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Add source location to task and tasktrace object #2707

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Add source location to task and tasktrace object #2707

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83e8292
Add a std::source_location (resume_point) to task object.
Mar 31, 2025
706bd36
Add calls to update resume_point
Mar 31, 2025
08d3c8a
Update backtrace with source locations of resume points
Mar 31, 2025
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5 changes: 5 additions & 0 deletions include/seastar/core/task.hh
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@

#ifndef SEASTAR_MODULE
#include <utility>
#include <source_location>
#endif

namespace seastar {
Expand All @@ -35,6 +36,8 @@ class task {
protected:
scheduling_group _sg;
private:
std::source_location resume_point = {};

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This is making a very heavily used object larger.

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After adding std::source_location

coroutine_traits_base<>::promise_type (which inherits from task) is 64 bytes,
continuation<Promise, Func, Wrapper, T> is around 104-120, depending on exact version.

No difference except for that single unlucky value, who is "promoted" to the next 64 byte cache line in case of continuation.

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I think it's okay.

#ifdef SEASTAR_TASK_BACKTRACE
shared_backtrace _bt;
#endif
Expand All @@ -53,6 +56,8 @@ public:
virtual void run_and_dispose() noexcept = 0;
/// Returns the next task which is waiting for this task to complete execution, or nullptr.
virtual task* waiting_task() noexcept = 0;
void update_resume_point(std::source_location sl) { resume_point = sl; }
auto get_resume_point() const { return resume_point; }
scheduling_group group() const { return _sg; }
shared_backtrace get_backtrace() const;
#ifdef SEASTAR_TASK_BACKTRACE
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