From 5792a72c29dbc7af6a28603136206e97ef58943d Mon Sep 17 00:00:00 2001
From: Liam <byteslice@airmail.cc>
Date: Sun, 7 May 2023 01:19:13 -0400
Subject: [PATCH] vfs_vector: avoid n^2 lookup in layeredfs building
---
src/core/file_sys/vfs_vector.cpp | 19 +++++++++++++++++++
src/core/file_sys/vfs_vector.h | 4 ++++
2 files changed, 23 insertions(+)
diff --git a/src/core/file_sys/vfs_vector.cpp b/src/core/file_sys/vfs_vector.cpp
index 251d9d7c9f..af1df4c514 100644
--- a/src/core/file_sys/vfs_vector.cpp
+++ b/src/core/file_sys/vfs_vector.cpp
@@ -67,6 +67,23 @@ VectorVfsDirectory::VectorVfsDirectory(std::vector<VirtualFile> files_,
VectorVfsDirectory::~VectorVfsDirectory() = default;
+VirtualFile VectorVfsDirectory::GetFile(std::string_view file_name) const {
+ if (!optimized_file_index_built) {
+ optimized_file_index.clear();
+ for (size_t i = 0; i < files.size(); i++) {
+ optimized_file_index.emplace(files[i]->GetName(), i);
+ }
+ optimized_file_index_built = true;
+ }
+
+ const auto it = optimized_file_index.find(file_name);
+ if (it != optimized_file_index.end()) {
+ return files[it->second];
+ }
+
+ return nullptr;
+}
+
std::vector<VirtualFile> VectorVfsDirectory::GetFiles() const {
return files;
}
@@ -107,6 +124,7 @@ bool VectorVfsDirectory::DeleteSubdirectory(std::string_view subdir_name) {
}
bool VectorVfsDirectory::DeleteFile(std::string_view file_name) {
+ optimized_file_index_built = false;
return FindAndRemoveVectorElement(files, file_name);
}
@@ -124,6 +142,7 @@ VirtualFile VectorVfsDirectory::CreateFile(std::string_view file_name) {
}
void VectorVfsDirectory::AddFile(VirtualFile file) {
+ optimized_file_index_built = false;
files.push_back(std::move(file));
}
diff --git a/src/core/file_sys/vfs_vector.h b/src/core/file_sys/vfs_vector.h
index bfedb6e42a..c9955755bf 100644
--- a/src/core/file_sys/vfs_vector.h
+++ b/src/core/file_sys/vfs_vector.h
@@ -105,6 +105,7 @@ public:
VirtualDir parent = nullptr);
~VectorVfsDirectory() override;
+ VirtualFile GetFile(std::string_view file_name) const override;
std::vector<VirtualFile> GetFiles() const override;
std::vector<VirtualDir> GetSubdirectories() const override;
bool IsWritable() const override;
@@ -126,6 +127,9 @@ private:
VirtualDir parent;
std::string name;
+
+ mutable std::map<std::string, size_t, std::less<>> optimized_file_index;
+ mutable bool optimized_file_index_built{};
};
} // namespace FileSys