From d871fa3c1ef1ecef17fa7c0871c80734c6abcf9f Mon Sep 17 00:00:00 2001
From: Martin Ndegwa <mndegwa@ona.io>
Date: Wed, 4 Sep 2024 20:34:12 +0300
Subject: [PATCH] Parallelize DB resource deserialization to Optimize Database
 API

---
 .../google/android/fhir/db/impl/DatabaseImpl.kt    | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt b/engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt
index cf8ab22c07..ef8156e790 100644
--- a/engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt
+++ b/engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt
@@ -40,6 +40,9 @@ import com.google.android.fhir.search.SearchQuery
 import com.google.android.fhir.toLocalChange
 import java.time.Instant
 import java.util.UUID
+import kotlinx.coroutines.async
+import kotlinx.coroutines.awaitAll
+import kotlinx.coroutines.coroutineScope
 import org.hl7.fhir.r4.model.Resource
 import org.hl7.fhir.r4.model.ResourceType
 
@@ -205,7 +208,7 @@ internal class DatabaseImpl(
     query: SearchQuery,
   ): List<ResourceWithUUID<R>> {
     return db.withTransaction {
-      resourceDao.getResources(SimpleSQLiteQuery(query.query, query.args.toTypedArray())).map {
+      resourceDao.getResources(SimpleSQLiteQuery(query.query, query.args.toTypedArray())).pmap {
         ResourceWithUUID(it.uuid, iParser.parseResource(it.serializedResource) as R)
       }
     }
@@ -217,7 +220,7 @@ internal class DatabaseImpl(
     return db.withTransaction {
       resourceDao
         .getForwardReferencedResources(SimpleSQLiteQuery(query.query, query.args.toTypedArray()))
-        .map {
+        .pmap {
           ForwardIncludeSearchResult(
             it.matchingIndex,
             it.baseResourceUUID,
@@ -233,7 +236,7 @@ internal class DatabaseImpl(
     return db.withTransaction {
       resourceDao
         .getReverseReferencedResources(SimpleSQLiteQuery(query.query, query.args.toTypedArray()))
-        .map {
+        .pmap {
           ReverseIncludeSearchResult(
             it.matchingIndex,
             it.baseResourceTypeAndId,
@@ -413,6 +416,11 @@ internal class DatabaseImpl(
     }
   }
 
+  /** Implementation of a parallelized map */
+  suspend fun <A, B> Iterable<A>.pmap(f: suspend (A) -> B): List<B> = coroutineScope {
+    map { async { f(it) } }.awaitAll()
+  }
+
   companion object {
     /**
      * The name for unencrypted database.