From b807ac8cdc3475b3d6dd6fbaf9f4c3f1f8263d10 Mon Sep 17 00:00:00 2001
From: "Brian S. O'Neill" <bronee@gmail.com>
Date: Wed, 31 Dec 2008 20:55:22 +0000
Subject: Revert automatic initial version number if insert fails.

---
 .../com/amazon/carbonado/gen/CodeBuilderUtil.java  | 36 +++++++++++++++++
 .../carbonado/gen/MasterStorableGenerator.java     | 47 ++++++++++++++++++++++
 .../amazon/carbonado/layout/LayoutProperty.java    |  8 ++++
 3 files changed, 91 insertions(+)

diff --git a/src/main/java/com/amazon/carbonado/gen/CodeBuilderUtil.java b/src/main/java/com/amazon/carbonado/gen/CodeBuilderUtil.java
index 82be9f2..f25d6f1 100644
--- a/src/main/java/com/amazon/carbonado/gen/CodeBuilderUtil.java
+++ b/src/main/java/com/amazon/carbonado/gen/CodeBuilderUtil.java
@@ -578,6 +578,42 @@ public class CodeBuilderUtil {
         b.convert(primitiveType, type);
     }
 
+    /**
+     * Generates code to push a blank value to the stack. For objects, it is
+     * null, and for primitive types it is zero or false.
+     */
+    public static void blankValue(CodeBuilder b, TypeDesc type) {
+        switch (type.getTypeCode()) {
+        default:
+            b.loadNull();
+            break;
+
+        case TypeDesc.BYTE_CODE:
+        case TypeDesc.CHAR_CODE:
+        case TypeDesc.SHORT_CODE:
+        case TypeDesc.INT_CODE:
+            b.loadConstant(0);
+            break;
+
+        case TypeDesc.BOOLEAN_CODE:
+            b.loadConstant(false);
+            break;
+
+        case TypeDesc.LONG_CODE:
+            b.loadConstant(0L);
+            break;
+
+        case TypeDesc.FLOAT_CODE:
+            b.loadConstant(0.0f);
+            break;
+
+        case TypeDesc.DOUBLE_CODE:
+
+            b.loadConstant(0.0);
+            break;
+        }
+    }
+
     /**
      * Determines which overloaded "with" method on Query should be bound to.
      */
diff --git a/src/main/java/com/amazon/carbonado/gen/MasterStorableGenerator.java b/src/main/java/com/amazon/carbonado/gen/MasterStorableGenerator.java
index 82d8c7a..21af6cf 100644
--- a/src/main/java/com/amazon/carbonado/gen/MasterStorableGenerator.java
+++ b/src/main/java/com/amazon/carbonado/gen/MasterStorableGenerator.java
@@ -403,12 +403,16 @@ public final class MasterStorableGenerator<S extends Storable> {
 
             Label tryStart = addEnterTransaction(b, INSERT_OP, txnVar);
 
+            LocalVariable wasVersionInitVar = null;
             if (mFeatures.contains(MasterFeature.VERSIONING)) {
                 if (!mInfo.getVersionProperty().isDerived()) {
                     // Only set if uninitialized.
                     b.loadThis();
                     b.invokeVirtual(StorableGenerator.IS_VERSION_INITIALIZED_METHOD_NAME,
                                     TypeDesc.BOOLEAN, null);
+                    wasVersionInitVar = b.createLocalVariable(null, TypeDesc.BOOLEAN);
+                    b.storeLocal(wasVersionInitVar);
+                    b.loadLocal(wasVersionInitVar);
                     Label isInitialized = b.createLabel();
                     b.ifZeroComparisonBranch(isInitialized, "!=");
                     addAdjustVersionProperty(b, null, 1);
@@ -535,6 +539,23 @@ public final class MasterStorableGenerator<S extends Storable> {
 
             b.loadThis();
             b.invokeVirtual(DO_TRY_INSERT_MASTER_METHOD_NAME, TypeDesc.BOOLEAN, null);
+
+            if (wasVersionInitVar != null) {
+                // Decide if version property needs to rollback to uninitialized.
+
+                b.dup();
+                Label noRollback = b.createLabel();
+                // Don't rollback if insert succeeded.
+                b.ifZeroComparisonBranch(noRollback, "!=");
+
+                b.loadLocal(wasVersionInitVar);
+                // Rollback only if version was automatically set.
+                b.ifZeroComparisonBranch(noRollback, "!=");
+                unsetVersionProperty(b);
+
+                noRollback.setLocation();
+            }
+
             addNormalizationRollback(b, doTryStart, unnormalized);
 
             if (tryStart == null) {
@@ -1080,6 +1101,32 @@ public final class MasterStorableGenerator<S extends Storable> {
         b.invoke(versionProperty.getWriteMethod());
     }
 
+    /**
+     * Sets the version property to its initial uninitialized state.
+     */
+    private void unsetVersionProperty(CodeBuilder b) throws SupportException {
+        StorableProperty<?> property = mInfo.getVersionProperty();
+
+        // Set the property state to uninitialized.
+        {
+            String stateFieldName =
+                StorableGenerator.PROPERTY_STATE_FIELD_NAME + (property.getNumber() >> 4);
+            b.loadThis();
+            b.loadThis();
+            b.loadField(stateFieldName, TypeDesc.INT);
+            int shift = (property.getNumber() & 0xf) * 2;
+            b.loadConstant(~(StorableGenerator.PROPERTY_STATE_MASK << shift));
+            b.math(Opcode.IAND);
+            b.storeField(stateFieldName, TypeDesc.INT);
+        }
+
+        // Zero the property value.
+        TypeDesc type = TypeDesc.forClass(property.getType());
+        b.loadThis();
+        CodeBuilderUtil.blankValue(b, type);
+        b.storeField(property.getName(), type);
+    }
+
     private List<PropertyCopy> addNormalization(CodeBuilder b, boolean forUpdate) {
         List<PropertyCopy> unnormalized = null;
 
diff --git a/src/main/java/com/amazon/carbonado/layout/LayoutProperty.java b/src/main/java/com/amazon/carbonado/layout/LayoutProperty.java
index a0ce48f..bf35073 100644
--- a/src/main/java/com/amazon/carbonado/layout/LayoutProperty.java
+++ b/src/main/java/com/amazon/carbonado/layout/LayoutProperty.java
@@ -20,6 +20,7 @@ package com.amazon.carbonado.layout;
 
 import org.cojen.classfile.TypeDesc;
 
+import com.amazon.carbonado.FetchException;
 import com.amazon.carbonado.PersistException;
 import com.amazon.carbonado.SupportException;
 
@@ -187,6 +188,13 @@ public class LayoutProperty {
 
     void store() throws PersistException {
         if (!mStoredLayoutProperty.tryInsert()) {
+            StoredLayoutProperty existing = mStoredLayoutProperty.copy();
+            try {
+                existing.load();
+                existing.copyVersionProperty(mStoredLayoutProperty);
+            } catch (FetchException e) {
+                throw e.toPersistException();
+            }
             mStoredLayoutProperty.update();
         }
     }
-- 
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