be/src/io/cache/mem_file_cache_storage.cpp

// Licensed to the Apache Software Foundation (ASF) under one
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// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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
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// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#include "io/cache/mem_file_cache_storage.h"

#include <filesystem>
#include <mutex>
#include <system_error>

#include "common/logging.h"
#include "io/cache/block_file_cache.h"
#include "io/cache/file_block.h"
#include "io/cache/file_cache_common.h"
#include "runtime/exec_env.h"
#include "vec/common/hex.h"

namespace doris::io {

MemFileCacheStorage::~MemFileCacheStorage() {}

Status MemFileCacheStorage::init(BlockFileCache* _mgr) {
    LOG_INFO("init in-memory file cache storage");
    _mgr->_async_open_done = true; // no data to load for memory storage
    return Status::OK();
}

Status MemFileCacheStorage::append(const FileCacheKey& key, const Slice& value) {
    std::lock_guard<std::mutex> lock(_cache_map_mtx);

    auto map_key = std::make_pair(key.hash, key.offset);
    auto iter = _cache_map.find(map_key);
    if (iter != _cache_map.end()) {
        // despite the name append, it is indeed a put, so the key should not exist
        LOG_WARNING("key already exists in in-memory cache map")
                .tag("hash", key.hash.to_string())
                .tag("offset", key.offset);
        DCHECK(false);
        return Status::IOError("key already exists in in-memory cache map");
    }
    // TODO(zhengyu): allocate in mempool
    auto mem_block =
            MemBlock {std::shared_ptr<char[]>(new char[value.size], std::default_delete<char[]>())};
    DCHECK(mem_block.addr != nullptr);
    _cache_map[map_key] = mem_block;
    char* dst = mem_block.addr.get();
    // TODO(zhengyu): zero copy!
    memcpy(dst, value.data, value.size);

    return Status::OK();
}

Status MemFileCacheStorage::finalize(const FileCacheKey& key, const size_t size) {
    // do nothing for in memory cache coz nothing to persist
    // download state in FileBlock::finalize will inform the readers when finish
    return Status::OK();
}

Status MemFileCacheStorage::read(const FileCacheKey& key, size_t value_offset, Slice buffer) {
    std::lock_guard<std::mutex> lock(_cache_map_mtx);
    auto map_key = std::make_pair(key.hash, key.offset);
    auto iter = _cache_map.find(map_key);
    if (iter == _cache_map.end()) {
        LOG_WARNING("key not found in cache map")
                .tag("hash", key.hash.to_string())
                .tag("offset", key.offset);
        return Status::IOError("key not found in in-memory cache map when read");
    }
    auto mem_block = iter->second;
    DCHECK(mem_block.addr != nullptr);
    char* src = mem_block.addr.get();
    char* dst = buffer.data;
    size_t size = buffer.size;
    memcpy(dst, src, size);
    return Status::OK();
}

Status MemFileCacheStorage::remove(const FileCacheKey& key) {
    // find and clear the one in _cache_map
    std::lock_guard<std::mutex> lock(_cache_map_mtx);
    auto map_key = std::make_pair(key.hash, key.offset);
    auto iter = _cache_map.find(map_key);
    if (iter == _cache_map.end()) {
        LOG_WARNING("key not found in cache map")
                .tag("hash", key.hash.to_string())
                .tag("offset", key.offset);
        return Status::IOError("key not found in in-memory cache map when remove");
    }
    _cache_map.erase(iter);

    return Status::OK();
}

Status MemFileCacheStorage::change_key_meta_type(const FileCacheKey& key, const FileCacheType type,
                                                 const size_t size) {
    // do nothing for in memory cache coz nothing to persist
    return Status::OK();
}

void MemFileCacheStorage::load_blocks_directly_unlocked(BlockFileCache* _mgr,
                                                        const FileCacheKey& key,
                                                        std::lock_guard<std::mutex>& cache_lock) {
    // load nothing for in memory cache coz nothing is persisted
}

Status MemFileCacheStorage::clear(std::string& msg) {
    std::lock_guard<std::mutex> lock(_cache_map_mtx);
    _cache_map.clear();
    return Status::OK();
}

std::string MemFileCacheStorage::get_local_file(const FileCacheKey& key) {
    return "";
}

} // namespace doris::io