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vfs_real: lock concurrent accesses

nce_cpp
Liam 3 years ago
parent
7a546be139
commit
217bb87494
2 changed files with 45 additions and 25 deletions
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  1. 45
      src/core/file_sys/vfs_real.cpp
  2. 15
      src/core/file_sys/vfs_real.h

45
src/core/file_sys/vfs_real.cpp
View File

@ -76,6 +76,7 @@ VfsEntryType RealVfsFilesystem::GetEntryType(std::string_view path_) const {
VirtualFile RealVfsFilesystem::OpenFileFromEntry(std::string_view path_, std::optional<u64> size,
Mode perms) {
const auto path = FS::SanitizePath(path_, FS::DirectorySeparator::PlatformDefault);
std::scoped_lock lk{list_lock};
if (auto it = cache.find(path); it != cache.end()) {
if (auto file = it->second.lock(); file) {
@ -88,7 +89,7 @@ VirtualFile RealVfsFilesystem::OpenFileFromEntry(std::string_view path_, std::op
}
auto reference = std::make_unique<FileReference>();
this->InsertReferenceIntoList(*reference);
this->InsertReferenceIntoListLocked(*reference);
auto file = std::shared_ptr<RealVfsFile>(
new RealVfsFile(*this, std::move(reference), path, perms, size));
@ -103,7 +104,10 @@ VirtualFile RealVfsFilesystem::OpenFile(std::string_view path_, Mode perms) {
VirtualFile RealVfsFilesystem::CreateFile(std::string_view path_, Mode perms) {
const auto path = FS::SanitizePath(path_, FS::DirectorySeparator::PlatformDefault);
{
std::scoped_lock lk{list_lock};
cache.erase(path);
}
// Current usages of CreateFile expect to delete the contents of an existing file.
if (FS::IsFile(path)) {
@ -133,8 +137,11 @@ VirtualFile RealVfsFilesystem::CopyFile(std::string_view old_path_, std::string_
VirtualFile RealVfsFilesystem::MoveFile(std::string_view old_path_, std::string_view new_path_) {
const auto old_path = FS::SanitizePath(old_path_, FS::DirectorySeparator::PlatformDefault);
const auto new_path = FS::SanitizePath(new_path_, FS::DirectorySeparator::PlatformDefault);
{
std::scoped_lock lk{list_lock};
cache.erase(old_path);
cache.erase(new_path);
}
if (!FS::RenameFile(old_path, new_path)) {
return nullptr;
}
@ -143,7 +150,10 @@ VirtualFile RealVfsFilesystem::MoveFile(std::string_view old_path_, std::string_
bool RealVfsFilesystem::DeleteFile(std::string_view path_) {
const auto path = FS::SanitizePath(path_, FS::DirectorySeparator::PlatformDefault);
{
std::scoped_lock lk{list_lock};
cache.erase(path);
}
return FS::RemoveFile(path);
}
@ -182,14 +192,17 @@ bool RealVfsFilesystem::DeleteDirectory(std::string_view path_) {
return FS::RemoveDirRecursively(path);
}
void RealVfsFilesystem::RefreshReference(const std::string& path, Mode perms,
std::unique_lock<std::mutex> RealVfsFilesystem::RefreshReference(const std::string& path,
Mode perms,
FileReference& reference) {
std::unique_lock lk{list_lock};
// Temporarily remove from list.
this->RemoveReferenceFromList(reference);
this->RemoveReferenceFromListLocked(reference);
// Restore file if needed.
if (!reference.file) {
this->EvictSingleReference();
this->EvictSingleReferenceLocked();
reference.file =
FS::FileOpen(path, ModeFlagsToFileAccessMode(perms), FS::FileType::BinaryFile);
@ -199,12 +212,16 @@ void RealVfsFilesystem::RefreshReference(const std::string& path, Mode perms,
}
// Reinsert into list.
this->InsertReferenceIntoList(reference);
this->InsertReferenceIntoListLocked(reference);
return lk;
}
void RealVfsFilesystem::DropReference(std::unique_ptr<FileReference>&& reference) {
std::scoped_lock lk{list_lock};
// Remove from list.
this->RemoveReferenceFromList(*reference);
this->RemoveReferenceFromListLocked(*reference);
// Close the file.
if (reference->file) {
@ -213,14 +230,14 @@ void RealVfsFilesystem::DropReference(std::unique_ptr<FileReference>&& reference
}
}
void RealVfsFilesystem::EvictSingleReference() {
void RealVfsFilesystem::EvictSingleReferenceLocked() {
if (num_open_files < MaxOpenFiles || open_references.empty()) {
return;
}
// Get and remove from list.
auto& reference = open_references.back();
this->RemoveReferenceFromList(reference);
this->RemoveReferenceFromListLocked(reference);
// Close the file.
if (reference.file) {
@ -229,10 +246,10 @@ void RealVfsFilesystem::EvictSingleReference() {
}
// Reinsert into closed list.
this->InsertReferenceIntoList(reference);
this->InsertReferenceIntoListLocked(reference);
}
void RealVfsFilesystem::InsertReferenceIntoList(FileReference& reference) {
void RealVfsFilesystem::InsertReferenceIntoListLocked(FileReference& reference) {
if (reference.file) {
open_references.push_front(reference);
} else {
@ -240,7 +257,7 @@ void RealVfsFilesystem::InsertReferenceIntoList(FileReference& reference) {
}
}
void RealVfsFilesystem::RemoveReferenceFromList(FileReference& reference) {
void RealVfsFilesystem::RemoveReferenceFromListLocked(FileReference& reference) {
if (reference.file) {
open_references.erase(open_references.iterator_to(reference));
} else {
@ -271,7 +288,7 @@ std::size_t RealVfsFile::GetSize() const {
bool RealVfsFile::Resize(std::size_t new_size) {
size.reset();
base.RefreshReference(path, perms, *reference);
auto lk = base.RefreshReference(path, perms, *reference);
return reference->file ? reference->file->SetSize(new_size) : false;
}
@ -288,7 +305,7 @@ bool RealVfsFile::IsReadable() const {
}
std::size_t RealVfsFile::Read(u8* data, std::size_t length, std::size_t offset) const {
base.RefreshReference(path, perms, *reference);
auto lk = base.RefreshReference(path, perms, *reference);
if (!reference->file || !reference->file->Seek(static_cast<s64>(offset))) {
return 0;
}
@ -297,7 +314,7 @@ std::size_t RealVfsFile::Read(u8* data, std::size_t length, std::size_t offset)
std::size_t RealVfsFile::Write(const u8* data, std::size_t length, std::size_t offset) {
size.reset();
base.RefreshReference(path, perms, *reference);
auto lk = base.RefreshReference(path, perms, *reference);
if (!reference->file || !reference->file->Seek(static_cast<s64>(offset))) {
return 0;
}

15
src/core/file_sys/vfs_real.h
View File

@ -4,6 +4,7 @@
#pragma once
#include <map>
#include <mutex>
#include <optional>
#include <string_view>
#include "common/intrusive_list.h"
@ -48,22 +49,24 @@ private:
std::map<std::string, std::weak_ptr<VfsFile>, std::less<>> cache;
ReferenceListType open_references;
ReferenceListType closed_references;
std::mutex list_lock;
size_t num_open_files{};
private:
friend class RealVfsFile;
void RefreshReference(const std::string& path, Mode perms, FileReference& reference);
std::unique_lock<std::mutex> RefreshReference(const std::string& path, Mode perms,
FileReference& reference);
void DropReference(std::unique_ptr<FileReference>&& reference);
void EvictSingleReference();
private:
void InsertReferenceIntoList(FileReference& reference);
void RemoveReferenceFromList(FileReference& reference);
private:
friend class RealVfsDirectory;
VirtualFile OpenFileFromEntry(std::string_view path, std::optional<u64> size,
Mode perms = Mode::Read);
private:
void EvictSingleReferenceLocked();
void InsertReferenceIntoListLocked(FileReference& reference);
void RemoveReferenceFromListLocked(FileReference& reference);
};
// An implementation of VfsFile that represents a file on the user's computer.

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