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simplify and clean up the handling of name in internal_file_entry. move should be more efficient now, by not copying the name

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This commit is contained in:
Arvid Norberg 2019-03-21 13:15:23 +01:00 committed by Arvid Norberg
parent 808a615c87
commit 19dbfce9c0
5 changed files with 37 additions and 44 deletions
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2
include/libtorrent/file_storage.hpp
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@ -123,7 +123,7 @@ namespace libtorrent {
internal_file_entry& operator=(internal_file_entry&& fe) & noexcept;
~internal_file_entry();
void set_name(char const* n, bool borrow_string = false, int string_len = 0);
void set_name(string_view n, bool borrow_string = false);
string_view filename() const;
enum {

2
include/libtorrent/string_util.hpp
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@ -106,7 +106,7 @@ namespace libtorrent {
// strdup is not part of the C standard. Some systems
// don't have it and it won't be available when building
// in strict ansi mode
char* allocate_string_copy(char const* str);
char* allocate_string_copy(string_view str);
// searches for separator ('sep') in the string 'last'.
// if found, returns the string_view representing the range from the start of

1
src/disk_io_thread.cpp
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@ -33,7 +33,6 @@ POSSIBILITY OF SUCH DAMAGE.
#include "libtorrent/config.hpp"
#include "libtorrent/storage.hpp"
#include "libtorrent/disk_io_thread.hpp"
#include "libtorrent/string_util.hpp" // for allocate_string_copy
#include "libtorrent/disk_buffer_holder.hpp"
#include "libtorrent/aux_/alloca.hpp"
#include "libtorrent/aux_/throw.hpp"

65
src/file_storage.cpp
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@ -122,7 +122,7 @@ namespace {
if (is_complete(path))
{
TORRENT_ASSERT(set_name);
e.set_name(path.c_str());
e.set_name(path);
e.path_index = -2;
return;
}
@ -137,7 +137,7 @@ namespace {
if (branch_path.empty())
{
if (set_name) e.set_name(leaf.data());
if (set_name) e.set_name(leaf);
e.path_index = -1;
return;
}
@ -162,7 +162,7 @@ namespace {
}
e.path_index = get_or_add_path(branch_path);
if (set_name) e.set_name(leaf.data());
if (set_name) e.set_name(leaf);
}
int file_storage::get_or_add_path(string_view const path)
@ -227,10 +227,8 @@ namespace {
, name(nullptr)
, path_index(fe.path_index)
{
if (fe.name_len == name_is_owned)
name = allocate_string_copy(fe.name);
else
name = fe.name;
bool const borrow = fe.name_len != name_is_owned;
set_name(fe.filename(), borrow);
}
internal_file_entry& internal_file_entry::operator=(internal_file_entry const& fe) &
@ -245,7 +243,10 @@ namespace {
executable_attribute = fe.executable_attribute;
symlink_attribute = fe.symlink_attribute;
no_root_dir = fe.no_root_dir;
set_name(fe.filename().to_string().c_str());
// if the name is not owned, don't allocate memory, we can point into the
// same metadata buffer
bool const borrow = fe.name_len != name_is_owned;
set_name(fe.filename(), borrow);
return *this;
}
@ -262,7 +263,7 @@ namespace {
, name(fe.name)
, path_index(fe.path_index)
{
fe.name_len = name_is_owned;
fe.name_len = 0;
fe.name = nullptr;
}
@ -281,35 +282,32 @@ namespace {
name = fe.name;
name_len = fe.name_len;
fe.name_len = name_is_owned;
fe.name_len = 0;
fe.name = nullptr;
return *this;
}
// if borrow_chars >= 0, don't take ownership over n, just
// point to it. It points to borrow_chars number of characters.
// if borrow_chars == -1, n is a 0-terminated string that
// should be copied.
void internal_file_entry::set_name(char const* n, bool const borrow_string
, int string_len)
// if borrow_string is true, don't take ownership over n, just
// point to it.
// if borrow_string is false, n will be copied and owned by the
// internal_file_entry.
void internal_file_entry::set_name(string_view n, bool const borrow_string)
{
TORRENT_ASSERT(string_len >= 0);
// we have limited space in the length field. truncate string
// if it's too long
if (string_len >= name_is_owned) string_len = name_is_owned - 1;
// free the current string, before assigning the new one
if (name_len == name_is_owned) delete[] name;
if (n == nullptr)
if (n.empty())
{
TORRENT_ASSERT(borrow_string == false);
name = nullptr;
}
else if (borrow_string)
{
name = n;
name_len = aux::numeric_cast<std::uint64_t>(string_len);
// we have limited space in the length field. truncate string
// if it's too long
if (n.size() >= name_is_owned) n = n.substr(name_is_owned - 1);
name = n.data();
name_len = aux::numeric_cast<std::uint64_t>(n.size());
}
else
{
@ -615,7 +613,7 @@ namespace {
// filename is allowed to be empty, in which case we just use path
if (!filename.empty())
e.set_name(filename.data(), true, int(filename.size()));
e.set_name(filename, true);
e.size = aux::numeric_cast<std::uint64_t>(file_size);
e.offset = aux::numeric_cast<std::uint64_t>(m_total_size);
@ -680,15 +678,14 @@ namespace {
template <class CRC>
void process_path_lowercase(
std::unordered_set<std::uint32_t>& table
, CRC crc
, char const* str, int len)
, CRC crc, string_view str)
{
if (len == 0) return;
for (int i = 0; i < len; ++i, ++str)
if (str.empty()) return;
for (char const c : str)
{
if (*str == TORRENT_SEPARATOR)
if (c == TORRENT_SEPARATOR)
table.insert(crc.checksum());
crc.process_byte(to_lower(*str) & 0xff);
crc.process_byte(to_lower(c) & 0xff);
}
table.insert(crc.checksum());
}
@ -707,9 +704,7 @@ namespace {
}
for (auto const& p : m_paths)
{
process_path_lowercase(table, crc, p.c_str(), int(p.size()));
}
process_path_lowercase(table, crc, p);
}
std::uint32_t file_storage::file_path_hash(file_index_t const index

11
src/string_util.cpp
View File

@ -140,13 +140,12 @@ namespace libtorrent {
return static_cast<int>(it - target.begin());
}
char* allocate_string_copy(char const* str)
char* allocate_string_copy(string_view str)
{
if (str == nullptr) return nullptr;
std::size_t const len = std::strlen(str);
auto* tmp = new char[len + 1];
std::copy(str, str + len, tmp);
tmp[len] = '\0';
if (str.empty()) return nullptr;
auto* tmp = new char[str.size() + 1];
std::copy(str.data(), str.data() + str.size(), tmp);
tmp[str.size()] = '\0';
return tmp;
}