From: Julian Andres Klode Date: Tue, 27 Sep 2016 22:05:31 +0000 (+0200) Subject: debListParser: Micro-optimize AvailableDescriptionLanguages() X-Git-Tag: 1.4_beta1~17 X-Git-Url: https://git.saurik.com/apt.git/commitdiff_plain/c0723bf1a60daf45096998d4ae9feee3c44343f8?ds=inline debListParser: Micro-optimize AvailableDescriptionLanguages() Generating a string for each version we see is somewhat inefficient. The problem here is that the Description tag names are longer than 15 byte, and thus require an allocation on the heap, which we should avoid. It seems reasonable that 20 characters works for all languages codes used for archive descriptions, but if not, there's a warning, so we'll catch that. This should improve performance by about 2%. --- diff --git a/apt-pkg/deb/deblistparser.cc b/apt-pkg/deb/deblistparser.cc index 15251bce4..ea4d8e063 100644 --- a/apt-pkg/deb/deblistparser.cc +++ b/apt-pkg/deb/deblistparser.cc @@ -254,18 +254,17 @@ std::vector debListParser::AvailableDescriptionLanguages() std::vector const understood = APT::Configuration::getLanguages(); std::vector avail; static constexpr int prefixLen = 12; - static constexpr int avgLanguageLen = 5; - std::string tagname; - - tagname.reserve(prefixLen + avgLanguageLen); - tagname.assign("Description-"); + char buf[32] = "Description-"; if (Section.Exists("Description") == true) avail.push_back(""); for (std::vector::const_iterator lang = understood.begin(); lang != understood.end(); ++lang) { - tagname.resize(prefixLen); - tagname.append(*lang); - if (Section.Exists(tagname) == true) + if (unlikely(lang->size() > sizeof(buf) - prefixLen)) { + _error->Warning("Ignoring translated description %s", lang->c_str()); + continue; + } + memcpy(buf + prefixLen, lang->c_str(), lang->size()); + if (Section.Exists(StringView(buf, prefixLen + lang->size())) == true) avail.push_back(*lang); } return avail;