From: Peter van Dijk <peter.van.dijk@powerdns.com>
Date: Fri, 15 Nov 2019 12:01:01 +0000 (+0100)
Subject: lmdbbackend: use nested transaction in lookup() when possible/needed
X-Git-Tag: auth-4.3.0-alpha1~38^2~9
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a1c121f924be391f0c06a70fc3b8c5a5e00a4c96;p=thirdparty%2Fpdns.git

lmdbbackend: use nested transaction in lookup() when possible/needed
---

diff --git a/modules/lmdbbackend/lmdbbackend.cc b/modules/lmdbbackend/lmdbbackend.cc
index 938a3f397d..ad9b5565ba 100644
--- a/modules/lmdbbackend/lmdbbackend.cc
+++ b/modules/lmdbbackend/lmdbbackend.cc
@@ -450,18 +450,27 @@ std::shared_ptr<LMDBBackend::RecordsRWTransaction> LMDBBackend::getRecordsRWTran
   return ret;
 }
 
-std::shared_ptr<LMDBBackend::RecordsROTransaction> LMDBBackend::getRecordsROTransaction(uint32_t id)
+std::shared_ptr<LMDBBackend::RecordsROTransaction> LMDBBackend::getRecordsROTransaction(uint32_t id, std::shared_ptr<LMDBBackend::RecordsRWTransaction> rwtxn)
 {
   auto& shard =d_trecords[id % d_shards];
   if(!shard.env) {
+    if (rwtxn) {
+      throw DBException("attempting to start nested transaction without open parent env");
+    }
     shard.env = getMDBEnv( (getArg("filename")+"-"+std::to_string(id % d_shards)).c_str(),
                            MDB_NOSUBDIR | d_asyncFlag, 0600);
     shard.dbi = shard.env->openDB("records", MDB_CREATE | MDB_DUPSORT);
   }
   
-  auto ret = std::make_shared<RecordsROTransaction>(shard.env->getROTransaction());
-  ret->db = std::make_shared<RecordsDB>(shard);
-  return ret;
+  if (rwtxn) {
+    auto ret = std::make_shared<RecordsROTransaction>(rwtxn->txn->getROTransaction());
+    ret->db = std::make_shared<RecordsDB>(shard);
+    return ret;
+  } else {
+    auto ret = std::make_shared<RecordsROTransaction>(shard.env->getROTransaction());
+    ret->db = std::make_shared<RecordsDB>(shard);
+    return ret;
+  }
 }
 
 
@@ -571,7 +580,7 @@ void LMDBBackend::lookup(const QType &type, const DNSName &qdomain, int zoneId,
     
   DNSName relqname = qdomain.makeRelative(hunt);
   //  cout<<"get will look for "<<relqname<< " in zone "<<hunt<<" with id "<<zoneId<<endl;
-  d_rotxn = getRecordsROTransaction(zoneId);
+  d_rotxn = getRecordsROTransaction(zoneId, d_rwtxn);
 
   compoundOrdername co;
   d_getcursor = std::make_shared<MDBROCursor>(d_rotxn->txn->getCursor(d_rotxn->db->dbi));
diff --git a/modules/lmdbbackend/lmdbbackend.hh b/modules/lmdbbackend/lmdbbackend.hh
index 7d5e8bdb3a..5918067edf 100644
--- a/modules/lmdbbackend/lmdbbackend.hh
+++ b/modules/lmdbbackend/lmdbbackend.hh
@@ -252,7 +252,7 @@ private:
   shared_ptr<RecordsROTransaction> d_rotxn; // for lookup and list
   shared_ptr<RecordsRWTransaction> d_rwtxn; // for feedrecord within begin/aborttransaction
   std::shared_ptr<RecordsRWTransaction> getRecordsRWTransaction(uint32_t id);
-  std::shared_ptr<RecordsROTransaction> getRecordsROTransaction(uint32_t id);
+  std::shared_ptr<RecordsROTransaction> getRecordsROTransaction(uint32_t id, std::shared_ptr<LMDBBackend::RecordsRWTransaction> rwtxn = nullptr);
   int genChangeDomain(const DNSName& domain, std::function<void(DomainInfo&)> func);
   int genChangeDomain(uint32_t id, std::function<void(DomainInfo&)> func);
   void deleteDomainRecords(RecordsRWTransaction& txn, uint32_t domain_id, uint16_t qtype=QType::ANY);