From 0478949c72310b9749d5b959adad8bdf5c2c0841 Mon Sep 17 00:00:00 2001
From: eldritch horrors <pennae@lix.systems>
Date: Sun, 1 Sep 2024 01:37:10 +0200
Subject: libstore: turn builder output processing into event loop

this removes the rather janky did-you-mean-async poll loop we had so
far. sadly kj does not play well with pty file descriptors, so we do
have to add our own async input stream that does not eat pty EIO and
turns it into an exception. that's still a *lot* better than the old
code, and using a real even loop makes everything else easier later.

Change-Id: Idd7e0428c59758602cc530bcad224cd2fed4c15e
---
 src/libstore/build/derivation-goal.hh | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

(limited to 'src/libstore/build/derivation-goal.hh')

diff --git a/src/libstore/build/derivation-goal.hh b/src/libstore/build/derivation-goal.hh
index 020388d5a..46b07fc0b 100644
--- a/src/libstore/build/derivation-goal.hh
+++ b/src/libstore/build/derivation-goal.hh
@@ -8,6 +8,7 @@
 #include "store-api.hh"
 #include "pathlocks.hh"
 #include "goal.hh"
+#include <kj/time.h>
 
 namespace nix {
 
@@ -17,7 +18,7 @@ struct HookInstance;
 
 struct HookReplyBase {
     struct [[nodiscard]] Accept {
-        std::set<int> fds;
+        kj::Promise<Outcome<void, Goal::Finished>> promise;
     };
     struct [[nodiscard]] Decline {};
     struct [[nodiscard]] Postpone {};
@@ -70,6 +71,8 @@ struct InitialOutput {
  */
 struct DerivationGoal : public Goal
 {
+    struct InputStream;
+
     /**
      * Whether to use an on-disk .drv file.
      */
@@ -242,7 +245,7 @@ struct DerivationGoal : public Goal
         BuildMode buildMode = bmNormal);
     virtual ~DerivationGoal() noexcept(false);
 
-    Finished timedOut(Error && ex) override;
+    Finished timedOut(Error && ex);
 
     std::string key() override;
 
@@ -312,13 +315,19 @@ struct DerivationGoal : public Goal
     virtual void cleanupPostOutputsRegisteredModeCheck();
     virtual void cleanupPostOutputsRegisteredModeNonCheck();
 
-    /**
-     * Callback used by the worker to write to the log.
-     */
-    WorkResult handleChildOutput(int fd, std::string_view data) override;
-    void handleEOF(int fd) override;
+protected:
+    kj::TimePoint lastChildActivity = kj::minValue;
+
+    kj::Promise<Outcome<void, Finished>> handleChildOutput() noexcept;
+    kj::Promise<Outcome<void, Finished>>
+    handleChildStreams(InputStream & builderIn, InputStream * hookIn) noexcept;
+    kj::Promise<Outcome<void, Finished>> handleBuilderOutput(InputStream & in) noexcept;
+    kj::Promise<Outcome<void, Finished>> handleHookOutput(InputStream & in) noexcept;
+    kj::Promise<Outcome<void, Finished>> monitorForSilence() noexcept;
+    Finished tooMuchLogs();
     void flushLine();
 
+public:
     /**
      * Wrappers around the corresponding Store methods that first consult the
      * derivation.  This is currently needed because when there is no drv file
@@ -357,6 +366,11 @@ struct DerivationGoal : public Goal
 
     void waiteeDone(GoalPtr waitee) override;
 
+    virtual bool respectsTimeouts()
+    {
+        return false;
+    }
+
     StorePathSet exportReferences(const StorePathSet & storePaths);
 
     JobCategory jobCategory() const override {
-- 
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