@ piece of issued paper.</p>
 <h2>States<a class="headerlink" href="#states" title="Permalink to this headline">¶</a></h2>
 <p>A state is a class that stores data that is checked by the contract.</p>
 <div class="codeset container">
-<div class="highlight-kotlin"><div class="highlight"><pre><span class="n">data</span> <span class="k">class</span> <span class="nc">State</span><span class="p">(</span>
+<div class="highlight-kotlin"><div class="highlight"><pre><span class="k">data</span> <span class="k">class</span> <span class="nc">State</span><span class="p">(</span>
   <span class="k">val</span> <span class="py">issuance</span><span class="p">:</span> <span class="n">InstitutionReference</span><span class="p">,</span>
   <span class="k">val</span> <span class="py">owner</span><span class="p">:</span> <span class="n">PublicKey</span><span class="p">,</span>
   <span class="k">val</span> <span class="py">faceValue</span><span class="p">:</span> <span class="n">Amount</span><span class="p">,</span>
@@ -316,7 +317,7 @@ checked, so from the contract code&#8217;s perspective, a command is simply a da
 public keys. Each key had a signature proving that the corresponding private key was used to sign.</p>
 <p>Let&#8217;s define a few commands now:</p>
 <div class="codeset container">
-<div class="highlight-kotlin"><div class="highlight"><pre><span class="n">interface</span> <span class="n">Commands</span> <span class="p">:</span> <span class="n">Command</span> <span class="p">{</span>
+<div class="highlight-kotlin"><div class="highlight"><pre><span class="k">interface</span> <span class="nc">Commands</span> <span class="p">:</span> <span class="n">Command</span> <span class="p">{</span>
     <span class="k">object</span> <span class="nc">Move</span> <span class="p">:</span> <span class="n">Commands</span>
     <span class="k">object</span> <span class="nc">Redeem</span> <span class="p">:</span> <span class="n">Commands</span>
     <span class="k">object</span> <span class="nc">Issue</span> <span class="p">:</span> <span class="n">Commands</span>

docs/build/html/visualiser.html

@@ -97,6 +97,7 @@
 <ul class="current">
 <li class="toctree-l1 current"><a class="current reference internal" href="">Using the visualiser</a></li>
 <li class="toctree-l1"><a class="reference internal" href="roadmap.html">Roadmap</a></li>
+<li class="toctree-l1"><a class="reference internal" href="codestyle.html">Code style guide</a></li>
 </ul>
 
             

docs/source/codestyle.rst

@@ -0,0 +1,162 @@
+Code style guide
+================
+
+This document explains the coding style used in the R3 prototyping repository. You will be expected to follow these
+recommendations when submitting patches for review. Please take the time to read them and internalise them, to save
+time during code review.
+
+What follows are *recommendations* and not *rules*. They are in places intentionally vague, so use your good judgement
+when interpreting them.
+
+.. note:: Parts of the codebase may not follow this style guide yet. If you see a place that doesn't, please fix it!
+
+1. General style
+################
+
+We use the standard Java coding style from Sun, adapted for Kotlin in ways that should be fairly intuitive.
+
+We aim for line widths of no more than 120 characters. That is wide enough to avoid lots of pointless wrapping but
+narrow enough that with a widescreen monitor and a 12 point fixed width font (like Menlo) you can fit two files
+next to each other. This is not a rigidly enforced rule and if wrapping a line would be excessively awkward, let it
+overflow. Overflow of a few characters here and there isn't a big deal: the goal is general convenience.
+
+Code is vertically dense, blank lines in methods are used sparingly. This is so more code can fit on screen at once.
+
+Each file has a copyright notice at the top. Copy it from the existing files if you create a new one. We do not mark
+classes with @author Javadoc annotations.
+
+In Kotlin code, KDoc is used rather than JavaDoc. It's very similar except it uses Markdown for formatting instead
+of HTML tags.
+
+We target Java 8 and use the latest Java APIs whenever convenient. We use ``java.time.Instant`` to represent timestamps
+and ``java.nio.file.Path`` to represent file paths.
+
+We use spaces and not tabs.
+
+Never apply any design pattern religiously. There are no silver bullets in programming and if something is fashionable,
+that doesn't mean it's always better. In particular:
+
+* Use functional programming patterns like map, filter, fold only where it's genuinely more convenient. Never be afraid
+  to use a simple imperative construct like a for loop or a mutable counter if that results in more direct, English-like
+  code.
+* Use immutability when you don't anticipate very rapid or complex changes to the content. Immutability can help avoid
+  bugs, but over-used it can make code that has to adjust fields of an immutable object (in a clone) hard to read and
+  stress the garbage collector. When such code becomes a widespread pattern it can lead to code that is just generically
+  slow but without hotspots.
+* The tradeoffs between various thread safety techniques are complex, subtle, and no technique is always superior to
+  the others. Our code uses a mix of locks, worker threads and messaging depending on the situation.
+
+2. Comments
+###########
+
+We like them as long as they add detail that is missing from the code. Comments that simply repeat the story already
+told by the code are best deleted. Comments should:
+
+* Explain what the code is doing at a higher level than is obtainable from just examining the statement and
+  surrounding code.
+* Explain why certain choices were made and the tradeoffs considered.
+* Explain how things can go wrong, which is a detail often not easily seen just by reading the code.
+* Use good grammar with capital letters and full stops. This gets us in the right frame of mind for writing real
+  explanations of things.
+
+When writing code, imagine that you have an intelligent colleague looking over your shoulder asking you questions
+as you go. Think about what they might ask, and then put your answers in the code.
+
+Don’t be afraid of redundancy, many people will start reading your code in the middle with little or no idea of what
+it’s about, eg, due to a bug or a need to introduce a new feature. It’s OK to repeat basic facts or descriptions in
+different places if that increases the chance developers will see something important.
+
+API docs: all public methods, constants and classes should have doc comments in either JavaDoc or KDoc. API docs should:
+
+* Explain what the method does in words different to how the code describes it.
+* Always have some text, annotation-only JavaDocs don’t render well. Write “Returns a blah blah blah” rather
+  than “@returns blah blah blah” if that's the only content (or leave it out if you have nothing more to say than the
+  code already says).
+* Illustrate with examples when you might want to use the method or class. Point the user at alternatives if this code
+  is not always right.
+* Make good use of {@link} annotations.
+
+Bad JavaDocs look like this:
+
+.. sourcecode:: java
+
+   /** @return the size of the Bloom filter. */
+   public int getBloomFilterSize() {
+       return block;
+   }
+
+Good JavaDocs look like this:
+
+.. sourcecode:: java
+
+   /**
+    * Returns the size of the current {@link BloomFilter} in bytes. Larger filters have
+    * lower false positive rates for the same number of inserted keys and thus lower privacy,
+    * but bandwidth usage is also correspondingly reduced.
+    */
+   public int getBloomFilterSize() { ... }
+
+We use C-style (``/** */``) comments for API docs and we use C++ style comments (``//``) for explanations that are
+only intended to be viewed by people who read the code.
+
+3. Threading
+############
+
+Classes that are thread safe should be annotated with the ``@ThreadSafe`` annotation. The class or method comments
+should describe how threads are expected to interact with your code, unless it's obvious because the class is
+(for example) a simple immutable data holder.
+
+Code that supports callbacks or event listeners should always accept an ``Executor`` argument that defaults to
+``MoreExecutors.directThreadExecutor()`` (i.e. the calling thread) when registering the callback. This makes it easy
+to integrate the callbacks with whatever threading environment the calling code expects, e.g. serialised onto a single
+worker thread if necessary, or run directly on the background threads used by the class if the callback is thread safe
+and doesn't care in what context it's invoked.
+
+In the prototyping code it's OK to use synchronised methods i.e. with an exposed lock when the use of locking is quite
+trivial. If the synchronisation in your code is getting more complex, consider the following:
+
+1. Is the complexity necessary? At this early stage, don't worry too much about performance or scalability, as we're
+   exploring the design space rather than making an optimal implementation of a design that's already nailed down.
+2. Could you simplify it by making the data be owned by a dedicated, encapsulated worker thread? If so, remember to
+   think about flow control and what happens if a work queue fills up: the actor model can often be useful but be aware
+   of the downsides and try to avoid explicitly defining messages, prefer to send closures onto the worker thread
+   instead.
+3. If you use an explicit lock and the locking gets complex, and *always* if the class supports callbacks, use the
+   cycle detecting locks from the Guava library.
+4. Can you simplify some things by using thread-safe collections like ``CopyOnWriteArrayList`` or ``ConcurrentHashMap``?
+   These data structures are more expensive than their non-thread-safe equivalents but can be worth it if it lets us
+   simplify the code.
+
+Immutable data structures can be very useful for making it easier to reason about multi-threaded code. Kotlin makes it
+easy to define these via the "data" attribute, which auto-generates a copy() method. That lets you create clones of
+an immutable object with arbitrary fields adjusted in the clone. But if you can't use the data attribute for some
+reason, for instance, you are working in Java or because you need an inheritance heirarchy, then consider that making
+a class fully immutable may result in very awkward code if there's ever a need to make complex changes to it. If in
+doubt, ask. Remember, never apply any design pattern religiously.
+
+4. Assertions and errors
+########################
+
+We use them liberally and we use them at runtime, in production. That means we avoid the "assert" keyword in Java,
+and instead prefer to use the ``check()`` or ``require()`` functions in Kotlin (for an ``IllegalStateException`` or
+``IllegalArgumentException`` respectively), or the Guava ``Preconditions.check`` method from Java.
+
+We define new exception types liberally. We prefer not to provide English language error messages in exceptions at
+the throw site, instead we define new types with any useful information as fields, with a toString() method if
+really necessary. In other words, don't do this:
+
+.. sourcecode:: java
+
+   throw new Exception("The foo broke")
+
+instead do this
+
+.. sourcecode:: java
+
+   class FooBrokenException extends Exception {}
+   throw new FooBrokenException()
+
+The latter is easier to catch and handle if later necessary, and the type name should explain what went wrong.
+
+Note that Kotlin does not require exception types to be declared in method prototypes like Java does.
+

docs/source/index.rst

@@ -41,4 +41,5 @@ Read on to learn:
 
    visualiser
    roadmap
+   codestyle
 

src/main/kotlin/core/ContractsDSL.kt

@@ -105,7 +105,8 @@ fun Iterable<Amount>.sumOrZero(currency: Currency) = if (iterator().hasNext()) s
 //// Authenticated commands ///////////////////////////////////////////////////////////////////////////////////////////
 
 /** Filters the command list by type, party and public key all at once. */
-inline fun <reified T : CommandData> List<AuthenticatedObject<CommandData>>.select(signer: PublicKey? = null, party: Party? = null) =
+inline fun <reified T : CommandData> List<AuthenticatedObject<CommandData>>.select(signer: PublicKey? = null,
+                                                                                   party: Party? = null) =
         filter { it.value is T }.
         filter { if (signer == null) true else it.signers.contains(signer) }.
         filter { if (party == null) true else it.signingParties.contains(party) }.
@@ -118,7 +119,8 @@ inline fun <reified T : CommandData> List<AuthenticatedObject<CommandData>>.requ
 }
 
 // For Java
-fun List<AuthenticatedObject<CommandData>>.requireSingleCommand(klass: Class<out CommandData>) = filter { klass.isInstance(it) }.single()
+fun List<AuthenticatedObject<CommandData>>.requireSingleCommand(klass: Class<out CommandData>) =
+        filter { klass.isInstance(it) }.single()
 
 /** Returns a timestamp that was signed by the given authority, or returns null if missing. */
 fun List<AuthenticatedObject<CommandData>>.getTimestampBy(timestampingAuthority: Party): TimestampCommand? {

src/main/kotlin/core/messaging/InMemoryNetwork.kt

@@ -142,7 +142,8 @@ public class InMemoryNetwork {
      * An instance can be obtained by creating a builder and then using the start method.
      */
     inner class Node(private val manuallyPumped: Boolean, private val handle: Handle): MessagingService {
-        inner class Handler(val executor: Executor?, val topic: String, val callback: (Message, MessageHandlerRegistration) -> Unit) : MessageHandlerRegistration
+        inner class Handler(val executor: Executor?, val topic: String,
+                            val callback: (Message, MessageHandlerRegistration) -> Unit) : MessageHandlerRegistration
         @GuardedBy("this")
         protected val handlers: MutableList<Handler> = ArrayList()
         @GuardedBy("this")
@@ -156,16 +157,17 @@ public class InMemoryNetwork {
             override val timestampingNodes = if (timestampingAdvert != null) listOf(timestampingAdvert!!) else emptyList()
         }
 
-        protected val backgroundThread = if (manuallyPumped) null else thread(isDaemon = true, name = "In-memory message dispatcher ") {
+        protected val backgroundThread = if (manuallyPumped) null else
-            while (!currentThread.isInterrupted) {
+            thread(isDaemon = true, name = "In-memory message dispatcher ") {
-                try {
+                while (!currentThread.isInterrupted) {
-                    pumpInternal(true)
+                    try {
-                } catch(e: InterruptedException) {
+                        pumpInternal(true)
-                    if (synchronized(this) { running })
+                    } catch(e: InterruptedException) {
-                        throw e
+                        if (synchronized(this) { running })
+                            throw e
+                    }
                 }
             }
-        }
 
         @Synchronized
         override fun addMessageHandler(topic: String, executor: Executor?, callback: (Message, MessageHandlerRegistration) -> Unit): MessageHandlerRegistration {

src/main/kotlin/core/serialization/Kryo.kt

@@ -72,8 +72,12 @@ class SerializedBytes<T : Any>(bits: ByteArray) : OpaqueBytes(bits) {
 }
 
 // Some extension functions that make deserialisation convenient and provide auto-casting of the result.
-inline fun <reified T : Any> ByteArray.deserialize(kryo: Kryo = THREAD_LOCAL_KRYO.get()): T = kryo.readObject(Input(this), T::class.java)
+inline fun <reified T : Any> ByteArray.deserialize(kryo: Kryo = THREAD_LOCAL_KRYO.get()): T {
-inline fun <reified T : Any> OpaqueBytes.deserialize(kryo: Kryo = THREAD_LOCAL_KRYO.get()): T = kryo.readObject(Input(this.bits), T::class.java)
+    return kryo.readObject(Input(this), T::class.java)
+}
+inline fun <reified T : Any> OpaqueBytes.deserialize(kryo: Kryo = THREAD_LOCAL_KRYO.get()): T {
+    return kryo.readObject(Input(this.bits), T::class.java)
+}
 inline fun <reified T : Any> SerializedBytes<T>.deserialize(): T = bits.deserialize()
 
 /**
@@ -132,7 +136,8 @@ class ImmutableClassSerializer<T : Any>(val klass: KClass<T>) : Serializer<T>()
         // A few quick checks for data evolution. Note that this is not guaranteed to catch every problem! But it's
         // good enough for a prototype.
         if (numFields != constructor.parameters.size)
-            throw KryoException("Mismatch between number of constructor parameters and number of serialised fields for ${klass.qualifiedName} ($numFields vs ${constructor.parameters.size})")
+            throw KryoException("Mismatch between number of constructor parameters and number of serialised fields " +
+                    "for ${klass.qualifiedName} ($numFields vs ${constructor.parameters.size})")
         if (fieldTypeHash != constructor.parameters.hashCode())
             throw KryoException("Hashcode mismatch for parameter types for ${klass.qualifiedName}: unsupported type evolution has happened.")