Refactor thread filter mechanisms #209
thread filter - refactor recording implementation
remove the usage of the thread filter in the recording
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,114 +1,104 @@ | ||
| // Copyright (C) Datadog 2025 | ||
| // Implementation of thread filter management | ||
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| #include "threadFilter.h" | ||
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| #include <cstdlib> | ||
| #include <thread> | ||
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| ThreadFilter::ThreadFilter() | ||
| : _next_index(0), _enabled(false) { | ||
| std::unique_lock<std::mutex> lock(_slot_mutex); | ||
| _slots.emplace_back(); // Allocate first chunk | ||
| clear(); | ||
| } | ||
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| ThreadFilter::~ThreadFilter() { | ||
| std::unique_lock<std::mutex> lock(_slot_mutex); | ||
| _slots.clear(); | ||
| } | ||
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Comment on lines
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Collaborator
There was a problem hiding this comment. This looks good. Have you experimented with a custom stride or thread-local random starting offset to improve the contended situation? Basically, to prevent all contending threads starting at 0 and then competing for all subsequent slots until everyone is satisfied - forcing the most unlucky thread to do N checks, N being the number of competing threads. |
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| ThreadFilter::SlotID ThreadFilter::registerThread() { | ||
| SlotID index = _next_index.fetch_add(1, std::memory_order_relaxed); | ||
| if (index >= kMaxThreads) { | ||
| return -1; | ||
| } | ||
| const int outer_idx = index >> kChunkShift; | ||
| { | ||
| if (outer_idx < static_cast<int>(_slots.size())) { | ||
| return index; | ||
| } | ||
| } | ||
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| { | ||
| std::unique_lock<std::mutex> write_lock(_slot_mutex); | ||
| while (outer_idx >= static_cast<int>(_slots.size())) { | ||
| _slots.emplace_back(); | ||
| } | ||
| } | ||
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| return index; | ||
| } | ||
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| void ThreadFilter::clear() { | ||
| for (auto& chunk : _slots) { | ||
| for (auto& slot : chunk) { | ||
| slot.value.store(-1, std::memory_order_relaxed); | ||
| } | ||
| } | ||
| } | ||
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| bool ThreadFilter::accept(SlotID slot_id) const { | ||
| if (!_enabled) { | ||
| return true; | ||
| } | ||
| if (slot_id < 0) return false; | ||
| int outer_idx = slot_id >> kChunkShift; | ||
| int inner_idx = slot_id & kChunkMask; | ||
| if (outer_idx >= static_cast<int>(_slots.size())) return false; | ||
| return _slots[outer_idx][inner_idx].value.load(std::memory_order_acquire) != -1; | ||
| } | ||
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| void ThreadFilter::add(int tid, SlotID slot_id) { | ||
| int outer_idx = slot_id >> kChunkShift; | ||
| int inner_idx = slot_id & kChunkMask; | ||
| _slots[outer_idx][inner_idx].value.store(tid, std::memory_order_relaxed); | ||
| } | ||
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| void ThreadFilter::remove(SlotID slot_id) { | ||
| int outer_idx = slot_id >> kChunkShift; | ||
| int inner_idx = slot_id & kChunkMask; | ||
| _slots[outer_idx][inner_idx].value.store(-1, std::memory_order_relaxed); | ||
| } | ||
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| void ThreadFilter::unregisterThread(SlotID slot_id) { | ||
| if (slot_id < 0) return; | ||
| int outer_idx = slot_id >> kChunkShift; | ||
| int inner_idx = slot_id & kChunkMask; | ||
| _slots[outer_idx][inner_idx].value.store(-1, std::memory_order_relaxed); | ||
| } | ||
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| void ThreadFilter::collect(std::vector<int>& tids) const { | ||
| tids.clear(); | ||
| // std::unique_lock<std::mutex> lock(_slot_mutex); | ||
| for (const auto& chunk : _slots) { | ||
| for (const auto& slot : chunk) { | ||
| int slot_tid = slot.value.load(std::memory_order_acquire); | ||
| if (slot_tid != -1) { | ||
| tids.push_back(slot_tid); | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| void ThreadFilter::init(const char* filter) { | ||
| if (!filter) { | ||
| return; | ||
| } | ||
| // TODO: Implement parsing of filter string if needed | ||
| _enabled = true; | ||
| } | ||
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| bool ThreadFilter::enabled() const { | ||
| return _enabled; | ||
| } | ||
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Is it ok to remove this call? We should make sure that the recording thread is also included as events can be associated with it - recording info, settings, config - all point to _tid thread.
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I think I do (with the
threads.insert(_tid);)I had to move it down a few lines.