wroclaw-git-backups/nix
1
0
Fork 0
mirror of https://github.com/NixOS/nix synced 2025-06-28 05:21:16 +02:00
Code Activity

Add a ListBuilder helper for constructing list values

Browse source 
Previously, `state.mkList()` would set the type of the value to tList
and allocate the list vector, but it would not initialize the values
in the list. This has two problems:

* If an exception occurs, the list is left in an undefined state.

* More importantly, for multithreaded evaluation, if a value
  transitions from thunk to non-thunk, it should be final (i.e. other
  threads should be able to access the value safely).

To address this, there now is a `ListBuilder` class (analogous to
`BindingsBuilder`) to build the list vector prior to the call to
`Value::mkList()`. Typical usage:

   auto list = state.buildList(size);
   for (auto & v : list)
       v = ... set value ...;
   vRes.mkList(list);
This commit is contained in:
Eelco Dolstra 2024-03-14 19:10:31 +01:00
parent bff5c94184
commit fecff520d7
10 changed files with 228 additions and 157 deletions
Download patch file Download diff file Expand all files Collapse all files

6
src/libexpr/primops/context.cc
View file

@ -207,10 +207,10 @@ static void prim_getContext(EvalState & state, const PosIdx pos, Value * * args,
if (info.second.allOutputs)
infoAttrs.alloc(sAllOutputs).mkBool(true);
if (!info.second.outputs.empty()) {
auto & outputsVal = infoAttrs.alloc(state.sOutputs);
state.mkList(outputsVal, info.second.outputs.size());
auto list = state.buildList(info.second.outputs.size());
for (const auto & [i, output] : enumerate(info.second.outputs))
(outputsVal.listElems()[i] = state.allocValue())->mkString(output);
(list[i] = state.allocValue())->mkString(output);
infoAttrs.alloc(state.sOutputs).mkList(list);
}
attrs.alloc(state.store->printStorePath(info.first)).mkAttrs(infoAttrs);
}