Ichthyostega
d879ae7fbd
... which became apparent after switching to the new Thread-wrapper implementation ... the reason is a bug in the Thread-Monitor (which will also be reworked soon)
146 lines
5.1 KiB
C++
146 lines
5.1 KiB
C++
/*
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SyncBarrier(Test) - verify yield-waiting synchronisation latch
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Copyright (C) Lumiera.org
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2023, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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* *****************************************************/
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/** @file sync-barrier-test.cpp
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** unit test \ref SyncBarrier_test
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*/
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#include "lib/test/run.hpp"
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#include "lib/sync-barrier.hpp"
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#include "lib/iter-explorer.hpp"
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#include "lib/util-foreach.hpp"
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#include <chrono>
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#include <thread>
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#include <atomic>
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#include <array>
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using test::Test;
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using util::and_all;
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using lib::explore;
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using std::array;
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using std::atomic_uint;
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using std::this_thread::sleep_for;
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using namespace std::chrono_literals;
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namespace lib {
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namespace test {
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namespace {// Test setup for a concurrent calculation with checksum....
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const uint NUM_THREADS = 256;
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atomic_uint stage1{0};
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atomic_uint stage2{0};
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atomic_uint finish{0};
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SyncBarrier interThread{NUM_THREADS };
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SyncBarrier afterThread{NUM_THREADS+1};
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/**
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* A test thread to perform a summation protocol including synchronisation points
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* - build a compound sum of random numbers in the first stage
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* - wait for the compound sum to build up completely
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* - book in the compound sum plus a further random number
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*/
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class TestThread
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: std::thread ////////////////////////////////////////////////////////////////////OOO TOD-oh
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{
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public:
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TestThread()
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: thread{[&]()
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{ //-STAGE-1------------------------------
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localSum = rand() % 1000; // generate local value
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stage1.fetch_add (localSum); // book in local value
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interThread.sync(); // wait for all other threads to have booked in
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//-STAGE-2------------------------------
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uint sync = stage1; // pick up compounded sum from STAGE-1
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localSum += rand() % 1000; // add further local value for STAGE-2
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stage2.fetch_add (localSum+sync); // book in both local values and synced sum
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afterThread.sync(); // wait for other threads and supervisor
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finish.fetch_add(1); // mark completion of this thread
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thread::detach(); //////////////////////////////////////////////OOO Wech-oh
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}}
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{ }
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uint localSum; // *deliberately* not initialised to avoid race
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bool isRunning() const { return thread::joinable(); } ///////////////////////OOO Wack-oh
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};
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/** sum up all `localSum` fields from all TestThread instances in a container */
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template<class CON>
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uint
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sumLocals (CON const& threads)
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{
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return explore (threads)
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.reduce ([&](TestThread const& t){ return t.localSum; });
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}
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}//(End)Test setup
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/*******************************************************************//**
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* @test verify N-fold synchronisation points by multi-thread loat-test.
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* - start a _huge number_ of TestThread
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* - all those pick up the partial sum from stage1
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* @remark without coordinated synchronisation, some threads would see
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* an incomplete sum and thus the stage2 checksum would be lower
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* @see lib::SyncBarrier
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* @see steam::control::DispatcherLoop
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*/
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class SyncBarrier_test : public Test
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{
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virtual void
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run (Arg)
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{
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array<TestThread,NUM_THREADS> threads;
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CHECK (0 == finish);
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CHECK (and_all (threads, [](auto& t){ return t.isRunning(); }));
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afterThread.sync();
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sleep_for (5ms); // give the threads a chance to terminate
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CHECK (NUM_THREADS == finish); // all threads have passed out....
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CHECK (0 < stage1);
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CHECK (stage1 < stage2);
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CHECK (stage2 > sumLocals(threads));
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CHECK (stage2 == sumLocals(threads) + NUM_THREADS*stage1); // this holds only if all threads waited to get the complete stage1 sum
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}
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};
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/** Register this test class... */
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LAUNCHER (SyncBarrier_test, "function common");
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}} // namespace lib::test
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