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-rw-r--r--libbuild2/context.cxx34
1 files changed, 30 insertions, 4 deletions
diff --git a/libbuild2/context.cxx b/libbuild2/context.cxx
index 8052716..7944294 100644
--- a/libbuild2/context.cxx
+++ b/libbuild2/context.cxx
@@ -848,7 +848,7 @@ namespace build2
}
}
- bool run_phase_mutex::
+ optional<bool> run_phase_mutex::
relock (run_phase o, run_phase n)
{
// Pretty much a fused unlock/lock implementation except that we always
@@ -857,6 +857,7 @@ namespace build2
assert (o != n);
bool r;
+ bool s (true); // True switch.
if (o == run_phase::load)
lm_.unlock ();
@@ -919,6 +920,13 @@ namespace build2
{
if (!lm_.try_lock ())
{
+ // If we failed to acquire the load mutex, then we know there is (or
+ // was) someone before us in the load phase. And it's impossible to
+ // switch to a different phase between our calls to try_lock() above
+ // and lock() below because of our +1 in lc_.
+ //
+ s = false;
+
ctx_.sched.deactivate (false /* external */);
lm_.lock ();
ctx_.sched.activate (false /* external */);
@@ -928,7 +936,7 @@ namespace build2
r = !fail_; // Re-query.
}
- return r;
+ return r ? optional<bool> (s) : nullopt;
}
// C++17 deprecated uncaught_exception() so use uncaught_exceptions() if
@@ -1043,7 +1051,8 @@ namespace build2
phase_lock* pl (phase_lock_instance);
assert (&pl->ctx == &ctx);
- if (!ctx.phase_mutex.relock (old_phase, new_phase))
+ optional<bool> r (ctx.phase_mutex.relock (old_phase, new_phase));
+ if (!r)
{
ctx.phase_mutex.relock (new_phase, old_phase);
throw failed ();
@@ -1052,14 +1061,31 @@ namespace build2
pl->phase = new_phase;
if (new_phase == run_phase::load) // Note: load lock is exclusive.
+ {
ctx.load_generation++;
+ // Invalidate cached target base_scope values if we are switching from a
+ // non-load phase (we don't cache during load which means load->load
+ // switch doesn't have anything to invalidate).
+ //
+ // @@ This is still quite expensive on project like Boost with a large
+ // number of files (targets) and a large number of load phase
+ // switches (due to directory buildfiles).
+ //
+ if (*r)
+ {
+ for (const unique_ptr<target>& t: ctx.targets)
+ t->base_scope_.store (nullptr, memory_order_relaxed);
+ }
+ }
+
//text << this_thread::get_id () << " phase switch "
// << old_phase << " " << new_phase;
}
#if 0
- // NOTE: see push/pop_phase() logic if trying to enable this.
+ // NOTE: see push/pop_phase() logic if trying to enable this. Also
+ // the load stuff above.
//
phase_switch::
phase_switch (phase_unlock&& u, phase_lock&& l)