wallet: implement BerkeleyROBatch

Implement ReadKey and HasKey of BerkeleyROBatch, and Next of BerkeleyROCursor.
Also adds the containers for records to BerkeleyRODatabase so that
BerkeleyROBatch will be able to access the records.

1 files changed, 28 insertions, 3 deletions

diff --git a/src/wallet/migrate.cpp b/src/wallet/migrate.cpp
index e567cb0f51..f922d99a17 100644
--- a/src/wallet/migrate.cpp
+++ b/src/wallet/migrate.cpp
@@ -21,17 +21,42 @@ bool BerkeleyRODatabase::Backup(const std::string& dest) const
 
 bool BerkeleyROBatch::ReadKey(DataStream&& key, DataStream& value)
 {
-    return false;
+    SerializeData key_data{key.begin(), key.end()};
+    const auto it{m_database.m_records.find(key_data)};
+    if (it == m_database.m_records.end()) {
+        return false;
+    }
+    auto val = it->second;
+    value.clear();
+    value.write(Span(val));
+    return true;
 }
 
 bool BerkeleyROBatch::HasKey(DataStream&& key)
 {
-    return false;
+    SerializeData key_data{key.begin(), key.end()};
+    return m_database.m_records.count(key_data) > 0;
+}
+
+BerkeleyROCursor::BerkeleyROCursor(const BerkeleyRODatabase& database, Span<const std::byte> prefix)
+    : m_database(database)
+{
+    std::tie(m_cursor, m_cursor_end) = m_database.m_records.equal_range(BytePrefix{prefix});
 }
 
 DatabaseCursor::Status BerkeleyROCursor::Next(DataStream& ssKey, DataStream& ssValue)
 {
-    return DatabaseCursor::Status::FAIL;
+    if (m_cursor == m_cursor_end) {
+        return DatabaseCursor::Status::DONE;
+    }
+    ssKey.write(Span(m_cursor->first));
+    ssValue.write(Span(m_cursor->second));
+    m_cursor++;
+    return DatabaseCursor::Status::MORE;
 }
 
+std::unique_ptr<DatabaseCursor> BerkeleyROBatch::GetNewPrefixCursor(Span<const std::byte> prefix)
+{
+    return std::make_unique<BerkeleyROCursor>(m_database, prefix);
+}
 } // namespace wallet