why-depends: asyncify printNode

Instead of logging directly, we now write into a `Strings` set that is
referenced by the caller.

While at it, added a test-case to ensure that self-reference invocations
and --all behave properly.

Change-Id: Ib183ab8e8e90436300e1c870fb3ae8f18730abbf

lix/nix/why-depends.cc

@@ -3,6 +3,7 @@
 #include "lix/libstore/fs-accessor.hh"
 #include "lix/libmain/shared.hh"
 #include "lix/libutil/error.hh"
+#include "lix/libutil/generator.hh"
 #include "lix/libutil/result.hh"
 #include "why-depends.hh"
 
@@ -99,9 +100,6 @@ try {
     co_return result::current_exception();
 }
 
-struct BailOut : BaseException
-{};
-
 auto const inf = std::numeric_limits<size_t>::max();
 struct Node
 {
@@ -114,29 +112,32 @@ struct Node
     bool visited = false;
 };
 
-static void printNode(
+struct BailOut : BaseException
+{};
+
+static kj::Promise<Result<void>> printNode(
     Node & node,
     const std::string & firstPad,
     const std::string & tailPad,
     bool all,
     bool precise,
     Store & store,
-    AsyncIoRoot & aio,
     const StorePath & packagePath,
     const StorePath & dependencyPath,
-    std::map<StorePath, Node> & graph
+    std::map<StorePath, Node> & graph,
+    Strings & output
 )
-{
+try {
     auto pathS = store.printStorePath(node.path);
 
     assert(node.dist != inf);
     if (precise) {
-        logger->cout(
-            "%s%s%s%s" ANSI_NORMAL,
-            firstPad,
-            node.visited ? "\e[38;5;244m" : "",
-            firstPad != "" ? "→ " : "",
-            pathS
+        output.push_back(
+            fmt("%s%s%s%s" ANSI_NORMAL,
+                firstPad,
+                node.visited ? "\e[38;5;244m" : "",
+                firstPad != "" ? "→ " : "",
+                pathS)
         );
     }
 
@@ -145,8 +146,9 @@ static void printNode(
     }
 
     if (node.visited) {
-        return;
+        co_return result::success();
     }
+
     if (precise) {
         node.visited = true;
     }
@@ -175,7 +177,7 @@ static void printNode(
     // FIXME: should use scanForReferences().
 
     if (precise) {
-        hits = aio.blockOn(visitPath(
+        hits = TRY_AWAIT(visitPath(
             pathS, store, pathS, dependencyPath.hashPart(), hashes, packagePath, dependencyPath
         ));
     }
@@ -187,11 +189,11 @@ static void printNode(
 
         for (auto & hit : hits[hash]) {
             bool first = hit == *hits[hash].begin();
-            logger->cout(
-                "%s%s%s",
-                tailPad,
-                (first ? (last ? treeLast : treeConn) : (last ? treeNull : treeLine)),
-                hit
+            output.push_back(
+                fmt("%s%s%s",
+                    tailPad,
+                    (first ? (last ? treeLast : treeConn) : (last ? treeNull : treeLine)),
+                    hit)
             );
             if (!all) {
                 break;
@@ -200,29 +202,33 @@ static void printNode(
 
         if (!precise) {
             auto pathS = store.printStorePath(ref.second->path);
-            logger->cout(
-                "%s%s%s%s" ANSI_NORMAL,
-                firstPad,
-                ref.second->visited ? "\e[38;5;244m" : "",
-                last ? treeLast : treeConn,
-                pathS
+            output.push_back(
+                fmt("%s%s%s%s" ANSI_NORMAL,
+                    firstPad,
+                    ref.second->visited ? "\e[38;5;244m" : "",
+                    last ? treeLast : treeConn,
+                    pathS)
             );
             node.visited = true;
         }
 
-        printNode(
+        TRY_AWAIT(printNode(
             *ref.second,
             tailPad + (last ? treeNull : treeLine),
             tailPad + (last ? treeNull : treeLine),
             all,
             precise,
             store,
-            aio,
             packagePath,
             dependencyPath,
-            graph
-        );
+            graph,
+            output
+        ));
     }
+
+    co_return result::success();
+} catch (...) {
+    co_return result::current_exception();
 }
 
 struct CmdWhyDepends : SourceExprCommand, MixOperateOnOptions
@@ -356,23 +362,30 @@ struct CmdWhyDepends : SourceExprCommand, MixOperateOnOptions
            'dependency'). Print every edge on a path between `package`
            and `dependency`. */
         RunPager pager;
+        if (!precise) {
+            logger->cout("%s", store->printStorePath(graph.at(packagePath).path));
+        }
+
+        Strings output;
         try {
-            if (!precise) {
-                logger->cout("%s", store->printStorePath(graph.at(packagePath).path));
-            }
-            printNode(
+            aio().blockOn(printNode(
                 graph.at(packagePath),
                 "",
                 "",
                 all,
                 precise,
                 *store,
-                aio(),
                 packagePath,
                 dependencyPath,
-                graph
-            );
-        } catch (BailOut & ) { }
+                graph,
+                output
+            ));
+        } catch (BailOut &) {
+        }
+
+        for (auto & l : output) {
+            logger->cout("%s", l);
+        }
     }
 };
 

tests/functional/dependencies.builder0.sh

@@ -5,6 +5,7 @@ mkdir $out
 echo $(cat $input1/foo)$(cat $input2/bar) > $out/foobar
 
 ln -s $input2 $out/reference-to-input-2
+ln -s $input3 $out/reference-to-input-3
 
 # Self-reference.
 ln -s $out $out/self

tests/functional/dependencies.nix

@@ -20,9 +20,15 @@ let
       head -c 100k /dev/zero > $out/filler
       echo BAR > $out/bar
       echo ${input0} > $out/input0
+      echo ${input3} > $out/input3
     '';
   };
 
+  input3 = mkDerivation {
+    name = "dependencies-input-3";
+    buildCommand = "mkdir $out; echo FOO > $out/foo";
+  };
+
   fod_input = mkDerivation {
     name = "fod-input";
     buildCommand = ''
@@ -40,8 +46,10 @@ mkDerivation {
   builder = ./dependencies.builder0.sh + "/FOOBAR/../.";
   input1 = input1 + "/.";
   input2 = "${input2}/.";
+  input3 = "${input3}/.";
   input1_drv = input1;
   input2_drv = input2;
+  input3_drv = input3;
   input0_drv = input0;
   fod_input_drv = fod_input;
   meta.description = "Random test package";

tests/functional/export-graph.sh

@@ -11,7 +11,7 @@ checkRef() {
 
 outPath=$(nix-build ./export-graph.nix -A 'foo."bar.runtimeGraph"' -o $TEST_ROOT/result)
 
-test $(nix-store -q --references $TEST_ROOT/result | wc -l) = 3 || fail "bad nr of references"
+test $(nix-store -q --references $TEST_ROOT/result | wc -l) = 4 || fail "bad nr of references"
 
 checkRef input-2
 for i in $(cat $outPath); do checkRef $i; done

tests/functional/why-depends.sh

@@ -10,6 +10,7 @@ nix why-depends --derivation --file ./dependencies.nix input2_drv input1_drv
 nix why-depends --file ./dependencies.nix input2_drv input1_drv
 
 nix-build ./dependencies.nix -A input0_drv -o dep
+nix-build ./dependencies.nix -A input3_drv -o dep3
 nix-build ./dependencies.nix -o toplevel
 
 FAST_WHY_DEPENDS_OUTPUT=$(nix why-depends ./toplevel ./dep)
@@ -27,3 +28,14 @@ echo "$PRECISE_WHY_DEPENDS_OUTPUT" | grepQuiet reference-to-input-2
 <<<"$PRECISE_WHY_DEPENDS_OUTPUT" sed -n '3p' | grep "    →" | grepQuiet "dependencies-input-2"
 <<<"$PRECISE_WHY_DEPENDS_OUTPUT" sed -n '4p' | grepQuiet "    └───input0: …"                          # in input-2, file input0
 <<<"$PRECISE_WHY_DEPENDS_OUTPUT" sed -n '5p' | grep "        →" | grepQuiet "dependencies-input-0"    # is dependencies-input-0 referenced
+
+WHY_DEPENDS_SELF_REF="$(nix why-depends ./toplevel ./toplevel)"
+<<<"$WHY_DEPENDS_SELF_REF" sed -n '1p' | grepQuiet "dependencies-top"
+<<<"$WHY_DEPENDS_SELF_REF" sed -n '2p' | grep "└─" | grepQuiet "dependencies-top"
+test -z "$(<<<"$WHY_DEPENDS_SELF_REF" sed -n '3p')"
+
+WHY_DEPENDS_ALL="$(nix why-depends ./toplevel ./dep3 --all)"
+<<<"$WHY_DEPENDS_ALL" sed -n '1p' | grep -v "└─" | grepQuiet "dependencies-top"
+<<<"$WHY_DEPENDS_ALL" sed -n '2p' | grep "├─" | grepQuiet "input-3"
+<<<"$WHY_DEPENDS_ALL" sed -n '3p' | grep "└─" | grepQuiet "input-2"
+<<<"$WHY_DEPENDS_ALL" sed -n '4p' | grep "  └─" | grepQuiet "input-3"