eden-emu
/
eden
mirror of https://git.eden-emu.dev/eden-emu/eden.git
1
0
Fork 0
Code Releases Wiki Activity
Browse Source

Merge pull request #10463 from liamwhite/this-is-why-we-need-g 

vfs_concat: fix time complexity of read
pull/15/merge
liamwhite 3 years ago
committed by GitHub
parent
18595738fd 0596a4afb1
commit
93c17ee4da
No known key found for this signature in database GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 125 additions and 70 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 3
      src/core/core.cpp
  2. 3
      src/core/file_sys/romfs.cpp
  3. 161
      src/core/file_sys/vfs_concat.cpp
  4. 28
      src/core/file_sys/vfs_concat.h

3
src/core/core.cpp
View File

@ -117,8 +117,7 @@ FileSys::VirtualFile GetGameFileFromPath(const FileSys::VirtualFilesystem& vfs,
return nullptr;
}
return FileSys::ConcatenatedVfsFile::MakeConcatenatedFile(std::move(concat),
dir->GetName());
return FileSys::ConcatenatedVfsFile::MakeConcatenatedFile(concat, dir->GetName());
}
if (Common::FS::IsDir(path)) {

3
src/core/file_sys/romfs.cpp
View File

@ -140,7 +140,8 @@ VirtualFile CreateRomFS(VirtualDir dir, VirtualDir ext) {
return nullptr;
RomFSBuildContext ctx{dir, ext};
return ConcatenatedVfsFile::MakeConcatenatedFile(0, ctx.Build(), dir->GetName());
auto file_map = ctx.Build();
return ConcatenatedVfsFile::MakeConcatenatedFile(0, file_map, dir->GetName());
}
} // namespace FileSys

161
src/core/file_sys/vfs_concat.cpp
View File

@ -10,84 +10,105 @@
namespace FileSys {
static bool VerifyConcatenationMapContinuity(const std::multimap<u64, VirtualFile>& map) {
const auto last_valid = --map.end();
for (auto iter = map.begin(); iter != last_valid;) {
const auto old = iter++;
if (old->first + old->second->GetSize() != iter->first) {
ConcatenatedVfsFile::ConcatenatedVfsFile(ConcatenationMap&& concatenation_map_, std::string&& name_)
: concatenation_map(std::move(concatenation_map_)), name(std::move(name_)) {
DEBUG_ASSERT(this->VerifyContinuity());
}
bool ConcatenatedVfsFile::VerifyContinuity() const {
u64 last_offset = 0;
for (auto& entry : concatenation_map) {
if (entry.offset != last_offset) {
return false;
}
}
return map.begin()->first == 0;
}
ConcatenatedVfsFile::ConcatenatedVfsFile(std::vector<VirtualFile> files_, std::string name_)
: name(std::move(name_)) {
std::size_t next_offset = 0;
for (const auto& file : files_) {
files.emplace(next_offset, file);
next_offset += file->GetSize();
last_offset = entry.offset + entry.file->GetSize();
}
}
ConcatenatedVfsFile::ConcatenatedVfsFile(std::multimap<u64, VirtualFile> files_, std::string name_)
: files(std::move(files_)), name(std::move(name_)) {
ASSERT(VerifyConcatenationMapContinuity(files));
return true;
}
ConcatenatedVfsFile::~ConcatenatedVfsFile() = default;
VirtualFile ConcatenatedVfsFile::MakeConcatenatedFile(std::vector<VirtualFile> files,
std::string name) {
if (files.empty())
VirtualFile ConcatenatedVfsFile::MakeConcatenatedFile(const std::vector<VirtualFile>& files,
std::string&& name) {
// Fold trivial cases.
if (files.empty()) {
return nullptr;
if (files.size() == 1)
return files[0];
}
if (files.size() == 1) {
return files.front();
}
// Make the concatenation map from the input.
std::vector<ConcatenationEntry> concatenation_map;
concatenation_map.reserve(files.size());
u64 last_offset = 0;
for (auto& file : files) {
concatenation_map.emplace_back(ConcatenationEntry{
.offset = last_offset,
.file = file,
});
last_offset += file->GetSize();
}
return VirtualFile(new ConcatenatedVfsFile(std::move(files), std::move(name)));
return VirtualFile(new ConcatenatedVfsFile(std::move(concatenation_map), std::move(name)));
}
VirtualFile ConcatenatedVfsFile::MakeConcatenatedFile(u8 filler_byte,
std::multimap<u64, VirtualFile> files,
std::string name) {
if (files.empty())
const std::multimap<u64, VirtualFile>& files,
std::string&& name) {
// Fold trivial cases.
if (files.empty()) {
return nullptr;
if (files.size() == 1)
}
if (files.size() == 1) {
return files.begin()->second;
const auto last_valid = --files.end();
for (auto iter = files.begin(); iter != last_valid;) {
const auto old = iter++;
if (old->first + old->second->GetSize() != iter->first) {
files.emplace(old->first + old->second->GetSize(),
std::make_shared<StaticVfsFile>(filler_byte, iter->first - old->first -
old->second->GetSize()));
}
// Make the concatenation map from the input.
std::vector<ConcatenationEntry> concatenation_map;
concatenation_map.reserve(files.size());
u64 last_offset = 0;
// Iteration of a multimap is ordered, so offset will be strictly non-decreasing.
for (auto& [offset, file] : files) {
if (offset > last_offset) {
concatenation_map.emplace_back(ConcatenationEntry{
.offset = last_offset,
.file = std::make_shared<StaticVfsFile>(filler_byte, offset - last_offset),
});
}
// Ensure the map starts at offset 0 (start of file), otherwise pad to fill.
if (files.begin()->first != 0)
files.emplace(0, std::make_shared<StaticVfsFile>(filler_byte, files.begin()->first));
concatenation_map.emplace_back(ConcatenationEntry{
.offset = offset,
.file = file,
});
last_offset = offset + file->GetSize();
}
return VirtualFile(new ConcatenatedVfsFile(std::move(files), std::move(name)));
return VirtualFile(new ConcatenatedVfsFile(std::move(concatenation_map), std::move(name)));
}
std::string ConcatenatedVfsFile::GetName() const {
if (files.empty()) {
if (concatenation_map.empty()) {
return "";
}
if (!name.empty()) {
return name;
}
return files.begin()->second->GetName();
return concatenation_map.front().file->GetName();
}
std::size_t ConcatenatedVfsFile::GetSize() const {
if (files.empty()) {
if (concatenation_map.empty()) {
return 0;
}
return files.rbegin()->first + files.rbegin()->second->GetSize();
return concatenation_map.back().offset + concatenation_map.back().file->GetSize();
}
bool ConcatenatedVfsFile::Resize(std::size_t new_size) {
@ -95,10 +116,10 @@ bool ConcatenatedVfsFile::Resize(std::size_t new_size) {
}
VirtualDir ConcatenatedVfsFile::GetContainingDirectory() const {
if (files.empty()) {
if (concatenation_map.empty()) {
return nullptr;
}
return files.begin()->second->GetContainingDirectory();
return concatenation_map.front().file->GetContainingDirectory();
}
bool ConcatenatedVfsFile::IsWritable() const {
@ -110,25 +131,45 @@ bool ConcatenatedVfsFile::IsReadable() const {
}
std::size_t ConcatenatedVfsFile::Read(u8* data, std::size_t length, std::size_t offset) const {
auto entry = --files.end();
for (auto iter = files.begin(); iter != files.end(); ++iter) {
if (iter->first > offset) {
entry = --iter;
break;
const ConcatenationEntry key{
.offset = offset,
.file = nullptr,
};
// Read nothing if the map is empty.
if (concatenation_map.empty()) {
return 0;
}
// Binary search to find the iterator to the first position we can check.
// It must exist, since we are not empty and are comparing unsigned integers.
auto it = std::prev(std::upper_bound(concatenation_map.begin(), concatenation_map.end(), key));
u64 cur_length = length;
u64 cur_offset = offset;
while (cur_length > 0 && it != concatenation_map.end()) {
// Check if we can read the file at this position.
const auto& file = it->file;
const u64 file_offset = it->offset;
const u64 file_size = file->GetSize();
if (cur_offset >= file_offset + file_size) {
// Entirely out of bounds read.
break;
}
if (entry->first + entry->second->GetSize() <= offset)
return 0;
// Read the file at this position.
const u64 intended_read_size = std::min<u64>(cur_length, file_size);
const u64 actual_read_size =
file->Read(data + (cur_offset - offset), intended_read_size, cur_offset - file_offset);
const auto read_in =
std::min<u64>(entry->first + entry->second->GetSize() - offset, entry->second->GetSize());
if (length > read_in) {
return entry->second->Read(data, read_in, offset - entry->first) +
Read(data + read_in, length - read_in, offset + read_in);
// Update tracking.
cur_offset += actual_read_size;
cur_length -= actual_read_size;
it++;
}
return entry->second->Read(data, std::min<u64>(read_in, length), offset - entry->first);
return cur_offset - offset;
}
std::size_t ConcatenatedVfsFile::Write(const u8* data, std::size_t length, std::size_t offset) {

28
src/core/file_sys/vfs_concat.h
View File

@ -3,6 +3,7 @@
#pragma once
#include <compare>
#include <map>
#include <memory>
#include "core/file_sys/vfs.h"
@ -12,19 +13,33 @@ namespace FileSys {
// Class that wraps multiple vfs files and concatenates them, making reads seamless. Currently
// read-only.
class ConcatenatedVfsFile : public VfsFile {
explicit ConcatenatedVfsFile(std::vector<VirtualFile> files, std::string name_);
explicit ConcatenatedVfsFile(std::multimap<u64, VirtualFile> files, std::string name_);
private:
struct ConcatenationEntry {
u64 offset;
VirtualFile file;
auto operator<=>(const ConcatenationEntry& other) const {
return this->offset <=> other.offset;
}
};
using ConcatenationMap = std::vector<ConcatenationEntry>;
explicit ConcatenatedVfsFile(std::vector<ConcatenationEntry>&& concatenation_map,
std::string&& name);
bool VerifyContinuity() const;
public:
~ConcatenatedVfsFile() override;
/// Wrapper function to allow for more efficient handling of files.size() == 0, 1 cases.
static VirtualFile MakeConcatenatedFile(std::vector<VirtualFile> files, std::string name);
static VirtualFile MakeConcatenatedFile(const std::vector<VirtualFile>& files,
std::string&& name);
/// Convenience function that turns a map of offsets to files into a concatenated file, filling
/// gaps with a given filler byte.
static VirtualFile MakeConcatenatedFile(u8 filler_byte, std::multimap<u64, VirtualFile> files,
std::string name);
static VirtualFile MakeConcatenatedFile(u8 filler_byte,
const std::multimap<u64, VirtualFile>& files,
std::string&& name);
std::string GetName() const override;
std::size_t GetSize() const override;
@ -37,8 +52,7 @@ public:
bool Rename(std::string_view new_name) override;
private:
// Maps starting offset to file -- more efficient.
std::multimap<u64, VirtualFile> files;
ConcatenationMap concatenation_map;
std::string name;
};

Write Preview
Loading…
Cancel
Save