Merge pull request #1397 from embrace-io/telemetry-prioritisation

Implement prioritisation of stored telemetry

embrace-android-delivery/src/main/kotlin/io/embrace/android/embracesdk/internal/delivery/StoredTelemetryComparator.kt

@@ -0,0 +1,22 @@
+package io.embrace.android.embracesdk.internal.delivery
+
+/**
+ * Compares [StoredTelemetryMetadata] in priority order. Our priority rules are:
+ *
+ * Crash > Session
+ * Session > Log
+ * Log > Network
+ * Otherwise, older timestamps take precedence as they are more likely to get deleted if the SDK
+ * runs out of disk space.
+ *
+ * We considered the possibility of starvation & scoring payloads based on age, but we decided
+ * that crashes/sessions are generally far more important so should always be delivered first.
+ */
+internal object StoredTelemetryComparator : Comparator<StoredTelemetryMetadata> {
+
+    override fun compare(lhs: StoredTelemetryMetadata, rhs: StoredTelemetryMetadata): Int {
+        return compareBy(StoredTelemetryMetadata::envelopeType)
+            .thenBy(StoredTelemetryMetadata::timestamp)
+            .compare(lhs, rhs)
+    }
+}

embrace-android-delivery/src/main/kotlin/io/embrace/android/embracesdk/internal/delivery/StoredTelemetryMetadata.kt

@@ -10,8 +10,8 @@ import kotlin.Result.Companion.failure
 class StoredTelemetryMetadata(
     val timestamp: Long,
     val uuid: String,
-    val type: SupportedEnvelopeType,
-    val filename: String = "v1_${timestamp}_${type.description}_$uuid.json"
+    val envelopeType: SupportedEnvelopeType,
+    val filename: String = "v1_${timestamp}_${envelopeType.description}_$uuid.json"
 ) {
 
     companion object {

embrace-android-delivery/src/main/kotlin/io/embrace/android/embracesdk/internal/delivery/SupportedEnvelopeType.kt

@@ -7,12 +7,12 @@ import java.lang.reflect.Type
  * Enumerates the different types of telemetry that are supported when persisting to disk.
  */
 enum class SupportedEnvelopeType(
-    val type: Type,
+    val serializedType: Type,
     val description: String
 ) {
 
-    SESSION(Envelope.sessionEnvelopeType, "session"),
     CRASH(Envelope.logEnvelopeType, "crash"),
+    SESSION(Envelope.sessionEnvelopeType, "session"),
     LOG(Envelope.logEnvelopeType, "log"),
     NETWORK(Envelope.logEnvelopeType, "network");
 

embrace-android-delivery/src/test/kotlin/io/embrace/android/embracesdk/internal/delivery/StoredTelemetryComparatorTest.kt

@@ -0,0 +1,28 @@
+package io.embrace.android.embracesdk.internal.delivery
+
+import io.embrace.android.embracesdk.internal.delivery.SupportedEnvelopeType.CRASH
+import io.embrace.android.embracesdk.internal.delivery.SupportedEnvelopeType.LOG
+import io.embrace.android.embracesdk.internal.delivery.SupportedEnvelopeType.NETWORK
+import io.embrace.android.embracesdk.internal.delivery.SupportedEnvelopeType.SESSION
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class StoredTelemetryComparatorTest {
+
+    private val crash = StoredTelemetryMetadata(1, "crash", CRASH)
+    private val session = StoredTelemetryMetadata(1, "session", SESSION)
+    private val session2 = StoredTelemetryMetadata(100, "session2", SESSION)
+    private val session3 = StoredTelemetryMetadata(1000, "session3", SESSION)
+    private val log = StoredTelemetryMetadata(1, "log", LOG)
+    private val network = StoredTelemetryMetadata(1, "network", NETWORK)
+
+    @Test
+    fun `sort values`() {
+        val result = listOf(network, log, session2, crash, session3, session)
+            .sortedWith(StoredTelemetryComparator)
+            .map(StoredTelemetryMetadata::uuid)
+        val expected = listOf(crash, session, session2, session3, log, network)
+            .map(StoredTelemetryMetadata::uuid)
+        assertEquals(expected, result)
+    }
+}

embrace-android-delivery/src/test/kotlin/io/embrace/android/embracesdk/internal/delivery/StoredTelemetryMetadataTest.kt

@@ -52,7 +52,7 @@ class StoredTelemetryMetadataTest {
                 assertEquals(input, filename)
                 assertEquals(TIMESTAMP, timestamp)
                 assertEquals(UUID, uuid)
-                assertEquals(type, this.type)
+                assertEquals(type, this.envelopeType)
             }
         }
     }