libstore: remove Goal::key

this was a debugging aid from day one that should not have any impact on
build semantics, and if it *does* have an impact on build semantics then
build semantics are seriously broken. keeping the order imposed by these
keys will be impossible once we let a real event loop schedule our jobs.

Change-Id: I5c313324e1f213ab6453d82f41ae5e59de809a5b

src/libstore/build/derivation-goal.cc

@@ -113,16 +113,6 @@ DerivationGoal::~DerivationGoal() noexcept(false)
 }
 
 
-std::string DerivationGoal::key()
-{
-    /* Ensure that derivations get built in order of their name,
-       i.e. a derivation named "aardvark" always comes before
-       "baboon". And substitution goals always happen before
-       derivation goals (due to "b$"). */
-    return "b$" + std::string(drvPath.name()) + "$" + worker.store.printStorePath(drvPath);
-}
-
-
 void DerivationGoal::killChild()
 {
     hook.reset();

src/libstore/build/derivation-goal.hh

@@ -247,8 +247,6 @@ struct DerivationGoal : public Goal
 
     Finished timedOut(Error && ex);
 
-    std::string key() override;
-
     kj::Promise<Result<WorkResult>> work() noexcept override;
 
     /**

src/libstore/build/drv-output-substitution-goal.cc

@@ -166,13 +166,6 @@ try {
     return {std::current_exception()};
 }
 
-std::string DrvOutputSubstitutionGoal::key()
-{
-    /* "a$" ensures substitution goals happen before derivation
-       goals. */
-    return "a$" + std::string(id.to_string());
-}
-
 kj::Promise<Result<Goal::WorkResult>> DrvOutputSubstitutionGoal::work() noexcept
 {
     return (this->*state)(slotToken.valid());

src/libstore/build/drv-output-substitution-goal.hh

@@ -74,8 +74,6 @@ public:
     kj::Promise<Result<WorkResult>> outPathValid(bool inBuildSlot) noexcept;
     kj::Promise<Result<WorkResult>> finished() noexcept;
 
-    std::string key() override;
-
     kj::Promise<Result<WorkResult>> work() noexcept override;
 
     JobCategory jobCategory() const override {

src/libstore/build/goal.cc

@@ -6,13 +6,6 @@
 namespace nix {
 
 
-bool CompareGoalPtrs::operator() (const GoalPtr & a, const GoalPtr & b) const {
-    std::string s1 = a->key();
-    std::string s2 = b->key();
-    return s1 < s2;
-}
-
-
 void Goal::trace(std::string_view s)
 {
     debug("%1%: %2%", name, s);

src/libstore/build/goal.hh

@@ -22,14 +22,10 @@ class Worker;
  */
 typedef std::shared_ptr<Goal> GoalPtr;
 
-struct CompareGoalPtrs {
-    bool operator() (const GoalPtr & a, const GoalPtr & b) const;
-};
-
 /**
  * Set of goals.
  */
-typedef std::set<GoalPtr, CompareGoalPtrs> Goals;
+typedef std::set<GoalPtr> Goals;
 
 /**
  * Used as a hint to the worker on how to schedule a particular goal. For example,
@@ -167,8 +163,6 @@ public:
         return name;
     }
 
-    virtual std::string key() = 0;
-
     virtual void cleanup() { }
 
     /**

src/libstore/build/substitution-goal.hh

@@ -90,15 +90,6 @@ public:
     );
     ~PathSubstitutionGoal();
 
-    /**
-     * We prepend "a$" to the key name to ensure substitution goals
-     * happen before derivation goals.
-     */
-    std::string key() override
-    {
-        return "a$" + std::string(storePath.name()) + "$" + worker.store.printStorePath(storePath);
-    }
-
     kj::Promise<Result<WorkResult>> work() noexcept override;
 
     /**

tests/functional/build.sh

@@ -146,11 +146,8 @@ out="$(nix build -f fod-failing.nix -L 2>&1)" && status=0 || status=$?
 test "$status" = 1
 # one "hash mismatch" error, one "build of ... failed"
 test "$(<<<"$out" grep -E '^error:' | wc -l)" = 2
-<<<"$out" grepQuiet -E "hash mismatch in fixed-output derivation '.*-x1\\.drv'"
-<<<"$out" grepQuiet -vE "hash mismatch in fixed-output derivation '.*-x3\\.drv'"
-<<<"$out" grepQuiet -vE "hash mismatch in fixed-output derivation '.*-x2\\.drv'"
-<<<"$out" grepQuiet -E "likely URL: https://meow.puppy.forge/puppy.tar.gz"
-<<<"$out" grepQuiet -vE "likely URL: https://kitty.forge/cat.tar.gz"
+<<<"$out" grepQuiet -E "hash mismatch in fixed-output derivation '.*-x.\\.drv'"
+<<<"$out" grepQuiet -E "likely URL: "
 <<<"$out" grepQuiet -E "error: build of '.*-x[1-4]\\.drv\\^out', '.*-x[1-4]\\.drv\\^out', '.*-x[1-4]\\.drv\\^out', '.*-x[1-4]\\.drv\\^out' failed"
 
 out="$(nix build -f fod-failing.nix -L x1 x2 x3 --keep-going 2>&1)" && status=0 || status=$?