libstore: move log handling fully into handleBuilderOutput

it was split up like this only because the old worker system had no
promises. since we have them now we can use them for encapsulation.

Change-Id: Idbd523eff617d4c53c14b125ab3dfce4979cdab1

lix/libstore/build/derivation-goal.cc

@@ -1229,6 +1229,30 @@ Goal::WorkResult DerivationGoal::tooMuchLogs()
 kj::Promise<Result<std::optional<Goal::WorkResult>>>
 DerivationGoal::handleBuilderOutput(AsyncInputStream & in) noexcept
 try {
+    std::string currentLogLine;
+    size_t currentLogLinePos = 0; // to handle carriage return
+
+    auto flushLine = [&] {
+        KJ_DEFER({
+            currentLogLine = "";
+            currentLogLinePos = 0;
+        });
+
+        if (const auto state = handleJSONLogMessage(
+                currentLogLine, *act, builderActivities, "the derivation builder", false
+            ))
+        {
+            return *state;
+        } else {
+            logTail.push_back(currentLogLine);
+            if (logTail.size() > settings.logLines) {
+                logTail.pop_front();
+            }
+
+            return act->result(resBuildLogLine, currentLogLine);
+        }
+    };
+
     auto buf = kj::heapArray<char>(4096);
     while (true) {
         std::string_view data;
@@ -1417,27 +1441,6 @@ DerivationGoal::handleChildStreams(AsyncInputStream * builderIn, AsyncInputStrea
     co_return std::nullopt;
 }
 
-Logger::BufferState DerivationGoal::flushLine()
-{
-    KJ_DEFER({
-        currentLogLine = "";
-        currentLogLinePos = 0;
-    });
-
-    if (const auto state = handleJSONLogMessage(
-            currentLogLine, *act, builderActivities, "the derivation builder", false
-        ))
-    {
-        return *state;
-    } else {
-        logTail.push_back(currentLogLine);
-        if (logTail.size() > settings.logLines) logTail.pop_front();
-
-        return act->result(resBuildLogLine, currentLogLine);
-    }
-}
-
-
 kj::Promise<Result<OutputPathMap>> DerivationGoal::queryDerivationOutputMap()
 try {
     OutputPathMap res;

lix/libstore/build/derivation-goal.hh

@@ -201,9 +201,6 @@ struct DerivationGoal : public Goal
      */
     std::list<std::string> logTail;
 
-    std::string currentLogLine;
-    size_t currentLogLinePos = 0; // to handle carriage return
-
     std::string currentHookLine;
 
     /**
@@ -325,7 +322,6 @@ protected:
     kj::Promise<Result<std::optional<WorkResult>>> handleHookOutput(AsyncInputStream & in) noexcept;
     kj::Promise<Result<std::optional<WorkResult>>> monitorForSilence() noexcept;
     WorkResult tooMuchLogs();
-    Logger::BufferState flushLine();
 
     virtual std::string buildErrorContents(const std::string & exitMsg, bool diskFull);