PerfLogger.kt

package com.booking.debug.performance

import android.os.SystemClock
import android.util.Log

/**
 * Simple class to check the execution time between several execution points across threads.
 * Unlike [TraceCompat](https://developer.android.com/reference/androidx/core/os/TraceCompat)
 * it is not expected to 'begin' and 'end' sections but it will just print the time between
 * the points being tracked.
 *
 * Feel free to tune it for your use case, using milliseconds, nanoseconds,
 *
 * Example:
 * ```
 * val logger = PerfLogger("SearchResults")
 * ...
 * logger.reset()
 * logger.trace("User click")
 * ...
 * logger.trace("Request stared")
 * ...
 * logger.trace("Request sent")
 * ...
 * logger.trace("Response received")
 * ...
 * logger.trace("Response parsed")
 * ...
 * logger.trace("Data processed")
 * ...
 * logger.trace("Data handled")
 *
 * ```
 */
class PerfLogger(private val tag: String) {

    @Volatile
    private var lastAction: String = ""

    @Volatile
    private var lastTime: Long = -1L

    fun trace(action: String) {
        val current = SystemClock.elapsedRealtime()
        if (lastTime >= 0) {
            Log.e(
                tag,
                "%60s - %8d ms -> %60s | %s",
                lastAction,
                current - lastTime,
                action,
                Thread.currentThread()
            )
        }
        lastAction = action
        lastTime = current
    }

    fun reset() {
        lastAction = ""
        lastTime = -1L
    }
}