Ichthyostega
a20e233ca0
After augmenting our `lib/random.hpp` abstraction framework to add the necessary flexibility, a common seeding scheme was ''built into the Test-Runner.'' * all tests relying on some kind of randomness should invoke `seedRand()` * this draws a seed from the `entropyGen` — which is also documented in the log * individual tests can now be launched with `--seed` to force a dedicated seed * moreover, tests should build a coherent structure of linked generators, especially when running concurrently. The existing tests were adapted accordingly All usages of `rand()` in the code base were investigated and replaced by suitable calls to our abstraction framework; the code base is thus isolated from the actual implementation, simplifying further adaptation.
146 lines
4.9 KiB
C++
146 lines
4.9 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/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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