store

package
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 Go to latest Published: Mar 1, 2018 License: Apache-2.0 Imports: 18 Imported by: 12

Documentation

Overview

Package store handles storing metric values in memory.

Index

Constants

This section is empty.

Variables

View Source 
var (
	// AddBatch returns ErrInactive if endpoint is marked inactive.
	ErrInactive = errors.New("store: endpoint inactive.")
)

Functions

func Fetch 

func Fetch(
	p basicPageType,
	start, end float64,
	record *Record,
	result Appender) (keepGoing bool)

Fetch iterates over page data p from time start to time end. Fetch adds the data to result in descending order by time starting just before end and ending on or before start. start and end are seconds after Jan 1 1970. If caller should add more data from previous pages because caller is not back far enough in time, Fetch returns true. Otherwise Fetch returns false.

func FetchForward 

func FetchForward(
	p basicPageType,
	start, end float64,
	record *Record,
	result Appender) (keepGoing bool)

FetchForward works like Fetch but adds data to result in ascending order by time. If caller should continue to subsequent pages FetchForward returns true. Unlike Fetch where caller can start at the last page, it is the caller's responsibility to back up to the right page before calling FetchForward for the first time.

Types

type AppendFlusher 

type AppendFlusher interface {
	Appender
	// Caller must call this after appending all values even if Append
	// returns false
	Flush()
}

type Appender 

type Appender interface {
	// Append appends the contents record r to this instance.
	// Implementations must not hold onto the r pointer as the contents of
	// r may change between calls to Append.
	// Append should return false when it is done accepting records.
	Append(r *Record) bool
}

Appender appends records fetched from a Store to this instance.

func AppendTo 

func AppendTo(result *[]Record) Appender

AppendTo returns an Appender that appends Record instances to result.

func AppenderFilterFunc 

func AppenderFilterFunc(wrapped Appender, filter func(*Record) bool) Appender

AppenderFilterFunc returns an Appender that appends only when the filter function returns true

func AppenderLimit 

func AppenderLimit(wrapped Appender, limit int) Appender

AppenderLimit returns an Appender that appends at most limit items if limit is positve. If limit is 0 or negative, returns wrapped.

type Coordinator 

type Coordinator interface {
	// Lease acquires a lease. When possible, Lease will extend the
	// existing lease to include timeToInclude rather than acquiring a
	// brand new lease. If the current lease already includes timeToInclude,
	// it is returned unchanged. If the current process is not the leader,
	// and Lease must acquire a new lease or extend the existing lease to
	// include timeToInclude, Lease blocks the caller until such time that
	// the current process is elected leader. If Lease must extend the
	// existing lease or acquire a new lease, the returned lease will be
	// at least minSpanInSeconds in length and end at least minSpanInSeconds
	// after timeToInclude.
	Lease(minSpanInSeconds, timeToInclude float64) (
		startTimeInSecondsInclusive, endTimeInSecondsExclusive float64)
}

Coordinator coordinates writes to persistent stores across multiple scotty processes. Each scotty process should have only one coordinator shared among the goroutines writing to persistent store. This one coordinator assigns a lease to the scotty process. The lease gives the scotty process permission to write the metric values with timestamps falling within the lease's time range to persistent store.

The primary purpose of the lease system is to ensure that only one scotty process at any given time is writing to persistent store. We call this one scotty process the leader. Only the leader can acquire a new lease or extend an existing lease. If a non-leader tries to acquire or extend a lease, it blocks until such time that it is elected the leader. Eventually, more than one scotty process may think it is the leader for a short time; therefore, the second purpose of the lease system is to ensure that at most one scotty process writes metric values for each time range. Once a coordinator instance assigns a lease to its scotty process, the time range in that lease forever becomes the responsibility of that process. After that, no other scotty process will ever get a lease with a time range overlapping with the already assigned time range.

If a metric value time stamp comes before the start of the assigned lease, the scotty process should skip writing that particular value as likely the timestamp is the responsibility of another process. If a metric value timestamp falls within the assigned lease, the scotty process may safely write that value at any time as the lease will never be assigned to another process. If a metric value timestamp comes after the assigned lease, the scotty process should request an extension of its lease. If another scotty process is responsible for times after the assigned lease, an extension may not be possible. Whenever an extension can't be granted, the coordinator instance will assign a brand new lease to its scotty process with the earliest possible start time.

Although leases never expire, for simplicity sake, a coordinator instance maintains one and only one active lease for its scotty process. When the coordinator must assign a new lease instead of extending the old one, record of the old lease is gone even though in theory, it is still in effect as no other process will be assigned to it. This forgetting of previous leases is ok because once a scotty process gets a lease, it should maintain its leadership role as long as it is running. Therefore, it will always be able to extend its lease. However, in rare cases, a running scotty process may loose its leadership role over network failures. It is in these rare cases, that the scotty process would be given a brand new lease whenever it regained its leadership role.

Note that while the leasing system that coordinator instances use prevent multiple scotty processes from writing metrics for the same time, it makes no guarantee that values are being written for all times. For instance, a scotty process could die immediately after acquiring or extending a lease but before it can write the values falling within that lease leaving those values forever lost.

type DistributionTotals 

type DistributionTotals struct {
	Counts        []uint64
	Sum           float64
	RollOverCount uint64
}

DistributionTotals represents the distribution count at a given timestamp last recorded DistributionDelta. Instances of this type must be treated as immutable.

func (*DistributionTotals) Count 

func (d *DistributionTotals) Count() (result uint64)

Count returns the total number of values this instance represents.

type Filterer 

type Filterer interface {
	// Filter returns true to include passed metric value false otherwise.
	Filter(*Record) bool
}

Filterer filters metric values.

type FiltererFunc 

type FiltererFunc func(*Record) bool

FiltererFunc is an adapter allowing an ordinary function to be used as a Filterer.

func (FiltererFunc) Filter 

func (f FiltererFunc) Filter(r *Record) bool

type FloatVar 

type FloatVar struct {
	Sum   float64
	Count uint64
}

FloatVar represents a floating point random variable

func (*FloatVar) Add 

func (f *FloatVar) Add(a FloatVar)

Add adds the values in a to this random variable

func (FloatVar) Avg 

func (f FloatVar) Avg() float64

Avg computes the average of this random variable. Returns NaN if this instance is empty (Count == 0).

type Iterator 

type Iterator interface {
	// Next stores the next metric value at r and advances this instance.
	// Next returns false if there are no more values.
	Next(r *Record) bool
}

Iterator iterates over metric values stored in scotty.

func IteratorCoordinate 

func IteratorCoordinate(
	iterator Iterator,
	coord Coordinator,
	minLeaseSpanInSeconds float64,
	skipped *uint64) Iterator

IteratorCoordinate returns an Iterator like given one except that it waits to emit each record until it can obtain a lease for a time range including that record. minLeaseSpanInSeconds is the minimum size of a lease and must be positive. skipped is a pointer to a uint64 that gets incremented each time a record is skipped.

func IteratorFilter 

func IteratorFilter(
	iterator Iterator, filter Filterer) Iterator

IteratorFilter returns an Iterator like the given one except that it yields only metric values for which filter returns true.

func IteratorFilterFunc 

func IteratorFilterFunc(
	iterator Iterator, filter func(*Record) bool) Iterator

IteratorFilterFunc returns an Iterator like the given one except that it yields only metric values for which filter returns true.

type IteratorData 

type IteratorData struct {

	// Approximate maximum timespan of remaining values left to be iterated
	// once returned iterator is exhausted.
	// This second value is approximate because of concurrent access to
	// the store with no exlusive lock.
	RemainingValueInSeconds float64

	// Where this iterator is located within each time series group.
	// 0 means at the earliest time within scotty; 100 means at the most
	// recent time within scotty.
	PercentCaughtUp FloatVar

	// If true, this iterator starts past where last iterator of same name
	// was committed because values were evicted.
	Skipped bool
}

IteratorData contains statistics about a newly created iterator

type MetricGroupingStrategy 

type MetricGroupingStrategy func(*MetricInfo) interface{}

MetricGroupingStrategy type describes the strategy for grouping like metrics together. Two metrics are grouped together if and only if this instance returns equal values for each metric's MetricInfo field. 

var (
	// Groups metrics together if and only if their *MetricInfo field are
	// exactly the same.
	GroupMetricExactly MetricGroupingStrategy = func(m *MetricInfo) interface{} {
		return m
	}

	// Groups metrics together if and only if calling Key() on
	// their *MetricInfo field yields the same result.
	GroupMetricByKey MetricGroupingStrategy = func(m *MetricInfo) interface{} {
		return m.Key()
	}

	// Groups metrics together by their path and whether or not they
	// are numeric
	GroupMetricByPathAndNumeric MetricGroupingStrategy = func(
		m *MetricInfo) interface{} {
		return pathAndNumeric{
			Path:      m.Path(),
			IsNumeric: m.Kind().CanToFromFloat(),
		}
	}
)

func (MetricGroupingStrategy) Equal 

func (m MetricGroupingStrategy) Equal(
	maybeNilLeft, maybeNilRight *MetricInfo) bool

Equal returns true if and only if this strategy would group two metrics with the given MetricInfo fields together.

type MetricInfo 

type MetricInfo struct {
	// contains filtered or unexported fields
}

MetricInfo represents the meta data for a metric MetricInfo instances are immutable by contract MetricInfo instances must always support equality

func (*MetricInfo) Bits 

func (m *MetricInfo) Bits() int

The number of bits. Only set for Int and Uint, and Float metrics.

func (*MetricInfo) Description 

func (m *MetricInfo) Description() string

Description returns the description of the metric

func (*MetricInfo) GroupId 

func (m *MetricInfo) GroupId() int

The group ID of this metric

func (*MetricInfo) IsNotCumulative 

func (m *MetricInfo) IsNotCumulative() bool

IsNotCumulative returns true when Kind() == types.Dist and distribution is not cumulative. Returns false in all other cases.

func (*MetricInfo) Key 

func (m *MetricInfo) Key() interface{}

Key returns the key for this instance. Two MetricInfo instances return equal keys if and only if they are the same except for their group id.

func (*MetricInfo) Kind 

func (m *MetricInfo) Kind() types.Type

Kind returns the kind of the metric

func (*MetricInfo) Path 

func (m *MetricInfo) Path() string

Path returns the path of the metric

func (*MetricInfo) Ranges 

func (m *MetricInfo) Ranges() *Ranges

Ranges returns the ranges of the distribution when Kind() == types.Dist, otherwise returns nil.

func (*MetricInfo) SubType 

func (m *MetricInfo) SubType() types.Type

func (*MetricInfo) Unit 

func (m *MetricInfo) Unit() units.Unit

Unit returns the unit of the metric

func (*MetricInfo) ValuesAreEqual 

func (m *MetricInfo) ValuesAreEqual(lhs, rhs interface{}) bool

ValuesAreEqual returns true if lhs is equivalent to rhs. lhs and rhs must be values from the metric having this information.

type MetricInfoBuilder 

type MetricInfoBuilder struct {
	Path            string
	Description     string
	Unit            units.Unit
	Kind            types.Type
	SubType         types.Type
	Ranges          *Ranges
	IsNotCumulative bool
	GroupId         int
}

MetricInfoBuilder creates a brand new MetricInfo instance from scratch. Used for testing.

func (*MetricInfoBuilder) Build 

func (m *MetricInfoBuilder) Build() *MetricInfo

func (*MetricInfoBuilder) Init 

func (m *MetricInfoBuilder) Init(info *MetricInfo)

Init initializes this builder from an existing MetricInfo instance.

type NamedIterator 

type NamedIterator interface {
	// Name returns the name of the iterator.
	Name() string
	// Next stores the next metric value at r and advances this instance.
	// Next returns false if either there are no more values or it is
	// time to commit.
	Next(r *Record) bool
	// Commit permanently stores the progress of this instance so that
	// creating an iterator with the same name to iterate over the same
	// items will continue where this instance left off.
	// If caller does not call commit and then creates another iterator
	// with the same name to iterate over the same items, that new
	// iterator will start in the same place as this iterator and
	// attempt to visit the same values.
	Commit()
}

NamedIterator iterates over metric values stored in scotty. It is safe to use NamedIterator while new values are being added to scotty.

NamedIterator may report no more values before finishing. However, if the caller commits the progress, creating a new iterator with the same name to iterate over the same items will continue where the previous iterator left off. Put another way, the new iterator will not visit any of the values that the previous iterator visited.

As the name is used to track progress, a caller should create at most one NamedIterator with a particular name at a time to iterate over the same group of items. If the caller creates multiple NamedIterator instances with the same name to iterate over the same group of items and calls Commit on all of them, the last iterator to save its progress wins overwriting the progress of the others with its own.

func NamedIteratorCoordinate 

func NamedIteratorCoordinate(
	ni NamedIterator,
	coord Coordinator,
	minLeaseSpanInSeconds float64,
	updateSkipped func(uint64)) NamedIterator

NamedIteratorCoordinate returns an Iterator like given one except that it waits to emit each record until it can obtain a lease for a time range including that record. minLeaseSpanInSeconds is the minimum size of a lease and must be positive. Calling Commit on returned result calls updateSkipped with the number of records skipped since the last commit.

func NamedIteratorFilter 

func NamedIteratorFilter(
	ni NamedIterator, filter Filterer) NamedIterator

NamedIteratorFilter returns an Iterator like the given one except that it yields only metric values for which filter returns true. If filter is a TypeFilterer, the returned NamedIterator will apply opitimisations if possible.

func NamedIteratorFilterFunc 

func NamedIteratorFilterFunc(
	ni NamedIterator, filter func(*Record) bool) NamedIterator

NamedIteratorFilterFunc returns an Iterator like the given one except that it yields only metric values for which filter returns true.

type Ranges 

type Ranges struct {
	// The upper limits of the buckets.
	UpperLimits []float64
}

Ranges depicts the ranges for a distributions. Instances of this type must be treated as immutable

type Record 

type Record struct {
	EndpointId interface{}
	Info       *MetricInfo
	TimeStamp  float64
	// The equivalent of 0 for inactive flags.
	// If Value contains a reference type, as is the case for lists or
	// distributions, client code must treat what it references as
	// immutable.
	Value interface{}
	// true if active, false if an inactive flag
	Active bool
}

Record represents one value for one particular metric at a particular time.

type Store 

type Store struct {
	// contains filtered or unexported fields
}

Store is an in memory store of metrics. Client must register all the endpoints with the Store instance before storing any metrics. Store instances may be safely used with multiple goroutines as long they don't call RegisterEndpoint.

func NewStore 

func NewStore(
	valueCount,
	pageCount uint,
	inactiveThreshhold float64,
	degree uint) *Store

NewStore returns a new Store instance. valueCount is how many timestamp value pairs can fit on a page. pageCount is the number of pages in this store and remains constant. inactiveThreshhold is the minimum ratio (0-1) of pages that need to be in the high priority queue before they are reclaimed before the other pages. degree is the degree of the btrees (see github.com/Symantec/btree)

func NewStoreBytesPerPage 

func NewStoreBytesPerPage(
	bytesPerPage,
	pageCount uint,
	inactiveThreshhold float64,
	degree uint) *Store

NewStoreBytesPerPage returns a new Store instance. bytesPerPage is the size of a single page in bytes. pageCount is the number of pages in this store and remains constant. inactiveThreshhold is the minimum ratio (0-1) of pages that need to be in the high priority queue before they are reclaimed before the other pages. degree is the degree of the btrees (see github.com/Symantec/btree)

func (*Store) AddBatch 

func (s *Store) AddBatch(
	endpointId interface{},
	timestamp float64,
	metricList metrics.List) (numAdded uint, err error)

AddBatch adds metric values. AddBatch returns the total number of metric values added including any inactive flags. If endpoint is inactive, AddBatch returns err = ErrInactive. AddBatch uses timestamp for all new values in metricList. timestamp is seconds since Jan 1, 1970 GMT. If a time series already in the given endpoint does not have a new value in metricList, then AddBatch marks that time series as inactive by adding an inactive flag to it. That time series remains inactive until a subsequent call to AddBatch gives it a new value. The store may reuse pages used by an inactive time series more quickly than other pages.

timestamp is the timestamp from scotty and is provided in case metricList is missing timestamps.

func (*Store) ByEndpoint 

func (s *Store) ByEndpoint(
	endpointId interface{},
	start, end float64,
	result Appender)

ByEndpoint returns records for a metrics by endpoint and start and end times. ByEndpoint will go back just before start when possible so that the value of the metrics is known at time start. start and end are seconds after Jan 1, 1970 GMT ByEndpoint appends the records to result first grouped by metric exactly then sorted by time in descending order within each metric.

func (*Store) ByEndpointStrategy 

func (s *Store) ByEndpointStrategy(
	endpointId interface{},
	start, end float64,
	strategy MetricGroupingStrategy,
	result Appender)

ByEndpointStrategy work like ByEndpoint except that it appends records grouped by given strategy sorted from latest to earliest.

func (*Store) ByNameAndEndpoint 

func (s *Store) ByNameAndEndpoint(
	path string,
	endpointId interface{},
	start, end float64,
	result Appender)

ByNameAndEndpoint returns records for a metric by path and endpoint and start and end times. ByNameAndEndpoint will go back just before start when possible so that the value of the metric is known at time start. start and end are seconds after Jan 1, 1970 GMT ByNameAndEndpoint appends the records to result first grouped by metric exactly then sorted by time in descending order within each group. It is possible, but unlikely, that two different metrics exist with the same path. This could happen if the definition of a metric changes.

func (*Store) ByNameAndEndpointStrategy 

func (s *Store) ByNameAndEndpointStrategy(
	path string,
	endpointId interface{},
	start, end float64,
	strategy MetricGroupingStrategy,
	result Appender)

ByNameAndEndpointStrategy work like ByNameAndEndpoint except that it appends records grouped by given strategy sorted from latest to earliest.

func (*Store) ByPrefixAndEndpoint 

func (s *Store) ByPrefixAndEndpoint(
	prefix string,
	endpointId interface{},
	start, end float64,
	result Appender)

ByPrefixAndEndpoint returns records for metrics by endpoint and start and end times with paths that start with prefix. ByPrefixAndEndpoint will go back just before start when possible so that the value of the metric is known at time start. start and end are seconds after Jan 1, 1970 GMT ByPrefixAndEndpoint appends the records to result first grouped by metric exactly then sorted by time in descending order within each group. It is possible, but unlikely, that two different metrics exist with the same path. This could happen if the definition of a metric changes.

func (*Store) ByPrefixAndEndpointStrategy 

func (s *Store) ByPrefixAndEndpointStrategy(
	prefix string,
	endpointId interface{},
	start, end float64,
	strategy MetricGroupingStrategy,
	result Appender)

ByPrefixAndEndpointStrategy work like ByPrefixAndEndpoint except that it appends records grouped by given strategy sorted from latest to earliest.

func (*Store) Earliest 

func (s *Store) Earliest(name string, endpointId interface{}) float64

Earliest returns the earliest time for which a particular time series on a particular endpoint is valid. If no pages have been evicted from the time series or if no such time series exists, Earliest just returns 0.0

func (*Store) Endpoints 

func (s *Store) Endpoints() []interface{}

Endpoints returns all the endpoints in this store

func (*Store) FreeUpBytes 

func (s *Store) FreeUpBytes(bytesToFree uint64)

FreeUpBytes attempts to free up bytesToFree bytes by releasing pages.

func (*Store) IsEndpointActive 

func (s *Store) IsEndpointActive(endpointId interface{}) bool

IsEndpointActive returns true if given endpoint is active.

func (*Store) IsExpanding 

func (s *Store) IsExpanding() bool

IsExpanding returns true if the store allocates new pages as needed or false if it recycles existing pages.

func (*Store) IsRegistered 

func (s *Store) IsRegistered(endpointId interface{}) bool

IsRegistered returns true if given endpoint is registered.

func (*Store) LatestByEndpoint 

func (s *Store) LatestByEndpoint(
	endpointId interface{},
	result Appender)

LatestByEndpoint returns the latest records for each metric for a given endpoint. LatestByEndpoint appends the records to result in no particular order.

func (*Store) LatestByPrefixAndEndpointStrategy 

func (s *Store) LatestByPrefixAndEndpointStrategy(
	prefix string,
	endpointId interface{},
	strategy MetricGroupingStrategy,
	result Appender)

LatestByEndpointStraegy returns the latest record for each metric group in no particular order.

func (*Store) LessenPageCount 

func (s *Store) LessenPageCount(ratio float64)

LessenPageCount reduces the number of pages this store uses by ratio, a value between 0.0 and 1.0 exclusive. If the store is using 1 million pages and ratio is 0.1, then LessenPageCount will remove 100K pages from the system leaving only 900K pages once it returns.

For now we don't use this in our current memory management strategy. TODO: See if it is safe to remove this code.

func (*Store) MarkEndpointActive 

func (s *Store) MarkEndpointActive(endpointId interface{})

MarkEndpointActive marks given endpoint as active.

func (*Store) MarkEndpointInactive 

func (s *Store) MarkEndpointInactive(
	timestamp float64, endpointId interface{})

MarkEndpointInactive marks all time series for given endpint as inactive by adding an inactive flag with given timestamp to each time series. timestamp is seconds since Jan 1, 1970 GMT. The store may reuse pages used by an inactive time series more quickly than other pages.

func (*Store) NamedIteratorForEndpoint 

func (s *Store) NamedIteratorForEndpoint(
	name string,
	endpointId interface{},
	maxFrames uint) (iterator NamedIterator, data IteratorData)

NamedIteratorForEndpoint returns an iterator for the given name that iterates over metric values for all known timestamps for the given endpoint. Since the name is used to track progress of iterating over the given endpoint, caller should avoid creating two iterators with the same name iterating over the same endpoint at the same time. Although returned iterator iterates over values and timestamps in no particular order, it will iterate over values of the same metric by increasing timestamp. For now, this method uses the store.GroupMetricByPathAndNumeric strategy to determine whether or not two metrics are the same.

If maxFrames = 0, the returned iterator will make best effort to iterate over all the metric values in the endpoint. A positive maxFrames hints to the returned iterator that it should iterate over at most maxFrames values per metric. Returned iterator is free to iterate over fewer than maxFrames values for a metric even if that metric has additional values. Caller must commit progress and create a new iterator with the same name for the same endpoint to see the rest of the values.

func (*Store) NamedIteratorForEndpointRollUp 

func (s *Store) NamedIteratorForEndpointRollUp(
	name string,
	endpointId interface{},
	dur time.Duration,
	maxFrames uint,
	strategy MetricGroupingStrategy) (
	iterator NamedIterator, data IteratorData)

NamedIteratorForEndpointRollUp works like NamedItgeratorForEndpoint except that instead of reporting every individual value for each metric, it reports summarised values by averaging / rolling up values for each time period.

NamedIteratorForEndpointRollUp summarises values by averaging the values for each time period and emits each average with the start time of the corresponding time period. When averaging integer values, it rounds the average to the nearest integer. For non-numeric values such as strings, it summarises by reporting the first encountered value with the start timestamp of each time period. It ignores any inactive flags encountered when summarising values.

For each metric, NamedIteratorForEndpointRollUp reports at most one value for each time period. If a metric has no values or has only inactive flag(s) for a given time period, NamedIteratorForEndpointRollUp reports no value for that metric during that time period.

As described in the NamedIterator documentation, the name is used to track progress for iterating over the given endpoint. Therefore, caller should avoid having two iterators at once with the same name iterating over the same endpoint even if one iterator comes from this method while the other comes from NamedIteratorForEndpoint.

dur is the length of the time periods. For example, dur = 5 * time.Minute means use time periods 12:00-12:05; 12:05-12:10; 12:15-12:20. Each time period includes the lower bound and excludes the upper bound. For example, 12:15-12:20 includes 12:15 but not 12:20. To avoid confusion, dur should evenly divide 1 minute or 1 hour. dur = 2*time.Minute, dur = 3*time.Minute, dur = 4*time.Minute, and dur = 6*time.Minute are all good choices. dur = 7*time.Minute is not.

If maxFrames = 0, NamedIteratorForEndpointRollUp makes best effort to report the rest of the unreported summarised values. A positive maxFrames hints to the returned iterator that it should iterate over at most maxFrames time periods, not values, per metric.

strategy describes how NamedIteratorForEndpointRollUp groups metrics for aggregation. Generally, caller will pass store.GroupMetricByPathAndNumeric, but if a persistent store writer wishes to store additional metric data in rolled up metrics besides just its path, it will need to use a different strategy.

To avoid reporting summarised values for a time period before all the values are in, NamedIteratorForEndpointRollup will not report a summarised value for a given time period for a metric unless values for a later time period for that same metric are present.

func (*Store) RegisterEndpoint 

func (s *Store) RegisterEndpoint(endpointId interface{})

RegisterEndpoint registers a new endpoint.

func (*Store) RegisterMetrics 

func (s *Store) RegisterMetrics(d *tricorder.DirectorySpec) error

RegisterMetrics registers metrics under d associated with this Store instance Calling this covers any new store created by calling ShallowCopy on this instance.

func (*Store) SetExpanding 

func (s *Store) SetExpanding(expanding bool)

SetExpanding controls wither or not the store allocates new pages as needed (true) or tries to recycle existing pages (false)

func (*Store) SetIteratorTo 

func (s *Store) SetIteratorTo(
	endpointId interface{}, destName, srcName string)

SetIteratorTo sets the position of future iterators named destName to be the same as future iterators named srcName. Commiting an existing iterator named destName after making this call will have no effect.

func (*Store) ShallowCopy 

func (s *Store) ShallowCopy() *Store

ShallowCopy returns a shallow copy of this store. In an environment with multiple goroutines, a client can create a shallow copy to safely register more endpoints without creating data races.

func (*Store) StartAtBeginning 

func (s *Store) StartAtBeginning(endpointId interface{}, names ...string)

StartAtBeginning removes the stored state for iterators with given names.

func (*Store) TsdbTimeSeries 

func (s *Store) TsdbTimeSeries(
	name string,
	endpointId interface{},
	start, end float64) (result tsdb.TimeSeries, earliest float64, ok bool)

TsdbTimeSeries returns the time series with given name from given endpoint.

If no such metric exists for given endpoint, TsdbTimeSeries returns false instead of true for the second argument.

name is the name of the time series; endpointId identifies the endpoint. start and end are seconds since Jan 1, 1970 and denote the start time inclusive and the end time exclusive.

TsdbTimeSeries only works on time series with numeric values. For other time series, it returns (nil, false) as if the time series were not found. If multiple time series with different numeric types exist for the same name, TsdbTimeSeries merges them together in the result as floats. Any inactive flags found are not reflected in returned value.

func (*Store) VisitAllEndpoints 

func (s *Store) VisitAllEndpoints(v Visitor) error

VisitAllEndpoints visits each endpoint registered with this instance. If v.Visit() returns a non-nil error, VisitAllEndpoints returns that same error immediately.

type TypeFilterer 

type TypeFilterer interface {
	// If FilterByType returns false then Filter should return false for
	// any value from that metric for consistency. However, if FilterByType
	// returns true, the Filter method may stil return false.
	Filterer
	// FilterByType returns true if values of a given metric should
	// be included.
	FilterByType(info *MetricInfo) bool
}

TypeFilterer filters by metric type. Using filters that implement this interface provide for special optimisations. For intance, using filters of this type allow skipping and entire time series rather than visiting a time series while filtering out every value in. Using these filters allows scotty to traverse values not written to persistent storage up to 5X faster.

type TypeFiltererFuncActiveOnly 

type TypeFiltererFuncActiveOnly func(*MetricInfo) bool

TypeFilterFuncActiveOnly converts a function filtering by metric type into a TypeFilterer.

func (TypeFiltererFuncActiveOnly) Filter 

func (f TypeFiltererFuncActiveOnly) Filter(r *Record) bool

Filter returns true if and only if f returns true for the metric type and the metric value is flagged as active.

func (TypeFiltererFuncActiveOnly) FilterByType 

func (f TypeFiltererFuncActiveOnly) FilterByType(m *MetricInfo) bool

FilterByType returns true if and only if f returns true.

type Visitor 

type Visitor interface {

	// Called once for each endpoint registered with the Store instance
	Visit(store *Store, endpoint interface{}) error
}

Visitor visits endpoints registered with a Store instance.

Source Files

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Directories

Path Synopsis
Package btreepq implements a queue of pages for scotty based on btrees.
 Package btreepq implements a queue of pages for scotty based on btrees.

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