blob: 3479a777c2e75994f066c8eea96b7933debb0c8c (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
|
// file : build/timestamp -*- C++ -*-
// copyright : Copyright (c) 2014-2015 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#ifndef BUILD_TIMESTAMP
#define BUILD_TIMESTAMP
#include <chrono>
#include <string>
#include <iosfwd>
#include <build/path>
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&, const timestamp&);
std::ostream&
operator<< (std::ostream&, const 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_mtime (const path&);
};
#endif // BUILD_TIMESTAMP
|
