diff options
| -rw-r--r-- | src/libutil/lazy.hh | 48 | ||||
| -rw-r--r-- | src/libutil/util.cc | 34 |
2 files changed, 18 insertions, 64 deletions
diff --git a/src/libutil/lazy.hh b/src/libutil/lazy.hh deleted file mode 100644 index d073e486c..000000000 --- a/src/libutil/lazy.hh +++ /dev/null @@ -1,48 +0,0 @@ -#include <exception> -#include <functional> -#include <mutex> - -namespace nix { - -/* A helper class for lazily-initialized variables. - - Lazy<T> var([]() { return value; }); - - declares a variable of type T that is initialized to 'value' (in a - thread-safe way) on first use, that is, when var() is first - called. If the initialiser code throws an exception, then all - subsequent calls to var() will rethrow that exception. */ -template<typename T> -class Lazy -{ - - typedef std::function<T()> Init; - - Init init; - - std::once_flag done; - - T value; - - std::exception_ptr ex; - -public: - - Lazy(Init init) : init(init) - { } - - const T & operator () () - { - std::call_once(done, [&]() { - try { - value = init(); - } catch (...) { - ex = std::current_exception(); - } - }); - if (ex) std::rethrow_exception(ex); - return value; - } -}; - -} diff --git a/src/libutil/util.cc b/src/libutil/util.cc index 1a8873136..9804e9a51 100644 --- a/src/libutil/util.cc +++ b/src/libutil/util.cc @@ -1,4 +1,3 @@ -#include "lazy.hh" #include "util.hh" #include "affinity.hh" #include "sync.hh" @@ -522,21 +521,24 @@ std::string getUserName() } -static Lazy<Path> getHome2([]() { - auto homeDir = getEnv("HOME"); - if (!homeDir) { - std::vector<char> buf(16384); - struct passwd pwbuf; - struct passwd * pw; - if (getpwuid_r(geteuid(), &pwbuf, buf.data(), buf.size(), &pw) != 0 - || !pw || !pw->pw_dir || !pw->pw_dir[0]) - throw Error("cannot determine user's home directory"); - homeDir = pw->pw_dir; - } - return *homeDir; -}); - -Path getHome() { return getHome2(); } +Path getHome() +{ + static Path homeDir = []() + { + auto homeDir = getEnv("HOME"); + if (!homeDir) { + std::vector<char> buf(16384); + struct passwd pwbuf; + struct passwd * pw; + if (getpwuid_r(geteuid(), &pwbuf, buf.data(), buf.size(), &pw) != 0 + || !pw || !pw->pw_dir || !pw->pw_dir[0]) + throw Error("cannot determine user's home directory"); + homeDir = pw->pw_dir; + } + return *homeDir; + }(); + return homeDir; +} Path getCacheDir() |