Package org.apache.ignite.spi.checkpoint.sharedfs

## Class SharedFsCheckpointSpi

- java.lang.Object
- - org.apache.ignite.spi.IgniteSpiAdapter
  - - org.apache.ignite.spi.checkpoint.sharedfs.SharedFsCheckpointSpi

- All Implemented Interfaces:
    `CheckpointSpi`, `IgniteSpi`

      @IgniteSpiMultipleInstancesSupport(true)
      @IgniteSpiConsistencyChecked(optional=false)
      public class SharedFsCheckpointSpi
      extends IgniteSpiAdapter
      implements CheckpointSpi

  This class defines shared file system `CheckpointSpi` implementation for checkpoint SPI. All checkpoints are stored on shared storage and available for all nodes in the grid. Note that every node must have access to the shared directory. The reason the directory needs to be `shared` is because a job state can be saved on one node and loaded on another (e.g. if a job gets preempted on a different node after node failure). When started, this SPI tracks all checkpoints saved by localhost for expiration. Note that this SPI does not cache data stored in checkpoints - all the data is loaded from file system on demand.

  Directory paths for shared checkpoints should either be empty or contain previously stored checkpoint files.

  # Configuration

  ## Mandatory

  This SPI has no mandatory configuration parameters.

  ## Optional

  This SPI has following optional configuration parameters:
  - Directory paths (see `setDirectoryPaths(Collection)`)

  ## Java Example

  `SharedFsCheckpointSpi` can be configured as follows:

       IgniteConfiguration cfg = new IgniteConfiguration();

       SharedFsCheckpointSpi checkpointSpi = new SharedFsCheckpointSpi();

       // List of checkpoint directories where all files are stored.
       Collection dirPaths = new ArrayList();

       dirPaths.add("/my/directory/path");
       dirPaths.add("/other/directory/path");

       // Override default directory path.
       checkpointSpi.setDirectoryPaths(dirPaths);

       // Override default checkpoint SPI.
       cfg.setCheckpointSpi(checkpointSpi);

       // Starts grid.
       G.start(cfg);

  ## Spring Example

  `SharedFsCheckpointSpi` can be configured from Spring XML configuration file:

       <bean id="grid.custom.cfg" class="org.apache.ignite.configuration.IgniteConfiguration" singleton="true">
           ...
           <property name="checkpointSpi">
               <bean class="org.apache.ignite.spi.checkpoint.sharedfs.GridSharedFsCheckpointSpi">
                   <!-- Change to shared directory path in your environment. -->
                   <property name="directoryPaths">
                       <list>
                           <value>/my/directory/path</value>
                           <value>/other/directory/path</value>
                       </list>
                   </property>
               </bean>
           </property>
           ...
       </bean>

  For information about Spring framework visit www.springframework.org

  See Also:
    `CheckpointSpi`

- - ### Field Summary

    Fields
    Modifier and Type | Field | Description
    --- | --- | ---
    `static String` | `DFLT_DIR_PATH` | Default checkpoint directory.
    `static String` | `DFLT_ROOT` | Default root checkpoint directory.

  - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `SharedFsCheckpointSpi()` | Initializes default directory paths.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `String` | `getCurrentDirectoryPath()` | Gets path to the directory where all checkpoints are saved.
    `Collection<String>` | `getDirectoryPaths()` | Gets collection of all configured paths where checkpoints can be saved.
    `byte[]` | `loadCheckpoint​(String key)` | Loads checkpoint from storage by its unique key.
    `boolean` | `removeCheckpoint​(String key)` | This method instructs the checkpoint provider to clean saved data for a given `key`.
    `boolean` | `saveCheckpoint​(String key, byte[] state, long timeout, boolean overwrite)` | Saves checkpoint to the storage.
    `void` | `setCheckpointListener​(CheckpointListener lsnr)` | Sets the checkpoint listener.
    `SharedFsCheckpointSpi` | `setDirectoryPaths​(Collection<String> dirPaths)` | Sets path to a shared directory where checkpoints will be stored.
    `SharedFsCheckpointSpi` | `setName​(String name)` | Sets SPI name.
    `void` | `spiStart​(String igniteInstanceName)` | This method is called to start SPI.
    `void` | `spiStop()` | This method is called to stop SPI.
    `String` | `toString()`

    - ### Methods inherited from class org.apache.ignite.spi.IgniteSpiAdapter

      `addTimeoutObject, assertParameter, checkConfigurationConsistency0, clientFailureDetectionTimeout, configInfo, createSpiAttributeName, failureDetectionTimeout, failureDetectionTimeoutEnabled, failureDetectionTimeoutEnabled, getConsistentAttributeNames, getExceptionRegistry, getLocalNode, getName, getNodeAttributes, getSpiContext, ignite, initFailureDetectionTimeout, injectables, injectResources, isNodeStopping, onBeforeStart, onClientDisconnected, onClientReconnected, onContextDestroyed, onContextDestroyed0, onContextInitialized, onContextInitialized0, registerMBean, removeTimeoutObject, started, startInfo, startStopwatch, stopInfo, unregisterMBean`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

    - ### Methods inherited from interface org.apache.ignite.spi.IgniteSpi

      `getName, getNodeAttributes, onClientDisconnected, onClientReconnected, onContextDestroyed, onContextInitialized`

- - ### Field Detail

    - #### DFLT_ROOT

          public static final String DFLT_ROOT

      Default root checkpoint directory.
      See Also:
        Constant Field Values

    - #### DFLT_DIR_PATH

          public static final String DFLT_DIR_PATH

      Default checkpoint directory. Note that this path is relative to `IGNITE_HOME/work` folder if `IGNITE_HOME` system or environment variable specified, otherwise it is relative to `work` folder under system `java.io.tmpdir` folder.
      See Also:
        `IgniteConfiguration.getWorkDirectory()`, Constant Field Values

  - ### Constructor Detail

    - #### SharedFsCheckpointSpi

          public SharedFsCheckpointSpi()

      Initializes default directory paths.

  - ### Method Detail

    - #### getDirectoryPaths

          public Collection<String> getDirectoryPaths()

      Gets collection of all configured paths where checkpoints can be saved.
      Returns:
        Collection of all configured paths.

    - #### getCurrentDirectoryPath

          public String getCurrentDirectoryPath()

      Gets path to the directory where all checkpoints are saved.
      Returns:
        Path to the checkpoints directory.

    - #### setDirectoryPaths

          @IgniteSpiConfiguration(optional=true)
          public SharedFsCheckpointSpi setDirectoryPaths​(Collection<String> dirPaths)

      Sets path to a shared directory where checkpoints will be stored. The path can either be absolute or relative to `IGNITE_HOME` system or environment variable.

      If not provided, default value is `DFLT_DIR_PATH`.

      Parameters:
        `dirPaths` - Absolute or Ignite installation home folder relative path where checkpoints will be stored.
      Returns:
        `this` for chaining.

    - #### spiStart

          public void spiStart​(String igniteInstanceName)
                        throws IgniteSpiException

      This method is called to start SPI. After this method returns successfully kernel assumes that SPI is fully operational.
      Specified by:
        `spiStart` in interface `IgniteSpi`
      Parameters:
        `igniteInstanceName` - Name of Ignite instance this SPI is being started for (`null` for default Ignite instance).
      Throws:
        `IgniteSpiException` - Throws in case of any error during SPI start.

    - #### spiStop

          public void spiStop()
                       throws IgniteSpiException

      This method is called to stop SPI. After this method returns kernel assumes that this SPI is finished and all resources acquired by it are released.

      Note that this method can be called at any point including during recovery of failed start. It should make no assumptions on what state SPI will be in when this method is called.

      Specified by:
        `spiStop` in interface `IgniteSpi`
      Throws:
        `IgniteSpiException` - Thrown in case of any error during SPI stop.

    - #### loadCheckpoint

          public byte[] loadCheckpoint​(String key)
                                throws IgniteSpiException

      Loads checkpoint from storage by its unique key.
      Specified by:
        `loadCheckpoint` in interface `CheckpointSpi`
      Parameters:
        `key` - Checkpoint key.
      Returns:
        Loaded data or `null` if there is no data for a given key.
      Throws:
        `IgniteSpiException` - Thrown in case of any error while loading checkpoint data. Note that in case when given `key` is not found this method will return `null`.

    - #### saveCheckpoint

          public boolean saveCheckpoint​(String key,
                                        byte[] state,
                                        long timeout,
                                        boolean overwrite)
                                 throws IgniteSpiException

      Saves checkpoint to the storage.
      Specified by:
        `saveCheckpoint` in interface `CheckpointSpi`
      Parameters:
        `key` - Checkpoint unique key.
        `state` - Saved data.
        `timeout` - Every intermediate data stored by checkpoint provider should have a timeout. Timeout allows for effective resource management by checkpoint provider by cleaning saved data that are not needed anymore. Generally, the user should choose the minimum possible timeout to avoid long-term resource acquisition by checkpoint provider. Value `0` means that timeout will never expire.
        `overwrite` - Whether or not overwrite checkpoint if it already exists.
      Returns:
        `true` if checkpoint has been actually saved, `false` otherwise.
      Throws:
        `IgniteSpiException` - Thrown in case of any error while saving checkpoint data.

    - #### removeCheckpoint

          public boolean removeCheckpoint​(String key)

      This method instructs the checkpoint provider to clean saved data for a given `key`.
      Specified by:
        `removeCheckpoint` in interface `CheckpointSpi`
      Parameters:
        `key` - Key for the checkpoint to remove.
      Returns:
        `true` if data has been actually removed, `false` otherwise.

    - #### setCheckpointListener

          public void setCheckpointListener​(CheckpointListener lsnr)

      Sets the checkpoint listener.
      Specified by:
        `setCheckpointListener` in interface `CheckpointSpi`
      Parameters:
        `lsnr` - The listener to set or `null`.

    - #### setName

          public SharedFsCheckpointSpi setName​(String name)

      Sets SPI name.
      Overrides:
        `setName` in class `IgniteSpiAdapter`
      Parameters:
        `name` - SPI name.
      Returns:
        `this` for chaining.

    - #### toString

          public String toString()

      Overrides:
        `toString` in class `Object`