GH-1716 pop before execute as the executed lambda can switch to read-…

…only mode and spawn threads that access the queue.
AntelopeIO · Oct 4, 2023 · bb23fbe · bb23fbe
1 parent 18add6b
commit bb23fbe
Show file tree

Hide file tree

Showing 2 changed files with 6 additions and 4 deletions.
diff --git a/libraries/custom_appbase/include/eosio/chain/exec_pri_queue.hpp b/libraries/custom_appbase/include/eosio/chain/exec_pri_queue.hpp
@@ -106,8 +106,10 @@ class exec_pri_queue : public boost::asio::execution_context
       if (!lhs_que.empty() && (rhs_que.empty() || *rhs_que.top() < *lhs_que.top()))
          q = lhs;
       prio_queue& que = priority_que(q);
-      que.top()->execute();
-      que.pop();
+      assert(que.top());
+      // pop, then execute since read_write queue is used to switch to read window and the pop needs to happen before that lambda starts
+      auto t = pop(que);
+      t->execute();
       --size;
       return size > 0;
    }

diff --git a/libraries/custom_appbase/tests/custom_appbase_tests.cpp b/libraries/custom_appbase/tests/custom_appbase_tests.cpp
@@ -99,7 +99,7 @@ BOOST_AUTO_TEST_CASE( default_exec_window ) {
    app->executor().post( priority::lowest, exec_queue::read_only, [&]() {
       // read_only_queue should only contain the current lambda function,
       // and read_write_queue should have executed all its functions
-      BOOST_REQUIRE_EQUAL( app->executor().read_only_queue_size(), 1u); // pop()s after execute
+      BOOST_REQUIRE_EQUAL( app->executor().read_only_queue_size(), 0u); // pop()s before execute
       BOOST_REQUIRE_EQUAL( app->executor().read_exclusive_queue_size(), 0u );
       BOOST_REQUIRE_EQUAL( app->executor().read_write_queue_size(), 0u );
       app->quit();
@@ -239,7 +239,7 @@ BOOST_AUTO_TEST_CASE( execute_from_read_only_and_read_write_queues ) {
    // stop application. Use lowest at the end to make sure this executes the last
    app->executor().post( priority::lowest, exec_queue::read_only, [&]() {
       // read_queue should have current function and write_queue's functions are all executed 
-      BOOST_REQUIRE_EQUAL( app->executor().read_only_queue_size(), 1u); // pop()s after execute
+      BOOST_REQUIRE_EQUAL( app->executor().read_only_queue_size(), 0u); // pop()s before execute
       BOOST_REQUIRE_EQUAL( app->executor().read_exclusive_queue_size(), 0u);
       BOOST_REQUIRE_EQUAL( app->executor().read_write_queue_size(), 0u );
       app->quit();