From d0b28a6700e8ab96f136eff2a5cfbf96d057d981 Mon Sep 17 00:00:00 2001
From: David Schwartz <DavidJoelSchwartz@GMail.com>
Date: Fri, 1 May 2015 13:10:14 -0700
Subject: [PATCH] Compute validated ledger age from signing time

---
 src/ripple/app/ledger/LedgerMaster.cpp | 28 +++++++++++++++++++++-----
 src/ripple/app/misc/Validations.cpp    | 12 +++++++++++
 src/ripple/app/misc/Validations.h      |  5 +++++
 3 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/src/ripple/app/ledger/LedgerMaster.cpp b/src/ripple/app/ledger/LedgerMaster.cpp
index 4e4ddc4227..5a14c36383 100644
--- a/src/ripple/app/ledger/LedgerMaster.cpp
+++ b/src/ripple/app/ledger/LedgerMaster.cpp
@@ -41,6 +41,7 @@
 #include <algorithm>
 #include <cassert>
 #include <beast/cxx14/memory.h> // <memory>
+#include <vector>
 
 namespace ripple {
 
@@ -91,7 +92,7 @@ public:
 
     std::atomic <std::uint32_t> mPubLedgerClose;
     std::atomic <std::uint32_t> mPubLedgerSeq;
-    std::atomic <std::uint32_t> mValidLedgerClose;
+    std::atomic <std::uint32_t> mValidLedgerSign;
     std::atomic <std::uint32_t> mValidLedgerSeq;
     std::atomic <std::uint32_t> mBuildingLedgerSeq;
 
@@ -125,7 +126,7 @@ public:
         , mPathFindNewRequest (false)
         , mPubLedgerClose (0)
         , mPubLedgerSeq (0)
-        , mValidLedgerClose (0)
+        , mValidLedgerSign (0)
         , mValidLedgerSeq (0)
         , mBuildingLedgerSeq (0)
         , standalone_ (config.RUN_STANDALONE)
@@ -168,7 +169,7 @@ public:
 
     int getValidatedLedgerAge ()
     {
-        std::uint32_t valClose = mValidLedgerClose.load();
+        std::uint32_t valClose = mValidLedgerSign.load();
         if (!valClose)
         {
             WriteLog (lsDEBUG, LedgerMaster) << "No validated ledger";
@@ -190,7 +191,7 @@ public:
             reason = "No recently-published ledger";
             return false;
         }
-        std::uint32_t validClose = mValidLedgerClose.load();
+        std::uint32_t validClose = mValidLedgerSign.load();
         std::uint32_t pubClose = mPubLedgerClose.load();
         if (!validClose || !pubClose)
         {
@@ -207,8 +208,25 @@ public:
 
     void setValidLedger(Ledger::ref l)
     {
+        std::vector <std::uint32_t> times;
+        std::uint32_t signTime;
+        if (! getConfig().RUN_STANDALONE)
+            times = getApp().getValidations().getValidationTimes(
+                l->getHash());
+        if (! times.empty () && times.size() >= mMinValidations)
+        {
+            // Calculate the sample median
+            std::sort (times.begin (), times.end ());
+            signTime = (times[times.size() / 2] +
+                times[(times.size() - 1) / 2]) / 2;
+        }
+        else
+        {
+            signTime = l->getCloseTimeNC();
+        }
+
         mValidLedger.set (l);
-        mValidLedgerClose = l->getCloseTimeNC();
+        mValidLedgerSign = signTime;
         mValidLedgerSeq = l->getLedgerSeq();
         getApp().getOPs().updateLocalTx (l);
         getApp().getSHAMapStore().onLedgerClosed (getValidatedLedger());
diff --git a/src/ripple/app/misc/Validations.cpp b/src/ripple/app/misc/Validations.cpp
index ab5c088092..6d46824329 100644
--- a/src/ripple/app/misc/Validations.cpp
+++ b/src/ripple/app/misc/Validations.cpp
@@ -387,6 +387,18 @@ private:
         return ret;
     }
 
+    std::vector<uint32_t>
+    getValidationTimes (uint256 const& hash)
+    {
+        std::vector <std::uint32_t> times;
+        ScopedLockType sl (mLock);
+        if (auto j = findSet (hash))
+            for (auto& it : *j)
+                if (it.second->isTrusted())
+                    times.push_back (it.second->getSignTime());
+        return times;
+    }
+
     void flush ()
     {
         bool anyNew = false;
diff --git a/src/ripple/app/misc/Validations.h b/src/ripple/app/misc/Validations.h
index fef7843701..a916531f8b 100644
--- a/src/ripple/app/misc/Validations.h
+++ b/src/ripple/app/misc/Validations.h
@@ -22,6 +22,7 @@
 
 #include <ripple/protocol/STValidation.h>
 #include <beast/cxx14/memory.h> // <memory>
+#include <vector>
 
 namespace ripple {
 
@@ -64,6 +65,10 @@ public:
     virtual LedgerToValidationCounter getCurrentValidations (
         uint256 currentLedger, uint256 previousLedger) = 0;
 
+    /** Return the times of all validations for a particular ledger hash. */
+    virtual std::vector<std::uint32_t> getValidationTimes (
+        uint256 const& ledger) = 0;
+
     virtual std::list <STValidation::pointer>
     getCurrentTrustedValidations () = 0;