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Merge branch 'finish-timestamping'
# Conflicts: # docs/build/html/searchindex.js # src/core/serialization/Kryo.kt
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Mike Hearn
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@ -418,7 +418,8 @@ trade many different pieces of commercial paper in a single atomic step.</p>
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<p>After extracting the command and the groups, we then iterate over each group and verify it meets the required business
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logic.</p>
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<div class="codeset container">
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<div class="highlight-kotlin"><div class="highlight"><pre><span class="k">for</span> <span class="p">(</span><span class="n">group</span> <span class="k">in</span> <span class="n">groups</span><span class="p">)</span> <span class="p">{</span>
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<div class="highlight-kotlin"><div class="highlight"><pre><span class="k">val</span> <span class="py">time</span> <span class="p">=</span> <span class="n">tx</span><span class="p">.</span><span class="n">time</span>
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<span class="k">for</span> <span class="p">(</span><span class="n">group</span> <span class="k">in</span> <span class="n">groups</span><span class="p">)</span> <span class="p">{</span>
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<span class="k">when</span> <span class="p">(</span><span class="n">command</span><span class="p">.</span><span class="n">value</span><span class="p">)</span> <span class="p">{</span>
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<span class="k">is</span> <span class="n">Commands</span><span class="p">.</span><span class="n">Move</span> <span class="p">-></span> <span class="p">{</span>
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<span class="k">val</span> <span class="py">input</span> <span class="p">=</span> <span class="n">group</span><span class="p">.</span><span class="n">inputs</span><span class="p">.</span><span class="n">single</span><span class="p">()</span>
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@ -431,8 +432,9 @@ logic.</p>
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<span class="k">is</span> <span class="n">Commands</span><span class="p">.</span><span class="n">Redeem</span> <span class="p">-></span> <span class="p">{</span>
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<span class="k">val</span> <span class="py">input</span> <span class="p">=</span> <span class="n">group</span><span class="p">.</span><span class="n">inputs</span><span class="p">.</span><span class="n">single</span><span class="p">()</span>
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<span class="k">val</span> <span class="py">received</span> <span class="p">=</span> <span class="n">tx</span><span class="p">.</span><span class="n">outStates</span><span class="p">.</span><span class="n">sumCashBy</span><span class="p">(</span><span class="n">input</span><span class="p">.</span><span class="n">owner</span><span class="p">)</span>
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<span class="k">if</span> <span class="p">(</span><span class="n">time</span> <span class="p">==</span> <span class="k">null</span><span class="p">)</span> <span class="k">throw</span> <span class="n">IllegalArgumentException</span><span class="p">(</span><span class="s">"Redemption transactions must be timestamped"</span><span class="p">)</span>
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<span class="n">requireThat</span> <span class="p">{</span>
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<span class="s">"the paper must have matured"</span> <span class="k">by</span> <span class="p">(</span><span class="n">input</span><span class="p">.</span><span class="n">maturityDate</span> <span class="p"><</span> <span class="n">tx</span><span class="p">.</span><span class="n">time</span><span class="p">)</span>
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<span class="s">"the paper must have matured"</span> <span class="k">by</span> <span class="p">(</span><span class="n">time</span> <span class="p">></span> <span class="n">input</span><span class="p">.</span><span class="n">maturityDate</span><span class="p">)</span>
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<span class="s">"the received amount equals the face value"</span> <span class="k">by</span> <span class="p">(</span><span class="n">received</span> <span class="p">==</span> <span class="n">input</span><span class="p">.</span><span class="n">faceValue</span><span class="p">)</span>
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<span class="s">"the paper must be destroyed"</span> <span class="k">by</span> <span class="n">group</span><span class="p">.</span><span class="n">outputs</span><span class="p">.</span><span class="n">isEmpty</span><span class="p">()</span>
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<span class="s">"the transaction is signed by the owner of the CP"</span> <span class="k">by</span> <span class="p">(</span><span class="n">command</span><span class="p">.</span><span class="n">signers</span><span class="p">.</span><span class="n">contains</span><span class="p">(</span><span class="n">input</span><span class="p">.</span><span class="n">owner</span><span class="p">))</span>
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@ -441,12 +443,13 @@ logic.</p>
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<span class="k">is</span> <span class="n">Commands</span><span class="p">.</span><span class="n">Issue</span> <span class="p">-></span> <span class="p">{</span>
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<span class="k">val</span> <span class="py">output</span> <span class="p">=</span> <span class="n">group</span><span class="p">.</span><span class="n">outputs</span><span class="p">.</span><span class="n">single</span><span class="p">()</span>
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<span class="k">if</span> <span class="p">(</span><span class="n">time</span> <span class="p">==</span> <span class="k">null</span><span class="p">)</span> <span class="k">throw</span> <span class="n">IllegalArgumentException</span><span class="p">(</span><span class="s">"Issuance transactions must be timestamped"</span><span class="p">)</span>
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<span class="n">requireThat</span> <span class="p">{</span>
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<span class="c1">// Don't allow people to issue commercial paper under other entities identities.</span>
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<span class="s">"the issuance is signed by the claimed issuer of the paper"</span> <span class="k">by</span>
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<span class="p">(</span><span class="n">command</span><span class="p">.</span><span class="n">signers</span><span class="p">.</span><span class="n">contains</span><span class="p">(</span><span class="n">output</span><span class="p">.</span><span class="n">issuance</span><span class="p">.</span><span class="n">institution</span><span class="p">.</span><span class="n">owningKey</span><span class="p">))</span>
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<span class="s">"the face value is not zero"</span> <span class="k">by</span> <span class="p">(</span><span class="n">output</span><span class="p">.</span><span class="n">faceValue</span><span class="p">.</span><span class="n">pennies</span> <span class="p">></span> <span class="m">0</span><span class="p">)</span>
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<span class="s">"the maturity date is not in the past"</span> <span class="k">by</span> <span class="p">(</span><span class="n">output</span><span class="p">.</span><span class="n">maturityDate</span> <span class="p">></span> <span class="n">tx</span><span class="p">.</span><span class="n">time</span><span class="p">)</span>
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<span class="s">"the maturity date is not in the past"</span> <span class="k">by</span> <span class="p">(</span><span class="n">time</span> <span class="p"><</span> <span class="n">output</span><span class="p">.</span><span class="n">maturityDate</span> <span class="p">)</span>
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<span class="c1">// Don't allow an existing CP state to be replaced by this issuance.</span>
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<span class="s">"there is no input state"</span> <span class="k">by</span> <span class="n">group</span><span class="p">.</span><span class="n">inputs</span><span class="p">.</span><span class="n">isEmpty</span><span class="p">()</span>
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<span class="p">}</span>
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@ -458,7 +461,8 @@ logic.</p>
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<span class="p">}</span>
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</pre></div>
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</div>
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<div class="highlight-java"><div class="highlight"><pre><span class="k">for</span> <span class="o">(</span><span class="n">InOutGroup</span><span class="o"><</span><span class="n">State</span><span class="o">></span> <span class="n">group</span> <span class="o">:</span> <span class="n">groups</span><span class="o">)</span> <span class="o">{</span>
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<div class="highlight-java"><div class="highlight"><pre><span class="n">Instant</span> <span class="n">time</span> <span class="o">=</span> <span class="n">tx</span><span class="o">.</span><span class="na">getTime</span><span class="o">();</span> <span class="c1">// Can be null/missing.</span>
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<span class="k">for</span> <span class="o">(</span><span class="n">InOutGroup</span><span class="o"><</span><span class="n">State</span><span class="o">></span> <span class="n">group</span> <span class="o">:</span> <span class="n">groups</span><span class="o">)</span> <span class="o">{</span>
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<span class="n">List</span><span class="o"><</span><span class="n">State</span><span class="o">></span> <span class="n">inputs</span> <span class="o">=</span> <span class="n">group</span><span class="o">.</span><span class="na">getInputs</span><span class="o">();</span>
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<span class="n">List</span><span class="o"><</span><span class="n">State</span><span class="o">></span> <span class="n">outputs</span> <span class="o">=</span> <span class="n">group</span><span class="o">.</span><span class="na">getOutputs</span><span class="o">();</span>
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@ -478,9 +482,11 @@ logic.</p>
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<span class="k">throw</span> <span class="k">new</span> <span class="n">IllegalStateException</span><span class="o">(</span><span class="s">"Failed requirement: the output state is the same as the input state except for owner"</span><span class="o">);</span>
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<span class="o">}</span> <span class="k">else</span> <span class="k">if</span> <span class="o">(</span><span class="n">cmd</span><span class="o">.</span><span class="na">getValue</span><span class="o">()</span> <span class="k">instanceof</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Redeem</span><span class="o">)</span> <span class="o">{</span>
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<span class="n">Amount</span> <span class="n">received</span> <span class="o">=</span> <span class="n">CashKt</span><span class="o">.</span><span class="na">sumCashOrNull</span><span class="o">(</span><span class="n">inputs</span><span class="o">);</span>
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<span class="k">if</span> <span class="o">(</span><span class="n">time</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span>
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<span class="k">throw</span> <span class="k">new</span> <span class="n">IllegalArgumentException</span><span class="o">(</span><span class="s">"Redemption transactions must be timestamped"</span><span class="o">);</span>
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<span class="k">if</span> <span class="o">(</span><span class="n">received</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span>
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<span class="k">throw</span> <span class="k">new</span> <span class="n">IllegalStateException</span><span class="o">(</span><span class="s">"Failed requirement: no cash being redeemed"</span><span class="o">);</span>
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<span class="k">if</span> <span class="o">(</span><span class="n">input</span><span class="o">.</span><span class="na">getMaturityDate</span><span class="o">().</span><span class="na">isAfter</span><span class="o">(</span><span class="n">tx</span><span class="o">.</span><span class="na">getTime</span><span class="o">()))</span>
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<span class="k">if</span> <span class="o">(</span><span class="n">input</span><span class="o">.</span><span class="na">getMaturityDate</span><span class="o">().</span><span class="na">isAfter</span><span class="o">(</span><span class="n">time</span><span class="o">))</span>
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<span class="k">throw</span> <span class="k">new</span> <span class="n">IllegalStateException</span><span class="o">(</span><span class="s">"Failed requirement: the paper must have matured"</span><span class="o">);</span>
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<span class="k">if</span> <span class="o">(!</span><span class="n">input</span><span class="o">.</span><span class="na">getFaceValue</span><span class="o">().</span><span class="na">equals</span><span class="o">(</span><span class="n">received</span><span class="o">))</span>
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<span class="k">throw</span> <span class="k">new</span> <span class="n">IllegalStateException</span><span class="o">(</span><span class="s">"Failed requirement: the received amount equals the face value"</span><span class="o">);</span>
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@ -494,6 +500,15 @@ logic.</p>
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</div>
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</div>
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<p>This loop is the core logic of the contract.</p>
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<p>The first line simply gets the timestamp out of the transaction. Timestamping of transactions is optional, so a time
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may be missing here. We check for it being null later.</p>
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<div class="admonition note">
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<p class="first admonition-title">Note</p>
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<p class="last">In the Kotlin version, as long as we write a comparison with the transaction time first, the compiler will
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verify we didn’t forget to check if it’s missing. Unfortunately due to the need for smooth Java interop, this
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check won’t happen if we write e.g. <cite>someDate > time</cite>, it has to be <cite>time < someDate</cite>. So it’s good practice to
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always write the transaction timestamp first.</p>
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</div>
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<p>The first line (first three lines in Java) impose a requirement that there be a single piece of commercial paper in
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this group. We do not allow multiple units of CP to be split or merged even if they are owned by the same owner. The
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<code class="docutils literal"><span class="pre">single()</span></code> method is a static <em>extension method</em> defined by the Kotlin standard library: given a list, it throws an
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