ONOS-1048 - Define interfaces instead of using IntentManager

- Define IntentProcessor interface containing methods to process an intent
- Pull out IntentCompiler related tasks to CompilerRegistry
- Pull out IntentInstaller related tasks to InstallerRegistry
- Create an IntentProcessor subclass as inner class in IntentManager

Change-Id: Ia3e8d574a1053e7ddc9b961873ef758c9e0b1b26

+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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 org.onosproject.net.intent.impl;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import org.onosproject.net.intent.Intent;
+import org.onosproject.net.intent.IntentCompiler;
+import org.onosproject.net.intent.IntentException;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+// TODO: consider a better name
+class CompilerRegistry {
+
+    private final ConcurrentMap<Class<? extends Intent>,
+            IntentCompiler<? extends Intent>> compilers = new ConcurrentHashMap<>();
+
+    /**
+     * Registers the specified compiler for the given intent class.
+     *
+     * @param cls      intent class
+     * @param compiler intent compiler
+     * @param <T>      the type of intent
+     */
+    public <T extends Intent> void registerCompiler(Class<T> cls, IntentCompiler<T> compiler) {
+        compilers.put(cls, compiler);
+    }
+
+    /**
+     * Unregisters the compiler for the specified intent class.
+     *
+     * @param cls intent class
+     * @param <T> the type of intent
+     */
+    public <T extends Intent> void unregisterCompiler(Class<T> cls) {
+        compilers.remove(cls);
+    }
+
+    /**
+     * Returns immutable set of bindings of currently registered intent compilers.
+     *
+     * @return the set of compiler bindings
+     */
+    public Map<Class<? extends Intent>, IntentCompiler<? extends Intent>> getCompilers() {
+        return ImmutableMap.copyOf(compilers);
+    }
+
+    /**
+     * Compiles an intent recursively.
+     *
+     * @param intent intent
+     * @param previousInstallables previous intent installables
+     * @return result of compilation
+     */
+    List<Intent> compile(Intent intent, List<Intent> previousInstallables) {
+        if (intent.isInstallable()) {
+            return ImmutableList.of(intent);
+        }
+
+        registerSubclassCompilerIfNeeded(intent);
+        // FIXME: get previous resources
+        List<Intent> installable = new ArrayList<>();
+        for (Intent compiled : getCompiler(intent).compile(intent, previousInstallables, null)) {
+            installable.addAll(compile(compiled, previousInstallables));
+        }
+        return installable;
+    }
+
+    /**
+     * Returns the corresponding intent compiler to the specified intent.
+     *
+     * @param intent intent
+     * @param <T>    the type of intent
+     * @return intent compiler corresponding to the specified intent
+     */
+    private <T extends Intent> IntentCompiler<T> getCompiler(T intent) {
+        @SuppressWarnings("unchecked")
+        IntentCompiler<T> compiler = (IntentCompiler<T>) compilers.get(intent.getClass());
+        if (compiler == null) {
+            throw new IntentException("no compiler for class " + intent.getClass());
+        }
+        return compiler;
+    }
+
+    /**
+     * Registers an intent compiler of the specified intent if an intent compiler
+     * for the intent is not registered. This method traverses the class hierarchy of
+     * the intent. Once an intent compiler for a parent type is found, this method
+     * registers the found intent compiler.
+     *
+     * @param intent intent
+     */
+    private void registerSubclassCompilerIfNeeded(Intent intent) {
+        if (!compilers.containsKey(intent.getClass())) {
+            Class<?> cls = intent.getClass();
+            while (cls != Object.class) {
+                // As long as we're within the Intent class descendants
+                if (Intent.class.isAssignableFrom(cls)) {
+                    IntentCompiler<?> compiler = compilers.get(cls);
+                    if (compiler != null) {
+                        compilers.put(intent.getClass(), compiler);
+                        return;
+                    }
+                }
+                cls = cls.getSuperclass();
+            }
+        }
+    }
+}

+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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 org.onosproject.net.intent.impl;
+
+import org.onosproject.net.flow.FlowRuleOperations;
+import org.onosproject.net.intent.Intent;
+import org.onosproject.net.intent.IntentData;
+
+import java.util.List;
+
+/**
+ * A collection of methods to process an intent.
+ *
+ * This interface is public, but intended to be used only by IntentManager and
+ * IntentProcessPhase subclasses stored under phase package.
+ */
+public interface IntentProcessor {
+
+    /**
+     * Compiles an intent recursively.
+     *
+     * @param intent intent
+     * @param previousInstallables previous intent installables
+     * @return result of compilation
+     */
+    List<Intent> compile(Intent intent, List<Intent> previousInstallables);
+
+    /**
+     * Generate a {@link FlowRuleOperations} instance from the specified intent data.
+     *
+     * @param current intent data stored in the store
+     * @param pending intent data being processed
+     * @return flow rule operations
+     */
+    FlowRuleOperations coordinate(IntentData current, IntentData pending);
+
+    /**
+     * Generate a {@link FlowRuleOperations} instance from the specified intent data.
+     *
+     * @param current intent data stored in the store
+     * @param pending intent data being processed
+     * @return flow rule operations
+     */
+    FlowRuleOperations uninstallCoordinate(IntentData current, IntentData pending);
+
+    /**
+     * Applies a batch operation of FlowRules.
+     *
+     * @param flowRules batch operation to apply
+     */
+    // TODO: consider a better name
+    // This methods gives strangeness a bit because
+    // it doesn't receive/return intent related information
+    void applyFlowRules(FlowRuleOperations flowRules);
+}

@@ -18,7 +18,7 @@ package org.onosproject.net.intent.impl.phase;
 import org.onosproject.net.intent.Intent;
 import org.onosproject.net.intent.IntentData;
 import org.onosproject.net.intent.IntentException;
-import org.onosproject.net.intent.impl.IntentManager;
+import org.onosproject.net.intent.impl.IntentProcessor;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -34,13 +34,12 @@ final class Compiling implements IntentProcessPhase {
 
     private static final Logger log = LoggerFactory.getLogger(Compiling.class);
 
-    // TODO: define an interface and use it, instead of IntentManager
-    private final IntentManager intentManager;
+    private final IntentProcessor processor;
     private final IntentData pending;
     private final IntentData current;
 
-    Compiling(IntentManager intentManager, IntentData pending, IntentData current) {
-        this.intentManager = checkNotNull(intentManager);
+    Compiling(IntentProcessor processor, IntentData pending, IntentData current) {
+        this.processor = checkNotNull(processor);
         this.pending = checkNotNull(pending);
         this.current = current;
     }
@@ -49,11 +48,12 @@ final class Compiling implements IntentProcessPhase {
     public Optional<IntentProcessPhase> execute() {
         try {
             List<Intent> installables = (current != null) ? current.installables() : null;
-            pending.setInstallables(intentManager.compileIntent(pending.intent(), installables));
-            return Optional.of(new InstallCoordinating(intentManager, pending, current));
+            pending.setInstallables(processor.compile(pending.intent(), installables));
+            return Optional.of(new InstallCoordinating(processor, pending, current));
         } catch (IntentException e) {
             log.debug("Unable to compile intent {} due to: {}", pending.intent(), e);
             return Optional.of(new CompilingFailed(pending));
         }
     }
+
 }

@@ -18,7 +18,7 @@ package org.onosproject.net.intent.impl.phase;
 import org.onosproject.net.flow.FlowRuleOperations;
 import org.onosproject.net.intent.IntentData;
 import org.onosproject.net.intent.IntentException;
-import org.onosproject.net.intent.impl.IntentManager;
+import org.onosproject.net.intent.impl.IntentProcessor;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -34,13 +34,13 @@ final class InstallCoordinating implements IntentProcessPhase {
 
     private static final Logger log = LoggerFactory.getLogger(InstallCoordinating.class);
 
-    private final IntentManager intentManager;
+    private final IntentProcessor processor;
     private final IntentData pending;
     private final IntentData current;
 
     // TODO: define an interface and use it, instead of IntentManager
-    InstallCoordinating(IntentManager intentManager, IntentData pending, IntentData current) {
-        this.intentManager = checkNotNull(intentManager);
+    InstallCoordinating(IntentProcessor processor, IntentData pending, IntentData current) {
+        this.processor = checkNotNull(processor);
         this.pending = checkNotNull(pending);
         this.current = current;
     }
@@ -50,8 +50,8 @@ final class InstallCoordinating implements IntentProcessPhase {
         try {
             //FIXME we orphan flow rules that are currently on the data plane
             // ... should either reuse them or remove them
-            FlowRuleOperations flowRules = intentManager.coordinate(current, pending);
-            return Optional.of(new Installing(intentManager, pending, flowRules));
+            FlowRuleOperations flowRules = processor.coordinate(current, pending);
+            return Optional.of(new Installing(processor, pending, flowRules));
         } catch (IntentException e) {
             log.warn("Unable to generate a FlowRuleOperations from intent {} due to:", pending.intent().id(), e);
             return Optional.of(new InstallingFailed(pending));

@@ -16,7 +16,7 @@
 package org.onosproject.net.intent.impl.phase;
 
 import org.onosproject.net.intent.IntentData;
-import org.onosproject.net.intent.impl.IntentManager;
+import org.onosproject.net.intent.impl.IntentProcessor;
 
 import java.util.Optional;
 
@@ -27,13 +27,12 @@ import static com.google.common.base.Preconditions.checkNotNull;
  */
 public final class InstallRequest implements IntentProcessPhase {
 
-    // TODO: define an interface and use it, instead of IntentManager
-    private final IntentManager intentManager;
+    private final IntentProcessor intentManager;
     private final IntentData pending;
     private final Optional<IntentData> current;
 
-    public InstallRequest(IntentManager intentManager, IntentData intentData, Optional<IntentData> current) {
-        this.intentManager = checkNotNull(intentManager);
+    public InstallRequest(IntentProcessor processor, IntentData intentData, Optional<IntentData> current) {
+        this.intentManager = checkNotNull(processor);
         this.pending = checkNotNull(intentData);
         this.current = checkNotNull(current);
     }

@@ -18,7 +18,7 @@ package org.onosproject.net.intent.impl.phase;
 import org.onosproject.net.flow.FlowRuleOperations;
 import org.onosproject.net.intent.IntentData;
 import org.onosproject.net.intent.IntentException;
-import org.onosproject.net.intent.impl.IntentManager;
+import org.onosproject.net.intent.impl.IntentProcessor;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -34,13 +34,12 @@ final class Installing implements IntentProcessPhase {
 
     private static final Logger log = LoggerFactory.getLogger(Installing.class);
 
-    private final IntentManager intentManager;
+    private final IntentProcessor processor;
     private final IntentData pending;
     private final FlowRuleOperations flowRules;
 
-    // TODO: define an interface and use it, instead of IntentManager
-    Installing(IntentManager intentManager, IntentData pending, FlowRuleOperations flowRules) {
-        this.intentManager = checkNotNull(intentManager);
+    Installing(IntentProcessor processor, IntentData pending, FlowRuleOperations flowRules) {
+        this.processor = checkNotNull(processor);
         this.pending = checkNotNull(pending);
         this.flowRules = flowRules;
     }
@@ -48,7 +47,7 @@ final class Installing implements IntentProcessPhase {
     @Override
     public Optional<IntentProcessPhase> execute() {
         try {
-            intentManager.flowRuleService.apply(flowRules); // FIXME we need to provide a context
+            processor.applyFlowRules(flowRules);
             return Optional.of(new Installed(pending));
         // What kinds of exceptions are thrown by FlowRuleService.apply()?
         // Is IntentException a correct exception abstraction?

@@ -18,7 +18,7 @@ package org.onosproject.net.intent.impl.phase;
 import org.onosproject.net.flow.FlowRuleOperations;
 import org.onosproject.net.intent.IntentData;
 import org.onosproject.net.intent.IntentException;
-import org.onosproject.net.intent.impl.IntentManager;
+import org.onosproject.net.intent.impl.IntentProcessor;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -34,13 +34,12 @@ final class WithdrawCoordinating implements IntentProcessPhase {
 
     private static final Logger log = LoggerFactory.getLogger(WithdrawCoordinating.class);
 
-    // TODO: define an interface and use it, instead of IntentManager
-    private final IntentManager intentManager;
+    private final IntentProcessor processor;
     private final IntentData pending;
     private final IntentData current;
 
-    WithdrawCoordinating(IntentManager intentManager, IntentData pending, IntentData current) {
-        this.intentManager = checkNotNull(intentManager);
+    WithdrawCoordinating(IntentProcessor processor, IntentData pending, IntentData current) {
+        this.processor = checkNotNull(processor);
         this.pending = checkNotNull(pending);
         this.current = checkNotNull(current);
     }
@@ -49,9 +48,9 @@ final class WithdrawCoordinating implements IntentProcessPhase {
     public Optional<IntentProcessPhase> execute() {
         try {
             // Note: current.installables() are not null or empty due to createIntentUpdate check
-            FlowRuleOperations flowRules = intentManager.uninstallCoordinate(current, pending);
+            FlowRuleOperations flowRules = processor.uninstallCoordinate(current, pending);
             pending.setInstallables(current.installables());
-            return Optional.of(new Withdrawing(intentManager, pending, flowRules));
+            return Optional.of(new Withdrawing(processor, pending, flowRules));
         } catch (IntentException e) {
             log.warn("Unable to generate generate a FlowRuleOperations from intent {} due to:", pending.intent(), e);
             return Optional.of(new WithdrawingFailed(pending));

@@ -16,7 +16,7 @@
 package org.onosproject.net.intent.impl.phase;
 
 import org.onosproject.net.intent.IntentData;
-import org.onosproject.net.intent.impl.IntentManager;
+import org.onosproject.net.intent.impl.IntentProcessor;
 
 import java.util.Optional;
 
@@ -27,13 +27,12 @@ import static com.google.common.base.Preconditions.checkNotNull;
  */
 public final class WithdrawRequest implements IntentProcessPhase {
 
-    // TODO: define an interface and use it, instead of IntentManager
-    private final IntentManager intentManager;
+    private final IntentProcessor processor;
     private final IntentData pending;
     private final IntentData current;
 
-    public WithdrawRequest(IntentManager intentManager, IntentData intentData, IntentData current) {
-        this.intentManager = checkNotNull(intentManager);
+    public WithdrawRequest(IntentProcessor processor, IntentData intentData, IntentData current) {
+        this.processor = checkNotNull(processor);
         this.pending = checkNotNull(intentData);
         this.current = checkNotNull(current);
     }
@@ -43,6 +42,6 @@ public final class WithdrawRequest implements IntentProcessPhase {
         //TODO perhaps we want to validate that the pending and current are the
         // same version i.e. they are the same
         // Note: this call is not just the symmetric version of submit
-        return Optional.of(new WithdrawCoordinating(intentManager, pending, current));
+        return Optional.of(new WithdrawCoordinating(processor, pending, current));
     }
 }

@@ -17,7 +17,7 @@ package org.onosproject.net.intent.impl.phase;
 
 import org.onosproject.net.flow.FlowRuleOperations;
 import org.onosproject.net.intent.IntentData;
-import org.onosproject.net.intent.impl.IntentManager;
+import org.onosproject.net.intent.impl.IntentProcessor;
 
 import java.util.Optional;
 
@@ -29,20 +29,19 @@ import static com.google.common.base.Preconditions.checkNotNull;
  */
 class Withdrawing implements IntentProcessPhase {
 
-    // TODO: define an interface and use it, instead of IntentManager
-    private final IntentManager intentManager;
+    private final IntentProcessor processor;
     private final IntentData pending;
     private final FlowRuleOperations flowRules;
 
-    Withdrawing(IntentManager intentManager, IntentData pending, FlowRuleOperations flowRules) {
-        this.intentManager = checkNotNull(intentManager);
+    Withdrawing(IntentProcessor processor, IntentData pending, FlowRuleOperations flowRules) {
+        this.processor = checkNotNull(processor);
         this.pending = checkNotNull(pending);
         this.flowRules = checkNotNull(flowRules);
     }
 
     @Override
     public Optional<IntentProcessPhase> execute() {
-        intentManager.flowRuleService.apply(flowRules);
+        processor.applyFlowRules(flowRules);
         return Optional.of(new Withdrawn(pending));
     }
 }