Changes in engine to Remove SyncedResourceEntity from database. (#1902)

* Changes in engine to not store lastupdate per resource in the db anymore for sync purpose

* spotless apply

* Review comment changes

* moved function inline

demo/build.gradle.kts

@@ -47,6 +47,7 @@ dependencies {
  implementation(Dependencies.Androidx.activity)
  implementation(Dependencies.Androidx.appCompat)
  implementation(Dependencies.Androidx.constraintLayout)
+ implementation(Dependencies.Androidx.datastorePref)
  implementation(Dependencies.Androidx.fragmentKtx)
  implementation(Dependencies.Androidx.recyclerView)
  implementation(Dependencies.Androidx.workRuntimeKtx)

demo/src/main/java/com/google/android/fhir/demo/DemoDataStore.kt

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http:https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.android.fhir.demo
+
+import android.content.Context
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.stringPreferencesKey
+import androidx.datastore.preferences.preferencesDataStore
+import com.google.android.fhir.sync.DownloadWorkManager
+import kotlinx.coroutines.flow.first
+import org.hl7.fhir.r4.model.ResourceType
+
+private val Context.dataStorage: DataStore<Preferences> by
+ preferencesDataStore(name = "demo_app_storage")
+
+/**
+ * Stores the lastUpdated timestamp per resource to be used by [DownloadWorkManager]'s
+ * implementation for optimal sync. See
+ * [_lastUpdated](https://build.fhir.org/search.html#_lastUpdated).
+ */
+class DemoDataStore(private val context: Context) {
+
+ suspend fun saveLastUpdatedTimestamp(resourceType: ResourceType, timestamp: String) {
+ context.dataStorage.edit { pref -> pref[stringPreferencesKey(resourceType.name)] = timestamp }
+ }
+
+ suspend fun getLasUpdateTimestamp(resourceType: ResourceType): String? {
+ return context.dataStorage.data.first()[stringPreferencesKey(resourceType.name)]
+ }
+}

demo/src/main/java/com/google/android/fhir/demo/FhirApplication.kt

@@ -35,6 +35,8 @@ class FhirApplication : Application(), DataCaptureConfig.Provider {
 
  private var dataCaptureConfig: DataCaptureConfig? = null
 
+ private val dataStore by lazy { DemoDataStore(this) }
+
  override fun onCreate() {
  super.onCreate()
  if (BuildConfig.DEBUG) {
@@ -69,6 +71,8 @@ class FhirApplication : Application(), DataCaptureConfig.Provider {
 
  companion object {
  fun fhirEngine(context: Context) = (context.applicationContext as FhirApplication).fhirEngine
+
+ fun dataStore(context: Context) = (context.applicationContext as FhirApplication).dataStore
  }
 
  override fun getDataCaptureConfig(): DataCaptureConfig = dataCaptureConfig ?: DataCaptureConfig()

demo/src/main/java/com/google/android/fhir/demo/data/FhirSyncWorker.kt

@@ -27,7 +27,7 @@ class FhirSyncWorker(appContext: Context, workerParams: WorkerParameters) :
  FhirSyncWorker(appContext, workerParams) {
 
  override fun getDownloadWorkManager(): DownloadWorkManager {
- return DownloadWorkManagerImpl()
+ return TimestampBasedDownloadWorkManagerImpl(FhirApplication.dataStore(applicationContext))
  }
 
  override fun getConflictResolver() = AcceptLocalConflictResolver

demo/src/main/java/com/google/android/fhir/demo/data/DownloadWorkManagerImpl.kt → demo/src/main/java/com/google/android/fhir/demo/data/TimestampBasedDownloadWorkManagerImpl.kt

@@ -16,10 +16,14 @@
 
 package com.google.android.fhir.demo.data
 
-import com.google.android.fhir.SyncDownloadContext
+import com.google.android.fhir.demo.DemoDataStore
 import com.google.android.fhir.sync.DownloadWorkManager
 import com.google.android.fhir.sync.SyncDataParams
+import java.time.ZoneId
+import java.time.format.DateTimeFormatter
+import java.util.Date
 import java.util.LinkedList
+import java.util.Locale
 import org.hl7.fhir.exceptions.FHIRException
 import org.hl7.fhir.r4.model.Bundle
 import org.hl7.fhir.r4.model.ListResource
@@ -28,25 +32,29 @@ import org.hl7.fhir.r4.model.Reference
 import org.hl7.fhir.r4.model.Resource
 import org.hl7.fhir.r4.model.ResourceType
 
-class DownloadWorkManagerImpl : DownloadWorkManager {
+class TimestampBasedDownloadWorkManagerImpl(private val dataStore: DemoDataStore) :
+ DownloadWorkManager {
  private val resourceTypeList = ResourceType.values().map { it.name }
  private val urls =
- LinkedList(listOf("Patient?address-city=NAIROBI", "Binary?_id=android-fhir-thermometer-image"))
+ LinkedList(
+ listOf(
+ "Patient?address-city=NAIROBI&_sort=_lastUpdated",
+ "Binary?_id=android-fhir-thermometer-image"
+ )
+ )
 
- override suspend fun getNextRequestUrl(context: SyncDownloadContext): String? {
+ override suspend fun getNextRequestUrl(): String? {
  var url = urls.poll() ?: return null
 
  val resourceTypeToDownload =
  ResourceType.fromCode(url.findAnyOf(resourceTypeList, ignoreCase = true)!!.second)
- context.getLatestTimestampFor(resourceTypeToDownload)?.let {
- url = affixLastUpdatedTimestamp(url!!, it)
+ dataStore.getLasUpdateTimestamp(resourceTypeToDownload)?.let {
+ url = affixLastUpdatedTimestamp(url, it)
  }
  return url
  }
 
- override suspend fun getSummaryRequestUrls(
- context: SyncDownloadContext
- ): Map<ResourceType, String> {
+ override suspend fun getSummaryRequestUrls(): Map<ResourceType, String> {
  return urls.associate {
  ResourceType.fromCode(it.substringBefore("?")) to
  it.plus("&${SyncDataParams.SUMMARY_KEY}=${SyncDataParams.SUMMARY_COUNT_VALUE}")
@@ -86,10 +94,26 @@ class DownloadWorkManagerImpl : DownloadWorkManager {
  // Finally, extract the downloaded resources from the bundle.
  var bundleCollection: Collection<Resource> = mutableListOf()
  if (response is Bundle && response.type == Bundle.BundleType.SEARCHSET) {
- bundleCollection = response.entry.map { it.resource }
+ bundleCollection =
+ response.entry
+ .map { it.resource }
+ .also { extractAndSaveLastUpdateTimestampToFetchFutureUpdates(it) }
  }
  return bundleCollection
  }
+
+ private suspend fun extractAndSaveLastUpdateTimestampToFetchFutureUpdates(
+ resources: List<Resource>
+ ) {
+ resources
+ .groupBy { it.resourceType }
+ .entries.map { map ->
+ dataStore.saveLastUpdatedTimestamp(
+ map.key,
+ map.value.maxOfOrNull { it.meta.lastUpdated }?.toTimeZoneString() ?: ""
+ )
+ }
+ }
 }
 
 /**
@@ -121,3 +145,10 @@ private fun affixLastUpdatedTimestamp(url: String, lastUpdated: String): String
 
  return downloadUrl
 }
+
+private fun Date.toTimeZoneString(): String {
+ val simpleDateFormat =
+ DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSXXX", Locale.getDefault())
+ .withZone(ZoneId.systemDefault())
+ return simpleDateFormat.format(this.toInstant())
+}

engine/src/main/java/com/google/android/fhir/DatastoreUtil.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 Google LLC
+ * Copyright 2022 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,11 +26,10 @@ import java.time.OffsetDateTime
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.runBlocking
 
-val Context.dataStore: DataStore<Preferences> by preferencesDataStore(
- name = "FHIR_ENGINE_PREF_DATASTORE"
-)
+private val Context.dataStore: DataStore<Preferences> by
+ preferencesDataStore(name = "FHIR_ENGINE_PREF_DATASTORE")
 
-class DatastoreUtil(private val context: Context) {
+internal class DatastoreUtil(private val context: Context) {
  private val lastSyncTimestampKey by lazy { stringPreferencesKey("LAST_SYNC_TIMESTAMP") }
 
  fun readLastSyncTimestamp(): OffsetDateTime? {

engine/src/main/java/com/google/android/fhir/FhirEngine.kt

@@ -63,7 +63,7 @@ interface FhirEngine {
  */
  suspend fun syncDownload(
  conflictResolver: ConflictResolver,
- download: suspend (SyncDownloadContext) -> Flow<List<Resource>>
+ download: suspend () -> Flow<List<Resource>>
  )
 
  /**
@@ -127,7 +127,3 @@ suspend inline fun <reified R : Resource> FhirEngine.get(id: String): R {
 suspend inline fun <reified R : Resource> FhirEngine.delete(id: String) {
  delete(getResourceType(R::class.java), id)
 }
-
-interface SyncDownloadContext {
- suspend fun getLatestTimestampFor(type: ResourceType): String?
-}

engine/src/main/java/com/google/android/fhir/db/Database.kt

@@ -20,7 +20,6 @@ import com.google.android.fhir.db.impl.dao.LocalChangeToken
 import com.google.android.fhir.db.impl.dao.SquashedLocalChange
 import com.google.android.fhir.db.impl.entities.LocalChangeEntity
 import com.google.android.fhir.db.impl.entities.ResourceEntity
-import com.google.android.fhir.db.impl.entities.SyncedResourceEntity
 import com.google.android.fhir.search.SearchQuery
 import java.time.Instant
 import org.hl7.fhir.r4.model.Resource
@@ -79,22 +78,12 @@ internal interface Database {
  @Throws(ResourceNotFoundException::class)
  suspend fun selectEntity(type: ResourceType, id: String): ResourceEntity
 
- /**
- * Return the last update data of a resource based on the resource type. If no resource of
- * [resourceType] is inserted, return `null`.
- * @param resourceType The resource type
- */
- suspend fun lastUpdate(resourceType: ResourceType): String?
-
  /**
  * Insert resources that were synchronised.
  *
  * @param syncedResources The synced resource
  */
- suspend fun insertSyncedResources(
- syncedResources: List<SyncedResourceEntity>,
- resources: List<Resource>
- )
+ suspend fun insertSyncedResources(resources: List<Resource>)
 
  /**
  * Deletes the FHIR resource of type `clazz` with `id`.

engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt

@@ -30,7 +30,6 @@ import com.google.android.fhir.db.impl.dao.LocalChangeUtils
 import com.google.android.fhir.db.impl.dao.SquashedLocalChange
 import com.google.android.fhir.db.impl.entities.LocalChangeEntity
 import com.google.android.fhir.db.impl.entities.ResourceEntity
-import com.google.android.fhir.db.impl.entities.SyncedResourceEntity
 import com.google.android.fhir.index.ResourceIndexer
 import com.google.android.fhir.logicalId
 import com.google.android.fhir.search.SearchQuery
@@ -103,7 +102,7 @@ internal class DatabaseImpl(
  it.resourceIndexer = resourceIndexer
  }
  }
- private val syncedResourceDao = db.syncedResourceDao()
+
  private val localChangeDao = db.localChangeDao().also { it.iParser = iParser }
 
  override suspend fun <R : Resource> insert(vararg resource: R): List<String> {
@@ -154,18 +153,8 @@ internal class DatabaseImpl(
  } as Resource
  }
 
- override suspend fun lastUpdate(resourceType: ResourceType): String? {
- return db.withTransaction { syncedResourceDao.getLastUpdate(resourceType) }
- }
-
- override suspend fun insertSyncedResources(
- syncedResources: List<SyncedResourceEntity>,
- resources: List<Resource>
- ) {
- db.withTransaction {
- syncedResourceDao.insertAll(syncedResources)
- insertRemote(*resources.toTypedArray())
- }
+ override suspend fun insertSyncedResources(resources: List<Resource>) {
+ db.withTransaction { insertRemote(*resources.toTypedArray()) }
  }
 
  override suspend fun delete(type: ResourceType, id: String) {

engine/src/main/java/com/google/android/fhir/db/impl/ResourceDatabase.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 Google LLC
+ * Copyright 2022 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +21,6 @@ import androidx.room.RoomDatabase
 import androidx.room.TypeConverters
 import com.google.android.fhir.db.impl.dao.LocalChangeDao
 import com.google.android.fhir.db.impl.dao.ResourceDao
-import com.google.android.fhir.db.impl.dao.SyncedResourceDao
 import com.google.android.fhir.db.impl.entities.DateIndexEntity
 import com.google.android.fhir.db.impl.entities.DateTimeIndexEntity
 import com.google.android.fhir.db.impl.entities.LocalChangeEntity
@@ -31,7 +30,6 @@ import com.google.android.fhir.db.impl.entities.QuantityIndexEntity
 import com.google.android.fhir.db.impl.entities.ReferenceIndexEntity
 import com.google.android.fhir.db.impl.entities.ResourceEntity
 import com.google.android.fhir.db.impl.entities.StringIndexEntity
-import com.google.android.fhir.db.impl.entities.SyncedResourceEntity
 import com.google.android.fhir.db.impl.entities.TokenIndexEntity
 import com.google.android.fhir.db.impl.entities.UriIndexEntity
 
@@ -47,15 +45,14 @@ import com.google.android.fhir.db.impl.entities.UriIndexEntity
  DateIndexEntity::class,
  DateTimeIndexEntity::class,
  NumberIndexEntity::class,
- SyncedResourceEntity::class,
  LocalChangeEntity::class,
- PositionIndexEntity::class],
+ PositionIndexEntity::class
+ ],
  version = 1,
  exportSchema = false
 )
 @TypeConverters(DbTypeConverters::class)
 internal abstract class ResourceDatabase : RoomDatabase() {
  abstract fun resourceDao(): ResourceDao
- abstract fun syncedResourceDao(): SyncedResourceDao
  abstract fun localChangeDao(): LocalChangeDao
 }