Merge pull request #37 from Azure/sdk_973

[Automatic PR] SDK changes from pull request #973

.travis.yml

@@ -12,6 +12,3 @@ script:
 - mvn clean install
 - mvn checkstyle:check
 - cd ./azure-android-client-authentication && ./gradlew check
-env:
-  global:
-    secure: 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

azure-client-runtime/src/main/java/com/microsoft/azure/DAGNode.java

@@ -10,6 +10,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.locks.ReentrantLock;
 
 /**
  * The type representing node in a {@link DAGraph}.
@@ -20,6 +21,7 @@ public class DAGNode<T> extends Node<T> {
     private List<String> dependentKeys;
     private int toBeResolved;
     private boolean isPreparer;
+    private ReentrantLock lock;
 
     /**
      * Creates a DAG node.
@@ -30,6 +32,14 @@ public class DAGNode<T> extends Node<T> {
     public DAGNode(String key, T data) {
         super(key, data);
         dependentKeys = new ArrayList<>();
+        lock = new ReentrantLock();
+    }
+
+    /**
+     * @return the lock to be used while performing thread safe operation on this node.
+     */
+    public ReentrantLock lock() {
+        return this.lock;
     }
 
     /**

azure-client-runtime/src/main/java/com/microsoft/azure/DAGraph.java

@@ -7,9 +7,8 @@
 
 package com.microsoft.azure;
 
-import java.util.ArrayDeque;
 import java.util.Map;
-import java.util.Queue;
+import java.util.concurrent.ConcurrentLinkedQueue;
 
 /**
  * Type representing a DAG (directed acyclic graph).
@@ -20,7 +19,7 @@
  * @param <U> the type of the nodes in the graph
  */
 public class DAGraph<T, U extends DAGNode<T>> extends Graph<T, U> {
-    private Queue<String> queue;
+    private ConcurrentLinkedQueue<String> queue;
     private boolean hasParent;
     private U rootNode;
 
@@ -31,7 +30,7 @@ public class DAGraph<T, U extends DAGNode<T>> extends Graph<T, U> {
      */
     public DAGraph(U rootNode) {
         this.rootNode = rootNode;
-        this.queue = new ArrayDeque<>();
+        this.queue = new ConcurrentLinkedQueue<>();
         this.rootNode.setPreparer(true);
         this.addNode(rootNode);
     }
@@ -103,10 +102,14 @@ public void prepare() {
      * Gets next node in the DAG which has no dependency or all of it's dependencies are resolved and
      * ready to be consumed.
      *
-     * @return next node or null if all the nodes have been explored
+     * @return next node or null if all the nodes have been explored or no node is available at this moment.
      */
     public U getNext() {
-        return graph.get(queue.poll());
+        String nextItemKey = queue.poll();
+        if (nextItemKey == null) {
+            return null;
+        }
+        return graph.get(nextItemKey);
     }
 
     /**
@@ -129,9 +132,14 @@ public void reportedCompleted(U completed) {
         String dependency = completed.key();
         for (String dependentKey : graph.get(dependency).dependentKeys()) {
             DAGNode<T> dependent = graph.get(dependentKey);
-            dependent.reportResolved(dependency);
-            if (dependent.hasAllResolved()) {
-                queue.add(dependent.key());
+            dependent.lock().lock();
+            try {
+                dependent.reportResolved(dependency);
+                if (dependent.hasAllResolved()) {
+                    queue.add(dependent.key());
+                }
+            } finally {
+                dependent.lock().unlock();
             }
         }
     }
@@ -145,9 +153,8 @@ public void reportedCompleted(U completed) {
      */
     private void initializeDependentKeys() {
         visit(new Visitor<U>() {
-            // This 'visit' will be called only once per each node.
             @Override
-            public void visit(U node) {
+            public void visitNode(U node) {
                 if (node.dependencyKeys().isEmpty()) {
                     return;
                 }
@@ -158,6 +165,13 @@ public void visit(U node) {
                             .addDependent(dependentKey);
                 }
             }
+
+            @Override
+            public  void visitEdge(String fromKey, String toKey, EdgeType edgeType) {
+                if (edgeType == EdgeType.BACK) {
+                    throw new IllegalStateException("Detected circular dependency: " + findPath(fromKey, toKey));
+                }
+            }
         });
     }
 

azure-client-runtime/src/main/java/com/microsoft/azure/Graph.java

@@ -23,13 +23,23 @@
 public class Graph<T, U extends Node<T>> {
     protected Map<String, U> graph;
     private Set<String> visited;
+    private Integer time;
+    private Map<String, Integer> entryTime;
+    private Map<String, Integer> exitTime;
+    private Map<String, String> parent;
+    private Set<String> processed;
 
     /**
      * Creates a directed graph.
      */
     public Graph() {
         this.graph = new HashMap<>();
         this.visited = new HashSet<>();
+        this.time = 0;
+        this.entryTime = new HashMap<>();
+        this.exitTime = new HashMap<>();
+        this.parent = new HashMap<>();
+        this.processed = new HashSet<>();
     }
 
     /**
@@ -41,26 +51,11 @@ public void addNode(U node) {
         graph.put(node.key(), node);
     }
 
-    /**
-     * Represents a visitor to be implemented by the consumer who want to visit the
-     * graph's nodes in DFS order.
-     *
-     * @param <U> the type of the node
-     */
-    interface Visitor<U> {
-        /**
-         * visit a node.
-         *
-         * @param node the node to visited
-         */
-        void visit(U node);
-    }
-
     /**
      * Perform DFS visit in this graph.
      * <p>
      * The directed graph will be traversed in DFS order and the visitor will be notified as
-     * search explores each node
+     * search explores each node and edge.
      *
      * @param visitor the graph visitor
      */
@@ -71,15 +66,107 @@ public void visit(Visitor visitor) {
             }
         }
         visited.clear();
+        time = 0;
+        entryTime.clear();
+        exitTime.clear();
+        parent.clear();
+        processed.clear();
     }
 
     private void dfs(Visitor visitor, Node<T> node) {
-        visitor.visit(node);
-        visited.add(node.key());
-        for (String childKey : node.children()) {
-            if (!visited.contains(childKey)) {
-                this.dfs(visitor, this.graph.get(childKey));
+        visitor.visitNode(node);
+
+        String fromKey = node.key();
+        visited.add(fromKey);
+        time++;
+        entryTime.put(fromKey, time);
+        for (String toKey : node.children()) {
+            if (!visited.contains(toKey)) {
+                parent.put(toKey, fromKey);
+                visitor.visitEdge(fromKey, toKey, edgeType(fromKey, toKey));
+                this.dfs(visitor, this.graph.get(toKey));
+            } else {
+                visitor.visitEdge(fromKey, toKey, edgeType(fromKey, toKey));
             }
         }
+        time++;
+        exitTime.put(fromKey, time);
+        processed.add(fromKey);
+    }
+
+    private EdgeType edgeType(String fromKey, String toKey) {
+        if (parent.containsKey(toKey) && parent.get(toKey).equals(fromKey)) {
+            return EdgeType.TREE;
+        }
+
+        if (visited.contains(toKey) && !processed.contains(toKey)) {
+            return EdgeType.BACK;
+        }
+
+        if (processed.contains(toKey) && entryTime.containsKey(toKey) && entryTime.containsKey(fromKey)) {
+            if (entryTime.get(toKey) > entryTime.get(fromKey)) {
+                return EdgeType.FORWARD;
+            }
+
+            if (entryTime.get(toKey) < entryTime.get(fromKey)) {
+                return EdgeType.CROSS;
+            }
+        }
+
+        throw new IllegalStateException("Internal Error: Unable to locate the edge type {" + fromKey + ", " + toKey + "}");
+    }
+
+    protected String findPath(String start, String end) {
+        if (start.equals(end)) {
+            return start;
+        } else {
+            return findPath(start, parent.get(end)) + " -> " + end;
+        }
+    }
+
+    /**
+     * The edge types in a graph.
+     */
+    enum EdgeType {
+        /**
+         * An edge (u, v) is a tree edge if v is visited the first time.
+         */
+        TREE,
+        /**
+         * An edge (u, v) is a forward edge if v is descendant of u.
+         */
+        FORWARD,
+        /**
+         * An edge (u, v) is a back edge if v is ancestor of u.
+         */
+        BACK,
+        /**
+         * An edge (u, v) is a cross edge if v is neither ancestor or descendant of u.
+         */
+        CROSS
+    }
+
+    /**
+     * Represents a visitor to be implemented by the consumer who want to visit the
+     * graph's nodes in DFS order by calling visit method.
+     *
+     * @param <U> the type of the node
+     */
+    interface Visitor<U> {
+        /**
+         * visit a node.
+         *
+         * @param node the node to visited
+         */
+        void visitNode(U node);
+
+        /**
+         * visit an edge.
+         *
+         * @param fromKey key of the from node
+         * @param toKey key of the to node
+         * @param edgeType the edge type
+         */
+        void visitEdge(String fromKey, String toKey, EdgeType edgeType);
     }
 }

azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroup.java

@@ -63,7 +63,7 @@ public interface TaskGroup<T, U extends TaskItem<T>> {
      * @param callback the callback to call on failure or success
      * @return the handle to the REST call
      */
-    ServiceCall executeAsync(ServiceCallback<Void> callback);
+    ServiceCall executeAsync(ServiceCallback<T> callback);
 
     /**
      * Gets the result of execution of a task in the group.