From 1dd166f76653bee7f7c2a0a89929ee9232680536 Mon Sep 17 00:00:00 2001 From: Liam Date: Thu, 22 Jun 2023 22:05:08 -0400 Subject: vfs_real: lock concurrent accesses --- src/core/file_sys/vfs_real.cpp | 55 +++++++++++++++++++++++++++--------------- src/core/file_sys/vfs_real.h | 15 +++++++----- 2 files changed, 45 insertions(+), 25 deletions(-) diff --git a/src/core/file_sys/vfs_real.cpp b/src/core/file_sys/vfs_real.cpp index fcc81a664..b0515ec05 100644 --- a/src/core/file_sys/vfs_real.cpp +++ b/src/core/file_sys/vfs_real.cpp @@ -76,6 +76,7 @@ VfsEntryType RealVfsFilesystem::GetEntryType(std::string_view path_) const { VirtualFile RealVfsFilesystem::OpenFileFromEntry(std::string_view path_, std::optional 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(); - this->InsertReferenceIntoList(*reference); + this->InsertReferenceIntoListLocked(*reference); auto file = std::shared_ptr( 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); - cache.erase(path); + { + 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); - cache.erase(old_path); - cache.erase(new_path); + { + 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); - cache.erase(path); + { + 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, - FileReference& reference) { +std::unique_lock 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&& 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&& 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(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(offset))) { return 0; } diff --git a/src/core/file_sys/vfs_real.h b/src/core/file_sys/vfs_real.h index 67f4c4422..26ea7df62 100644 --- a/src/core/file_sys/vfs_real.h +++ b/src/core/file_sys/vfs_real.h @@ -4,6 +4,7 @@ #pragma once #include +#include #include #include #include "common/intrusive_list.h" @@ -48,22 +49,24 @@ private: std::map, 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 RefreshReference(const std::string& path, Mode perms, + FileReference& reference); void DropReference(std::unique_ptr&& reference); - void EvictSingleReference(); - -private: - void InsertReferenceIntoList(FileReference& reference); - void RemoveReferenceFromList(FileReference& reference); private: friend class RealVfsDirectory; VirtualFile OpenFileFromEntry(std::string_view path, std::optional 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. -- cgit v1.2.3