1 files changed, 73 insertions, 9 deletions

diff --git a/graphics/java/android/renderscript/ScriptGroup.java b/graphics/java/android/renderscript/ScriptGroup.java
index 4efb45b..8943f75 100644
--- a/graphics/java/android/renderscript/ScriptGroup.java
+++ b/graphics/java/android/renderscript/ScriptGroup.java
@@ -32,6 +32,12 @@ import java.util.ArrayList;
  * user supplied allocation. Inputs are similar but supply the
  * input of a kernal. Inputs bounds to a script are set directly
  * upon the script.
+ * <p>
+ * A ScriptGroup must contain at least one kernel. A ScriptGroup
+ * must contain only a single directed acyclic graph (DAG) of
+ * script kernels and connections. Attempting to create a
+ * ScriptGroup with multiple DAGs or attempting to create
+ * a cycle within a ScriptGroup will throw an exception.
  *
  **/
 public final class ScriptGroup extends BaseObj {
@@ -72,6 +78,7 @@ public final class ScriptGroup extends BaseObj {
         ArrayList<ConnectLine> mInputs = new ArrayList<ConnectLine>();
         ArrayList<ConnectLine> mOutputs = new ArrayList<ConnectLine>();
         boolean mSeen;
+        int dagNumber;
 
         Node mNext;
 
@@ -169,10 +176,10 @@ public final class ScriptGroup extends BaseObj {
             mRS = rs;
         }
 
-        private void validateRecurse(Node n, int depth) {
+        private void validateCycleRecurse(Node n, int depth) {
             n.mSeen = true;
 
-            //android.util.Log.v("RSR", " validateRecurse outputCount " + n.mOutputs.size());
+            //android.util.Log.v("RSR", " validateCycleRecurse outputCount " + n.mOutputs.size());
             for (int ct=0; ct < n.mOutputs.size(); ct++) {
                 final ConnectLine cl = n.mOutputs.get(ct);
                 if (cl.mToK != null) {
@@ -180,20 +187,20 @@ public final class ScriptGroup extends BaseObj {
                     if (tn.mSeen) {
                         throw new RSInvalidStateException("Loops in group not allowed.");
                     }
-                    validateRecurse(tn, depth + 1);
+                    validateCycleRecurse(tn, depth + 1);
                 }
                 if (cl.mToF != null) {
                     Node tn = findNode(cl.mToF.mScript);
                     if (tn.mSeen) {
                         throw new RSInvalidStateException("Loops in group not allowed.");
                     }
-                    validateRecurse(tn, depth + 1);
+                    validateCycleRecurse(tn, depth + 1);
                 }
             }
         }
 
-        private void validate() {
-            //android.util.Log.v("RSR", "validate");
+        private void validateCycle() {
+            //android.util.Log.v("RSR", "validateCycle");
 
             for (int ct=0; ct < mNodes.size(); ct++) {
                 for (int ct2=0; ct2 < mNodes.size(); ct2++) {
@@ -201,7 +208,53 @@ public final class ScriptGroup extends BaseObj {
                 }
                 Node n = mNodes.get(ct);
                 if (n.mInputs.size() == 0) {
-                    validateRecurse(n, 0);
+                    validateCycleRecurse(n, 0);
+                }
+            }
+        }
+
+        private void mergeDAGs(int valueUsed, int valueKilled) {
+            for (int ct=0; ct < mNodes.size(); ct++) {
+                if (mNodes.get(ct).dagNumber == valueKilled)
+                    mNodes.get(ct).dagNumber = valueUsed;
+            }
+        }
+
+        private void validateDAGRecurse(Node n, int dagNumber) {
+            // combine DAGs if this node has been seen already
+            if (n.dagNumber != 0 && n.dagNumber != dagNumber) {
+                mergeDAGs(n.dagNumber, dagNumber);
+                return;
+            }
+
+            n.dagNumber = dagNumber;
+            for (int ct=0; ct < n.mOutputs.size(); ct++) {
+                final ConnectLine cl = n.mOutputs.get(ct);
+                if (cl.mToK != null) {
+                    Node tn = findNode(cl.mToK.mScript);
+                    validateDAGRecurse(tn, dagNumber);
+                }
+                if (cl.mToF != null) {
+                    Node tn = findNode(cl.mToF.mScript);
+                    validateDAGRecurse(tn, dagNumber);
+                }
+            }
+        }
+
+        private void validateDAG() {
+            for (int ct=0; ct < mNodes.size(); ct++) {
+                Node n = mNodes.get(ct);
+                if (n.mInputs.size() == 0) {
+                    if (n.mOutputs.size() == 0 && mNodes.size() > 1) {
+                        throw new RSInvalidStateException("Groups cannot contain unconnected scripts");
+                    }
+                    validateDAGRecurse(n, ct+1);
+                }
+            }
+            int dagNumber = mNodes.get(0).dagNumber;
+            for (int ct=0; ct < mNodes.size(); ct++) {
+                if (mNodes.get(ct).dagNumber != dagNumber) {
+                    throw new RSInvalidStateException("Multiple DAGs in group not allowed.");
                 }
             }
         }
@@ -288,7 +341,7 @@ public final class ScriptGroup extends BaseObj {
             nf.mOutputs.add(cl);
             nt.mInputs.add(cl);
 
-            validate();
+            validateCycle();
             return this;
         }
 
@@ -323,7 +376,7 @@ public final class ScriptGroup extends BaseObj {
             nf.mOutputs.add(cl);
             nt.mInputs.add(cl);
 
-            validate();
+            validateCycle();
             return this;
         }
 
@@ -336,6 +389,17 @@ public final class ScriptGroup extends BaseObj {
          * @return ScriptGroup The new ScriptGroup
          */
         public ScriptGroup create() {
+
+            if (mNodes.size() == 0) {
+                throw new RSInvalidStateException("Empty script groups are not allowed");
+            }
+
+            // reset DAG numbers in case we're building a second group
+            for (int ct=0; ct < mNodes.size(); ct++) {
+                mNodes.get(ct).dagNumber = 0;
+            }
+            validateDAG();
+
             ArrayList<IO> inputs = new ArrayList<IO>();
             ArrayList<IO> outputs = new ArrayList<IO>();