Adding example for multitiered cache

Author: vinser52

examples/multitier_cache/CMakeLists.txt

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+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# 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.
+
+cmake_minimum_required (VERSION 3.12)
+
+project (cachelib-cmake-test-project VERSION 0.1)
+
+find_package(cachelib CONFIG REQUIRED)
+
+add_executable(multitier-cache-example main.cpp)
+
+target_link_libraries(multitier-cache-example cachelib)

examples/multitier_cache/build.sh

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+#!/bin/sh
+
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# 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.
+
+set -e
+
+# Root directory for the CacheLib project
+CLBASE="$PWD/../.."
+
+# Additional "FindXXX.cmake" files are here (e.g. FindSodium.cmake)
+CLCMAKE="$CLBASE/cachelib/cmake"
+
+# After ensuring we are in the correct directory, set the installation prefix"
+PREFIX="$CLBASE/opt/cachelib/"
+
+CMAKE_PARAMS="-DCMAKE_INSTALL_PREFIX='$PREFIX' -DCMAKE_MODULE_PATH='$CLCMAKE'"
+
+CMAKE_PREFIX_PATH="$PREFIX/lib/cmake:$PREFIX/lib64/cmake:$PREFIX/lib:$PREFIX/lib64:$PREFIX:${CMAKE_PREFIX_PATH:-}"
+export CMAKE_PREFIX_PATH
+PKG_CONFIG_PATH="$PREFIX/lib/pkgconfig:$PREFIX/lib64/pkgconfig:${PKG_CONFIG_PATH:-}"
+export PKG_CONFIG_PATH
+LD_LIBRARY_PATH="$PREFIX/lib:$PREFIX/lib64:${LD_LIBRARY_PATH:-}"
+export LD_LIBRARY_PATH
+
+mkdir -p build
+cd build
+cmake $CMAKE_PARAMS ..
+make

examples/multitier_cache/main.cpp

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+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * 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.
+ */
+
+#include "cachelib/allocator/CacheAllocator.h"
+#include "cachelib/allocator/MemoryTierCacheConfig.h"
+#include "folly/init/Init.h"
+
+namespace facebook {
+namespace cachelib_examples {
+using Cache = cachelib::LruAllocator; // or Lru2QAllocator, or TinyLFUAllocator
+using CacheConfig = typename Cache::Config;
+using CacheKey = typename Cache::Key;
+using CacheItemHandle = typename Cache::ItemHandle;
+using MemoryTierCacheConfig = typename cachelib::MemoryTierCacheConfig;
+
+// Global cache object and a default cache pool
+std::unique_ptr<Cache> gCache_;
+cachelib::PoolId defaultPool_;
+
+void initializeCache() {
+  CacheConfig config;
+  config
+      .setCacheSize(48 * 1024 * 1024) // 48 MB
+      .setCacheName("MultiTier Cache")
+      .enableCachePersistence("/tmp")
+      .setAccessConfig(
+          {25 /* bucket power */, 10 /* lock power */}) // assuming caching 20
+                                                        // million items
+      .configureMemoryTiers({
+		      MemoryTierCacheConfig::fromShm().setRatio(1),
+		      MemoryTierCacheConfig::fromFile("/tmp/file1").setRatio(2)})
+      .validate(); // will throw if bad config
+  gCache_ = std::make_unique<Cache>(Cache::SharedMemNew, config);
+  defaultPool_ =
+      gCache_->addPool("default", gCache_->getCacheMemoryStats().cacheSize);
+}
+
+void destroyCache() { gCache_.reset(); }
+
+CacheItemHandle get(CacheKey key) { return gCache_->find(key); }
+
+bool put(CacheKey key, const std::string& value) {
+  auto handle = gCache_->allocate(defaultPool_, key, value.size());
+  if (!handle) {
+    return false; // cache may fail to evict due to too many pending writes
+  }
+  std::memcpy(handle->getWritableMemory(), value.data(), value.size());
+  gCache_->insertOrReplace(handle);
+  return true;
+}
+} // namespace cachelib_examples
+} // namespace facebook
+
+using namespace facebook::cachelib_examples;
+
+int main(int argc, char** argv) {
+  folly::init(&argc, &argv);
+
+  initializeCache();
+
+  std::string value(4*1024, 'X'); // 4 KB value
+  const size_t NUM_ITEMS = 13000;
+
+  // Use cache
+  {
+    for(size_t i = 0; i < NUM_ITEMS; ++i) {
+	std::string key = "key" + std::to_string(i);
+    	auto res = put(key, value);
+
+        std::ignore = res;
+        assert(res);
+    }
+
+    size_t nFound = 0;
+    size_t nNotFound = 0;
+    for(size_t i = 0; i < NUM_ITEMS; ++i) {
+        std::string key = "key" + std::to_string(i);
+        auto item = get(key);
+        if(item) {
+            ++nFound;
+            folly::StringPiece sp{reinterpret_cast<const char*>(item->getMemory()),
+                                  item->getSize()};
+            std::ignore = sp;
+            assert(sp == value);
+        } else {
+            ++nNotFound;
+	}
+    }
+    std::cout << "Found:\t\t" << nFound << " items\n"
+              << "Not found:\t" << nNotFound << " items" << std::endl;
+  }
+
+  destroyCache();
+}