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This commit is contained in:
mutouyun 2018-11-23 21:58:49 +08:00
parent 3e7c97d9b6
commit ff0dbc8e2e
2 changed files with 27 additions and 13 deletions
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31
src/circ_elem_array.h
View File

@ -103,7 +103,7 @@ public:
void* acquire(void) { void* acquire(void) {
auto el = elem(wt_.fetch_add(1, std::memory_order_consume)); auto el = elem(wt_.fetch_add(1, std::memory_order_consume));
// check read flag // check read finished by all consumers
do { do {
uc_t expected = 0; uc_t expected = 0;
if (el->head_.rf_.compare_exchange_weak( if (el->head_.rf_.compare_exchange_weak(
@ -116,26 +116,39 @@ public:
} }
void commit(void* ptr) { void commit(void* ptr) {
auto el = elem(ptr); auto el = elem(ptr); // get the commit element
ui_t wt = index_of(el); ui_t cm = index_of(el); // get the index of this element
do { do {
bool no_next; bool no_next_check;
uc_t curr; uc_t curr;
do { do {
curr = cr_.load(std::memory_order_relaxed); curr = cr_.load(std::memory_order_relaxed);
no_next = (index_of(curr) != wt); no_next_check = (index_of(curr) != cm);
if (no_next) { if (no_next_check) {
/*
* set wf_ for the other producer thread which is commiting
* the element matches cr_ could see it has commited
*/
el->head_.wf_.store(1, std::memory_order_relaxed); el->head_.wf_.store(1, std::memory_order_relaxed);
} }
else { else {
/*
* no thread changes the cr_ except current thread at here
* so we could just fetch_add & break, no need to check cr_ again
*/
cr_.fetch_add(1, std::memory_order_relaxed); cr_.fetch_add(1, std::memory_order_relaxed);
el->head_.wf_.store(0, std::memory_order_release); el->head_.wf_.store(0, std::memory_order_release);
no_next = false; no_next_check = false;
break; break;
} }
/*
* it needs to go back and judge again
* when cr_ has been changed by the other producer thread
*/
} while(curr != cr_.load(std::memory_order_acq_rel)); } while(curr != cr_.load(std::memory_order_acq_rel));
if (no_next) return; // check next element has commited or not
} while(el = elem(++wt), el->head_.wf_.load(std::memory_order_consume)); if (no_next_check) return;
} while(el = elem(++cm), el->head_.wf_.load(std::memory_order_consume));
} }
uc_t cursor(void) const { uc_t cursor(void) const {

9
test/test_circ_elem_array.cpp
View File

@ -31,9 +31,9 @@ void Unit::test_inst(void) {
std::cout << "cq_t::elem_size = " << cq_t::elem_size << std::endl; std::cout << "cq_t::elem_size = " << cq_t::elem_size << std::endl;
std::cout << "cq_t::block_size = " << cq_t::block_size << std::endl; std::cout << "cq_t::block_size = " << cq_t::block_size << std::endl;
QCOMPARE(cq_t::data_size , 12); QCOMPARE(static_cast<std::size_t>(cq_t::data_size) , static_cast<std::size_t>(12));
QCOMPARE(cq_t::block_size, 4096); QCOMPARE(static_cast<std::size_t>(cq_t::block_size), static_cast<std::size_t>(4096));
QCOMPARE(sizeof(cq_t), cq_t::block_size + cq_t::head_size); QCOMPARE(sizeof(cq_t), static_cast<std::size_t>(cq_t::block_size + cq_t::head_size));
cq__ = new cq_t; cq__ = new cq_t;
std::cout << "sizeof(ipc::circ::elem_array<4096>) = " << sizeof(*cq__) << std::endl; std::cout << "sizeof(ipc::circ::elem_array<4096>) = " << sizeof(*cq__) << std::endl;
@ -50,7 +50,7 @@ void Unit::test_prod_cons_1vN(void) {
std::thread consumers[1]; std::thread consumers[1];
std::atomic_int fini { 0 }; std::atomic_int fini { 0 };
capo::stopwatch<> sw; capo::stopwatch<> sw;
constexpr static int loops = 1000000; constexpr static int loops = 10000000;
for (auto& c : consumers) { for (auto& c : consumers) {
c = std::thread{[&] { c = std::thread{[&] {
@ -78,6 +78,7 @@ void Unit::test_prod_cons_1vN(void) {
auto ts = sw.elapsed<std::chrono::microseconds>(); auto ts = sw.elapsed<std::chrono::microseconds>();
std::cout << "performance: " << (double(ts) / double(loops)) << " us/d" << std::endl; std::cout << "performance: " << (double(ts) / double(loops)) << " us/d" << std::endl;
} }
std::cout << "confirming..." << std::endl;
for (int d : list) { for (int d : list) {
QCOMPARE(i, d); QCOMPARE(i, d);
++i; ++i;