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authorJulian Andres Klode <jak@debian.org>2016-01-08 01:27:01 +0100
committerJulian Andres Klode <jak@debian.org>2016-01-08 01:30:18 +0100
commit869700d839a1695fe00734592bd504d59386e4b9 (patch)
tree3ad6f069d50aa4d44cc733c11b1231d04df4856b /apt-pkg
parent57590d3c6e6b055402c938c3baebf1d872c58f7e (diff)
pkgCacheGenerator::StoreString: Get rid of std::string
Instead of storing a string -> map_stringitem_t mapping, create our own data type that can point to either a normal string or a string inside the cache. This avoids the creation of any string and improves performance slightly (about 4%).
Diffstat (limited to 'apt-pkg')
-rw-r--r--apt-pkg/pkgcachegen.cc12
-rw-r--r--apt-pkg/pkgcachegen.h34
2 files changed, 34 insertions, 12 deletions
diff --git a/apt-pkg/pkgcachegen.cc b/apt-pkg/pkgcachegen.cc
index 577a6e474..79d633cb7 100644
--- a/apt-pkg/pkgcachegen.cc
+++ b/apt-pkg/pkgcachegen.cc
@@ -1257,23 +1257,21 @@ bool pkgCacheGenerator::SelectFile(std::string const &File,
map_stringitem_t pkgCacheGenerator::StoreString(enum StringType const type, const char *S,
unsigned int Size)
{
- std::string key(S, Size);
-
- std::unordered_map<std::string,map_stringitem_t> * strings;
+ auto strings = &strMixed;
switch(type) {
case MIXED: strings = &strMixed; break;
case PKGNAME: strings = &strPkgNames; break;
case VERSIONNUMBER: strings = &strVersions; break;
case SECTION: strings = &strSections; break;
- default: _error->Fatal("Unknown enum type used for string storage of '%s'", key.c_str()); return 0;
+ default: _error->Fatal("Unknown enum type used for string storage of '%.*s'", Size, S); return 0;
}
- std::unordered_map<std::string,map_stringitem_t>::const_iterator const item = strings->find(key);
+ auto const item = strings->find({S, Size, nullptr, 0});
if (item != strings->end())
- return item->second;
+ return item->item;
map_stringitem_t const idxString = WriteStringInMap(S,Size);
- strings->insert(std::make_pair(std::move(key), idxString));
+ strings->insert({nullptr, Size, this, idxString});
return idxString;
}
/*}}}*/
diff --git a/apt-pkg/pkgcachegen.h b/apt-pkg/pkgcachegen.h
index e4760d44d..d83ea6a25 100644
--- a/apt-pkg/pkgcachegen.h
+++ b/apt-pkg/pkgcachegen.h
@@ -27,7 +27,7 @@
#include <vector>
#include <string>
#if __cplusplus >= 201103L
-#include <unordered_map>
+#include <unordered_set>
#endif
#ifdef APT_PKG_EXPOSE_STRING_VIEW
#include <apt-pkg/string_view.h>
@@ -48,10 +48,34 @@ class APT_HIDDEN pkgCacheGenerator /*{{{*/
// Dirty hack for public users that do not use C++11 yet
#if __cplusplus >= 201103L
- std::unordered_map<std::string,map_stringitem_t> strMixed;
- std::unordered_map<std::string,map_stringitem_t> strSections;
- std::unordered_map<std::string,map_stringitem_t> strPkgNames;
- std::unordered_map<std::string,map_stringitem_t> strVersions;
+ struct string_pointer {
+ const char *data_;
+ size_t size;
+ pkgCacheGenerator *generator;
+ map_stringitem_t item;
+
+ const char *data() const {
+ return data_ != nullptr ? data_ : static_cast<char*>(generator->Map.Data()) + item;
+ }
+
+ bool operator ==(string_pointer const &other) const {
+ return size == other.size && memcmp(data(), other.data(), size) == 0;
+ }
+ };
+ struct hash {
+ uint32_t operator()(string_pointer const &that) const {
+ uint32_t Hash = 5381;
+ const char * const end = that.data() + that.size;
+ for (const char *I = that.data(); I != end; ++I)
+ Hash = 33 * Hash + tolower_ascii((signed char)*I);
+ return Hash;
+ }
+ };
+
+ std::unordered_set<string_pointer, hash> strMixed;
+ std::unordered_set<string_pointer, hash> strPkgNames;
+ std::unordered_set<string_pointer, hash> strVersions;
+ std::unordered_set<string_pointer, hash> strSections;
#endif
friend class pkgCacheListParser;