GeneralUtils.swift

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

import Foundation

/**
 Assertion for checking that the call is being made on the main thread.

 - parameter message: Message to display in case of assertion.
 */
public func assertIsMainThread(_ message: String) {
    assert(Thread.isMainThread, message)
}

// Simple timer for manual profiling. Not for production use.
// Prints only if timing is longer than a threshold (to reduce noisy output).
open class PerformanceTimer {
    let startTime: CFAbsoluteTime
    var endTime: CFAbsoluteTime?
    let threshold: Double
    let label: String
    
    public init(thresholdSeconds: Double = 0.001, label: String = "") {
        self.threshold = thresholdSeconds
        self.label = label
        startTime = CFAbsoluteTimeGetCurrent()
    }

    public func stopAndPrint() {
        if let t = stop() {
            print("Ran for \(t) seconds. [\(label)]")
        }
    }

    public func stop() -> String? {
        endTime = CFAbsoluteTimeGetCurrent()
        if let duration = duration {
            return "\(duration)"
        }
        return nil
    }

    public var duration: CFAbsoluteTime? {
        if let endTime = endTime {
            let time = endTime - startTime
            return time > threshold ? time : nil
        } else {
            return nil
        }
    }
}