GC finalizers may run after env_cleanup_hook, so Detach methods can

be called when the detached target is already closed. So I've removed
the precondition of `Detach+` methods and `DecrementPendingWork` from
both `Database` and `Transaction` classes.

Author: CMCDragonkai

src/rocksdb/napi/database.cpp

@@ -139,7 +139,6 @@ void Database::AttachSnapshot(napi_env env, uint32_t id, Snapshot* snapshot) {
 }
 
 void Database::DetachSnapshot(napi_env env, uint32_t id) {
-  assert(!hasClosed_);
   snapshots_.erase(id);
   DecrementPendingWork(env);
 }
@@ -151,7 +150,6 @@ void Database::AttachIterator(napi_env env, uint32_t id, Iterator* iterator) {
 }
 
 void Database::DetachIterator(napi_env env, uint32_t id) {
-  assert(!hasClosed_);
   iterators_.erase(id);
   DecrementPendingWork(env);
 }
@@ -164,7 +162,6 @@ void Database::AttachTransaction(napi_env env, uint32_t id,
 }
 
 void Database::DetachTransaction(napi_env env, uint32_t id) {
-  assert(!hasClosed_);
   transactions_.erase(id);
   DecrementPendingWork(env);
 }
@@ -175,7 +172,6 @@ void Database::IncrementPendingWork(napi_env env) {
 }
 
 void Database::DecrementPendingWork(napi_env env) {
-  assert(!hasClosed_);
   napi_reference_unref(env, ref_, &pendingWork_);
   // If the `closeWorker_` is set, then the closing operation
   // is waiting until all pending work is completed

src/rocksdb/napi/index.cpp

@@ -48,7 +48,8 @@ static void env_cleanup_hook(void* arg) {
     std::map<uint32_t, Iterator*>::iterator iterator_it;
     for (iterator_it = iterators.begin(); iterator_it != iterators.end();
          ++iterator_it) {
-      iterator_it->second->Close();
+      auto iterator = iterator_it->second;
+      iterator->Close();
     }
     std::map<uint32_t, Transaction*> transactions = database->transactions_;
     std::map<uint32_t, Transaction*>::iterator transaction_it;
@@ -69,7 +70,8 @@ static void env_cleanup_hook(void* arg) {
     std::map<uint32_t, Snapshot*>::iterator snapshot_it;
     for (snapshot_it = snapshots.begin(); snapshot_it != snapshots.end();
          ++snapshot_it) {
-      snapshot_it->second->Release();
+      auto snapshot = snapshot_it->second;
+      snapshot->Release();
     }
     database->Close();
   }

src/rocksdb/napi/transaction.cpp

@@ -133,7 +133,6 @@ void Transaction::AttachIterator(napi_env env, uint32_t id,
 }
 
 void Transaction::DetachIterator(napi_env env, uint32_t id) {
-  assert(!hasCommitted_ && !hasRollbacked_);
   iterators_.erase(id);
   DecrementPendingWork(env);
 }
@@ -144,7 +143,6 @@ void Transaction::IncrementPendingWork(napi_env env) {
 }
 
 void Transaction::DecrementPendingWork(napi_env env) {
-  assert(!hasCommitted_ && !hasRollbacked_);
   napi_reference_unref(env, ref_, &pendingWork_);
   // If the `closeWorker_` is set, then the closing operation
   // is waiting until all pending work is completed