Refactor Raft implementation as a standalone interface dependent only…

… on I/O and Cluster.

raft/pom.xml

@@ -29,7 +29,7 @@
   <dependencies>
     <dependency>
       <groupId>net.kuujo.copycat</groupId>
-      <artifactId>copycat-core</artifactId>
+      <artifactId>copycat-cluster</artifactId>
       <version>${project.version}</version>
     </dependency>
     <dependency>

raft/src/main/java/net/kuujo/copycat/protocol/raft/ApplicationException.java → raft/src/main/java/net/kuujo/copycat/raft/ApplicationException.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package net.kuujo.copycat.protocol.raft;
+package net.kuujo.copycat.raft;
 
 /**
  * Application exception.

raft/src/main/java/net/kuujo/copycat/raft/Apply.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * 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 net.kuujo.copycat.raft;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation for applying commands to the state machine.
+ *
+ * @author <a href="http://github.com/kuujo">Jordan Halterman</a>
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Apply {
+
+  /**
+   * The command types to apply.
+   */
+  Class<? extends Command>[] value();
+
+  /**
+   * Indicates that all commands should be applied.
+   */
+  static class All implements Command {
+  }
+
+}

raft/src/main/java/net/kuujo/copycat/protocol/raft/DeleteException.java → raft/src/main/java/net/kuujo/copycat/raft/Command.java

@@ -13,26 +13,25 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package net.kuujo.copycat.protocol.raft;
+package net.kuujo.copycat.raft;
 
 /**
- * Delete exception.
+ * Command operation.
  *
  * @author <a href="http://github.com/kuujo">Jordan Halterman</a>
  */
-public class DeleteException extends RaftException {
-  private static final RaftError.Type TYPE = RaftError.Type.DELETE_ERROR;
+public interface Command<T> extends Operation<T> {
 
-  public DeleteException(String message, Object... args) {
-    super(TYPE, message, args);
-  }
-
-  public DeleteException(Throwable cause, String message, Object... args) {
-    super(TYPE, cause, message, args);
-  }
+  /**
+   * Command builder.
+   */
+  static class Builder<T extends Builder<T, U>, U extends Command<?>> extends Operation.Builder<U> {
+    protected final U command;
 
-  public DeleteException(Throwable cause) {
-    super(TYPE, cause);
+    public Builder(U command) {
+      super(command);
+      this.command = command;
+    }
   }
 
 }

raft/src/main/java/net/kuujo/copycat/raft/Commit.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * 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 net.kuujo.copycat.raft;
+
+/**
+ * Protocol commit.
+ *
+ * @author <a href="http://github.com/kuujo">Jordan Halterman</a>
+ */
+public class Commit<T extends Operation> {
+  private final long index;
+  private final long timestamp;
+  private final T operation;
+
+  public Commit(long index, long timestamp, T operation) {
+    this.index = index;
+    this.timestamp = timestamp;
+    this.operation = operation;
+  }
+
+  /**
+   * Returns the commit index.
+   *
+   * @return The commit index.
+   */
+  public long index() {
+    return index;
+  }
+
+  /**
+   * Returns the commit timestamp.
+   *
+   * @return the commit timestamp.
+   */
+  public long timestamp() {
+    return timestamp;
+  }
+
+  /**
+   * Returns the commit type.
+   *
+   * @return The commit type.
+   */
+  @SuppressWarnings("unchecked")
+  public Class<T> type() {
+    return (Class<T>) operation.getClass();
+  }
+
+  /**
+   * Returns the operation.
+   *
+   * @return The operation.
+   */
+  public T operation() {
+    return operation;
+  }
+
+}

raft/src/main/java/net/kuujo/copycat/protocol/raft/IllegalMemberStateException.java → raft/src/main/java/net/kuujo/copycat/raft/IllegalMemberStateException.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package net.kuujo.copycat.protocol.raft;
+package net.kuujo.copycat.raft;
 
 /**
  * Illegal member state exception.

raft/src/main/java/net/kuujo/copycat/protocol/raft/NoLeaderException.java → raft/src/main/java/net/kuujo/copycat/raft/NoLeaderException.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package net.kuujo.copycat.protocol.raft;
+package net.kuujo.copycat.raft;
 
 /**
  * Not leader exception.

raft/src/main/java/net/kuujo/copycat/raft/Operation.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * 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 net.kuujo.copycat.raft;
+
+import java.io.Serializable;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * State machine operation.
+ *
+ * @author <a href="http://github.com/kuujo">Jordan Halterman</a>
+ */
+public interface Operation<T> extends Serializable {
+
+  /**
+   * Returns a cached instance of the given builder.
+   *
+   * @param type The builder type.
+   * @return The builder.
+   */
+  @SuppressWarnings("unchecked")
+  static <T extends Builder<U>, U extends Operation<?>> T builder(Class<T> type) {
+    return (T) Builder.BUILDERS.get().computeIfAbsent(type, t -> {
+      try {
+        return type.newInstance();
+      } catch (InstantiationException | IllegalAccessException e) {
+        throw new IllegalArgumentException("failed to instantiate builder: " + type, e);
+      }
+    });
+  }
+
+  /**
+   * Operation builder.
+   */
+  static abstract class Builder<T extends Operation<?>> implements net.kuujo.copycat.Builder<T> {
+    private static final ThreadLocal<Map<Class<? extends Builder>, Builder>> BUILDERS = new ThreadLocal<Map<Class<? extends Builder>, Builder>>() {
+      @Override
+      protected Map<Class<? extends Builder>, Builder> initialValue() {
+        return new HashMap<>();
+      }
+    };
+
+    private final T operation;
+
+    protected Builder(T operation) {
+      this.operation = operation;
+    }
+
+    @Override
+    public T build() {
+      return operation;
+    }
+  }
+
+}

raft/src/main/java/net/kuujo/copycat/raft/Query.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * 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 net.kuujo.copycat.raft;
+
+/**
+ * Query operation.
+ *
+ * @author <a href="http://github.com/kuujo">Jordan Halterman</a>
+ */
+public interface Query<T> extends Operation<T> {
+
+  /**
+   * Returns the query consistency.
+   *
+   * @return The query consistency.
+   */
+  Consistency consistency();
+
+  /**
+   * Query consistency.
+   */
+  static enum Consistency {
+
+    /**
+     * Provides serializable consistency.
+     */
+    SERIALIZABLE,
+
+    /**
+     * Provides linearizable consistency based on a leader lease.
+     */
+    LINEARIZABLE_LEASE,
+
+    /**
+     * Provides strict linearizable consistency.
+     */
+    LINEARIZABLE_STRICT
+
+  }
+
+  /**
+   * Query builder.
+   */
+  static class Builder<T extends Builder<T, U>, U extends Query<?>> extends Operation.Builder<U> {
+    protected final U query;
+
+    public Builder(U query) {
+      super(query);
+      this.query = query;
+    }
+  }
+
+}