ACTION constructor: accept "timeout scaling"

Allow rules to set the timeout-scaling factor for their actions to
indicate that some actions are expected to take longer than others,
e.g., because they call a foreign build tool or are a very complex
end-to-end test.

2 files changed, 20 insertions, 9 deletions

diff --git a/src/buildtool/build_engine/expression/expression.hpp b/src/buildtool/build_engine/expression/expression.hpp
index 5d84e131..86b6cc38 100644
--- a/src/buildtool/build_engine/expression/expression.hpp
+++ b/src/buildtool/build_engine/expression/expression.hpp
@@ -242,6 +242,7 @@ class Expression {
         Expression::FromJson("[]"_json);
     inline static ExpressionPtr const kEmptyMapExpr =
         Expression::FromJson(R"({"type": "empty_map"})"_json);
+    inline static ExpressionPtr const kOne = Expression::FromJson("1.0"_json);
 
   private:
     std::variant<none_t,
diff --git a/src/buildtool/build_engine/target_map/target_map.cpp b/src/buildtool/build_engine/target_map/target_map.cpp
index 13825148..c61e3670 100644
--- a/src/buildtool/build_engine/target_map/target_map.cpp
+++ b/src/buildtool/build_engine/target_map/target_map.cpp
@@ -551,15 +551,25 @@ void withDependencies(
                   }
               }
               bool no_cache = not no_cache_exp->List().empty();
-              auto action =
-                  BuildMaps::Target::Utils::createAction(outputs,
-                                                         output_dirs,
-                                                         std::move(cmd),
-                                                         env_exp,
-                                                         may_fail,
-                                                         no_cache,
-                                                         1.0,
-                                                         inputs_exp);
+              auto timeout_scale_exp =
+                  eval(expr->Get("timeout scaling", Expression::kOne), env);
+              if (not(timeout_scale_exp->IsNumber() or
+                      timeout_scale_exp->IsNone())) {
+                  throw Evaluator::EvaluationError{
+                      fmt::format("timeout scaling has to be number (or null "
+                                  "for default), but found {}",
+                                  timeout_scale_exp->ToString())};
+              }
+              auto action = BuildMaps::Target::Utils::createAction(
+                  outputs,
+                  output_dirs,
+                  std::move(cmd),
+                  env_exp,
+                  may_fail,
+                  no_cache,
+                  timeout_scale_exp->IsNumber() ? timeout_scale_exp->Number()
+                                                : 1.0,
+                  inputs_exp);
               auto action_id = action->Id();
               actions.emplace_back(std::move(action));
               for (auto const& out : outputs) {