From 8d1b169f5ac885a02eea376c8c5e007f5afe0188 Mon Sep 17 00:00:00 2001
From: Miguel Portilla <miguelportilla@pobros.com>
Date: Mon, 29 Jun 2015 12:41:55 -0400
Subject: [PATCH] Skip List unit test (RIPD-926)

---
 Builds/VisualStudio2013/RippleD.vcxproj       |   4 +
 .../VisualStudio2013/RippleD.vcxproj.filters  |   3 +
 src/ripple/ledger/tests/SkipList_test.cpp     | 112 ++++++++++++++++++
 src/ripple/unity/ledger.cpp                   |   5 +-
 4 files changed, 122 insertions(+), 2 deletions(-)
 create mode 100644 src/ripple/ledger/tests/SkipList_test.cpp

diff --git a/Builds/VisualStudio2013/RippleD.vcxproj b/Builds/VisualStudio2013/RippleD.vcxproj
index fd6110a9d..86abbb60a 100644
--- a/Builds/VisualStudio2013/RippleD.vcxproj
+++ b/Builds/VisualStudio2013/RippleD.vcxproj
@@ -2365,6 +2365,10 @@
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='debug|x64'">True</ExcludedFromBuild>
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='release|x64'">True</ExcludedFromBuild>
     </ClCompile>
+    <ClCompile Include="..\..\src\ripple\ledger\tests\SkipList_test.cpp">
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='debug|x64'">True</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='release|x64'">True</ExcludedFromBuild>
+    </ClCompile>
     <ClCompile Include="..\..\src\ripple\ledger\tests\View_test.cpp">
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='debug|x64'">True</ExcludedFromBuild>
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='release|x64'">True</ExcludedFromBuild>
diff --git a/Builds/VisualStudio2013/RippleD.vcxproj.filters b/Builds/VisualStudio2013/RippleD.vcxproj.filters
index e0e7611ba..a6b81c324 100644
--- a/Builds/VisualStudio2013/RippleD.vcxproj.filters
+++ b/Builds/VisualStudio2013/RippleD.vcxproj.filters
@@ -3096,6 +3096,9 @@
     <ClCompile Include="..\..\src\ripple\ledger\tests\PaymentSandbox_test.cpp">
       <Filter>ripple\ledger\tests</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\src\ripple\ledger\tests\SkipList_test.cpp">
+      <Filter>ripple\ledger\tests</Filter>
+    </ClCompile>
     <ClCompile Include="..\..\src\ripple\ledger\tests\View_test.cpp">
       <Filter>ripple\ledger\tests</Filter>
     </ClCompile>
diff --git a/src/ripple/ledger/tests/SkipList_test.cpp b/src/ripple/ledger/tests/SkipList_test.cpp
new file mode 100644
index 000000000..d1f5166a9
--- /dev/null
+++ b/src/ripple/ledger/tests/SkipList_test.cpp
@@ -0,0 +1,112 @@
+//-----------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2012, 2015 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <BeastConfig.h>
+#include <ripple/app/ledger/Ledger.h>
+#include <ripple/ledger/View.h>
+#include <ripple/basics/Log.h>
+#include <beast/unit_test/suite.h>
+
+namespace ripple {
+namespace test {
+
+class SkipList_test : public beast::unit_test::suite
+{
+    void
+    testSkipList()
+    {
+        beast::Journal const j;
+        std::vector<std::shared_ptr<Ledger>> history;
+        {
+            Config const config;
+            auto prev =
+                std::make_shared<Ledger>(create_genesis, config);
+            history.push_back(prev);
+            for (auto i = 0; i < 1023; ++i)
+            {
+                auto next = std::make_shared<Ledger>(
+                    open_ledger, *prev);
+                next->updateSkipList();
+                next->setClosed();
+                history.push_back(next);
+                prev = next;
+            }
+        }
+
+        {
+            auto l = *(std::next(std::begin(history)));
+            expect((*std::begin(history))->info().seq <
+                l->info().seq);
+            expect(hashOfSeq(*l, l->info().seq + 1,
+                j) == boost::none);
+            expect(hashOfSeq(*l, l->info().seq,
+                j) == l->info().hash);
+            expect(hashOfSeq(*l, l->info().seq - 1,
+                j) == l->info().parentHash);
+            expect(hashOfSeq(*history.back(),
+                l->info().seq, j) == boost::none);
+        }
+
+        // ledger skip lists store up to the previous 256 hashes
+        for (auto i = history.crbegin();
+            i != history.crend(); i += 256)
+        {
+            for (auto n = i;
+                n != std::next(i,
+                    (*i)->info().seq - 256 > 1 ? 257 : 256);
+                ++n)
+            {
+                expect(hashOfSeq(**i,
+                    (*n)->info().seq, j) ==
+                        (*n)->info().hash);
+            }
+
+            // edge case accessing beyond 256
+            expect(hashOfSeq(**i,
+                (*i)->info().seq - 258, j) ==
+                    boost::none);
+        }
+
+        // every 256th hash beyond the first 256 is stored
+        for (auto i = history.crbegin();
+            i != std::next(history.crend(), -512);
+            i += 256)
+        {
+            for (auto n = std::next(i, 512);
+                n != history.crend();
+                n += 256)
+            {
+                expect(hashOfSeq(**i,
+                    (*n)->info().seq, j) ==
+                        (*n)->info().hash);
+            }
+        }
+    }
+
+    void run()
+    {
+        LogSquelcher l;
+        testSkipList();
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(SkipList,ledger,ripple);
+
+}  // test
+}  // ripple
diff --git a/src/ripple/unity/ledger.cpp b/src/ripple/unity/ledger.cpp
index 9e9c4d14c..29a7b59b7 100644
--- a/src/ripple/unity/ledger.cpp
+++ b/src/ripple/unity/ledger.cpp
@@ -31,6 +31,7 @@
 #include <ripple/ledger/impl/TxMeta.cpp>
 #include <ripple/ledger/impl/View.cpp>
 
-#include <ripple/ledger/tests/PaymentSandbox_test.cpp>
-#include <ripple/ledger/tests/View_test.cpp>
 #include <ripple/ledger/tests/Directory_test.cpp>
+#include <ripple/ledger/tests/PaymentSandbox_test.cpp>
+#include <ripple/ledger/tests/SkipList_test.cpp>
+#include <ripple/ledger/tests/View_test.cpp>