fake_parallel_runner_testonly.h (2597B)
1 // Copyright (c) the JPEG XL Project Authors. All rights reserved. 2 // 3 // Use of this source code is governed by a BSD-style 4 // license that can be found in the LICENSE file. 5 6 #ifndef LIB_JXL_FAKE_PARALLEL_RUNNER_TESTONLY_H_ 7 #define LIB_JXL_FAKE_PARALLEL_RUNNER_TESTONLY_H_ 8 9 #include <jxl/parallel_runner.h> 10 11 #include <cstdint> 12 #include <vector> 13 14 #include "lib/jxl/base/compiler_specific.h" 15 #include "lib/jxl/base/random.h" 16 17 namespace jxl { 18 19 // A parallel runner implementation that runs all the jobs in a single thread 20 // (the caller thread) but runs them pretending to use multiple threads and 21 // potentially out of order. This is useful for testing conditions that only 22 // occur under heavy load where the order of operations is different. 23 class FakeParallelRunner { 24 public: 25 FakeParallelRunner(uint32_t order_seed, uint32_t num_threads) 26 : order_seed_(order_seed), rng_(order_seed), num_threads_(num_threads) { 27 if (num_threads_ < 1) num_threads_ = 1; 28 } 29 30 JxlParallelRetCode Run(void* jxl_opaque, JxlParallelRunInit init, 31 JxlParallelRunFunction func, uint32_t start, 32 uint32_t end) { 33 JxlParallelRetCode ret = init(jxl_opaque, num_threads_); 34 if (ret != 0) return ret; 35 36 if (order_seed_ == 0) { 37 for (uint32_t i = start; i < end; i++) { 38 func(jxl_opaque, i, i % num_threads_); 39 } 40 } else { 41 std::vector<uint32_t> order(end - start); 42 for (uint32_t i = start; i < end; i++) { 43 order[i - start] = i; 44 } 45 rng_.Shuffle(order.data(), order.size()); 46 for (uint32_t i = start; i < end; i++) { 47 func(jxl_opaque, order[i - start], i % num_threads_); 48 } 49 } 50 return ret; 51 } 52 53 private: 54 // Seed for the RNG for defining the execution order. A value of 0 means 55 // sequential order from start to end. 56 uint32_t order_seed_; 57 58 // The PRNG object, initialized with the order_seed_. Only used if the seed is 59 // not 0. 60 Rng rng_; 61 62 // Number of fake threads. All the tasks are run on the same thread, but using 63 // different thread_id values based on this num_threads. 64 uint32_t num_threads_; 65 }; 66 67 } // namespace jxl 68 69 extern "C" { 70 // Function to pass as the parallel runner. 71 JXL_INLINE JxlParallelRetCode JxlFakeParallelRunner( 72 void* runner_opaque, void* jpegxl_opaque, JxlParallelRunInit init, 73 JxlParallelRunFunction func, uint32_t start_range, uint32_t end_range) { 74 return static_cast<jxl::FakeParallelRunner*>(runner_opaque) 75 ->Run(jpegxl_opaque, init, func, start_range, end_range); 76 } 77 } 78 79 #endif // LIB_JXL_FAKE_PARALLEL_RUNNER_TESTONLY_H_