Expose RestController all handlers iterator.

Signed-off-by: dblock <[email protected]>

server/src/main/java/org/opensearch/common/path/PathTrie.java

@@ -37,6 +37,7 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.NoSuchElementException;
+import java.util.Stack;
 import java.util.function.BiFunction;
 import java.util.function.Supplier;
 
@@ -405,4 +406,45 @@ public T next() {
             }
         };
     }
+
+    public Iterator<T> retrieveAll() {
+        Stack<TrieNode> stack = new Stack<>();
+        stack.add(root);
+
+        return new Iterator<T>() {
+            @Override
+            public boolean hasNext() {
+                while (!stack.empty()) {
+                    TrieNode node = stack.peek();
+
+                    if (node.value != null) {
+                        return true;
+                    }
+
+                    advance();
+                }
+
+                return false;
+            }
+
+            @Override
+            public T next() {
+                while (!stack.empty()) {
+                    TrieNode node = advance();
+
+                    if (node.value != null) {
+                        return node.value;
+                    }
+                }
+
+                throw new NoSuchElementException("called next() without validating hasNext()! no more nodes available");
+            }
+
+            private TrieNode advance() {
+                TrieNode node = stack.pop();
+                stack.addAll(node.children.values());
+                return node;
+            }
+        };
+    }
 }

server/src/main/java/org/opensearch/rest/MethodHandlers.java

@@ -43,7 +43,7 @@
  *
  * @opensearch.api
  */
-final class MethodHandlers {
+public final class MethodHandlers {
 
     private final String path;
     private final Map<RestRequest.Method, RestHandler> methodHandlers;
@@ -79,9 +79,16 @@ RestHandler getHandler(RestRequest.Method method) {
     }
 
     /**
-     * Return a set of all valid HTTP methods for the particular path
+     * Return a set of all valid HTTP methods for the particular path.
      */
-    Set<RestRequest.Method> getValidMethods() {
+    public Set<RestRequest.Method> getValidMethods() {
         return methodHandlers.keySet();
     }
+
+    /**
+     * Returns the relative HTTP path of the set of method handlers.
+     */
+    public String getPath() {
+        return path;
+    }
 }

server/src/main/java/org/opensearch/rest/RestController.java

@@ -144,6 +144,14 @@ public RestController(
         );
     }
 
+    /**
+     * Returns an iterator over registered REST method handlers.
+     * @return {@link Iterator} of {@link MethodHandlers}
+     */
+    public Iterator<MethodHandlers> getAllHandlers() {
+        return handlers.retrieveAll();
+    }
+
     /**
      * Registers a REST handler to be executed when the provided {@code method} and {@code path} match the request.
      *

server/src/test/java/org/opensearch/common/path/PathTrieTests.java

@@ -36,8 +36,10 @@
 import org.opensearch.rest.RestUtils;
 import org.opensearch.test.OpenSearchTestCase;
 
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Map;
 
 import static org.hamcrest.Matchers.equalTo;
@@ -286,4 +288,33 @@ public void testEscapedSlashWithinUrl() {
         assertThat(params.get("type"), equalTo("type"));
         assertThat(params.get("id"), equalTo("id"));
     }
+
+    public void testRetrieveAllEmpty() {
+        PathTrie<String> trie = new PathTrie<>(NO_DECODER);
+        Iterator<String> allPaths = trie.retrieveAll();
+        assertFalse(allPaths.hasNext());
+    }
+
+    public void testRetrieveAll() {
+        PathTrie<String> trie = new PathTrie<>(NO_DECODER);
+        trie.insert("{testA}", "test1");
+        trie.insert("{testA}/{testB}", "test2");
+        trie.insert("a/{testB}", "test3");
+        trie.insert("{testA}/b", "test4");
+        trie.insert("{testA}/b/c", "test5");
+
+        Iterator<String> iterator = trie.retrieveAll();
+        assertTrue(iterator.hasNext());
+        List<String> paths = new ArrayList<>();
+        iterator.forEachRemaining(paths::add);
+        assertEquals(paths, List.of("test1", "test4", "test5", "test2", "test3"));
+        assertFalse(iterator.hasNext());
+    }
+
+    public void testRetrieveAllWithNllValue() {
+        PathTrie<String> trie = new PathTrie<>(NO_DECODER);
+        trie.insert("{testA}", null);
+        Iterator<String> iterator = trie.retrieveAll();
+        assertFalse(iterator.hasNext());
+    }
 }

server/src/test/java/org/opensearch/rest/RestControllerTests.java

@@ -138,6 +138,37 @@ public void teardown() throws IOException {
         IOUtils.close(client);
     }
 
+    public void testDefaultRestControllerGetAllHandlersContainsFavicon() {
+        final RestController restController = new RestController(null, null, null, circuitBreakerService, usageService, identityService);
+        Iterator<MethodHandlers> handlers = restController.getAllHandlers();
+        assertTrue(handlers.hasNext());
+        MethodHandlers faviconHandler = handlers.next();
+        assertEquals(faviconHandler.getPath(), "/favicon.ico");
+        assertEquals(faviconHandler.getValidMethods(), Set.of(RestRequest.Method.GET));
+        assertFalse(handlers.hasNext());
+    }
+
+    public void testRestControllerGetAllHandlers() {
+        final RestController restController = new RestController(null, null, null, circuitBreakerService, usageService, identityService);
+
+        restController.registerHandler(RestRequest.Method.PATCH, "/foo", mock(RestHandler.class));
+        restController.registerHandler(RestRequest.Method.GET, "/foo", mock(RestHandler.class));
+
+        Iterator<MethodHandlers> handlers = restController.getAllHandlers();
+
+        assertTrue(handlers.hasNext());
+        MethodHandlers rootHandler = handlers.next();
+        assertEquals(rootHandler.getPath(), "/foo");
+        assertEquals(rootHandler.getValidMethods(), Set.of(RestRequest.Method.GET, RestRequest.Method.PATCH));
+
+        assertTrue(handlers.hasNext());
+        MethodHandlers faviconHandler = handlers.next();
+        assertEquals(faviconHandler.getPath(), "/favicon.ico");
+        assertEquals(faviconHandler.getValidMethods(), Set.of(RestRequest.Method.GET));
+
+        assertFalse(handlers.hasNext());
+    }
+
     public void testApplyRelevantHeaders() throws Exception {
         final ThreadContext threadContext = client.threadPool().getThreadContext();
         Set<RestHeaderDefinition> headers = new HashSet<>(