1 files changed, 127 insertions, 0 deletions
diff --git a/src/seastar/tests/unit/slab_test.cc b/src/seastar/tests/unit/slab_test.cc
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+++ b/src/seastar/tests/unit/slab_test.cc
@@ -0,0 +1,127 @@
+/*
+ * This file is open source software, licensed to you under the terms
+ * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership.  You may not use this file except in compliance with the License.
+ *
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+/*
+ * Copyright (C) 2015 Cloudius Systems, Ltd.
+ *
+ * To compile: g++ -std=c++14 slab_test.cc
+ */
+
+#include <iostream>
+#include <assert.h>
+#include <seastar/core/slab.hh>
+
+using namespace seastar;
+
+namespace bi = boost::intrusive;
+
+static constexpr size_t max_object_size = 1024*1024;
+
+class item : public slab_item_base {
+public:
+    bi::list_member_hook<> _cache_link;
+    uint32_t _slab_page_index;
+
+    item(uint32_t slab_page_index) : _slab_page_index(slab_page_index) {}
+
+    const uint32_t get_slab_page_index() {
+        return _slab_page_index;
+    }
+    const bool is_unlocked() {
+        return true;
+    }
+};
+
+template<typename Item>
+static void free_vector(slab_allocator<Item>& slab, std::vector<item *>& items) {
+    for (auto item : items) {
+        slab.free(item);
+    }
+}
+
+static void test_allocation_1(const double growth_factor, const unsigned slab_limit_size) {
+    slab_allocator<item> slab(growth_factor, slab_limit_size, max_object_size);
+    size_t size = max_object_size;
+
+    slab.print_slab_classes();
+
+    std::vector<item *> items;
+
+    assert(slab_limit_size % size == 0);
+    for (auto i = 0u; i < (slab_limit_size / size); i++) {
+        auto item = slab.create(size);
+        items.push_back(item);
+    }
+    assert(slab.create(size) == nullptr);
+
+    free_vector<item>(slab, items);
+    std::cout << __FUNCTION__ << " done!\n";
+}
+
+static void test_allocation_2(const double growth_factor, const unsigned slab_limit_size) {
+    slab_allocator<item> slab(growth_factor, slab_limit_size, max_object_size);
+    size_t size = 1024;
+
+    std::vector<item *> items;
+
+    auto allocations = 0u;
+    for (;;) {
+        auto item = slab.create(size);
+        if (!item) {
+            break;
+        }
+        items.push_back(item);
+        allocations++;
+    }
+
+    auto class_size = slab.class_size(size);
+    auto per_slab_page = max_object_size / class_size;
+    auto available_slab_pages = slab_limit_size / max_object_size;
+    assert(allocations == (per_slab_page * available_slab_pages));
+
+    free_vector<item>(slab, items);
+    std::cout << __FUNCTION__ << " done!\n";
+}
+
+static void test_allocation_with_lru(const double growth_factor, const unsigned slab_limit_size) {
+    bi::list<item, bi::member_hook<item, bi::list_member_hook<>, &item::_cache_link>> _cache;
+    unsigned evictions = 0;
+
+    slab_allocator<item> slab(growth_factor, slab_limit_size, max_object_size,
+        [&](item& item_ref) { _cache.erase(_cache.iterator_to(item_ref)); evictions++; });
+    size_t size = max_object_size;
+
+    auto max = slab_limit_size / max_object_size;
+    for (auto i = 0u; i < max * 1000; i++) {
+        auto item = slab.create(size);
+        assert(item != nullptr);
+        _cache.push_front(*item);
+    }
+    assert(evictions == max * 999);
+
+    _cache.clear();
+
+    std::cout << __FUNCTION__ << " done!\n";
+}
+
+int main(int ac, char** av) {
+    test_allocation_1(1.25, 5*1024*1024);
+    test_allocation_2(1.07, 5*1024*1024); // 1.07 is the growth factor used by facebook.
+    test_allocation_with_lru(1.25, 5*1024*1024);
+
+    return 0;
+}