cachelib/allocator/nvmcache/NavySetup.cpp

/*
 * 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/nvmcache/NavySetup.h"

#include <folly/File.h>
#include <folly/logging/xlog.h>

#include "cachelib/allocator/nvmcache/NavyConfig.h"
#include "cachelib/navy/Factory.h"
#include "cachelib/navy/scheduler/JobScheduler.h"

namespace facebook {
namespace cachelib {

namespace {

// Default value for (almost) 1TB flash device = 5GB reserved for metadata
constexpr double kDefaultMetadataPercent = 0.5;
uint64_t megabytesToBytes(uint64_t mb) { return mb << 20; }

// Return a number that's equal or smaller than @num and aligned on @alignment
uint64_t alignDown(uint64_t num, uint64_t alignment) {
  return num - num % alignment;
}

// Return a number that's equal or bigger than @num and aligned on @alignment
uint64_t alignUp(uint64_t num, uint64_t alignment) {
  return alignDown(num + alignment - 1, alignment);
}

uint64_t setupBigHash(const navy::BigHashConfig& bigHashConfig,
                      uint32_t ioAlignSize,
                      uint64_t totalCacheSize,
                      uint64_t metadataSize,
                      cachelib::navy::CacheProto& proto) {
  auto bucketSize = bigHashConfig.getBucketSize();
  if (bucketSize != alignUp(bucketSize, ioAlignSize)) {
    throw std::invalid_argument(
        folly::sformat("Bucket size: {} is not aligned to ioAlignSize: {}",
                       bucketSize, ioAlignSize));
  }

  // If enabled, BigHash's storage starts after BlockCache's.
  const auto sizeReservedForBigHash =
      totalCacheSize * bigHashConfig.getSizePct() / 100ul;

  const uint64_t bigHashCacheOffset =
      alignUp(totalCacheSize - sizeReservedForBigHash, bucketSize);
  const uint64_t bigHashCacheSize =
      alignDown(totalCacheSize - bigHashCacheOffset, bucketSize);

  auto bigHash = cachelib::navy::createBigHashProto();
  bigHash->setLayout(bigHashCacheOffset, bigHashCacheSize, bucketSize);

  // Bucket Bloom filter size, bytes
  //
  // Experiments showed that if we have 16 bytes for BF with 25 entries,
  // then optimal number of hash functions is 4 and false positive rate
  // below 10%.
  if (bigHashConfig.isBloomFilterEnabled()) {
    // We set 4 hash function unconditionally. This seems to be the best
    // for our use case. If BF size to bucket size ratio gets lower, try
    // to reduce number of hashes.
    constexpr uint32_t kNumHashes = 4;
    const uint32_t bitsPerHash =
        bigHashConfig.getBucketBfSize() * 8 / kNumHashes;
    bigHash->setBloomFilter(kNumHashes, bitsPerHash);
  }

  proto.setBigHash(std::move(bigHash), bigHashConfig.getSmallItemMaxSize());

  if (bigHashCacheOffset <= metadataSize) {
    throw std::invalid_argument("NVM cache size is not big enough!");
  }
  XLOG(INFO) << "metadataSize: " << metadataSize
             << " bigHashCacheOffset: " << bigHashCacheOffset
             << " bigHashCacheSize: " << bigHashCacheSize;
  return bigHashCacheOffset;
}

void setupBlockCache(const navy::BlockCacheConfig& blockCacheConfig,
                     uint64_t blockCacheSize,
                     uint32_t ioAlignSize,
                     uint64_t metadataSize,
                     bool usesRaidFiles,
                     bool itemDestructorEnabled,
                     cachelib::navy::CacheProto& proto) {
  auto regionSize = blockCacheConfig.getRegionSize();
  if (regionSize != alignUp(regionSize, ioAlignSize)) {
    throw std::invalid_argument(
        folly::sformat("Region size: {} is not aligned to ioAlignSize: {}",
                       regionSize, ioAlignSize));
  }

  // Adjust starting size of block cache to ensure it is aligned to region
  // size which is what we use for the stripe size when using RAID0Device.
  uint64_t blockCacheOffset = metadataSize;
  if (usesRaidFiles) {
    auto adjustedBlockCacheOffset = alignUp(blockCacheOffset, regionSize);
    auto cacheSizeAdjustment = adjustedBlockCacheOffset - blockCacheOffset;
    XDCHECK_LT(cacheSizeAdjustment, blockCacheSize);
    blockCacheSize -= cacheSizeAdjustment;
    blockCacheOffset = adjustedBlockCacheOffset;
  }
  blockCacheSize = alignDown(blockCacheSize, regionSize);

  XLOG(INFO) << "blockcache: starting offset: " << blockCacheOffset
             << ", block cache size: " << blockCacheSize;

  auto blockCache = cachelib::navy::createBlockCacheProto();
  blockCache->setLayout(blockCacheOffset, blockCacheSize, regionSize);
  blockCache->setChecksum(blockCacheConfig.getDataChecksum());

  // set eviction policy
  auto segmentRatio = blockCacheConfig.getSFifoSegmentRatio();
  if (!segmentRatio.empty()) {
    blockCache->setSegmentedFifoEvictionPolicy(std::move(segmentRatio));
  } else if (blockCacheConfig.isLruEnabled()) {
    blockCache->setLruEvictionPolicy();
  } else {
    blockCache->setFifoEvictionPolicy();
  }
  blockCache->setCleanRegionsPool(blockCacheConfig.getCleanRegions());

  blockCache->setReinsertionConfig(blockCacheConfig.getReinsertionConfig());

  blockCache->setNumInMemBuffers(blockCacheConfig.getNumInMemBuffers());
  blockCache->setItemDestructorEnabled(itemDestructorEnabled);
  blockCache->setPreciseRemove(blockCacheConfig.isPreciseRemove());

  proto.setBlockCache(std::move(blockCache));
}

// Setup the CacheProto, includes BigHashProto and BlockCacheProto,
// which is the configuration interface from Navy engine, and can be used to
// create BigHash and BlockCache engines.
//
// @param config            the configured NavyConfig
// @param device            the flash device
// @param proto             the output CacheProto
//
// @throw std::invalid_argument if input arguments are invalid
void setupCacheProtos(const navy::NavyConfig& config,
                      const navy::Device& device,
                      cachelib::navy::CacheProto& proto,
                      const bool itemDestructorEnabled) {
  auto getDefaultMetadataSize = [](size_t size, size_t alignment) {
    XDCHECK(folly::isPowTwo(alignment));
    auto mask = ~(alignment - 1);
    return (static_cast<size_t>(kDefaultMetadataPercent * size / 100) & mask);
  };

  auto ioAlignSize = device.getIOAlignmentSize();
  const uint64_t totalCacheSize = device.getSize();

  auto metadataSize = config.getDeviceMetadataSize();
  if (metadataSize == 0) {
    metadataSize = getDefaultMetadataSize(totalCacheSize, ioAlignSize);
  }
  metadataSize = alignUp(metadataSize, ioAlignSize);
  if (metadataSize >= totalCacheSize) {
    throw std::invalid_argument{
        folly::sformat("Invalid metadata size: {}. Cache size: {}",
                       metadataSize,
                       totalCacheSize)};
  }
  proto.setMetadataSize(metadataSize);

  uint64_t blockCacheSize = 0;

  // Set up BigHash if enabled
  if (config.isBigHashEnabled()) {
    auto bigHashCacheOffset = setupBigHash(config.bigHash(), ioAlignSize,
                                           totalCacheSize, metadataSize, proto);
    blockCacheSize = bigHashCacheOffset - metadataSize;
  } else {
    XLOG(INFO) << "metadataSize: " << metadataSize << ". No bighash.";
    blockCacheSize = totalCacheSize - metadataSize;
  }

  // Set up BlockCache if enabled
  if (blockCacheSize > 0) {
    setupBlockCache(config.blockCache(), blockCacheSize, ioAlignSize,
                    metadataSize, config.usesRaidFiles(), itemDestructorEnabled,
                    proto);
  }
}

void setAdmissionPolicy(const cachelib::navy::NavyConfig& config,
                        cachelib::navy::CacheProto& proto) {
  const std::string& policyName = config.getAdmissionPolicy();
  if (policyName.empty()) {
    return;
  }
  if (policyName == navy::NavyConfig::kAdmPolicyRandom) {
    proto.setRejectRandomAdmissionPolicy(config.randomAdmPolicy());
  } else if (policyName == navy::NavyConfig::kAdmPolicyDynamicRandom) {
    proto.setDynamicRandomAdmissionPolicy(config.dynamicRandomAdmPolicy());
  } else {
    throw std::invalid_argument{
        folly::sformat("invalid policy name {}", policyName)};
  }
}

std::unique_ptr<cachelib::navy::JobScheduler> createJobScheduler(
    const navy::NavyConfig& config) {
  auto readerThreads = config.getReaderThreads();
  auto writerThreads = config.getWriterThreads();
  auto reqOrderShardsPower = config.getNavyReqOrderingShards();
  return cachelib::navy::createOrderedThreadPoolJobScheduler(
      readerThreads, writerThreads, reqOrderShardsPower);
}
} // namespace

std::unique_ptr<cachelib::navy::Device> createDevice(
    const navy::NavyConfig& config,
    std::shared_ptr<navy::DeviceEncryptor> encryptor) {
  auto blockSize = config.getBlockSize();
  auto maxDeviceWriteSize = config.getDeviceMaxWriteSize();

  if (config.usesRaidFiles()) {
    auto stripeSize = config.getRaidStripeSize();
    return cachelib::navy::createRAIDDevice(
        config.getRaidPaths(),
        alignDown(config.getFileSize(), stripeSize),
        config.getTruncateFile(),
        blockSize,
        stripeSize,
        std::move(encryptor),
        maxDeviceWriteSize > 0 ? alignDown(maxDeviceWriteSize, blockSize) : 0);
  } else if (config.usesSimpleFile()) {
    return cachelib::navy::createFileDevice(
        config.getFileName(),
        config.getFileSize(),
        config.getTruncateFile(),
        blockSize,
        std::move(encryptor),
        maxDeviceWriteSize > 0 ? alignDown(maxDeviceWriteSize, blockSize) : 0);
  } else {
    return cachelib::navy::createMemoryDevice(config.getFileSize(),
                                              std::move(encryptor), blockSize);
  }
}

std::unique_ptr<navy::AbstractCache> createNavyCache(
    const navy::NavyConfig& config,
    navy::DestructorCallback cb,
    bool truncate,
    std::shared_ptr<navy::DeviceEncryptor> encryptor,
    bool itemDestructorEnabled) {
  auto device = createDevice(config, std::move(encryptor));

  auto proto = cachelib::navy::createCacheProto();
  auto* devicePtr = device.get();
  proto->setDevice(std::move(device));
  proto->setJobScheduler(createJobScheduler(config));
  proto->setMaxConcurrentInserts(config.getMaxConcurrentInserts());
  proto->setMaxParcelMemory(megabytesToBytes(config.getMaxParcelMemoryMB()));
  setAdmissionPolicy(config, *proto);
  proto->setDestructorCallback(cb);

  setupCacheProtos(config, *devicePtr, *proto, itemDestructorEnabled);

  auto cache = createCache(std::move(proto));
  XDCHECK(cache != nullptr);

  if (truncate) {
    cache->reset();
    return cache;
  }

  if (!cache->recover()) {
    XLOG(WARN) << "No recovery data found. Continuing with clean cache.";
  }
  return cache;
}
} // namespace cachelib
} // namespace facebook