Atmosphere-libs/libstratosphere/include/stratosphere/kvdb/kvdb_file_key_value_cache.hpp

383 lines
15 KiB
C++

/*
* Copyright (c) Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stratosphere/fs/fs_filesystem.hpp>
#include <stratosphere/fs/fs_file.hpp>
#include <stratosphere/kvdb/kvdb_bounded_string.hpp>
#include <stratosphere/kvdb/kvdb_file_key_value_store.hpp>
namespace ams::kvdb {
namespace impl {
template<class Key, size_t Capacity>
class LruList {
private:
/* Subtypes. */
struct LruHeader {
u32 entry_count;
};
public:
static constexpr size_t BufferSize = sizeof(Key) * Capacity;
static constexpr size_t FileSize = sizeof(LruHeader) + BufferSize;
using Path = FileKeyValueStore::Path;
private:
Path m_file_path;
Key *m_keys;
LruHeader m_header;
public:
static Result CreateNewList(const char *path) {
/* Create new lru_list.dat. */
R_TRY(fs::CreateFile(path, FileSize));
/* Open the file. */
fs::FileHandle file;
R_TRY(fs::OpenFile(std::addressof(file), path, fs::OpenMode_Write));
ON_SCOPE_EXIT { fs::CloseFile(file); };
/* Write new header with zero entries to the file. */
LruHeader new_header = { .entry_count = 0, };
R_TRY(fs::WriteFile(file, 0, std::addressof(new_header), sizeof(new_header), fs::WriteOption::Flush));
return ResultSuccess();
}
private:
void RemoveIndex(size_t i) {
AMS_ABORT_UNLESS(i < this->GetCount());
std::memmove(m_keys + i, m_keys + i + 1, sizeof(*m_keys) * (this->GetCount() - (i + 1)));
this->DecrementCount();
}
void IncrementCount() {
m_header.entry_count++;
}
void DecrementCount() {
m_header.entry_count--;
}
public:
LruList() : m_keys(nullptr), m_header() { /* ... */ }
Result Initialize(const char *path, void *buf, size_t size) {
/* Only initialize once, and ensure we have sufficient memory. */
AMS_ABORT_UNLESS(m_keys == nullptr);
AMS_ABORT_UNLESS(size >= BufferSize);
/* Setup member variables. */
m_keys = static_cast<Key *>(buf);
m_file_path.Assign(path);
std::memset(m_keys, 0, BufferSize);
/* Open file. */
fs::FileHandle file;
R_TRY(fs::OpenFile(std::addressof(file), m_file_path, fs::OpenMode_Read));
ON_SCOPE_EXIT { fs::CloseFile(file); };
/* Read header. */
R_TRY(fs::ReadFile(file, 0, std::addressof(m_header), sizeof(m_header)));
/* Read entries. */
R_TRY(fs::ReadFile(file, sizeof(m_header), m_keys, BufferSize));
return ResultSuccess();
}
Result Save() {
/* Open file. */
fs::FileHandle file;
R_TRY(fs::OpenFile(std::addressof(file), m_file_path, fs::OpenMode_Read));
ON_SCOPE_EXIT { fs::CloseFile(file); };
/* Write header. */
R_TRY(fs::WriteFile(file, 0, std::addressof(m_header), sizeof(m_header), fs::WriteOption::None));
/* Write entries. */
R_TRY(fs::WriteFile(file, sizeof(m_header), m_keys, BufferSize, fs::WriteOption::None));
/* Flush. */
R_TRY(fs::FlushFile(file));
return ResultSuccess();
}
size_t GetCount() const {
return m_header.entry_count;
}
bool IsEmpty() const {
return this->GetCount() == 0;
}
bool IsFull() const {
return this->GetCount() >= Capacity;
}
Key Get(size_t i) const {
AMS_ABORT_UNLESS(i < this->GetCount());
return m_keys[i];
}
Key Peek() const {
AMS_ABORT_UNLESS(!this->IsEmpty());
return this->Get(0);
}
void Push(const Key &key) {
AMS_ABORT_UNLESS(!this->IsFull());
m_keys[this->GetCount()] = key;
this->IncrementCount();
}
Key Pop() {
AMS_ABORT_UNLESS(!this->IsEmpty());
this->RemoveIndex(0);
}
bool Remove(const Key &key) {
const size_t count = this->GetCount();
/* Iterate over the list, removing the last entry that matches the key. */
for (size_t i = 0; i < count; i++) {
if (m_keys[count - 1 - i] == key) {
this->RemoveIndex(count - 1 - i);
return true;
}
}
return false;
}
bool Contains(const Key &key) const {
const size_t count = this->GetCount();
/* Iterate over the list, checking to see if we have the key. */
for (size_t i = 0; i < count; i++) {
if (m_keys[count - 1 - i] == key) {
return true;
}
}
return false;
}
bool Update(const Key &key) {
if (this->Remove(key)) {
this->Push(key);
return true;
}
return false;
}
};
}
template<class Key, size_t Capacity>
class FileKeyValueCache {
static_assert(util::is_pod<Key>::value, "FileKeyValueCache Key must be pod!");
static_assert(sizeof(Key) <= FileKeyValueStore::MaxKeySize, "FileKeyValueCache Key is too big!");
public:
using LeastRecentlyUsedList = impl::LruList<Key, Capacity>;
/* Note: Nintendo code in NS uses Path = BoundedString<0x180> here. */
/* It's unclear why, since they use 0x300 everywhere else. */
/* We'll just use 0x300, since it shouldn't make a difference, */
/* as FileKeyValueStore paths are limited to 0x100 anyway. */
using Path = typename LeastRecentlyUsedList::Path;
private:
FileKeyValueStore m_kvs;
LeastRecentlyUsedList m_lru_list;
private:
static constexpr Path GetLeastRecentlyUsedListPath(const char *dir) {
return Path::MakeFormat("%s/%s", dir, "lru_list.dat");
}
static constexpr Path GetFileKeyValueStorePath(const char *dir) {
return Path::MakeFormat("%s/%s", dir, "kvs");
}
static Result Exists(bool *out, const char *path, fs::DirectoryEntryType type) {
/* Set out to false initially. */
*out = false;
/* Try to get the entry type. */
fs::DirectoryEntryType entry_type;
R_TRY_CATCH(fs::GetEntryType(std::addressof(entry_type), path)) {
/* If the path doesn't exist, nothing has gone wrong. */
R_CONVERT(fs::ResultPathNotFound, ResultSuccess());
} R_END_TRY_CATCH;
/* Check that the entry type is correct. */
R_UNLESS(entry_type == type, kvdb::ResultInvalidFilesystemState());
/* The entry exists and is the correct type. */
*out = true;
return ResultSuccess();
}
static Result DirectoryExists(bool *out, const char *path) {
return Exists(out, path, fs::DirectoryEntryType_Directory);
}
static Result FileExists(bool *out, const char *path) {
return Exists(out, path, fs::DirectoryEntryType_File);
}
public:
static Result CreateNewCache(const char *dir) {
/* Make a new key value store filesystem, and a new lru_list.dat. */
R_TRY(LeastRecentlyUsedList::CreateNewList(GetLeastRecentlyUsedListPath(dir)));
R_TRY(fs::CreateDirectory(dir));
return ResultSuccess();
}
static Result ValidateExistingCache(const char *dir) {
/* Check for existence. */
bool has_lru = false, has_kvs = false;
R_TRY(FileExists(std::addressof(has_lru), GetLeastRecentlyUsedListPath(dir)));
R_TRY(DirectoryExists(std::addressof(has_kvs), GetFileKeyValueStorePath(dir)));
/* If neither exists, CreateNewCache was never called. */
R_UNLESS(has_lru || has_kvs, kvdb::ResultNotCreated());
/* If one exists but not the other, we have an invalid state. */
R_UNLESS(has_lru && has_kvs, kvdb::ResultInvalidFilesystemState());
return ResultSuccess();
}
private:
void RemoveOldestKey() {
const Key &oldest_key = m_lru_list.Peek();
m_lru_list.Pop();
m_kvs.Remove(oldest_key);
}
public:
Result Initialize(const char *dir, void *buf, size_t size) {
/* Initialize list. */
R_TRY(m_lru_list.Initialize(GetLeastRecentlyUsedListPath(dir), buf, size));
/* Initialize kvs. */
/* NOTE: Despite creating the kvs folder and returning an error if it does not exist, */
/* Nintendo does not use the kvs folder, and instead uses the passed dir. */
/* This causes lru_list.dat to be in the same directory as the store's .val files */
/* instead of in the same directory as a folder containing the store's .val files. */
/* This is probably a Nintendo bug, but because system saves contain data in the wrong */
/* layout it can't really be fixed without breaking existing devices... */
R_TRY(m_kvs.Initialize(dir));
return ResultSuccess();
}
size_t GetCount() const {
return m_lru_list.GetCount();
}
size_t GetCapacity() const {
return Capacity;
}
Key GetKey(size_t i) const {
return m_lru_list.Get(i);
}
bool Contains(const Key &key) const {
return m_lru_list.Contains(key);
}
Result Get(size_t *out_size, void *out_value, size_t max_out_size, const Key &key) {
/* Note that we accessed the key. */
m_lru_list.Update(key);
return m_kvs.Get(out_size, out_value, max_out_size, key);
}
template<typename Value>
Result Get(Value *out_value, const Key &key) {
/* Note that we accessed the key. */
m_lru_list.Update(key);
return m_kvs.Get(out_value, key);
}
Result GetSize(size_t *out_size, const Key &key) {
return m_kvs.GetSize(out_size, key);
}
Result Set(const Key &key, const void *value, size_t value_size) {
if (m_lru_list.Update(key)) {
/* If an entry for the key exists, delete the existing value file. */
m_kvs.Remove(key);
} else {
/* If the list is full, we need to remove the oldest key. */
if (m_lru_list.IsFull()) {
this->RemoveOldestKey();
}
/* Add the key to the list. */
m_lru_list.Push(key);
}
/* Loop, trying to save the new value to disk. */
while (true) {
/* Try to set the key. */
R_TRY_CATCH(m_kvs.Set(key, value, value_size)) {
R_CATCH(fs::ResultNotEnoughFreeSpace) {
/* If our entry is the only thing in the Lru list, remove it. */
if (m_lru_list.GetCount() == 1) {
m_lru_list.Pop();
R_TRY(m_lru_list.Save());
return fs::ResultNotEnoughFreeSpace();
}
/* Otherwise, remove the oldest element from the cache and try again. */
this->RemoveOldestKey();
continue;
}
} R_END_TRY_CATCH;
/* If we got here, we succeeded. */
break;
}
/* Save the list. */
R_TRY(m_lru_list.Save());
return ResultSuccess();
}
template<typename Value>
Result Set(const Key &key, const Value &value) {
return this->Set(key, &value, sizeof(Value));
}
Result Remove(const Key &key) {
/* Remove the key. */
m_lru_list.Remove(key);
R_TRY(m_kvs.Remove(key));
R_TRY(m_lru_list.Save());
return ResultSuccess();
}
Result RemoveAll() {
/* TODO: Nintendo doesn't check errors here. Should we? */
while (!m_lru_list.IsEmpty()) {
this->RemoveOldestKey();
}
R_TRY(m_lru_list.Save());
return ResultSuccess();
}
};
}