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Commit fe807fd9 authored by Yurii Zubrytskyi's avatar Yurii Zubrytskyi
Browse files

[incfs] Optimize path::join for appending 

Append path strings to the first argument if it's an rvalue

Bug: 183435580
Test: atest libincfs-test service.incremental_test
Change-Id: I52c4a1f0e4ad3547aeccac96a3393323e3be9adb
parent cb1cc4f5

services/incremental/path.cpp

+8 −7
Original line number Diff line number Diff line
@@ -44,19 +44,20 @@ bool PathLess::operator()(std::string_view l, std::string_view r) const { 
                                        PathCharsLess());

}



static void preparePathComponent(std::string_view& path, bool trimFront) {

    if (trimFront) {

        while (!path.empty() && path.front() == '/') {

static void preparePathComponent(std::string_view& path, bool trimAll) {

    // need to check for double front slash as a single one has a separate meaning in front

    while (!path.empty() && path.front() == '/' &&

           (trimAll || (path.size() > 1 && path[1] == '/'))) {

        path.remove_prefix(1);

    }

    }

    while (!path.empty() && path.back() == '/') {

    // for the back we don't care about double-vs-single slash difference

    while (path.size() > !trimAll && path.back() == '/') {

        path.remove_suffix(1);

    }

}



void details::append_next_path(std::string& target, std::string_view path) {

    preparePathComponent(path, true);

    preparePathComponent(path, !target.empty());

    if (path.empty()) {

        return;

    }

services/incremental/path.h

+15 −5
Original line number Diff line number Diff line
@@ -89,15 +89,25 @@ std::optional<bool> isEmptyDir(std::string_view dir); 
bool startsWith(std::string_view path, std::string_view prefix);



template <class... Paths>

std::string join(std::string_view first, std::string_view second, Paths&&... paths) {

    std::string result;

std::string join(std::string&& first, std::string_view second, Paths&&... paths) {

    std::string& result = first;

    {

        using std::size;

        result.reserve(first.size() + second.size() + 1 + (sizeof...(paths) + ... + size(paths)));

    }

    result.assign(first);

    (details::append_next_path(result, second), ..., details::append_next_path(result, paths));

    return result;

    (details::append_next_path(result, second), ...,

     details::append_next_path(result, std::forward<Paths>(paths)));

    return std::move(result);

}



template <class... Paths>

std::string join(std::string_view first, std::string_view second, Paths&&... paths) {

    return path::join(std::string(), first, second, std::forward<Paths>(paths)...);

}



template <class... Paths>

std::string join(const char* first, std::string_view second, Paths&&... paths) {

    return path::join(std::string_view(first), second, std::forward<Paths>(paths)...);

}



} // namespace android::incremental::path

services/incremental/test/path_test.cpp

+20 −0
Original line number Diff line number Diff line
@@ -40,4 +40,24 @@ TEST(Path, Comparator) { 
    EXPECT_TRUE(!PathLess()("/a/b", "/a"));

}



TEST(Path, Join) {

    EXPECT_STREQ("", path::join("", "").c_str());



    EXPECT_STREQ("/", path::join("", "/").c_str());

    EXPECT_STREQ("/", path::join("/", "").c_str());

    EXPECT_STREQ("/", path::join("/", "/").c_str());

    EXPECT_STREQ("/", path::join("/"s, "/").c_str());

    EXPECT_STREQ("/", path::join("/"sv, "/").c_str());

    EXPECT_STREQ("/", path::join("/", "/", "/", "/", "/", "/", "/", "/", "/", "/").c_str());



    EXPECT_STREQ("/a/b/c/d", path::join("/a/b/"s, "c", "d").c_str());

    EXPECT_STREQ("/a/b/c/d", path::join("/a/b/", "c", "d").c_str());

    EXPECT_STREQ("/a/b/c/d", path::join("/", "a/b/", "c", "d").c_str());

    EXPECT_STREQ("/a/b/c/d", path::join("/", "a/b", "c", "d").c_str());

    EXPECT_STREQ("/a/b/c/d", path::join("/", "//a/b//", "c", "d").c_str());

    EXPECT_STREQ("/a/b/c/d", path::join("", "", "/", "//a/b//", "c", "d").c_str());

    EXPECT_STREQ("/a/b/c/d", path::join(""s, "", "/", "//a/b//", "c", "d").c_str());

    EXPECT_STREQ("/a/b/c/d", path::join("/a/b", "", "", "/", "", "/", "/", "/c", "d").c_str());

}



} // namespace android::incremental::path