clock-0.8.2: High-resolution clock functions: monotonic, realtime, cputime.
Safe HaskellSafe-Inferred
LanguageHaskell2010

System.Clock

Description

High-resolution, realtime clock and timer functions for Posix systems. This module is being developed according to IEEE Std 1003.1-2008: http://www.opengroup.org/onlinepubs/9699919799/, http://www.opengroup.org/onlinepubs/9699919799/functions/clock_getres.html#

Synopsis

Documentation

data Clock Source #

Clock types. A clock may be system-wide (that is, visible to all processes) or per-process (measuring time that is meaningful only within a process). All implementations shall support Realtime.

Constructors

Monotonic

The identifier for the system-wide monotonic clock, which is defined as a clock measuring real time, whose value cannot be set via clock_settime and which cannot have negative clock jumps. The maximum possible clock jump shall be implementation defined. For this clock, the value returned by getTime represents the amount of time (in seconds and nanoseconds) since an unspecified point in the past (for example, system start-up time, or the Epoch). This point does not change after system start-up time. Note that the absolute value of the monotonic clock is meaningless (because its origin is arbitrary), and thus there is no need to set it. Furthermore, realtime applications can rely on the fact that the value of this clock is never set. (Identical to Boottime since Linux 4.17, see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d6ed449afdb38f89a7b38ec50e367559e1b8f71f) CLOCK_MONOTONIC (macOS - SYSTEM_CLOCK)

Realtime

The identifier of the system-wide clock measuring real time. For this clock, the value returned by getTime represents the amount of time (in seconds and nanoseconds) since the Epoch. CLOCK_REALTIME (macOS - CALENDAR_CLOCK, Windows - GetSystemTimeAsFileTime)

ProcessCPUTime

The identifier of the CPU-time clock associated with the calling process. For this clock, the value returned by getTime represents the amount of execution time of the current process.

ThreadCPUTime

The identifier of the CPU-time clock associated with the calling OS thread. For this clock, the value returned by getTime represents the amount of execution time of the current OS thread.

MonotonicRaw

(since Linux 2.6.28, macOS 10.12) Similar to Monotonic, but provides access to a raw hardware-based time that is not subject to NTP adjustments or the incremental adjustments performed by adjtime(3). CLOCK_MONOTONIC_RAW (Windows - QueryPerformanceCounter, QueryPerformanceFrequency)

Boottime

(since Linux 2.6.39; Linux-specific) Identical to Monotonic, except it also includes any time that the system is suspended. This allows applications to get a suspend-aware monotonic clock without having to deal with the complications of Realtime, which may have discontinuities if the time is changed using settimeofday(2). (since Linux 4.17; identical to Monotonic) CLOCK_BOOTTIME

MonotonicCoarse

(since Linux 2.6.32; Linux-specific) A faster but less precise version of Monotonic. Use when you need very fast, but not fine-grained timestamps. CLOCK_MONOTONIC_COARSE

RealtimeCoarse

(since Linux 2.6.32; Linux-specific) A faster but less precise version of Realtime. Use when you need very fast, but not fine-grained timestamps. CLOCK_REALTIME_COARSE

Instances

Instances details
Enum Clock Source # 
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Eq Clock Source # 
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Methods

(==) :: Clock -> Clock -> Bool #

(/=) :: Clock -> Clock -> Bool #

Read Clock Source # 
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Show Clock Source # 
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Methods

showsPrec :: Int -> Clock -> ShowS #

show :: Clock -> String #

showList :: [Clock] -> ShowS #

Generic Clock Source # 
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Associated Types

type Rep Clock :: Type -> Type #

Methods

from :: Clock -> Rep Clock x #

to :: Rep Clock x -> Clock #

type Rep Clock Source # 
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Defined in System.Clock

type Rep Clock = D1 ('MetaData "Clock" "System.Clock" "clock-0.8.2-Gn00uvh2IWgKr3x8wn0zeC" 'False) (((C1 ('MetaCons "Monotonic" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "Realtime" 'PrefixI 'False) (U1 :: Type -> Type)) :+: (C1 ('MetaCons "ProcessCPUTime" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "ThreadCPUTime" 'PrefixI 'False) (U1 :: Type -> Type))) :+: ((C1 ('MetaCons "MonotonicRaw" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "Boottime" 'PrefixI 'False) (U1 :: Type -> Type)) :+: (C1 ('MetaCons "MonotonicCoarse" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "RealtimeCoarse" 'PrefixI 'False) (U1 :: Type -> Type))))

data TimeSpec Source #

TimeSpec structure

Constructors

TimeSpec 

Fields

Instances

Instances details
Eq TimeSpec Source # 
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Num TimeSpec Source # 
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Ord TimeSpec Source # 
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Read TimeSpec Source # 
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Show TimeSpec Source # 
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Generic TimeSpec Source # 
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Associated Types

type Rep TimeSpec :: Type -> Type #

Methods

from :: TimeSpec -> Rep TimeSpec x #

to :: Rep TimeSpec x -> TimeSpec #

Storable TimeSpec Source # 
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type Rep TimeSpec Source # 
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type Rep TimeSpec = D1 ('MetaData "TimeSpec" "System.Clock" "clock-0.8.2-Gn00uvh2IWgKr3x8wn0zeC" 'False) (C1 ('MetaCons "TimeSpec" 'PrefixI 'True) (S1 ('MetaSel ('Just "sec") 'SourceUnpack 'SourceStrict 'DecidedStrict) (Rec0 Int64) :*: S1 ('MetaSel ('Just "nsec") 'SourceUnpack 'SourceStrict 'DecidedStrict) (Rec0 Int64)))

getTime :: Clock -> IO TimeSpec Source #

The getTime function shall return the current value for the specified clock.

getRes :: Clock -> IO TimeSpec Source #

The getRes function shall return the resolution of any clock. Clock resolutions are implementation-defined and cannot be set by a process.

fromNanoSecs :: Integer -> TimeSpec Source #

TimeSpec from nano seconds.

toNanoSecs :: TimeSpec -> Integer Source #

TimeSpec to nano seconds.

diffTimeSpec :: TimeSpec -> TimeSpec -> TimeSpec Source #

Compute the absolute difference.

timeSpecAsNanoSecs :: TimeSpec -> Integer Source #

Deprecated: Use toNanoSecs instead! Replaced timeSpecAsNanoSecs with the same signature TimeSpec -> Integer

TimeSpec as nano seconds.