This class takes on the duties of CLOCK_MONOTONIC, a time without a
defined reference point that always increases. This informs some
important design decisions about the class API: MonotonicTime cannot be
constructed from external time data, except as a computation based on
other monotonic time, or the current monotonic time. Importantly, there
is no default constructor, since the reference point of monotonic time
is unspecified and therefore without meaning as a default.
The current use of monotonic time (via Duration) includes some potential
problems that may be caught when we move most to all code to
MonotonicTime in the next commit.
The API restrictions have one important relaxation:
Kernel::TimeManagement is allowed to exchange raw time data within
MonotonicTime freely. This is required for the clock-agnostic time
accessors for timeouts and syscalls, as well as creating monotonic time
data from hardware in the first place.
This is a generic wrapper for a time instant relative to the unix epoch,
and does not account for leap seconds. It should be used in place of
Duration in most current cases.
This is a trivial change, and since this batch of commits will make a
large-scale rebuild necessary anyways, it seems sensible. The feature is
useful for e.g. building compound constant durations at compile time in
a readable way.
That's what this class really is; in fact that's what the first line of
the comment says it is.
This commit does not rename the main files, since those will contain
other time-related classes in a little bit.
This allows us to make all comparision operators on the class constexpr
without pulling in a bunch of boilerplate. We don't use the `<compare>`
header because it doesn't compile in the main serenity cross-build due
to the include paths to LibC being incompatible with how libc++ expects
them to be for clang builds.
This is the initial port of Lagom to win32. This will enable developers
to use Lagom as an alternative to vanilla STL/StandardC++Library - which
gives a much richer environment (think QtCore - but modern).
My main incentive - is to have a native Windows Ladybird working.
I am starting with AK, which does not yet fully compile (on mingw). When
AK is compiling (currently fails building StringBuffer.cpp) - I will
continue to LibCore and then the rest of the user space libraries
(excluding the GUI, which will be another different effort).
Most of the code is happily stollen from Andrew Kaster's fork - he
deserves the credit.
Co-authored-by: Andrew Kaster <akaster@serenityos.org>
In the quest of removing as timespec / timeval usage in the Userland as
possible, we need a way to conveniently retrieving the current clock
time from the kernel and storing it in `AK::Time` format.
Problem:
- Function local `constexpr` variables do not need to be
`static`. This consumes memory which is unnecessary and can prevent
some optimizations.
- C-style arrays are not as safe as AK::Arrays and require the user to
specify the length of the array manually.
Solution:
- Remove `static` keyword.
- Change from C-style array for AK::Array.
We had some inconsistencies before:
- Sometimes "The", sometimes "the"
- Sometimes trailing ".", sometimes no trailing "."
I picked the most common one (lowecase "the", trailing ".") and applied
it to all copyright headers.
By using the exact same string everywhere we can ensure nothing gets
missed during a global search (and replace), and that these
inconsistencies are not spread any further (as copyright headers are
commonly copied to new files).
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
By making the Time constructor constexpr we can optimize creating a
Time instance from hardcoded values.
Also add more functions to convert between Time and various time units.
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
The implementation in LibC did a timestamp->day-of-week conversion
which looks like a valuable thing to have. But we only need it in
time_to_tm, where we already computed year/month/day -- so let's
consolidate on the day_of_week function in DateTime (which is
getting extracted to AK).
The JS tests pointed out that the implementation in DateTime
had an off-by-one in the month when doing the leap year check,
so this change fixes that bug.
