From 8b25d2c0ce64d7f8577a0c2e601e505c9f1140bf Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Tue, 25 Apr 2017 11:29:46 -0700
Subject: Upgrade from per-tx database to per-txout

---
 src/txdb.cpp | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

(limited to 'src/txdb.cpp')

diff --git a/src/txdb.cpp b/src/txdb.cpp
index 19c9002506..f4a6fad85b 100644
--- a/src/txdb.cpp
+++ b/src/txdb.cpp
@@ -252,3 +252,48 @@ bool CBlockTreeDB::LoadBlockIndexGuts(std::function<CBlockIndex*(const uint256&)
 
     return true;
 }
+
+/** Upgrade the database from older formats.
+ *
+ * Currently implemented: from the per-tx utxo model (0.8..0.14.x) to per-txout.
+ */
+bool CCoinsViewDB::Upgrade() {
+    std::unique_ptr<CDBIterator> pcursor(db.NewIterator());
+    pcursor->Seek(std::make_pair(DB_COINS, uint256()));
+    if (!pcursor->Valid()) {
+        return true;
+    }
+
+    LogPrintf("Upgrading database...\n");
+    size_t batch_size = 1 << 24;
+    CDBBatch batch(db);
+    while (pcursor->Valid()) {
+        boost::this_thread::interruption_point();
+        std::pair<unsigned char, uint256> key;
+        if (pcursor->GetKey(key) && key.first == DB_COINS) {
+            CCoins old_coins;
+            if (!pcursor->GetValue(old_coins)) {
+                return error("%s: cannot parse CCoins record", __func__);
+            }
+            COutPoint outpoint(key.second, 0);
+            for (size_t i = 0; i < old_coins.vout.size(); ++i) {
+                if (!old_coins.vout[i].IsNull() && !old_coins.vout[i].scriptPubKey.IsUnspendable()) {
+                    Coin newcoin(std::move(old_coins.vout[i]), old_coins.nHeight, old_coins.fCoinBase);
+                    outpoint.n = i;
+                    CoinEntry entry(&outpoint);
+                    batch.Write(entry, newcoin);
+                }
+            }
+            batch.Erase(key);
+            if (batch.SizeEstimate() > batch_size) {
+                db.WriteBatch(batch);
+                batch.Clear();
+            }
+            pcursor->Next();
+        } else {
+            break;
+        }
+    }
+    db.WriteBatch(batch);
+    return true;
+}
-- 
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