org.apache.mesos

Class Log.Reader

java.lang.Object

org.apache.mesos.Log.Reader

Enclosing class:

Log

public static class Log.Reader
extends java.lang.Object

Provides read access to the Log. This class is safe for use from multiple threads and for the life of the log regardless of any exceptions thrown from its methods.

Constructor Summary

Constructors

Constructor and Description
Reader(Log log) Returns an instance of a reader that will access the given instance of the Log.

Method Summary

Modifier and Type	Method and Description
Log.Position	beginning() Returns the beginning position of the log (might be out of date with respect to another replica).
Log.Position	catchup(long timeout, java.util.concurrent.TimeUnit unit) Attempts to catch-up positions from the log for reading.
Log.Position	ending() Returns the ending position of the log (might be out of date with respect to another replica).
protected void	finalize()
protected void	initialize(Log log)
java.util.List<Log.Entry>	read(Log.Position from, Log.Position to, long timeout, java.util.concurrent.TimeUnit unit) Attempts to read from the log between the specified positions (inclusive).

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Reader

public Reader(Log log)

Returns an instance of a reader that will access the given instance of the Log.

Parameters:

log - The log that this reader will access.

Method Detail

read

public java.util.List<Log.Entry> read(Log.Position from,
                                      Log.Position to,
                                      long timeout,
                                      java.util.concurrent.TimeUnit unit)
                               throws java.util.concurrent.TimeoutException,
                                      Log.OperationFailedException

Attempts to read from the log between the specified positions (inclusive). If either of the positions are invalid, an Log.OperationFailedException will get thrown. Unfortunately, this will also get thrown in other circumstances (e.g., disk failure) and therefore it is currently impossible to tell these two cases apart.

Parameters:

from - Where to start reading.

to - Where to finish reading.

timeout - Max number of time units to wait before a TimeoutException.

unit - Type of units used for the timeout, e.g. seconds, minutes, etc.

Returns:

The list of entries fetched from the Log.

Throws:

java.util.concurrent.TimeoutException - If the read doesn't happen before the timeout.

Log.OperationFailedException - If the read fails due that the read no longer has the ability to perform its operations.

See Also:

Log.Position, TimeUnit

beginning

public Log.Position beginning()

Returns the beginning position of the log (might be out of date with respect to another replica).

Returns:

The beginning position of the log.

ending

public Log.Position ending()

Returns the ending position of the log (might be out of date with respect to another replica).

Returns:

The ending position of the log

catchup

public Log.Position catchup(long timeout,
                            java.util.concurrent.TimeUnit unit)
                     throws java.util.concurrent.TimeoutException,
                            Log.OperationFailedException

Attempts to catch-up positions from the log for reading.

Parameters:

timeout - Max number of time units to wait before a TimeoutException.

unit - Type of time units used for the timeout, e.g. seconds, minutes, etc.

Returns:

The ending position of the caught-up range.

Throws:

java.util.concurrent.TimeoutException - If the catch-up doesn't happen before the timeout.

Log.OperationFailedException - If the catch-up fails.

initialize

protected void initialize(Log log)

finalize

protected void finalize()

Overrides:

finalize in class java.lang.Object