comment,doc: added javadoc comments

src/main/java/com/github/sttk/sabi/AsyncGroup.java

@@ -4,10 +4,35 @@
  */
 package com.github.sttk.sabi;
 
+/**
+ * An interface for asynchronously executing multiple {@link Runner} instances and waiting for their
+ * completion.
+ *
+ * <p>Implementations of this interface allow adding multiple {@link Runner} objects, which are then
+ * executed concurrently. The group waits until all added runners have finished their execution. Any
+ * errors occurring during the execution of a {@link Runner} are stored and can be retrieved by
+ * their names in a map.
+ */
 public interface AsyncGroup {
+
+  /**
+   * Represents the reason for a new {@link com.github.sttk.errs.Exc} exception object when an
+   * exception occurred during the execution of a {@link Runner} and the exception class was not the
+   * {@link com.github.sttk.errs.Exc}.
+   */
   record RunnerFailed() {}
 
+  /**
+   * Represents the reason for an {@link com.github.sttk.errs.Exc} exception object when the
+   * creation of a thread for asynchronous execution of a {@link Runner} fails.
+   */
   record RunnerInterrupted() {}
 
+  /**
+   * Adds a {@link Runner} to this group for asynchronous execution. The added runner will be
+   * executed in a separate thread.
+   *
+   * @param runner The {@link Runner} to be added and executed asynchronously.
+   */
   void add(final Runner runner);
 }

src/main/java/com/github/sttk/sabi/DataAcc.java

@@ -6,6 +6,26 @@
 
 import com.github.sttk.errs.Exc;
 
+/**
+ * An interface designed for implementing data access operations through default methods in its
+ * sub-interfaces.
+ *
+ * <p>Sub-interfaces of {@code DataAcc} are expected to define and implement data access methods as
+ * default methods. Within these default methods, the connection to the underlying data store should
+ * be obtained using the {@link #getDataConn(String, Class)} method provided by this interface. This
+ * design promotes a clear separation of concerns, allowing data access logic to be encapsulated
+ * within the interface itself.
+ */
 public interface DataAcc {
+  /**
+   * Retrieves a connection to a data store. This method is intended to be used by default methods
+   * in sub-interfaces to obtain the necessary connection for performing data access operations.
+   *
+   * @param <C> The type of the data connection, which must extend {@link DataConn}.
+   * @param name The name identifying the specific data connection to retrieve.
+   * @param cls The {@link Class} object representing the type of the desired data connection.
+   * @return A data connection object of the specified type.
+   * @throws Exc if an error occurs while obtaining the data connection.
+   */
   <C extends DataConn> C getDataConn(String name, Class<C> cls) throws Exc;
 }

src/main/java/com/github/sttk/sabi/DataConn.java

@@ -6,20 +6,77 @@
 
 import com.github.sttk.errs.Exc;
 
+/**
+ * The interface that abstracts a connection per session to an external data service, such as a
+ * database, file system, or messaging service.
+ *
+ * <p>Its primary purpose is to enable cohesive transaction operations across multiple external data
+ * services within a single transaction context. Implementations of this interface provide the
+ * concrete input/output operations for their respective data services.
+ *
+ * <p>Methods declared within this interface are designed to handle transactional logic. The
+ * AsyncGroup parameter in various methods allows for asynchronous processing when commit or
+ * rollback operations are time-consuming.
+ */
 public interface DataConn {
+  /**
+   * Commits the changes made within the current session to the external data service. This method
+   * is responsible for finalizing all operations performed since the last commit or rollback.
+   *
+   * @param ag An {@link AsyncGroup} that can be used to perform asynchronous operations if the
+   *     commit process is time-consuming.
+   * @throws Exc if an error occurs during the commit operation.
+   */
   void commit(AsyncGroup ag) throws Exc;
 
+  /**
+   * Performs any necessary pre-commit operations. This method is called before the {@link
+   * #commit(AsyncGroup)} method.
+   *
+   * @param ag An {@link AsyncGroup} that can be used for asynchronous pre-commit tasks.
+   * @throws Exc if an error occurs during the pre-commit operation.
+   */
   default void preCommit(AsyncGroup ag) throws Exc {}
 
+  /**
+   * Performs any necessary post-commit operations. This method is called after the {@link
+   * #commit(AsyncGroup)} method has successfully completed.
+   *
+   * @param ag An {@link AsyncGroup} that can be used for asynchronous post-commit tasks.
+   */
   default void postCommit(AsyncGroup ag) {}
 
+  /**
+   * Indicates whether a force-back operation should be performed. A force-back is a mechanism to
+   * revert the committed changes when this connection had been already committed but the other
+   * connection had failed.
+   *
+   * @return {@code true} if a force-back is required, {@code false} otherwise.
+   */
   default boolean shouldForceBack() {
     return false;
   }
 
+  /**
+   * Rolls back the changes made within the current session, discarding all operations performed
+   * since the last commit or rollback.
+   *
+   * @param ag An {@link AsyncGroup} that can be used to perform asynchronous operations if the
+   *     rollback process is time-consuming.
+   */
   void rollback(AsyncGroup ag);
 
+  /**
+   * Performs a force-back operation to revert the committed changes when this connection had been
+   * already committed but the other connection had failed.
+   *
+   * @param ag An {@link AsyncGroup} that can be used for asynchronous force-back tasks.
+   */
   default void forceBack(AsyncGroup ag) {}
 
+  /**
+   * Closes the connection to the external data service, releasing any associated resources. This
+   * method should be called to ensure proper resource management.
+   */
   void close();
 }

src/main/java/com/github/sttk/sabi/DataHub.java

@@ -8,39 +8,137 @@
 import com.github.sttk.sabi.internal.DataHubInner;
 import java.util.Map;
 
+/**
+ * {@code DataHub} is a central component in the Sabi framework that manages {@link DataSrc} and
+ * {@link DataConn} instances, facilitating data access and transaction management. It implements
+ * both {@link DataAcc} for data access operations and {@link AutoCloseable} for resource
+ * management.
+ *
+ * <p>This class allows for the registration and unregistration of local {@link DataSrc} objects,
+ * and provides methods to execute application logic with or without transactional boundaries.
+ */
 public class DataHub implements DataAcc, AutoCloseable {
+  /**
+   * Represents an error reason that occurred when failing to set up global {@link DataSrc}
+   * instances.
+   *
+   * @param errors A map containing the names of the data sources and the corresponding exceptions
+   *     that occurred during their setup.
+   */
   public record FailToSetupGlobalDataSrcs(Map<String, Exc> errors) {}
 
+  /**
+   * Represents an error reason that occurred when failing to set up local {@link DataSrc}
+   * instances.
+   *
+   * @param errors A map containing the names of the data sources and the corresponding exceptions
+   *     that occurred during their setup.
+   */
   public record FailToSetupLocalDataSrcs(Map<String, Exc> errors) {}
 
+  /**
+   * Represents an error reason that occurred when failing to commit one or more {@link DataConn}
+   * instances.
+   *
+   * @param errors A map containing the names of the data connections and the corresponding
+   *     exceptions that occurred during their commit.
+   */
   public record FailToCommitDataConn(Map<String, Exc> errors) {}
 
+  /**
+   * Represents an error reason that occurred when failing to pre-commit one or more {@link
+   * DataConn} instances.
+   *
+   * @param errors A map containing the names of the data connections and the corresponding
+   *     exceptions that occurred during their pre-commit.
+   */
   public record FailToPreCommitDataConn(Map<String, Exc> errors) {}
 
+  /**
+   * Represents an error reason where no {@link DataSrc} was found to create a {@link DataConn} with
+   * the specified name and type.
+   *
+   * @param name The name of the data source requested.
+   * @param dataConnType The type of the data connection requested.
+   */
   public record NoDataSrcToCreateDataConn(String name, String dataConnType) {}
 
+  /**
+   * Represents an error reason that occurred when failing to create a {@link DataConn} instance.
+   *
+   * @param name The name of the data source from which the connection was attempted.
+   * @param dataConnType The type of the data connection that failed to be created.
+   */
   public record FailToCreateDataConn(String name, String dataConnType) {}
 
+  /**
+   * Represents an error reason where the created {@link DataConn} instance was null.
+   *
+   * @param name The name of the data source.
+   * @param dataConnType The type of the data connection expected.
+   */
   public record CreatedDataConnIsNull(String name, String dataConnType) {}
 
+  /**
+   * Represents an error reason that occurred when failing to cast a {@link DataConn} to the
+   * requested type.
+   *
+   * @param name The name of the data connection.
+   * @param castToType The type to which the data connection was attempted to be cast.
+   */
   public record FailToCastDataConn(String name, String castToType) {}
 
+  /**
+   * Represents an error reason that occurred when failing to cast the {@code DataHub} instance
+   * itself to the expected data access interface type for a {@link Logic}.
+   *
+   * @param castFromType The actual type of the {@code DataHub} instance that failed to cast.
+   */
   public record FailToCastDataHub(String castFromType) {}
 
-  public record RuntimeExceptionOccured() {}
+  /**
+   * Represents an unexpected {@link RuntimeException} that occurred during pre-commit or commit
+   * operations.
+   */
+  public record RuntimeExceptionOccurred() {}
 
   private final DataHubInner inner = new DataHubInner();
 
+  /** Constructs a new {@code DataHub} instance. */
   public DataHub() {}
 
+  /**
+   * Registers a local {@link DataSrc} with the specified name for use within this {@code DataHub}
+   * instance. This allows specific data sources to be managed independently from globally
+   * registered ones.
+   *
+   * @param name The unique name for the {@link DataSrc}.
+   * @param ds The {@link DataSrc} instance to register.
+   */
   public void uses(String name, DataSrc ds) {
     inner.uses(name, ds);
   }
 
+  /**
+   * Unregisters a local {@link DataSrc} with the given name from this {@code DataHub} instance.
+   *
+   * @param name The name of the {@link DataSrc} to unregister.
+   */
   public void disuses(String name) {
     inner.disuses(name);
   }
 
+  /**
+   * Executes the provided application {@link Logic} without transactional boundaries. The {@code
+   * DataHub} instance itself is passed as the data access object {@code D} to the {@link Logic}'s
+   * {@code run} method.
+   *
+   * @param <D> The type of the data access object, which typically is {@code DataHub} or an
+   *     interface implemented by {@code DataHub} that {@link Logic} expects.
+   * @param logic The application logic to execute.
+   * @throws Exc if an {@link Exc} or {@link RuntimeException} occurs during logic execution or if
+   *     the {@code DataHub} cannot be cast to the expected data access type.
+   */
   public <D> void run(Logic<D> logic) throws Exc {
     D data;
     try {
@@ -60,6 +158,19 @@ public <D> void run(Logic<D> logic) throws Exc {
     }
   }
 
+  /**
+   * Executes the provided application {@link Logic} within a transactional context. The {@code
+   * DataHub} instance is passed as the data access object {@code D} to the {@link Logic}'s {@code
+   * run} method. If the logic completes successfully, a commit operation is attempted. If any
+   * {@link Exc}, {@link RuntimeException}, or {@link Error} occurs, a rollback operation is
+   * performed.
+   *
+   * @param <D> The type of the data access object, which typically is {@code DataHub} or an
+   *     interface implemented by {@code DataHub} that {@link Logic} expects.
+   * @param logic The application logic to execute transactionally.
+   * @throws Exc if an {@link Exc}, {@link RuntimeException}, or {@link Error} occurs during logic
+   *     execution, pre-commit, or commit. The original exception is re-thrown after rollback.
+   */
   public <D> void txn(Logic<D> logic) throws Exc {
     D data;
     try {
@@ -82,11 +193,27 @@ public <D> void txn(Logic<D> logic) throws Exc {
     }
   }
 
+  /**
+   * Retrieves a {@link DataConn} instance from the managed data sources. This method is part of the
+   * {@link DataAcc} interface implementation.
+   *
+   * @param <C> The type of the {@link DataConn} to retrieve, which must extend {@link DataConn}.
+   * @param name The name of the data source from which to get the connection.
+   * @param cls The {@link Class} object representing the desired type of the data connection.
+   * @return A {@link DataConn} instance of the specified type.
+   * @throws Exc if no data source is found, if the connection cannot be created, if the created
+   *     connection is null, or if the connection cannot be cast to the specified class.
+   */
   @Override
   public <C extends DataConn> C getDataConn(String name, Class<C> cls) throws Exc {
     return inner.getDataConn(name, cls);
   }
 
+  /**
+   * Closes all {@link DataConn} instances managed by this {@code DataHub}, releasing their
+   * resources. This method is part of the {@link AutoCloseable} interface and should be called to
+   * ensure proper resource cleanup, ideally in a try-with-resources statement.
+   */
   @Override
   public void close() {
     inner.close();

src/main/java/com/github/sttk/sabi/DataSrc.java

@@ -6,10 +6,39 @@
 
 import com.github.sttk.errs.Exc;
 
+/**
+ * The interface that abstracts a data source responsible for managing connections to external data
+ * services, such as databases, file systems, or messaging services.
+ *
+ * <p>It receives configuration for connecting to an external data service and then creates and
+ * supplies a {@link DataConn} instance, representing a single session connection.
+ */
 public interface DataSrc {
+  /**
+   * Sets up the data source, performing any necessary initialization or configuration to establish
+   * connectivity to the external data service. This method is typically called once at the
+   * application startup.
+   *
+   * @param ag An {@link AsyncGroup} that can be used for asynchronous setup operations, especially
+   *     if initialization is time-consuming.
+   * @throws Exc if an error occurs during the setup process.
+   */
   void setup(AsyncGroup ag) throws Exc;
 
+  /**
+   * Closes the data source, releasing all resources and shutting down connections managed by this
+   * source. This method should be called when the application is shutting down to ensure proper
+   * resource cleanup.
+   */
   void close();
 
+  /**
+   * Creates and returns a new {@link DataConn} instance, representing a single session connection
+   * to the external data service. Each call to this method should yield a new, independent
+   * connection.
+   *
+   * @return A new {@link DataConn} instance for a session.
+   * @throws Exc if an error occurs while creating the data connection.
+   */
   DataConn createDataConn() throws Exc;
 }

src/main/java/com/github/sttk/sabi/Logic.java

@@ -6,7 +6,28 @@
 
 import com.github.sttk.errs.Exc;
 
+/**
+ * Represents the application's business logic, designed to separate data access concerns from the
+ * core logic.
+ *
+ * <p>Implementations of this functional interface should focus solely on the business logic,
+ * utilizing the provided {@code data} object of type {@code D} for all data access operations. The
+ * {@link #run(Object)} method should not contain any direct data access code; instead, it should
+ * delegate such operations to methods of the {@code D} object.
+ *
+ * <p>If an exceptional condition occurs during the execution of the logic, an {@link Exc} object
+ * should be thrown.
+ *
+ * @param <D> The type of the data access object through which data operations are performed.
+ */
 @FunctionalInterface
 public interface Logic<D> {
+  /**
+   * Executes the application's business logic. This method should implement the core logic, relying
+   * on the {@code data} object for all data access needs.
+   *
+   * @param data The data access object, providing methods for interacting with data.
+   * @throws Exc if an error or exceptional condition occurs during the logic execution.
+   */
   void run(D data) throws Exc;
 }