feat: increase flag polling interval; add flag poller interval config

sdk/src/main/java/com/amplitude/experiment/DefaultExperimentClient.kt

@@ -46,7 +46,7 @@ import com.amplitude.experiment.analytics.ExposureEvent as OldExposureEvent
 
 private const val EU_SERVER_URL = "https://api.lab.eu.amplitude.com/"
 private const val EU_FLAGS_SERVER_URL = "https://flag.lab.eu.amplitude.com/"
-private const val FLAG_POLLER_INTERVAL_MILLIS: Long = 60000
+private const val MIN_FLAG_POLLING_INTERVAL_MILLIS: Long = 60000
 
 internal class DefaultExperimentClient internal constructor(
     private val apiKey: String,
@@ -96,7 +96,19 @@ internal class DefaultExperimentClient internal constructor(
             scalar = 1.5f,
         )
 
-    private val poller: Poller = Poller(this.executorService, ::doFlags, FLAG_POLLER_INTERVAL_MILLIS)
+    internal val flagConfigPollingIntervalMillis =
+        if (config.flagConfigPollingIntervalMillis < MIN_FLAG_POLLING_INTERVAL_MILLIS) {
+            MIN_FLAG_POLLING_INTERVAL_MILLIS
+        } else {
+            config.flagConfigPollingIntervalMillis
+        }
+
+    private val poller: Poller =
+        Poller(
+            this.executorService,
+            ::doFlags,
+            flagConfigPollingIntervalMillis,
+        )
 
     internal val serverUrl: HttpUrl =
         if (config.serverUrl == ExperimentConfig.Defaults.SERVER_URL &&

sdk/src/main/java/com/amplitude/experiment/ExperimentConfig.kt

@@ -46,6 +46,8 @@ class ExperimentConfig internal constructor(
     @JvmField
     val pollOnStart: Boolean = Defaults.POLL_ON_START,
     @JvmField
+    val flagConfigPollingIntervalMillis: Long = Defaults.FLAG_CONFIG_POLLING_INTERVAL_MILLIS,
+    @JvmField
     val fetchOnStart: Boolean = Defaults.FETCH_ON_START,
     @JvmField
     val automaticFetchOnAmplitudeIdentityChange: Boolean = Defaults.AUTOMATIC_FETCH_ON_AMPLITUDE_IDENTITY_CHANGE,
@@ -131,6 +133,11 @@ class ExperimentConfig internal constructor(
          */
         const val POLL_ON_START = true
 
+        /**
+         * 300000
+         */
+        const val FLAG_CONFIG_POLLING_INTERVAL_MILLIS = 300000L
+
         /**
          * null
          */
@@ -179,6 +186,7 @@ class ExperimentConfig internal constructor(
         private var retryFetchOnFailure = Defaults.RETRY_FETCH_ON_FAILURE
         private var automaticExposureTracking = Defaults.AUTOMATIC_EXPOSURE_TRACKING
         private var pollOnStart = Defaults.POLL_ON_START
+        private var flagConfigPollingIntervalMillis = Defaults.FLAG_CONFIG_POLLING_INTERVAL_MILLIS
         private var fetchOnStart = Defaults.FETCH_ON_START
         private var automaticFetchOnAmplitudeIdentityChange = Defaults.AUTOMATIC_FETCH_ON_AMPLITUDE_IDENTITY_CHANGE
         private var userProvider = Defaults.USER_PROVIDER
@@ -250,6 +258,11 @@ class ExperimentConfig internal constructor(
                 this.pollOnStart = pollOnStart
             }
 
+        fun flagConfigPollingIntervalMillis(flagConfigPollingIntervalMillis: Long) =
+            apply {
+                this.flagConfigPollingIntervalMillis = flagConfigPollingIntervalMillis
+            }
+
         fun fetchOnStart(fetchOnStart: Boolean?) =
             apply {
                 this.fetchOnStart = fetchOnStart ?: true
@@ -291,6 +304,7 @@ class ExperimentConfig internal constructor(
                 retryFetchOnFailure = retryFetchOnFailure,
                 automaticExposureTracking = automaticExposureTracking,
                 pollOnStart = pollOnStart,
+                flagConfigPollingIntervalMillis = flagConfigPollingIntervalMillis,
                 fetchOnStart = fetchOnStart,
                 automaticFetchOnAmplitudeIdentityChange = automaticFetchOnAmplitudeIdentityChange,
                 userProvider = userProvider,
@@ -315,6 +329,7 @@ class ExperimentConfig internal constructor(
             .retryFetchOnFailure(retryFetchOnFailure)
             .automaticExposureTracking(automaticExposureTracking)
             .pollOnStart(pollOnStart)
+            .flagConfigPollingIntervalMillis(flagConfigPollingIntervalMillis)
             .fetchOnStart(fetchOnStart)
             .automaticFetchOnAmplitudeIdentityChange((automaticFetchOnAmplitudeIdentityChange))
             .userProvider(userProvider)

sdk/src/test/java/com/amplitude/experiment/ExperimentClientTest.kt

@@ -1295,4 +1295,47 @@ class ExperimentClientTest {
             verify(exactly = retryCalled) { client["startRetries"](any<ExperimentUser>(), any<FetchOptions>()) }
         }
     }
+
+    @Test
+    fun `test flag config polling interval, config not set`() {
+        val client =
+            DefaultExperimentClient(
+                API_KEY,
+                ExperimentConfig(),
+                OkHttpClient(),
+                mockStorage,
+                Experiment.executorService,
+            )
+        Assert.assertEquals(300000, client.flagConfigPollingIntervalMillis)
+    }
+
+    @Test
+    fun `test flag config polling interval, config set under min`() {
+        val client =
+            DefaultExperimentClient(
+                API_KEY,
+                ExperimentConfig(
+                    flagConfigPollingIntervalMillis = 1000,
+                ),
+                OkHttpClient(),
+                mockStorage,
+                Experiment.executorService,
+            )
+        Assert.assertEquals(60000, client.flagConfigPollingIntervalMillis)
+    }
+
+    @Test
+    fun `test flag config polling interval, config set over min`() {
+        val client =
+            DefaultExperimentClient(
+                API_KEY,
+                ExperimentConfig(
+                    flagConfigPollingIntervalMillis = 900000,
+                ),
+                OkHttpClient(),
+                mockStorage,
+                Experiment.executorService,
+            )
+        Assert.assertEquals(900000, client.flagConfigPollingIntervalMillis)
+    }
 }