System.Clock

High-resolution, realtime clock and timer functions for Posix

Documentation

data Clock

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 CLOCK_REALTIME. (The only suspend-aware monotonic is CLOCK_BOOTTIME on Linux.)

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.

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.

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; Linux-specific) Similar to CLOCK_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).

Boottime

(since Linux 2.6.39; Linux-specific) Identical to CLOCK_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 CLOCK_REALTIME, which may have discontinuities if the time is changed using settimeofday(2).

MonotonicCoarse

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

RealtimeCoarse

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

Instances

Enum Clock

Methods

succ :: Clock -> Clock

pred :: Clock -> Clock

toEnum :: Int -> Clock

fromEnum :: Clock -> Int

enumFrom :: Clock -> [Clock]

enumFromThen :: Clock -> Clock -> [Clock]

enumFromTo :: Clock -> Clock -> [Clock]

enumFromThenTo :: Clock -> Clock -> Clock -> [Clock]

Eq Clock

Methods

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

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

Read Clock

Methods

readsPrec :: Int -> ReadS Clock

readList :: ReadS [Clock]

readPrec :: ReadPrec Clock

readListPrec :: ReadPrec [Clock]

Show Clock

Methods

showsPrec :: Int -> Clock -> ShowS

show :: Clock -> String

showList :: [Clock] -> ShowS

Generic Clock

Associated Types

type Rep Clock :: * -> *

Methods

from :: Clock -> Rep Clock x

to :: Rep Clock x -> Clock

type Rep Clock

type Rep Clock = D1 (MetaData "Clock" "System.Clock" "clock-0.7.2-bxVecpUqndAMeayDi5R9Y" False) ((:+:) ((:+:) ((:+:) (C1 (MetaCons "Monotonic" PrefixI False) U1) (C1 (MetaCons "Realtime" PrefixI False) U1)) ((:+:) (C1 (MetaCons "ProcessCPUTime" PrefixI False) U1) (C1 (MetaCons "ThreadCPUTime" PrefixI False) U1))) ((:+:) ((:+:) (C1 (MetaCons "MonotonicRaw" PrefixI False) U1) (C1 (MetaCons "Boottime" PrefixI False) U1)) ((:+:) (C1 (MetaCons "MonotonicCoarse" PrefixI False) U1) (C1 (MetaCons "RealtimeCoarse" PrefixI False) U1))))

data TimeSpec

TimeSpec structure

Constructors

TimeSpec

Fields

• sec :: !Int64

  seconds

• nsec :: !Int64

  nanoseconds

Instances

Eq TimeSpec

Methods

(==) :: TimeSpec -> TimeSpec -> Bool

(/=) :: TimeSpec -> TimeSpec -> Bool

Num TimeSpec

Methods

(+) :: TimeSpec -> TimeSpec -> TimeSpec

(-) :: TimeSpec -> TimeSpec -> TimeSpec

(*) :: TimeSpec -> TimeSpec -> TimeSpec

negate :: TimeSpec -> TimeSpec

abs :: TimeSpec -> TimeSpec

signum :: TimeSpec -> TimeSpec

fromInteger :: Integer -> TimeSpec

Ord TimeSpec

Methods

compare :: TimeSpec -> TimeSpec -> Ordering

(<) :: TimeSpec -> TimeSpec -> Bool

(<=) :: TimeSpec -> TimeSpec -> Bool

(>) :: TimeSpec -> TimeSpec -> Bool

(>=) :: TimeSpec -> TimeSpec -> Bool

max :: TimeSpec -> TimeSpec -> TimeSpec

min :: TimeSpec -> TimeSpec -> TimeSpec

Read TimeSpec

Methods

readsPrec :: Int -> ReadS TimeSpec

readList :: ReadS [TimeSpec]

readPrec :: ReadPrec TimeSpec

readListPrec :: ReadPrec [TimeSpec]

Show TimeSpec

Methods

showsPrec :: Int -> TimeSpec -> ShowS

show :: TimeSpec -> String

showList :: [TimeSpec] -> ShowS

Generic TimeSpec

Associated Types

type Rep TimeSpec :: * -> *

Methods

from :: TimeSpec -> Rep TimeSpec x

to :: Rep TimeSpec x -> TimeSpec

Storable TimeSpec

Methods

sizeOf :: TimeSpec -> Int

alignment :: TimeSpec -> Int

peekElemOff :: Ptr TimeSpec -> Int -> IO TimeSpec

pokeElemOff :: Ptr TimeSpec -> Int -> TimeSpec -> IO ()

peekByteOff :: Ptr b -> Int -> IO TimeSpec

pokeByteOff :: Ptr b -> Int -> TimeSpec -> IO ()

peek :: Ptr TimeSpec -> IO TimeSpec

poke :: Ptr TimeSpec -> TimeSpec -> IO ()

type Rep TimeSpec

type Rep TimeSpec = D1 (MetaData "TimeSpec" "System.Clock" "clock-0.7.2-bxVecpUqndAMeayDi5R9Y" False) (C1 (MetaCons "TimeSpec" PrefixI True) ((:*:) (S1 (MetaSel (Just Symbol "sec") SourceUnpack SourceStrict DecidedUnpack) (Rec0 Int64)) (S1 (MetaSel (Just Symbol "nsec") SourceUnpack SourceStrict DecidedUnpack) (Rec0 Int64))))

getTime :: Clock -> IO TimeSpec

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

getRes :: Clock -> IO TimeSpec

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

TimeSpec from nano seconds.

toNanoSecs :: TimeSpec -> Integer

TimeSpec to nano seconds.

diffTimeSpec :: TimeSpec -> TimeSpec -> TimeSpec

Compute the absolute difference.

timeSpecAsNanoSecs :: TimeSpec -> Integer

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

TimeSpec as nano seconds.