semaphore: expiry_handler: tunnel exception_ptr to entry

Accept an optional exception_ptr in the expiry_handler and pass it on to the entry promise, so that the original abort exception can be passed to the user. This way we can distinguish between, e.g. timed_out_error and abort_requested_error. Signed-off-by: Benny Halevy <[email protected]>
scylladb · Jan 9, 2025 · f8c36db · f8c36db
1 parent d415e57
commit f8c36db
Show file tree

Hide file tree

Showing 2 changed files with 17 additions and 1 deletion.
diff --git a/include/seastar/core/semaphore.hh b/include/seastar/core/semaphore.hh
@@ -186,9 +186,11 @@ private:
     }
     struct expiry_handler {
         basic_semaphore& sem;
-        void operator()(entry& e) noexcept {
+        void operator()(entry& e, const std::optional<std::exception_ptr>& ex) noexcept {
             if (e.timer) {
                 e.pr.set_exception(sem.get_timeout_exception());
+            } else if (ex) {
+                e.pr.set_exception(*ex);
             } else if (sem._ex) {
                 e.pr.set_exception(sem._ex);
             } else {

diff --git a/tests/unit/semaphore_test.cc b/tests/unit/semaphore_test.cc
@@ -32,6 +32,7 @@
 #include <seastar/core/sleep.hh>
 #include <seastar/core/shared_mutex.hh>
 #include <ranges>
+#include <stdexcept>
 
 #include "expected_exception.hh"
 
@@ -428,6 +429,19 @@ SEASTAR_THREAD_TEST_CASE(test_semaphore_abort_after_wait) {
     BOOST_REQUIRE_EQUAL(x, 0);
 }
 
+SEASTAR_THREAD_TEST_CASE(test_semaphore_abort_with_exception_after_wait) {
+    auto sem = semaphore(0);
+    abort_source as;
+    int x = 0;
+    auto fut1 = sem.wait(as).then([&x] {
+        x++;
+    });
+    as.request_abort_ex(expected_exception());
+    sem.signal();
+    BOOST_CHECK_THROW(fut1.get(), expected_exception);
+    BOOST_REQUIRE_EQUAL(x, 0);
+}
+
 SEASTAR_THREAD_TEST_CASE(test_semaphore_abort_before_wait) {
     auto sem = semaphore(0);
     abort_source as;