BatchOperation: set "yield allowed" after every 500 operations

Author: rfc2822

lib/src/main/kotlin/at/bitfire/ical4android/BatchOperation.kt

@@ -19,7 +19,15 @@ import java.util.logging.Logger
 class BatchOperation(
     private val providerClient: ContentProviderClient
 ) {
-    
+
+    companion object {
+
+        /** Maximum number of operations per yield point. Taken from SQLiteContentProvider, which most content providers
+         * are based on. */
+        const val MAX_OPERATIONS_PER_YIELD_POINT = 500
+
+    }
+
     private val logger = Logger.getLogger(javaClass.name)
 
     private val queue = LinkedList<CpoBuilder>()
@@ -133,6 +141,7 @@ class BatchOperation(
          * 2. If a back reference points to a row outside of start/end,
          *    replace it by the actual result, which has already been calculated. */
 
+        var currentIdx = 0
         for (cpoBuilder in queue.subList(start, end)) {
             for ((backrefKey, backref) in cpoBuilder.valueBackrefs) {
                 val originalIdx = backref.originalIndex
@@ -148,6 +157,9 @@ class BatchOperation(
                     backref.setIndex(originalIdx - start)
             }
 
+            if (currentIdx++.mod(MAX_OPERATIONS_PER_YIELD_POINT) == 0)
+                cpoBuilder.withYieldAllowed()
+
             cpo += cpoBuilder.build()
         }
         return cpo
@@ -158,7 +170,7 @@ class BatchOperation(
             /** index of the referenced row in the original, nonsplitted transaction */
             val originalIndex: Int
     ) {
-        /** overriden index, i.e. index within the splitted transaction */
+        /** overridden index, i.e. index within the splitted transaction */
         private var index: Int? = null
 
         /**
@@ -182,8 +194,8 @@ class BatchOperation(
      * value back references.
      */
     class CpoBuilder private constructor(
-            val uri: Uri,
-            val type: Type
+        val uri: Uri,
+        val type: Type
     ) {
 
         enum class Type { INSERT, UPDATE, DELETE }
@@ -203,6 +215,8 @@ class BatchOperation(
         val values = mutableMapOf<String, Any?>()
         val valueBackrefs = mutableMapOf<String, BackReference>()
 
+        private var yieldAllowed = false
+
 
         fun withSelection(select: String, args: Array<String>): CpoBuilder {
             selection = select
@@ -226,6 +240,10 @@ class BatchOperation(
             return this
         }
 
+        fun withYieldAllowed() {
+            yieldAllowed = true
+        }
+
 
         fun build(): ContentProviderOperation {
             val builder = when (type) {
@@ -242,6 +260,9 @@ class BatchOperation(
             for ((key, backref) in valueBackrefs)
                 builder.withValueBackReference(key, backref.getIndex())
 
+            if (yieldAllowed)
+                builder.withYieldAllowed(true)
+
             return builder.build()
         }