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move labels equality check out of critical section in summary/histogr…
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…am (#61)

* move labels equality check out of critical section in summary/histogram

* preconditions, addressing review comments
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@avolokhov
avolokhov authored Aug 31, 2021
1 parent 196573e commit ba329da
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Showing 4 changed files with 168 additions and 54 deletions.
89 changes: 57 additions & 32 deletions Sources/Prometheus/MetricTypes/Histogram.swift
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,12 +6,12 @@ import Dispatch
/// See https://prometheus.io/docs/concepts/metric_types/#Histogram
public struct Buckets: ExpressibleByArrayLiteral {
public typealias ArrayLiteralElement = Double

public init(arrayLiteral elements: Double...) {
self.init(elements)
}
fileprivate init (_ r: [Double]) {

fileprivate init(_ r: [Double]) {
if r.isEmpty {
self = Buckets.defaultBuckets
return
Expand All @@ -24,13 +24,13 @@ public struct Buckets: ExpressibleByArrayLiteral {
assert(Array(Set(r)).sorted(by: <) == r.sorted(by: <), "Buckets contain duplicate values.")
self.buckets = r
}

/// The upper bounds
public let buckets: [Double]

/// Default buckets used by Histograms
public static let defaultBuckets: Buckets = [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10]

/// Create linear buckets used by Histograms
///
/// - Parameters:
Expand All @@ -42,7 +42,7 @@ public struct Buckets: ExpressibleByArrayLiteral {
let arr = (0..<count).map { Double(start) + Double($0) * Double(width) }
return Buckets(arr)
}

/// Create exponential buckets used by Histograms
///
/// - Parameters:
Expand Down Expand Up @@ -88,28 +88,28 @@ public class PromHistogram<NumType: DoubleRepresentable, Labels: HistogramLabels
public let name: String
/// Help text of this Histogram, optional
public let help: String?

/// Type of the metric, used for formatting
public let _type: PromMetricType = .histogram

/// Bucketed values for this Histogram
private var buckets: [PromCounter<NumType, EmptyLabels>] = []

/// Buckets used by this Histogram
internal let upperBounds: [Double]

/// Labels for this Histogram
internal let labels: Labels

/// Sub Histograms for this Histogram
fileprivate var subHistograms: [Labels: PromHistogram<NumType, Labels>] = [:]

/// Total value of the Histogram
private let sum: PromCounter<NumType, EmptyLabels>

/// Lock used for thread safety
private let lock: Lock

/// Creates a new Histogram
///
/// - Parameters:
Expand All @@ -125,18 +125,18 @@ public class PromHistogram<NumType: DoubleRepresentable, Labels: HistogramLabels
self.prometheus = p

self.sum = .init("\(self.name)_sum", nil, 0, p)

self.labels = labels

self.upperBounds = buckets.buckets

self.lock = Lock()

buckets.buckets.forEach { _ in
self.buckets.append(.init("\(name)_bucket", nil, 0, p))
}
}

/// Gets the metric string for this Histogram
///
/// - Returns:
Expand All @@ -147,6 +147,8 @@ public class PromHistogram<NumType: DoubleRepresentable, Labels: HistogramLabels
}

var output = [String]()
// HELP/TYPE + (histogram + subHistograms) * (buckets + sum + count)
output.reserveCapacity(2 + (subHistograms.count + 1) * (buckets.count + 2))

if let help = self.help {
output.append("# HELP \(self.name) \(help)")
Expand Down Expand Up @@ -200,11 +202,9 @@ public class PromHistogram<NumType: DoubleRepresentable, Labels: HistogramLabels
/// - value: Value to observe
/// - labels: Labels to attach to the observed value
public func observe(_ value: NumType, _ labels: Labels? = nil) {
if let labels = labels, type(of: labels) != type(of: EmptySummaryLabels()) {
let his: PromHistogram<NumType, Labels> = self.lock.withLock {
self.getOrCreateHistogram(with: labels)
}
his.observe(value)
if let labels = labels, type(of: labels) != type(of: EmptyHistogramLabels()) {
self.getOrCreateHistogram(with: labels)
.observe(value)
}
self.sum.inc(value)

Expand All @@ -215,7 +215,7 @@ public class PromHistogram<NumType: DoubleRepresentable, Labels: HistogramLabels
}
}
}

/// Time the duration of a closure and observe the resulting time in seconds.
///
/// - parameters:
Expand All @@ -233,14 +233,39 @@ public class PromHistogram<NumType: DoubleRepresentable, Labels: HistogramLabels

/// Helper for histograms & labels
fileprivate func getOrCreateHistogram(with labels: Labels) -> PromHistogram<NumType, Labels> {
let histogram = self.subHistograms[labels]
if let histogram = histogram, histogram.name == self.name, histogram.help == self.help {
let subHistograms = lock.withLock { self.subHistograms }
if let histogram = subHistograms[labels] {
precondition(histogram.name == self.name,
"""
Somehow got 2 subHistograms with the same data type / labels
but different names: expected \(self.name), got \(histogram.name)
""")
precondition(histogram.help == self.help,
"""
Somehow got 2 subHistograms with the same data type / labels
but different help messages: expected \(self.help ?? "nil"), got \(histogram.help ?? "nil")
""")
return histogram
} else {
guard let prometheus = prometheus else { fatalError("Lingering Histogram") }
let newHistogram = PromHistogram(self.name, self.help, labels, Buckets(self.upperBounds), prometheus)
self.subHistograms[labels] = newHistogram
return newHistogram
return lock.withLock {
if let histogram = subHistograms[labels] {
precondition(histogram.name == self.name,
"""
Somehow got 2 subHistograms with the same data type / labels
but different names: expected \(self.name), got \(histogram.name)
""")
precondition(histogram.help == self.help,
"""
Somehow got 2 subHistograms with the same data type / labels
but different help messages: expected \(self.help ?? "nil"), got \(histogram.help ?? "nil")
""")
return histogram
}
guard let prometheus = prometheus else { fatalError("Lingering Histogram") }
let newHistogram = PromHistogram(self.name, self.help, labels, Buckets(self.upperBounds), prometheus)
self.subHistograms[labels] = newHistogram
return newHistogram
}
}
}
}
66 changes: 44 additions & 22 deletions Sources/Prometheus/MetricTypes/Summary.swift
View file
Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,7 @@ public class PromSummary<NumType: DoubleRepresentable, Labels: SummaryLabels>: P
internal let quantiles: [Double]

/// Sub Summaries for this Summary
fileprivate var subSummaries: [PromSummary<NumType, Labels>] = []
fileprivate var subSummaries: [Labels: PromSummary<NumType, Labels>] = [:]

/// Lock used for thread safety
private let lock: Lock
Expand Down Expand Up @@ -100,6 +100,8 @@ public class PromSummary<NumType: DoubleRepresentable, Labels: SummaryLabels>: P
}

var output = [String]()
// HELP/TYPE + (summary + subSummaries) * (quantiles + sum + count)
output.reserveCapacity(2 + (subSummaries.count + 1) * (quantiles.count + 2))

if let help = self.help {
output.append("# HELP \(self.name) \(help)")
Expand All @@ -117,7 +119,7 @@ public class PromSummary<NumType: DoubleRepresentable, Labels: SummaryLabels>: P
output.append("\(self.name)_count\(labelsString) \(self.count.get())")
output.append("\(self.name)_sum\(labelsString) \(format(self.sum.get().doubleValue))")

subSummaries.forEach { subSum in
subSummaries.values.forEach { subSum in
var subSumLabels = subSum.labels
let subSumValues = lock.withLock { subSum.values }
calculateQuantiles(quantiles: self.quantiles, values: subSumValues.map { $0.doubleValue }).sorted { $0.key < $1.key }.forEach { (arg) in
Expand Down Expand Up @@ -162,13 +164,13 @@ public class PromSummary<NumType: DoubleRepresentable, Labels: SummaryLabels>: P
/// - value: Value to observe
/// - labels: Labels to attach to the observed value
public func observe(_ value: NumType, _ labels: Labels? = nil) {
if let labels = labels, type(of: labels) != type(of: EmptySummaryLabels()) {
let sum = self.getOrCreateSummary(withLabels: labels)
sum.observe(value)
}
self.count.inc(1)
self.sum.inc(value)
self.lock.withLock {
if let labels = labels, type(of: labels) != type(of: EmptySummaryLabels()) {
guard let sum = self.prometheus?.getOrCreateSummary(withLabels: labels, forSummary: self) else { fatalError("Lingering Summary") }
sum.observe(value)
}
self.count.inc(1)
self.sum.inc(value)
if self.values.count == self.capacity {
_ = self.values.popFirst()
}
Expand All @@ -190,22 +192,42 @@ public class PromSummary<NumType: DoubleRepresentable, Labels: SummaryLabels>: P
}
return try body()
}
}

extension PrometheusClient {
/// Helper for summaries & labels
fileprivate func getOrCreateSummary<T: Numeric, U: SummaryLabels>(withLabels labels: U, forSummary summary: PromSummary<T, U>) -> PromSummary<T, U> {
let summaries = summary.subSummaries.filter { (metric) -> Bool in
guard metric.name == summary.name, metric.help == summary.help, metric.labels == labels else { return false }
return true
}
if summaries.count > 2 { fatalError("Somehow got 2 summaries with the same data type") }
if let summary = summaries.first {
fileprivate func getOrCreateSummary(withLabels labels: Labels) -> PromSummary<NumType, Labels> {
let subSummaries = self.lock.withLock { self.subSummaries }
if let summary = subSummaries[labels] {
precondition(summary.name == self.name,
"""
Somehow got 2 subSummaries with the same data type / labels
but different names: expected \(self.name), got \(summary.name)
""")
precondition(summary.help == self.help,
"""
Somehow got 2 subSummaries with the same data type / labels
but different help messages: expected \(self.help ?? "nil"), got \(summary.help ?? "nil")
""")
return summary
} else {
let newSummary = PromSummary<T, U>(summary.name, summary.help, labels, summary.capacity, summary.quantiles, self)
summary.subSummaries.append(newSummary)
return newSummary
return lock.withLock {
if let summary = self.subSummaries[labels] {
precondition(summary.name == self.name,
"""
Somehow got 2 subSummaries with the same data type / labels
but different names: expected \(self.name), got \(summary.name)
""")
precondition(summary.help == self.help,
"""
Somehow got 2 subSummaries with the same data type / labels
but different help messages: expected \(self.help ?? "nil"), got \(summary.help ?? "nil")
""")
return summary
}
guard let prometheus = prometheus else {
fatalError("Lingering Summary")
}
let newSummary = PromSummary(self.name, self.help, labels, self.capacity, self.quantiles, prometheus)
self.subSummaries[labels] = newSummary
return newSummary
}
}
}
}
Expand Down
34 changes: 34 additions & 0 deletions Tests/SwiftPrometheusTests/HistogramTests.swift
View file
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,40 @@ final class HistogramTests: XCTestCase {
self.prom = nil
try! self.group.syncShutdownGracefully()
}

func testConcurrent() throws {
let prom = PrometheusClient()
let histogram = prom.createHistogram(forType: Double.self, named: "my_histogram",
helpText: "Histogram for testing",
buckets: Buckets.exponential(start: 1, factor: 2, count: 63),
labels: DimensionHistogramLabels.self)
let elg = MultiThreadedEventLoopGroup(numberOfThreads: 8)
let semaphore = DispatchSemaphore(value: 2)
_ = elg.next().submit {
for _ in 1...1_000 {
let labels = DimensionHistogramLabels([("myValue", "1")])
let labels2 = DimensionHistogramLabels([("myValue", "2")])

histogram.observe(1.0, labels)
histogram.observe(1.0, labels2)
}
semaphore.signal()
}
_ = elg.next().submit {
for _ in 1...1_000 {
let labels = DimensionHistogramLabels([("myValue", "1")])
let labels2 = DimensionHistogramLabels([("myValue", "2")])

histogram.observe(1.0, labels2)
histogram.observe(1.0, labels)
}
semaphore.signal()
}
semaphore.wait()
try elg.syncShutdownGracefully()
XCTAssertTrue(histogram.collect().contains("my_histogram_count 4000.0"))
XCTAssertTrue(histogram.collect().contains("my_histogram_sum 4000.0"))
}

func testHistogramSwiftMetrics() {
let recorder = Recorder(label: "my_histogram")
Expand Down
33 changes: 33 additions & 0 deletions Tests/SwiftPrometheusTests/SummaryTests.swift
View file
Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,39 @@ final class SummaryTests: XCTestCase {
my_summary_sum{myValue="labels"} 123.0\n
""")
}

func testConcurrent() throws {
let prom = PrometheusClient()
let summary = prom.createSummary(forType: Double.self, named: "my_summary",
helpText: "Summary for testing",
labels: DimensionSummaryLabels.self)
let elg = MultiThreadedEventLoopGroup(numberOfThreads: 8)
let semaphore = DispatchSemaphore(value: 2)
_ = elg.next().submit {
for _ in 1...1_000 {
let labels = DimensionSummaryLabels([("myValue", "1")])
let labels2 = DimensionSummaryLabels([("myValue", "2")])

summary.observe(1.0, labels)
summary.observe(1.0, labels2)
}
semaphore.signal()
}
_ = elg.next().submit {
for _ in 1...1_000 {
let labels = DimensionSummaryLabels([("myValue", "1")])
let labels2 = DimensionSummaryLabels([("myValue", "2")])

summary.observe(1.0, labels2)
summary.observe(1.0, labels)
}
semaphore.signal()
}
semaphore.wait()
try elg.syncShutdownGracefully()
XCTAssertTrue(summary.collect().contains("my_summary_count 4000.0"))
XCTAssertTrue(summary.collect().contains("my_summary_sum 4000.0"))
}

func testSummaryWithPreferredDisplayUnit() {
let summary = Timer(label: "my_summary", preferredDisplayUnit: .seconds)
Expand Down

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