Add Copy, IncrementLong, and Composition

megadesk-core/src/main/java/com/liveramp/megadesk/base/transaction/BaseDependency.java

@@ -4,8 +4,10 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Set;
 
 import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
 
 import com.liveramp.megadesk.core.state.Variable;
 import com.liveramp.megadesk.core.transaction.Dependency;
@@ -107,7 +109,7 @@ public Builder reads(Variable[]... dependencies) {
       return reads(concatenate(dependencies));
     }
 
-    public Builder reads(List<Variable> dependencies) {
+    public Builder reads(Collection<Variable> dependencies) {
       this.reads = Lists.newArrayList(dependencies);
       return this;
     }
@@ -120,7 +122,7 @@ public Builder writes(Variable[]... dependencies) {
       return writes(concatenate(dependencies));
     }
 
-    public Builder writes(List<Variable> dependencies) {
+    public Builder writes(Collection<Variable> dependencies) {
       this.writes = Lists.newArrayList(dependencies);
       return this;
     }
@@ -151,11 +153,14 @@ public static Builder builder() {
   }
 
   public static BaseDependency merge(Dependency... dependencies) {
-    Builder builder = BaseDependency.builder();
-    List<VariableDependency> all = Lists.newArrayList();
+    Set<Variable> reads = Sets.newHashSet();
+    Set<Variable> writes = Sets.newHashSet();
     for (Dependency dependency : dependencies) {
-      all.addAll(dependency.all());
+      reads.addAll(dependency.reads());
+      writes.addAll(dependency.writes());
     }
-    return builder.all(all).build();
+    // Promote reads to writes
+    reads.removeAll(Sets.intersection(reads, writes));
+    return BaseDependency.builder().reads(reads).writes(writes).build();
   }
 }

megadesk-recipes/src/main/java/com/liveramp/megadesk/recipes/transaction/Copy.java

@@ -0,0 +1,41 @@
+/**
+ *  Copyright 2014 LiveRamp
+ *
+ *  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://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.liveramp.megadesk.recipes.transaction;
+
+import com.liveramp.megadesk.base.transaction.BaseDependency;
+import com.liveramp.megadesk.base.transaction.BaseTransaction;
+import com.liveramp.megadesk.core.state.Variable;
+import com.liveramp.megadesk.core.transaction.Context;
+
+public class Copy<VALUE> extends BaseTransaction<VALUE> {
+
+  private final Variable<VALUE> source;
+  private final Variable<VALUE> destination;
+
+  public Copy(Variable<VALUE> source, Variable<VALUE> destination) {
+    super(BaseDependency.builder().reads(source).writes(destination).build());
+    this.source = source;
+    this.destination = destination;
+  }
+
+  @Override
+  public VALUE run(Context context) throws Exception {
+    VALUE value = context.read(source);
+    context.write(destination, value);
+    return value;
+  }
+}

megadesk-recipes/src/main/java/com/liveramp/megadesk/recipes/transaction/IncrementLong.java

@@ -0,0 +1,39 @@
+/**
+ *  Copyright 2014 LiveRamp
+ *
+ *  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://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.liveramp.megadesk.recipes.transaction;
+
+import com.liveramp.megadesk.core.state.Variable;
+import com.liveramp.megadesk.core.transaction.Transaction;
+
+public class IncrementLong extends Alter<Long> implements Transaction<Long> {
+
+  private final long increment;
+
+  public IncrementLong(Variable<Long> variable) {
+    this(variable, 1L);
+  }
+
+  public IncrementLong(Variable<Long> variable, long increment) {
+    super(variable);
+    this.increment = increment;
+  }
+
+  @Override
+  protected Long alter(Long value) {
+    return value + increment;
+  }
+}

megadesk-recipes/src/test/java/com/liveramp/megadesk/recipes/transaction/TestComposition.java

@@ -0,0 +1,51 @@
+/**
+ *  Copyright 2014 LiveRamp
+ *
+ *  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://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.liveramp.megadesk.recipes.transaction;
+
+import org.junit.Test;
+
+import com.liveramp.megadesk.base.state.InMemoryLocal;
+import com.liveramp.megadesk.base.transaction.BaseTransactionExecutor;
+import com.liveramp.megadesk.core.state.Variable;
+import com.liveramp.megadesk.core.transaction.TransactionExecutor;
+import com.liveramp.megadesk.test.BaseTestCase;
+
+import static org.junit.Assert.assertEquals;
+
+public class TestComposition extends BaseTestCase {
+
+  @Test
+  public void testMain() throws Exception {
+    TransactionExecutor executor = new BaseTransactionExecutor();
+
+    Variable<Long> v1 = new InMemoryLocal<Long>(0L);
+    Variable<Long> v2 = new InMemoryLocal<Long>(0L);
+    Variable<Long> v3 = new InMemoryLocal<Long>(0L);
+
+    executor.execute(new Composition(
+        new Write<Long>(v1, 1L),
+        new Copy<Long>(v1, v2),
+        new IncrementLong(v2, 2),
+        new Copy<Long>(v2, v3),
+        new IncrementLong(v3, 3)
+    ));
+
+    assertEquals(1, (long)executor.execute(new Read<Long>(v1)));
+    assertEquals(3, (long)executor.execute(new Read<Long>(v2)));
+    assertEquals(6, (long)executor.execute(new Read<Long>(v3)));
+  }
+}