Ichthyostega
806db414dd
* Lumiera source code always was copyrighted by individual contributors * there is no entity "Lumiera.org" which holds any copyrights * Lumiera source code is provided under the GPL Version 2+ == Explanations == Lumiera as a whole is distributed under Copyleft, GNU General Public License Version 2 or above. For this to become legally effective, the ''File COPYING in the root directory is sufficient.'' The licensing header in each file is not strictly necessary, yet considered good practice; attaching a licence notice increases the likeliness that this information is retained in case someone extracts individual code files. However, it is not by the presence of some text, that legally binding licensing terms become effective; rather the fact matters that a given piece of code was provably copyrighted and published under a license. Even reformatting the code, renaming some variables or deleting parts of the code will not alter this legal situation, but rather creates a derivative work, which is likewise covered by the GPL! The most relevant information in the file header is the notice regarding the time of the first individual copyright claim. By virtue of this initial copyright, the first author is entitled to choose the terms of licensing. All further modifications are permitted and covered by the License. The specific wording or format of the copyright header is not legally relevant, as long as the intention to publish under the GPL remains clear. The extended wording was based on a recommendation by the FSF. It can be shortened, because the full terms of the license are provided alongside the distribution, in the file COPYING.
137 lines
4.5 KiB
C++
137 lines
4.5 KiB
C++
/*
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SyncBarrier(Test) - verify yield-waiting synchronisation latch
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Copyright (C)
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2023, Hermann Vosseler <Ichthyostega@web.de>
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**Lumiera** is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2 of the License, or (at your
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option) any later version. See the file COPYING for further details.
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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/thread.hpp"
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#include <chrono>
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#include <atomic>
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#include <array>
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using test::Test;
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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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: public lib::Thread
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{
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public:
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TestThread()
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: Thread{"Load Test"
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,[&, ran=lib::Random{seedFromDefaultGen()}]
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() mutable
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{ //-STAGE-1------------------------------
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localSum = ran.i(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 += ran.i(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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}}
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{ }
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uint localSum; // *deliberately* not initialised to avoid race
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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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seedRand();
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// Launch several TestThread
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array<TestThread,NUM_THREADS> threads;
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CHECK (0 == finish);
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CHECK (explore(threads).and_all());
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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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