Create capabilities rest endpoints

(cherry picked from commit af4299b)

h2o-core/src/main/java/water/H2O.java

@@ -176,7 +176,7 @@ public static void printHelp() {
 
     System.out.print(s);
 
-    for (AbstractH2OExtension e : H2O.getExtensions()) {
+    for (AbstractH2OExtension e : H2O.getCoreExtensions()) {
       e.printHelp();
     }
   }
@@ -408,7 +408,7 @@ public int parseInt(String a) {
    * Dead stupid argument parser.
    */
   private static void parseArguments(String[] args) {
-    for (AbstractH2OExtension e : H2O.getExtensions()) {
+    for (AbstractH2OExtension e : H2O.getCoreExtensions()) {
       args = e.parseArguments(args);
     }
 
@@ -613,7 +613,7 @@ private static void validateArguments() {
     }
 
     // Validate extension arguments
-    for (AbstractH2OExtension e : H2O.getExtensions()) {
+    for (AbstractH2OExtension e : H2O.getCoreExtensions()) {
       e.validateArguments();
     }
   }
@@ -771,7 +771,7 @@ public static void configureLogging() {
    * Register H2O extensions.
    * <p/>
    * Use SPI to find all classes that extends water.AbstractH2OExtension
-   * and call H2O.addExtension() for each.
+   * and call H2O.addCoreExtension() for each.
    */
   public static void registerExtensions() {
     if (extensionsRegistered) {
@@ -783,22 +783,31 @@ public static void registerExtensions() {
     for (AbstractH2OExtension ext : extensionsLoader) {
       if (ext.isEnabled()) {
         ext.init();
-        addExtension(ext);
+        addCoreExtension(ext);
       }
     }
     extensionsRegistered = true;
 
     registerExtensionsMillis = System.currentTimeMillis() - before;
   }
 
-  private static ArrayList<AbstractH2OExtension> extensions = new ArrayList<>();
+  private static ArrayList<AbstractH2OExtension> coreExtensions = new ArrayList<>();
 
-  public static void addExtension(AbstractH2OExtension e) {
-    extensions.add(e);
+  public static void addCoreExtension(AbstractH2OExtension e) {
+    coreExtensions.add(e);
   }
 
-  public static ArrayList<AbstractH2OExtension> getExtensions() {
-    return extensions;
+  private static ArrayList<RestApiExtension> restApiExtensions = new ArrayList<>();
+
+  public static void addRestAPIExtension(RestApiExtension e){
+    restApiExtensions.add(e);
+  }
+  public static ArrayList<AbstractH2OExtension> getCoreExtensions() {
+    return coreExtensions;
+  }
+
+  public static ArrayList<RestApiExtension> getRestApiExtensions(){
+    return restApiExtensions;
   }
 
   //-------------------------------------------------------------------------------------------------------------------
@@ -821,12 +830,12 @@ public static void registerRestApis(String relativeResourcePath) {
 
     // Log extension registrations here so the message is grouped in the right spot.
     List<String> registeredH2OExts = new ArrayList<>();
-    for (AbstractH2OExtension e : H2O.getExtensions()) {
+    for (AbstractH2OExtension e : H2O.getCoreExtensions()) {
       e.printInitialized();
       registeredH2OExts.add(e.getExtensionName());
     }
-    Log.info("Registered " + H2O.getExtensions().size() + " extensions in: " + registerExtensionsMillis + "ms");
-    Log.info("Registered H2O extensions: " + Arrays.toString(registeredH2OExts.toArray()));
+    Log.info("Registered " + H2O.getCoreExtensions().size() + " core extensions in: " + registerExtensionsMillis + "ms");
+    Log.info("Registered H2O core extensions: " + Arrays.toString(registeredH2OExts.toArray()));
 
     long before = System.currentTimeMillis();
     RequestServer.DummyRestApiContext dummyRestApiContext = new RequestServer.DummyRestApiContext();
@@ -838,6 +847,7 @@ public static void registerRestApis(String relativeResourcePath) {
         r.registerEndPoints(dummyRestApiContext);
         r.registerSchemas(dummyRestApiContext);
         registeredRestApiExts.add(r.getName());
+        H2O.addRestAPIExtension(r);
       } catch (Exception e) {
         Log.info("Cannot register extension: " + r + ". Skipping it...");
       }
@@ -1488,7 +1498,7 @@ private static void printAndLogVersion(String[] arguments) {
       Log.warn("");
     }
 
-    for (AbstractH2OExtension e : H2O.getExtensions()) {
+    for (AbstractH2OExtension e : H2O.getCoreExtensions()) {
       String n = e.getExtensionName() + " ";
       AbstractBuildVersion abv = e.getBuildVersion();
       Log.info(n + "Build git branch: ", abv.branchName());
@@ -2018,9 +2028,9 @@ public static void main( String[] args ) {
     long time5 = System.currentTimeMillis();
     startLocalNode();
 
-    // Allow extensions to perform initialization that requires the network.
+    // Allow core extensions to perform initialization that requires the network.
     long time6 = System.currentTimeMillis();
-    for (AbstractH2OExtension ext: extensions) {
+    for (AbstractH2OExtension ext: coreExtensions) {
       ext.onLocalNodeStarted();
     }
 

h2o-core/src/main/java/water/api/CapabilitiesHandler.java

@@ -0,0 +1,54 @@
+package water.api;
+
+import water.AbstractH2OExtension;
+import water.H2O;
+import water.api.schemas3.CapabilitiesV3;
+import water.api.schemas3.CapabilityEntryV3;
+
+import java.util.ArrayList;
+
+
+public class CapabilitiesHandler extends Handler{
+
+  private ArrayList<CapabilityEntryV3> getCoreExtensionEntries(){
+    ArrayList<CapabilityEntryV3> entries = new ArrayList<>();
+    for(AbstractH2OExtension ext: H2O.getCoreExtensions()){
+      entries.add(new CapabilityEntryV3(ext.getExtensionName()));
+    }
+    return entries;
+  }
+
+  private ArrayList<CapabilityEntryV3> getRestAPIExtensionEntries(){
+    ArrayList<CapabilityEntryV3> entries = new ArrayList<>();
+    for(RestApiExtension ext: H2O.getRestApiExtensions()){
+      entries.add(new CapabilityEntryV3(ext.getName()));
+    }
+    return entries;
+  }
+
+
+  @SuppressWarnings("unused") // called through reflection by RequestServer
+  public CapabilitiesV3 listAll(int version, CapabilitiesV3 s) {
+    ArrayList<CapabilityEntryV3> entries = new ArrayList<>();
+    entries.addAll(getCoreExtensionEntries());
+    entries.addAll(getRestAPIExtensionEntries());
+    s.capabilities = entries.toArray(new CapabilityEntryV3[entries.size()]);
+    return s;
+  }
+
+  @SuppressWarnings("unused") // called through reflection by RequestServer
+  public CapabilitiesV3 listCore(int version, CapabilitiesV3 s) {
+    ArrayList<CapabilityEntryV3> entries = new ArrayList<>();
+    entries.addAll(getCoreExtensionEntries());
+    s.capabilities = entries.toArray(new CapabilityEntryV3[entries.size()]);
+    return s;
+  }
+
+  @SuppressWarnings("unused") // called through reflection by RequestServer
+  public CapabilitiesV3 listRest(int version, CapabilitiesV3 s) {
+    ArrayList<CapabilityEntryV3> entries = new ArrayList<>();
+    entries.addAll(getRestAPIExtensionEntries());
+    s.capabilities = entries.toArray(new CapabilityEntryV3[entries.size()]);
+    return s;
+  }
+}

h2o-core/src/main/java/water/api/RegisterV3Api.java

@@ -436,6 +436,18 @@ public void register(String relativeResourcePath) {
     RequestServer.registerEndpoint("steamMetrics",
         "GET /3/SteamMetrics", SteamMetricsHandler.class, "fetch",
         "Get metrics for Steam from H2O.");
+
+    RequestServer.registerEndpoint("list_all_capabilities",
+            "GET /3/Capabilities", CapabilitiesHandler.class, "listAll",
+            "List of all registered capabilities");
+
+    RequestServer.registerEndpoint("list_core_capabilities",
+            "GET /3/Capabilities/Core", CapabilitiesHandler.class, "listCore",
+            "List registered core capabilities");
+
+    RequestServer.registerEndpoint("list_rest_capabilities",
+            "GET /3/Capabilities/API", CapabilitiesHandler.class, "listRest",
+            "List of all registered Rest API capabilities");
   }
 
   @Override

h2o-core/src/main/java/water/api/schemas3/CapabilitiesV3.java

@@ -0,0 +1,11 @@
+package water.api.schemas3;
+
+
+import water.Iced;
+import water.api.API;
+
+public class CapabilitiesV3 extends RequestSchemaV3<Iced, CapabilitiesV3> {
+
+  @API(help = "List of H2O capabilities", direction = API.Direction.OUTPUT)
+  public CapabilityEntryV3[] capabilities;
+}

h2o-core/src/main/java/water/api/schemas3/CapabilityEntryV3.java

@@ -0,0 +1,14 @@
+package water.api.schemas3;
+
+import water.Iced;
+import water.api.API;
+
+public class CapabilityEntryV3 extends SchemaV3<Iced, CapabilityEntryV3> {
+  @API(help = "Extension name", direction = API.Direction.OUTPUT)
+  public String name;
+
+  public CapabilityEntryV3() {}
+  public CapabilityEntryV3(String name) {
+    this.name = name;
+  }
+}

h2o-core/src/main/resources/META-INF/services/water.api.Schema

@@ -99,6 +99,7 @@ water.api.schemas3.SchemaMetadataV3
 water.api.schemas3.SchemaV3
 water.api.schemas3.ShutdownV3
 water.api.schemas3.SplitFrameV3
+water.api.schemas3.SteamMetricsV3
 water.api.schemas3.TabulateV3
 water.api.schemas3.TimelineV3
 water.api.schemas3.TimelineV3$EventV3
@@ -128,4 +129,6 @@ water.api.schemas4.output.JobV4
 water.api.schemas99.AssemblyV99
 water.api.schemas99.GridsV99
 water.api.schemas99.RapidsV99
-water.util.WaterMeterIo$IoStatsEntry
+water.util.WaterMeterIo$IoStatsEntry
+water.api.schemas3.CapabilitiesV3
+water.api.schemas3.CapabilityEntryV3