scheduling_group: improve scheduling group creation exception safety #2617
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mlitvk
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The CI fails in Seastar.unit.rpc with timeout |
| @@ -37,17 +37,66 @@ namespace seastar { | |||
| namespace internal { | |||
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| struct scheduling_group_specific_thread_local_data { | |||
| using val_ptr = std::unique_ptr<void, void (*)(void*) noexcept>; | |||
| using cfg_ptr = std::shared_ptr<scheduling_group_key_config>; | |||
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Can it be seastar::lw_shared_ptr<scheduling_group_key_config>?
| @@ -37,17 +37,66 @@ namespace seastar { | |||
| namespace internal { | |||
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| struct scheduling_group_specific_thread_local_data { | |||
| using val_ptr = std::unique_ptr<void, void (*)(void*) noexcept>; | |||
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What's the point in making it smart-pointer if you track construction/destruction by hand anyway?
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The point is to manage the dynamic memory allocation and free it automatically
| inline auto& get_sg_data(unsigned sg_id) { | ||
| return _scheduling_group_specific_data.per_scheduling_group_data[sg_id]; | ||
| } | ||
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There's no need in those helpers, AFAICS, the existing get_scheduling_group_specific_thread_local_data() (and Co) already provide access to the array of per_scheduling_group_data-s
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I added it because in several places we access the sg data and we do
auto& sg_data = _scheduling_group_specific_data;
auto& this_sg = sg_data.per_scheduling_group_data[sg._id];
which I thought is a little cumbersome and I didn't find another method for this
| @@ -393,7 +401,6 @@ private: | |||
| task_queue* pop_active_task_queue(sched_clock::time_point now); | |||
| void insert_activating_task_queues(); | |||
| void account_runtime(task_queue& tq, sched_clock::duration runtime); | |||
| void allocate_scheduling_group_specific_data(scheduling_group sg, unsigned long key_id); | |||
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I'd appreciate if the change "Move allocate_scheduling_group_specific_data() from reactor class to internal namespace" was made as separate preparational patch (in the same PR)
Move the function allocate_scheduling_group_specific_data from reactor class to an internal static function. Change it to handle only the allocation and construction of the data object, while the caller handles the assignment of it.
Improve handling of exceptions during scheduling group and scheduling group key creation, where a user-provided constructor for the keys may fail, for example. We use a new struct `specific_val` and smart pointers to manage memory allocation, construction and destruction of scheduling group data in a safe manner. We also reorder the initialization order to make it safer. For example, when creating a scheduling group, first allocate all data and then swap it into the scheduling group's data structure. Fixes scylladb#2222
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Improve handling of exceptions during scheduling group and scheduling group key creation, where a user-provided constructor for the keys may fail, for example.
We use a new struct
specific_valand smart pointers to manage memory allocation, construction and destruction of scheduling group data in a safe manner.We also reorder the initialization order to make it safer. For example, when creating a scheduling group, first allocate all data and then swap it into the scheduling group's data structure.
Fixes #2222