[1287] cleanup: moved main logic of getIterator() to the DatabaseIterator

constructor.  Since we should manage the transaction inside the
DatabaseIterator class, it will make more sense to start it within the class.

src/lib/datasrc/database.cc

@@ -705,15 +705,37 @@ namespace {
 class DatabaseIterator : public ZoneIterator {
 public:
     DatabaseIterator(shared_ptr<DatabaseAccessor> accessor,
-                     ConstRRsetPtr soa,
-                     const DatabaseAccessor::IteratorContextPtr& context,
+                     const Name& zone_name,
                      const RRClass& rrclass) :
         accessor_(accessor),
-        context_(context),
         class_(rrclass),
-        soa_(soa),
         ready_(true)
     {
+        // Get the zone
+        const pair<bool, int> zone(accessor_->getZone(zone_name.toText()));
+        if (!zone.first) {
+            // No such zone, can't continue
+            isc_throw(DataSourceError, "Zone " + zone_name.toText() +
+                      " can not be iterated, because it doesn't exist "
+                      "in this data source");
+        }
+
+        // Start a separate transaction.
+        accessor_->startTransaction();
+
+        // Find the SOA of the zone (may or may not succeed).  Note that
+        // this must be done before starting the iteration context.
+        soa_ = DatabaseClient::Finder(accessor_, zone.second, zone_name).
+            find(zone_name, RRType::SOA(), NULL).rrset;
+
+        // Request the context
+        context_ = accessor_->getAllRecords(zone.second);
+        // It must not return NULL, that's a bug of the implementation
+        if (!context_) {
+            isc_throw(isc::Unexpected, "Iterator context null at " +
+                      zone_name.toText());
+        }
+
         // Prepare data for the next time
         getData();
     }
@@ -778,9 +800,9 @@ private:
     // The dedicated accessor
     shared_ptr<DatabaseAccessor> accessor_;
     // The context
-    const DatabaseAccessor::IteratorContextPtr context_;
+    DatabaseAccessor::IteratorContextPtr context_;
     // Class of the zone
-    RRClass class_;
+    const RRClass class_;
     // SOA of the zone, if any (it should normally exist)
     ConstRRsetPtr soa_;
     // Status
@@ -793,40 +815,13 @@ private:
 
 ZoneIteratorPtr
 DatabaseClient::getIterator(const isc::dns::Name& name) const {
-    shared_ptr<DatabaseAccessor> iterator_accessor(accessor_->clone());
-    // Get the zone
-    std::pair<bool, int> zone(iterator_accessor->getZone(name.toText()));
-    if (!zone.first) {
-        // No such zone, can't continue
-        isc_throw(DataSourceError, "Zone " + name.toText() +
-                  " can not be iterated, because it doesn't exist "
-                  "in this data source");
-    }
-
-    iterator_accessor->startTransaction();
-
-    // Find the SOA of the zone (may or may not succeed).  Note that
-    // this must be done before starting the iteration context.
-    ConstRRsetPtr soa = DatabaseClient::Finder(iterator_accessor, zone.second, name).
-        find(name, RRType::SOA(), NULL).rrset;
-
-    // Request the context
-    DatabaseAccessor::IteratorContextPtr
-        context(iterator_accessor->getAllRecords(zone.second));
-    // It must not return NULL, that's a bug of the implementation
-    if (context == DatabaseAccessor::IteratorContextPtr()) {
-        isc_throw(isc::Unexpected, "Iterator context null at " +
-                  name.toText());
-    }
-    // Create the iterator and return it
-    // TODO: Once #1062 is merged with this, we need to get the
-    // actual zone class from the connection, as the DatabaseClient
-    // doesn't know it and the iterator needs it (so it wouldn't query
-    // it each time)
+    ZoneIteratorPtr iterator = ZoneIteratorPtr(new DatabaseIterator(
+                                                   accessor_->clone(), name,
+                                                   RRClass::IN()));
     LOG_DEBUG(logger, DBG_TRACE_DETAILED, DATASRC_DATABASE_ITERATE).
         arg(name);
-    return (ZoneIteratorPtr(new DatabaseIterator(iterator_accessor, soa, context,
-                                                 RRClass::IN())));
+
+    return (iterator);
 }
 
 //