Disallow zero-size stream pools (#873)

An exception is now thrown when zero is passed as the size parameter to the `cuda_stream_pool` constructor. Also adds a test for this exception.

Fixes #871

Authors:
  - Mark Harris (https://github.com/harrism)

Approvers:
  - Jake Hemstad (https://github.com/jrhemstad)
  - Rong Ou (https://github.com/rongou)

URL: #873

include/rmm/cuda_stream_pool.hpp

@@ -39,11 +39,15 @@ class cuda_stream_pool {
   static constexpr std::size_t default_size{16};  ///< Default stream pool size
 
   /**
-   * @brief Construct a new cuda stream pool object of the given size
+   * @brief Construct a new cuda stream pool object of the given non-zero size
    *
+   * @throws logic_error if `pool_size` is zero
    * @param pool_size The number of streams in the pool
    */
-  explicit cuda_stream_pool(std::size_t pool_size = default_size) : streams_(pool_size) {}
+  explicit cuda_stream_pool(std::size_t pool_size = default_size) : streams_(pool_size)
+  {
+    RMM_EXPECTS(pool_size > 0, "Stream pool size must be greater than zero");
+  }
   ~cuda_stream_pool() = default;
 
   cuda_stream_pool(cuda_stream_pool&&)      = delete;

tests/cuda_stream_pool_tests.cpp

@@ -26,6 +26,11 @@ struct CudaStreamPoolTest : public ::testing::Test {
   rmm::cuda_stream_pool pool{};
 };
 
+TEST_F(CudaStreamPoolTest, ZeroSizePoolException)
+{
+  EXPECT_THROW(rmm::cuda_stream_pool pool{0}, rmm::logic_error);
+}
+
 TEST_F(CudaStreamPoolTest, Unequal)
 {
   auto const stream_a = this->pool.get_stream();