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Fixed issue #546 by adding an "is_empty" method to the queue instead of the buggy approx_size

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This commit is contained in:
gabime
2017-11-05 00:21:00 +02:00
parent 6fd5f3c866
commit f5fe681a41
2 changed files with 102 additions and 106 deletions
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2
include/spdlog/details/async_log_helper.h
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@@ -384,7 +384,7 @@ inline void spdlog::details::async_log_helper::sleep_or_yield(const spdlog::log_
inline void spdlog::details::async_log_helper::wait_empty_q() inline void spdlog::details::async_log_helper::wait_empty_q()
{ {
auto last_op = details::os::now(); auto last_op = details::os::now();
while (_q.approx_size() > 0) while (!_q.is_empty())
{ {
sleep_or_yield(details::os::now(), last_op); sleep_or_yield(details::os::now(), last_op);
} }

60
include/spdlog/details/mpmc_bounded_q.h
View File

@@ -50,22 +50,22 @@ Distributed under the MIT License (http://opensource.org/licenses/MIT)
namespace spdlog namespace spdlog
{ {
namespace details namespace details
{ {
template<typename T> template<typename T>
class mpmc_bounded_queue class mpmc_bounded_queue
{ {
public: public:
using item_type = T; using item_type = T;
mpmc_bounded_queue(size_t buffer_size) mpmc_bounded_queue(size_t buffer_size)
:max_size_(buffer_size), :max_size_(buffer_size),
buffer_(new cell_t [buffer_size]), buffer_(new cell_t[buffer_size]),
buffer_mask_(buffer_size - 1) buffer_mask_(buffer_size - 1)
{ {
//queue size must be power of two //queue size must be power of two
if(!((buffer_size >= 2) && ((buffer_size & (buffer_size - 1)) == 0))) if (!((buffer_size >= 2) && ((buffer_size & (buffer_size - 1)) == 0)))
throw spdlog_ex("async logger queue size must be power of two"); throw spdlog_ex("async logger queue size must be power of two");
for (size_t i = 0; i != buffer_size; i += 1) for (size_t i = 0; i != buffer_size; i += 1)
@@ -76,7 +76,7 @@ public:
~mpmc_bounded_queue() ~mpmc_bounded_queue()
{ {
delete [] buffer_; delete[] buffer_;
} }
@@ -84,22 +84,18 @@ public:
{ {
cell_t* cell; cell_t* cell;
size_t pos = enqueue_pos_.load(std::memory_order_relaxed); size_t pos = enqueue_pos_.load(std::memory_order_relaxed);
for (;;) for (;;) {
{
cell = &buffer_[pos & buffer_mask_]; cell = &buffer_[pos & buffer_mask_];
size_t seq = cell->sequence_.load(std::memory_order_acquire); size_t seq = cell->sequence_.load(std::memory_order_acquire);
intptr_t dif = static_cast<intptr_t>(seq) - static_cast<intptr_t>(pos); intptr_t dif = static_cast<intptr_t>(seq) - static_cast<intptr_t>(pos);
if (dif == 0) if (dif == 0) {
{
if (enqueue_pos_.compare_exchange_weak(pos, pos + 1, std::memory_order_relaxed)) if (enqueue_pos_.compare_exchange_weak(pos, pos + 1, std::memory_order_relaxed))
break; break;
} }
else if (dif < 0) else if (dif < 0) {
{
return false; return false;
} }
else else {
{
pos = enqueue_pos_.load(std::memory_order_relaxed); pos = enqueue_pos_.load(std::memory_order_relaxed);
} }
} }
@@ -112,14 +108,12 @@ public:
{ {
cell_t* cell; cell_t* cell;
size_t pos = dequeue_pos_.load(std::memory_order_relaxed); size_t pos = dequeue_pos_.load(std::memory_order_relaxed);
for (;;) for (;;) {
{
cell = &buffer_[pos & buffer_mask_]; cell = &buffer_[pos & buffer_mask_];
size_t seq = size_t seq =
cell->sequence_.load(std::memory_order_acquire); cell->sequence_.load(std::memory_order_acquire);
intptr_t dif = static_cast<intptr_t>(seq) - static_cast<intptr_t>(pos + 1); intptr_t dif = static_cast<intptr_t>(seq) - static_cast<intptr_t>(pos + 1);
if (dif == 0) if (dif == 0) {
{
if (dequeue_pos_.compare_exchange_weak(pos, pos + 1, std::memory_order_relaxed)) if (dequeue_pos_.compare_exchange_weak(pos, pos + 1, std::memory_order_relaxed))
break; break;
} }
@@ -133,17 +127,19 @@ public:
return true; return true;
} }
size_t approx_size() bool is_empty()
{ {
size_t first_pos = dequeue_pos_.load(std::memory_order_relaxed); unsigned front, front1, back;
size_t last_pos = enqueue_pos_.load(std::memory_order_relaxed); // try to take a consistent snapshot of front/tail.
if (last_pos <= first_pos) do {
return 0; front = enqueue_pos_.load(std::memory_order_acquire);
auto size = last_pos - first_pos; back = dequeue_pos_.load(std::memory_order_acquire);
return size < max_size_ ? size : max_size_; front1 = enqueue_pos_.load(std::memory_order_relaxed);
} while (front != front1);
return back == front;
} }
private: private:
struct cell_t struct cell_t
{ {
std::atomic<size_t> sequence_; std::atomic<size_t> sequence_;
@@ -153,7 +149,7 @@ private:
size_t const max_size_; size_t const max_size_;
static size_t const cacheline_size = 64; static size_t const cacheline_size = 64;
typedef char cacheline_pad_t [cacheline_size]; typedef char cacheline_pad_t[cacheline_size];
cacheline_pad_t pad0_; cacheline_pad_t pad0_;
cell_t* const buffer_; cell_t* const buffer_;
@@ -166,7 +162,7 @@ private:
mpmc_bounded_queue(mpmc_bounded_queue const&) = delete; mpmc_bounded_queue(mpmc_bounded_queue const&) = delete;
void operator= (mpmc_bounded_queue const&) = delete; void operator= (mpmc_bounded_queue const&) = delete;
}; };
} // ns details } // ns details
} // ns spdlog } // ns spdlog