Batch writing of records to SQLite store (#498)

apollo-ios/Sources/ApolloSQLite/SQLiteDatabase.swift

@@ -16,14 +16,25 @@ public protocol SQLiteDatabase {
 
   func selectRawRows(forKeys keys: Set<CacheKey>) throws -> [DatabaseRow]
 
-  func addOrUpdateRecordString(_ recordString: String, for cacheKey: CacheKey) throws
-  
+  func addOrUpdate(records: [(cacheKey: CacheKey, recordString: String)]) throws
+
   func deleteRecord(for cacheKey: CacheKey) throws
 
   func deleteRecords(matching pattern: CacheKey) throws
 
   func clearDatabase(shouldVacuumOnClear: Bool) throws
 
+  @available(*, deprecated, renamed: "addOrUpdate(records:)")
+  func addOrUpdateRecordString(_ recordString: String, for cacheKey: CacheKey) throws
+
+}
+
+extension SQLiteDatabase {
+
+  public func addOrUpdateRecordString(_ recordString: String, for cacheKey: CacheKey) throws {
+    try addOrUpdate(records: [(cacheKey, recordString)])
+  }
+
 }
 
 public extension SQLiteDatabase {

apollo-ios/Sources/ApolloSQLite/SQLiteDotSwiftDatabase.swift

@@ -43,11 +43,17 @@ public final class SQLiteDotSwiftDatabase: SQLiteDatabase {
       return DatabaseRow(cacheKey: key, storedInfo: record)
     }
   }
-
-  public func addOrUpdateRecordString(_ recordString: String, for cacheKey: CacheKey) throws {
-    try self.db.run(self.records.insert(or: .replace, self.keyColumn <- cacheKey, self.recordColumn <- recordString))
+
+  public func addOrUpdate(records: [(cacheKey: CacheKey, recordString: String)]) throws {
+    guard !records.isEmpty else { return }
+
+    let setters = records.map {
+      [self.keyColumn <- $0.cacheKey, self.recordColumn <- $0.recordString]
+    }
+
+    try self.db.run(self.records.insertMany(or: .replace, setters))
   }
-  
+
   public func deleteRecord(for cacheKey: CacheKey) throws {
     let query = self.records.filter(keyColumn == cacheKey)
     try self.db.run(query.delete())

apollo-ios/Sources/ApolloSQLite/SQLiteNormalizedCache.swift

@@ -61,17 +61,21 @@ public final class SQLiteNormalizedCache {
     var recordSet = RecordSet(records: try self.selectRecords(for: records.keys))
     let changedFieldKeys = recordSet.merge(records: records)
     let changedRecordKeys = changedFieldKeys.map { self.recordCacheKey(forFieldCacheKey: $0) }
-    for recordKey in Set(changedRecordKeys) {
-      if let recordFields = recordSet[recordKey]?.fields {
-        let recordData = try SQLiteSerialization.serialize(fields: recordFields)
-        guard let recordString = String(data: recordData, encoding: .utf8) else {
-          assertionFailure("Serialization should yield UTF-8 data")
-          continue
+
+    let serializedRecords = try Set(changedRecordKeys)
+      .compactMap { recordKey -> (CacheKey, String)? in
+        if let recordFields = recordSet[recordKey]?.fields {
+          let recordData = try SQLiteSerialization.serialize(fields: recordFields)
+          guard let recordString = String(data: recordData, encoding: .utf8) else {
+            assertionFailure("Serialization should yield UTF-8 data")
+            return nil
+          }
+          return (recordKey, recordString)
         }
-
-        try self.database.addOrUpdateRecordString(recordString, for: recordKey)
+        return nil
       }
-    }
+
+    try self.database.addOrUpdate(records: serializedRecords)
     return Set(changedFieldKeys)
   }