From 985e8f5f28da87be779b80942577f088321024af Mon Sep 17 00:00:00 2001 From: Boris Kolpackov Date: Fri, 5 Dec 2014 13:26:29 +0200 Subject: Add support for starting processes, getting file timestamps g++-4.9 -std=c++11 -I.. -o bd bd.cxx process.cxx timestamp.cxx --- build/timestamp | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 build/timestamp (limited to 'build/timestamp') diff --git a/build/timestamp b/build/timestamp new file mode 100644 index 0000000..6ed2f2c --- /dev/null +++ b/build/timestamp @@ -0,0 +1,52 @@ +// file : build/timestamp -*- C++ -*- +// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC +// license : MIT; see accompanying LICENSE file + +#ifndef BUILD_TIMESTAMP +#define BUILD_TIMESTAMP + +#include +#include +#include + +namespace build +{ + // On all three main platforms that we target (GNU/Linux, Windows (both + // VC++ and GCC/MinGW64), and MacOS X) with recent C++ runtimes, + // system_clock has nanoseconds resolution and counts from the UNIX + // epoch. The latter is important since struct stat also returns times + // based on UNIX epoch. + // + // The underlying type for nanoseconds duration is signed integer type + // of at least 64 bits (currently int64_t). Because it is signed, we + // will overflow in year 2262 but by then the underlying type will + // most likely have changed to something larger than 64-bit. + // + // So to support other platforms that could possibly use a different + // system_clock resolutions (e.g., microseconds), we actually not going + // to assume anywhere (except perhaps timestamp.cxx) that we are dealing + // with nanoseconds or the 64-bit underlying type. + // + using std::chrono::system_clock; + + using timestamp = system_clock::time_point; + using duration = system_clock::duration; + + const timestamp timestamp_unknown {duration {-1}}; + const timestamp timestamp_nonexistent {duration {0}}; + + std::ostream& + operator<< (std::ostream&, timestamp); + + std::ostream& + operator<< (std::ostream&, duration); + + // Returns timestamp_nonexistent if the entry at the specified path + // does not exist. All other errors are reported by throwing + // std::system_error. + // + timestamp + path_timestamp (const std::string&); +}; + +#endif // BUILD_TIMESTAMP -- cgit v1.1