Safe Haskell	None
Language	GHC2021

Ecluse.Core.Rules.Outage

Contents

What one evaluation saw
What the fold produces
A reporter over shared state

Description

Bounded reporting of an advisory source the rules cannot consult. Each advisory-reading evaluation reports what it saw, and the state machine turns that stream into three reports: the outage began, it continues (at most once per period), and it recovered. The outage also records which admissions the gate has logged evidence for, once per identity, so traffic volume cannot multiply the lines. Ecluse.Core.Rules.Outage.Internal holds the fold itself.

Synopsis

data SourceHealth
- = SourceAnswered Text
- | SourceUnavailable Text Reason
data SourceReporter = SourceReporter {
- reportSource :: SourceHealth -> IO ()
- noteAdmission :: AdmissionIdentity -> IO Bool
}
noSourceReporter :: SourceReporter
data OutageState = Healthy
data OutageReport
- = OutageBegan Text Reason
- | OutageContinues UTCTime (Map Text Reason)
- | OutageRecovered UTCTime
data AdmissionIdentity = AdmissionIdentity {
- aiPackage :: Text
- aiVersion :: Text
- aiSkipped :: Set Text
}
data OutageStore
tvarOutageStore :: TVar OutageState -> OutageStore
sourceReporter :: NominalDiffTime -> IO UTCTime -> OutageStore -> (OutageReport -> IO ()) -> SourceReporter

What one evaluation saw

data SourceHealth Source #

What one rule's evaluation established about the source it reads.

Constructors

SourceAnswered Text	The named rule consulted its source, whatever it decided.
SourceUnavailable Text Reason	The named rule could not consult its source, for the given cause.

Instances

Instances details

Show SourceHealth Source #
Instance details Defined in Ecluse.Core.Rules.Outage.Internal Methods showsPrec :: Int -> SourceHealth -> ShowS # show :: SourceHealth -> String # showList :: [SourceHealth] -> ShowS #
Eq SourceHealth Source #
Instance details Defined in Ecluse.Core.Rules.Outage.Internal Methods (==) :: SourceHealth -> SourceHealth -> Bool # (/=) :: SourceHealth -> SourceHealth -> Bool #

data SourceReporter Source #

The observer every advisory-reading evaluation reports to. The composition root installs the live one.

Constructors

SourceReporter
Fields reportSource :: SourceHealth -> IO () Report one evaluation's reading. noteAdmission :: AdmissionIdentity -> IO Bool Whether the gate logs this admission's evidence: once per identity for the life of the outage.

noSourceReporter :: SourceReporter Source #

The inert reporter, for an ecosystem with no advisory source to observe. It logs every admission.

What the fold produces

data OutageState Source #

One source's outage state. It carries no Eq: comparing two states walks the logged record, so a change is decided by the fold that made it, never by comparison.

Constructors

Healthy

Instances

Instances details

Show OutageState Source #
Instance details Defined in Ecluse.Core.Rules.Outage.Internal Methods showsPrec :: Int -> OutageState -> ShowS # show :: OutageState -> String # showList :: [OutageState] -> ShowS #

data OutageReport Source #

The three reports an outage produces, each carrying what an operator line needs.

Constructors

OutageBegan Text Reason	The first rule unable to consult the source, with its cause.
OutageContinues UTCTime (Map Text Reason)	The reminder: when the outage began, and every rule still unable, with its latest cause.
OutageRecovered UTCTime	Every rule consults the source again. Carries when the outage began.

Instances

Instances details

Show OutageReport Source #
Instance details Defined in Ecluse.Core.Rules.Outage.Internal Methods showsPrec :: Int -> OutageReport -> ShowS # show :: OutageReport -> String # showList :: [OutageReport] -> ShowS #
Eq OutageReport Source #
Instance details Defined in Ecluse.Core.Rules.Outage.Internal Methods (==) :: OutageReport -> OutageReport -> Bool # (/=) :: OutageReport -> OutageReport -> Bool #

data AdmissionIdentity Source #

What identifies one admission's evidence line: the package, the version, and the checks it skipped.

Constructors

AdmissionIdentity
Fields aiPackage :: Text aiVersion :: Text aiSkipped :: Set Text The rules skipped for unavailability. A different set is a different line.

Instances

Instances details

Show AdmissionIdentity Source #
Instance details Defined in Ecluse.Core.Rules.Outage.Internal Methods showsPrec :: Int -> AdmissionIdentity -> ShowS # show :: AdmissionIdentity -> String # showList :: [AdmissionIdentity] -> ShowS #
Eq AdmissionIdentity Source #
Instance details Defined in Ecluse.Core.Rules.Outage.Internal Methods (==) :: AdmissionIdentity -> AdmissionIdentity -> Bool # (/=) :: AdmissionIdentity -> AdmissionIdentity -> Bool #
Ord AdmissionIdentity Source #
Instance details Defined in Ecluse.Core.Rules.Outage.Internal Methods compare :: AdmissionIdentity -> AdmissionIdentity -> Ordering # (<) :: AdmissionIdentity -> AdmissionIdentity -> Bool # (<=) :: AdmissionIdentity -> AdmissionIdentity -> Bool # (>) :: AdmissionIdentity -> AdmissionIdentity -> Bool # (>=) :: AdmissionIdentity -> AdmissionIdentity -> Bool # max :: AdmissionIdentity -> AdmissionIdentity -> AdmissionIdentity # min :: AdmissionIdentity -> AdmissionIdentity -> AdmissionIdentity #

A reporter over shared state

data OutageStore Source #

Where one source's outage state lives: a plain read, and a fold committed as one unit.

tvarOutageStore :: TVar OutageState -> OutageStore Source #

The live store: one TVar shared by every mount of an ecosystem.

sourceReporter :: NominalDiffTime -> IO UTCTime -> OutageStore -> (OutageReport -> IO ()) -> SourceReporter Source #

A reporter folding into one source's store. Only a transition or a due reminder commits, so a healthy source costs one read and an unchanged outage one read and one clock reading.