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Commit d3f8fc56 authored by Ioana Alexandru's avatar Ioana Alexandru
Browse files

Implement hit-ratio dumping for NotifCollectionCache 

This will allow us to keep an eye on whether we end up with too many
cache misses.

Bug: 371174789
Test: NotifCollectionCacheTest for the counters, but the actual printing
isn't tested yet, we can test it manually in a follow-up
Flag: EXEMPT logging only change

Change-Id: Ie7eef8c733ca96c979e2c82b1ca3be3a2a864d8b
parent f0ccc4f7

packages/SystemUI/multivalentTests/src/com/android/systemui/statusbar/notification/collection/NotifCollectionCacheTest.kt

+26 −0
Original line number Diff line number Diff line
@@ -202,5 +202,31 @@ class NotifCollectionCacheTest : SysuiTestCase() { 
        assertNotNull(noLivesCache.cache[C])

    }



    @Test

    fun hitsAndMisses_areAccurate() {

        val fetch = { key: String -> key }



        // Construct the cache

        assertThat(underTest.getOrFetch(A, fetch)).isEqualTo(A)

        assertThat(underTest.getOrFetch(B, fetch)).isEqualTo(B)

        assertThat(underTest.getOrFetch(C, fetch)).isEqualTo(C)

        assertThat(underTest.hits.get()).isEqualTo(0)

        assertThat(underTest.misses.get()).isEqualTo(3)



        // Verify that further calls count as hits

        underTest.getOrFetch(A, fetch)

        underTest.getOrFetch(A, fetch)

        underTest.getOrFetch(B, fetch)

        underTest.getOrFetch(C, fetch)

        assertThat(underTest.hits.get()).isEqualTo(4)

        assertThat(underTest.misses.get()).isEqualTo(3)



        // Verify that a miss is counted again if the entries are cleared

        underTest.clear()

        underTest.getOrFetch(A, fetch)

        assertThat(underTest.hits.get()).isEqualTo(4)

        assertThat(underTest.misses.get()).isEqualTo(4)

    }



    private fun <V> NotifCollectionCache<V>.getLives(key: String) = this.cache[key]?.lives

}

packages/SystemUI/src/com/android/systemui/statusbar/notification/collection/NotifCollectionCache.kt

+35 −1
Original line number Diff line number Diff line
@@ -16,10 +16,17 @@ 


package com.android.systemui.statusbar.notification.collection



import android.annotation.SuppressLint

import com.android.internal.annotations.VisibleForTesting

import com.android.systemui.Dumpable

import com.android.systemui.util.asIndenting

import com.android.systemui.util.printCollection

import com.android.systemui.util.time.SystemClock

import com.android.systemui.util.time.SystemClockImpl

import com.android.systemui.util.withIncreasedIndent

import java.io.PrintWriter

import java.util.concurrent.ConcurrentHashMap

import java.util.concurrent.atomic.AtomicInteger



/**

 * A cache in which entries can "survive" getting purged [retainCount] times, given consecutive
@@ -29,13 +36,18 @@ import java.util.concurrent.ConcurrentHashMap 
 * resolve (such as drawables, or things that require binder calls). As such, [getOrFetch] is

 * recommended to be run on a background thread, while [purge] can be done from any thread.

 */

@SuppressLint("DumpableNotRegistered") // this will be dumped by container classes

class NotifCollectionCache<V>(

    private val retainCount: Int = 1,

    private val purgeTimeoutMillis: Long = 1000L,

    private val systemClock: SystemClock = SystemClockImpl(),

) {

) : Dumpable {

    @get:VisibleForTesting val cache = ConcurrentHashMap<String, CacheEntry>()



    // Counters for cache hits and misses to be used to calculate and dump the hit ratio

    @get:VisibleForTesting val misses = AtomicInteger(0)

    @get:VisibleForTesting val hits = AtomicInteger(0)



    init {

        if (retainCount < 0) {

            throw IllegalArgumentException("retainCount cannot be negative")
@@ -102,11 +114,13 @@ class NotifCollectionCache<V>( 
    fun getOrFetch(key: String, fetch: (String) -> V): V {

        val entry = cache[key]

        if (entry != null) {

            hits.incrementAndGet()

            // Refresh lives on access

            entry.resetLives()

            return entry.value

        }



        misses.incrementAndGet()

        val value = fetch(key)

        cache[key] = CacheEntry(key, value)

        return value
@@ -151,4 +165,24 @@ class NotifCollectionCache<V>( 
    fun clear() {

        cache.clear()

    }



    override fun dump(pwOrig: PrintWriter, args: Array<out String>) {

        val pw = pwOrig.asIndenting()



        pw.println("$TAG(retainCount = $retainCount, purgeTimeoutMillis = $purgeTimeoutMillis)")

        pw.withIncreasedIndent {

            pw.printCollection("keys present in cache", cache.keys.stream().sorted().toList())



            val misses = misses.get()

            val hits = hits.get()

            pw.println(

                "cache hit ratio = ${(hits.toFloat() / (hits + misses)) * 100}% " +

                    "($hits hits, $misses misses)"

            )

        }

    }



    companion object {

        const val TAG = "NotifCollectionCache"

    }

}