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AK: Implement C++ 'Time' type for easier time-calculations

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This adds a bunch of code in the hope that other, wrong code can be deleted.

Related to #5315.
This commit is contained in:
Ben Wiederhake 2021-02-14 18:01:12 +01:00 committed by Andreas Kling
parent b374dd03bd
commit bd6be910e5
Notes: sideshowbarker 2024-07-18 21:48:18 +09:00 
Author: https://github.com/BenWiederhake
Commit: https://github.com/SerenityOS/serenity/commit/bd6be910e5e
Pull-request: https://github.com/SerenityOS/serenity/pull/5323
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/bgianfo
4 changed files with 386 additions and 0 deletions
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1
AK/Tests/CMakeLists.txt
View file

@ -41,6 +41,7 @@ set(AK_TEST_SOURCES
TestString.cpp
TestStringUtils.cpp
TestStringView.cpp
TestTime.cpp
TestTrie.cpp
TestTypeTraits.cpp
TestTypedTransfer.cpp

205
AK/Tests/TestTime.cpp Normal file
View file

@ -0,0 +1,205 @@
/*
* Copyright (c) 2021, Ben Wiederhake <BenWiederhake.GitHub@gmx.de>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/TestSuite.h>
#include <AK/Time.h>
#include <sys/time.h>
#define EXPECT_TIME(t, s, ns) \
do { \
auto ts = (t).to_timespec(); \
EXPECT_EQ(ts.tv_sec, (s)); \
EXPECT_EQ(ts.tv_nsec, (ns)); \
} while (0)
TEST_CASE(is_sane)
{
auto t0 = Time::from_seconds(0);
auto t2 = Time::from_seconds(2);
auto t5 = Time::from_seconds(5);
auto tn3 = Time::from_seconds(-3);
EXPECT(t0 == t0);
EXPECT(t2 == t2);
EXPECT(t5 == t5);
EXPECT(t0 != t2);
EXPECT(t2 != tn3);
EXPECT(t2 != t5);
EXPECT_TIME(t0, 0, 0);
EXPECT_TIME(t2, 2, 0);
EXPECT_TIME(t5, 5, 0);
EXPECT_TIME(t2 + t5, 7, 0);
EXPECT_TIME(tn3 + t2, -1, 0);
EXPECT_TIME(tn3 + t5, 2, 0);
}
TEST_CASE(limits)
{
EXPECT_TIME(Time::min(), (i64)-0x8000'0000'0000'0000, 0);
EXPECT_TIME(Time::max(), 0x7fff'ffff'ffff'ffff, 999'999'999);
}
TEST_CASE(seconds_parsing)
{
EXPECT_TIME(Time::from_seconds(0), 0, 0);
EXPECT_TIME(Time::from_seconds(42), 42, 0);
EXPECT_TIME(Time::from_seconds(-1), -1, 0);
// "6.4.4.1.5: The type of an integer constant is the first of the corresponding list in which its value can be represented."
// In the case of "0x8000'0000", the list is "int, unsigned int, …", and unsigned int (u32) matches.
// Then the unary minus: On unsigned 32-bit integers, -0x8000'0000 == 0x8000'0000, which only then is made signed again.
// So we would pass a medium-large *positive* number to 'from_seconds', which is not what we want to test here.
// That's why this is the only place that needs an "LL" suffix.
EXPECT_TIME(Time::from_seconds(-0x8000'0000LL), -0x8000'0000LL, 0);
EXPECT_TIME(Time::from_seconds(-0x8000'0000'0000'0000), (i64)-0x8000'0000'0000'0000, 0);
EXPECT_TIME(Time::from_seconds(0x7fff'ffff'ffff'ffff), 0x7fff'ffff'ffff'ffff, 0);
}
TEST_CASE(timespec_parsing)
{
EXPECT_TIME(Time::from_timespec(timespec { 2, 4 }), 2, 4);
EXPECT_TIME(Time::from_timespec(timespec { 1234, 5678 }), 1234, 5678);
EXPECT_TIME(Time::from_timespec(timespec { 0, 1'000'000'000 }), 1, 0);
EXPECT_TIME(Time::from_timespec(timespec { 8, 2'000'000'000 }), 10, 0);
EXPECT_TIME(Time::from_timespec(timespec { 0, 2'147'483'647 }), 2, 147'483'647);
EXPECT_TIME(Time::from_timespec(timespec { 1, -1 }), 0, 999'999'999);
EXPECT_TIME(Time::from_timespec(timespec { 0, -1 }), -1, 999'999'999);
EXPECT_TIME(Time::from_timespec(timespec { -1, 0 }), -1, 0);
EXPECT_TIME(Time::from_timespec(timespec { -1, 1'000'000'001 }), 0, 1);
EXPECT_TIME(Time::from_timespec(timespec { -2, 2'000'000'003 }), 0, 3);
EXPECT_TIME(Time::from_timespec(timespec { -2, 1'999'999'999 }), -1, 999'999'999);
EXPECT_TIME(Time::from_timespec(timespec { 0x7fff'ffff'ffff'fffe, 999'999'998 }), 0x7fff'ffff'ffff'fffe, 999'999'998);
EXPECT_TIME(Time::from_timespec(timespec { 0x7fff'ffff'ffff'fffe, 1'999'999'998 }), 0x7fff'ffff'ffff'ffff, 999'999'998);
EXPECT_TIME(Time::from_timespec(timespec { 0x7fff'ffff'ffff'fffe, 1'999'999'999 }), 0x7fff'ffff'ffff'ffff, 999'999'999);
EXPECT_TIME(Time::from_timespec(timespec { 0x7fff'ffff'ffff'fffe, 2'000'000'000 }), 0x7fff'ffff'ffff'ffff, 999'999'999);
EXPECT_TIME(Time::from_timespec(timespec { -0x7fff'ffff'ffff'fffe, -1 }), -0x7fff'ffff'ffff'ffff, 999'999'999);
EXPECT_TIME(Time::from_timespec(timespec { -0x7fff'ffff'ffff'fffe, -999'999'999 }), -0x7fff'ffff'ffff'ffff, 1);
EXPECT_TIME(Time::from_timespec(timespec { -0x7fff'ffff'ffff'fffe, -1'999'999'999 }), (i64)-0x8000'0000'0000'0000, 1);
EXPECT_TIME(Time::from_timespec(timespec { -0x7fff'ffff'ffff'fffe, -2'000'000'000 }), (i64)-0x8000'0000'0000'0000, 0);
EXPECT_TIME(Time::from_timespec(timespec { -0x7fff'ffff'ffff'fffe, -2'000'000'001 }), (i64)-0x8000'0000'0000'0000, 0);
}
TEST_CASE(timeval_parsing)
{
EXPECT_TIME(Time::from_timeval(timeval { 2, 4 }), 2, 4'000);
EXPECT_TIME(Time::from_timeval(timeval { 1234, 5'678 }), 1234, 5'678'000);
EXPECT_TIME(Time::from_timeval(timeval { -123, -45'678 }), -124, 954'322'000);
EXPECT_TIME(Time::from_timeval(timeval { 0, 1'000'000 }), 1, 0);
EXPECT_TIME(Time::from_timeval(timeval { 0, 1'000'000'000 }), 1'000, 0);
EXPECT_TIME(Time::from_timeval(timeval { 8, 2'000'000 }), 10, 0);
EXPECT_TIME(Time::from_timeval(timeval { 0, 2'147'483'647 }), 2'147, 483'647'000);
EXPECT_TIME(Time::from_timeval(timeval { 1, -1 }), 0, 999'999'000);
EXPECT_TIME(Time::from_timeval(timeval { 0, -1 }), -1, 999'999'000);
EXPECT_TIME(Time::from_timeval(timeval { -1, 0 }), -1, 0);
EXPECT_TIME(Time::from_timeval(timeval { -1, 1'000'001 }), 0, 1'000);
EXPECT_TIME(Time::from_timeval(timeval { -2, 2'000'003 }), 0, 3'000);
EXPECT_TIME(Time::from_timeval(timeval { -2, 1'999'999 }), -1, 999'999'000);
EXPECT_TIME(Time::from_timeval(timeval { 0x7fff'ffff'ffff'fffe, 999'998 }), 0x7fff'ffff'ffff'fffe, 999'998'000);
EXPECT_TIME(Time::from_timeval(timeval { 0x7fff'ffff'ffff'fffe, 1'999'998 }), 0x7fff'ffff'ffff'ffff, 999'998'000);
EXPECT_TIME(Time::from_timeval(timeval { 0x7fff'ffff'ffff'fffe, 1'999'999 }), 0x7fff'ffff'ffff'ffff, 999'999'000);
EXPECT_TIME(Time::from_timeval(timeval { 0x7fff'ffff'ffff'fffe, 2'000'000 }), 0x7fff'ffff'ffff'ffff, 999'999'999);
EXPECT_TIME(Time::from_timeval(timeval { -0x7fff'ffff'ffff'fffe, -1 }), -0x7fff'ffff'ffff'ffff, 999'999'000);
EXPECT_TIME(Time::from_timeval(timeval { -0x7fff'ffff'ffff'fffe, -999'999 }), -0x7fff'ffff'ffff'ffff, 1'000);
EXPECT_TIME(Time::from_timeval(timeval { -0x7fff'ffff'ffff'fffe, -1'999'999 }), (i64)-0x8000'0000'0000'0000, 1'000);
EXPECT_TIME(Time::from_timeval(timeval { -0x7fff'ffff'ffff'fffe, -2'000'000 }), (i64)-0x8000'0000'0000'0000, 0);
EXPECT_TIME(Time::from_timeval(timeval { -0x7fff'ffff'ffff'fffe, -2'000'001 }), (i64)-0x8000'0000'0000'0000, 0);
}
#define TIME(s, ns) \
Time::from_timespec(timespec { (s), (ns) })
TEST_CASE(addition)
{
#define EXPECT_ADDITION(s1, ns1, s2, ns2, sr, nsr) \
EXPECT_TIME(TIME(s1, ns1) + TIME(s2, ns2), sr, nsr); \
EXPECT_TIME(TIME(s2, ns2) + TIME(s1, ns1), sr, nsr);
EXPECT_ADDITION(11, 123'456'789, 22, 900'000'000, 34, 23'456'789);
EXPECT_ADDITION(0, 0, 9223372036854775807LL, 999'999'998, 0x7fff'ffff'ffff'ffff, 999'999'998);
EXPECT_ADDITION(0, 1, 9223372036854775807LL, 999'999'998, 0x7fff'ffff'ffff'ffff, 999'999'999);
EXPECT_ADDITION(0, 2, 9223372036854775807LL, 999'999'998, 0x7fff'ffff'ffff'ffff, 999'999'999);
EXPECT_ADDITION(0x80, 40, 0x7fff'ffff'ffff'ff7f, 999'999'958, 0x7fff'ffff'ffff'ffff, 999'999'998);
EXPECT_ADDITION(0x80, 41, 0x7fff'ffff'ffff'ff7f, 999'999'958, 0x7fff'ffff'ffff'ffff, 999'999'999);
EXPECT_ADDITION(0x80, 42, 0x7fff'ffff'ffff'ff7f, 999'999'958, 0x7fff'ffff'ffff'ffff, 999'999'999);
EXPECT_ADDITION(-2, 5, -3, 7, -5, 12);
EXPECT_ADDITION(-2, 999'999'995, -3, 999'999'997, -4, 999'999'992);
EXPECT_ADDITION(-0x7fff'ffff'ffff'ffff, 999'999'995, -1, 6, -0x7fff'ffff'ffff'ffff, 1);
EXPECT_ADDITION(-0x7fff'ffff'ffff'ffff, 999'999'995, -2, 6, (i64)-0x8000'0000'0000'0000, 1);
EXPECT_ADDITION(-0x7fff'ffff'ffff'ffff, 999'999'995, -2, 5, (i64)-0x8000'0000'0000'0000, 0);
EXPECT_ADDITION(-0x7fff'ffff'ffff'ffff, 999'999'995, -2, 4, (i64)-0x8000'0000'0000'0000, 0);
EXPECT_ADDITION((i64)-0x8000'0000'0000'0000, 999'999'995, 0x7fff'ffff'ffff'ffff, 4, -1, 999'999'999);
EXPECT_ADDITION((i64)-0x8000'0000'0000'0000, 999'999'995, 0x7fff'ffff'ffff'ffff, 5, 0, 0);
EXPECT_ADDITION((i64)-0x8000'0000'0000'0000, 999'999'995, 0x7fff'ffff'ffff'ffff, 6, 0, 1);
#undef EXPECT_ADDITION
}
TEST_CASE(subtraction)
{
#define EXPECT_SUBTRACTION(s1, ns1, s2, ns2, sr, nsr) \
EXPECT_TIME(TIME(s1, ns1) - TIME(s2, ns2), sr, nsr);
EXPECT_SUBTRACTION(5, 0, 3, 0, 2, 0);
EXPECT_SUBTRACTION(0, 0, 0, 0, 0, 0);
EXPECT_SUBTRACTION(0, 5, 0, 3, 0, 2);
EXPECT_SUBTRACTION(0x7fff'ffff'ffff'ffff, 999'999'999, 8, 123, 0x7fff'ffff'ffff'fff7, 999'999'876);
EXPECT_SUBTRACTION(1, 0, 0, 999'999'999, 0, 1);
EXPECT_SUBTRACTION(0x7fff'ffff'ffff'ffff, 0, 1, 999'999'999, 0x7fff'ffff'ffff'fffd, 1);
EXPECT_SUBTRACTION(3, 0, 5, 0, -2, 0);
EXPECT_SUBTRACTION(0, 3, 0, 5, -1, 999'999'998);
EXPECT_SUBTRACTION(0, 0, 0x7fff'ffff'ffff'ffff, 999'999'999, (i64)-0x8000'0000'0000'0000, 1);
EXPECT_SUBTRACTION(0, 0, (i64)-0x8000'0000'0000'0000, 0, 0x7fff'ffff'ffff'ffff, 999'999'999);
EXPECT_SUBTRACTION(-1, 999'999'999, (i64)-0x8000'0000'0000'0000, 0, 0x7fff'ffff'ffff'ffff, 999'999'999);
EXPECT_SUBTRACTION(-1, 999'999'998, (i64)-0x8000'0000'0000'0000, 0, 0x7fff'ffff'ffff'ffff, 999'999'998);
EXPECT_SUBTRACTION(123, 456, 123, 455, 0, 1);
EXPECT_SUBTRACTION(123, 456, 123, 456, 0, 0);
EXPECT_SUBTRACTION(123, 456, 123, 457, -1, 999'999'999);
EXPECT_SUBTRACTION(124, 456, 123, 455, 1, 1);
EXPECT_SUBTRACTION(124, 456, 123, 456, 1, 0);
EXPECT_SUBTRACTION(124, 456, 123, 457, 0, 999'999'999);
EXPECT_SUBTRACTION(-0x7fff'ffff'ffff'ffff, 999'999'995, 1, 999'999'994, (i64)-0x8000'0000'0000'0000, 1);
EXPECT_SUBTRACTION(-0x7fff'ffff'ffff'ffff, 999'999'995, 1, 999'999'995, (i64)-0x8000'0000'0000'0000, 0);
EXPECT_SUBTRACTION(-0x7fff'ffff'ffff'ffff, 999'999'995, 1, 999'999'996, (i64)-0x8000'0000'0000'0000, 0);
}
TEST_MAIN(Time)

133
AK/Time.cpp
View file

@ -25,8 +25,18 @@
*/
#include <AK/Assertions.h>
#include <AK/Checked.h>
#include <AK/LogStream.h>
#include <AK/Time.h>
// Make a reasonable guess as to which timespec/timeval definition to use.
// It doesn't really matter, since both are identical.
#ifdef KERNEL
# include <Kernel/UnixTypes.h>
#else
# include <sys/time.h>
#endif
namespace AK {
int day_of_year(int year, unsigned month, int day)
@ -61,4 +71,127 @@ unsigned day_of_week(int year, unsigned month, int day)
return (year + year / 4 - year / 100 + year / 400 + seek_table[month - 1] + day) % 7;
}
ALWAYS_INLINE static i32 sane_mod(i32& numerator, i32 denominator)
{
VERIFY(2 <= denominator && denominator <= 1'000'000'000);
// '%' in C/C++ does not work in the obvious way:
// For example, -9 % 7 is -2, not +5.
// However, we want a representation like "(-2)*7 + (+5)".
i32 dividend = numerator / denominator;
numerator %= denominator;
if (numerator < 0) {
// Does not overflow: different signs.
numerator += denominator;
// Does not underflow: denominator >= 2.
dividend -= 1;
}
return dividend;
}
Time Time::from_timespec(const struct timespec& ts)
{
i32 nsecs = ts.tv_nsec;
i32 extra_secs = sane_mod(nsecs, 1'000'000'000);
return Time::from_half_sanitized(ts.tv_sec, extra_secs, nsecs);
}
Time Time::from_timeval(const struct timeval& tv)
{
i32 usecs = tv.tv_usec;
i32 extra_secs = sane_mod(usecs, 1'000'000);
VERIFY(0 <= usecs && usecs < 1'000'000);
return Time::from_half_sanitized(tv.tv_sec, extra_secs, usecs * 1'000);
}
timespec Time::to_timespec() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
return { static_cast<i64>(m_seconds), static_cast<i32>(m_nanoseconds) };
}
timeval Time::to_timeval() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
return { static_cast<i64>(m_seconds), static_cast<i32>(m_nanoseconds) / 1000 };
}
Time Time::operator+(const Time& other) const
{
VERIFY(m_nanoseconds < 1'000'000'000);
VERIFY(other.m_nanoseconds < 1'000'000'000);
u32 new_nsecs = m_nanoseconds + other.m_nanoseconds;
u32 extra_secs = new_nsecs / 1'000'000'000;
new_nsecs %= 1'000'000'000;
i64 this_secs = m_seconds;
i64 other_secs = other.m_seconds;
// We would like to just add "this_secs + other_secs + extra_secs".
// However, computing this naively may overflow even though the result is in-bounds.
// Example in 8-bit: (-127) + (-2) + (+1) = (-128), which fits in an i8.
// Example in 8-bit, the other way around: (-2) + (127) + (+1) = 126.
// So we do something more sophisticated:
if (extra_secs) {
VERIFY(extra_secs == 1);
if (this_secs != 0x7fff'ffff'ffff'ffff) {
this_secs += 1;
} else if (other_secs != 0x7fff'ffff'ffff'ffff) {
other_secs += 1;
} else {
/* If *both* are INT64_MAX, then adding them will overflow in any case. */
return Time::max();
}
extra_secs = 0;
}
Checked<i64> new_secs { this_secs };
new_secs += other_secs;
if (new_secs.has_overflow()) {
if (other_secs > 0)
return Time::max();
else
return Time::min();
}
return Time { new_secs.value(), new_nsecs };
}
Time Time::operator-(const Time& other) const
{
VERIFY(m_nanoseconds < 1'000'000'000);
VERIFY(other.m_nanoseconds < 1'000'000'000);
if (other.m_nanoseconds)
return *this + Time((i64) ~(u64)other.m_seconds, 1'000'000'000 - other.m_nanoseconds);
if (other.m_seconds != (i64)-0x8000'0000'0000'0000)
return *this + Time(-other.m_seconds, 0);
// Only remaining case: We want to subtract -0x8000'0000'0000'0000 seconds,
// i.e. add a very large number.
if (m_seconds >= 0)
return Time::max();
return Time { (m_seconds + 0x4000'0000'0000'0000) + 0x4000'0000'0000'0000, m_nanoseconds };
}
Time Time::from_half_sanitized(i64 seconds, i32 extra_seconds, u32 nanoseconds)
{
VERIFY(nanoseconds < 1'000'000'000);
if ((seconds <= 0 && extra_seconds > 0) || (seconds >= 0 && extra_seconds < 0)) {
// Opposite signs mean that we can definitely add them together without fear of overflowing i64:
seconds += extra_seconds;
extra_seconds = 0;
}
// Now the only possible way to become invalid is overflowing i64 towards positive infinity:
if (Checked<i64>::addition_would_overflow<i64, i64>(seconds, extra_seconds)) {
if (seconds < 0) {
return Time::min();
} else {
return Time::max();
}
}
return Time { seconds + extra_seconds, nanoseconds };
}
}

47
AK/Time.h
View file

@ -27,6 +27,12 @@
#pragma once
#include <AK/Platform.h>
#include <AK/Types.h>
// Kernel and Userspace pull in the definitions from different places.
// Avoid trying to figure out which one.
struct timeval;
struct timespec;
namespace AK {
@ -66,6 +72,46 @@ inline int years_to_days_since_epoch(int year)
return days;
}
/*
* Represents a time amount in a "safe" way.
* Minimum: 0 seconds, 0 nanoseconds
* Maximum: 2**63-1 seconds, 999'999'999 nanoseconds
* If any operation (e.g. 'from_timeval' or operator-) would over- or underflow, the closest legal value is returned instead.
* Inputs (e.g. to 'from_timespec') are allowed to be in non-normal form (e.g. "1 second, 2'012'345'678 nanoseconds" or "1 second, -2 microseconds").
* Outputs (e.g. from 'to_timeval') are always in normal form.
*/
class Time {
public:
Time(const Time&) = default;
static Time from_seconds(i64 seconds) { return Time(seconds, 0); };
static Time from_timespec(const struct timespec&);
static Time from_timeval(const struct timeval&);
static Time min() { return Time(-0x8000'0000'0000'0000LL, 0); };
static Time zero() { return Time(0, 0); };
static Time max() { return Time(0x7fff'ffff'ffff'ffffLL, 999'999'999); };
timespec to_timespec() const;
timeval to_timeval() const;
bool operator==(const Time& other) const { return this->m_seconds == other.m_seconds && this->m_nanoseconds == other.m_nanoseconds; }
bool operator!=(const Time& other) const { return !(*this == other); }
Time operator+(const Time& other) const;
Time operator-(const Time& other) const;
private:
explicit Time(i64 seconds, u32 nanoseconds)
: m_seconds(seconds)
, m_nanoseconds(nanoseconds)
{
}
static Time from_half_sanitized(i64 seconds, i32 extra_seconds, u32 nanoseconds);
i64 m_seconds;
u32 m_nanoseconds; // Always less than 1'000'000'000
};
template<typename TimevalType>
inline void timeval_sub(const TimevalType& a, const TimevalType& b, TimevalType& result)
{
@ -178,6 +224,7 @@ using AK::day_of_year;
using AK::days_in_month;
using AK::days_in_year;
using AK::is_leap_year;
using AK::Time;
using AK::timespec_add;
using AK::timespec_add_timeval;
using AK::timespec_sub;