pack-priv Class RAFContainer4

Use when seeing an exception during IO and when another thread is presumably doing the recovery.

If stealthMode == false, wait for another thread to recover the container after an interrupt. If stealthMode == true, throw internal exception InterruptDetectedException to do retry from higher in the stack.

If stealthMode == false, maximum wait time for the container to become available again is determined by the product InterruptStatus.MAX_INTERRUPT_RETRIES * InterruptStatus.INTERRUPT_RETRY_SLEEP. There is a chance this thread will not see any recovery occuring (yet), in which case it waits for a bit and just returns, so the caller must retry IO until success.

If for some reason the recovering thread has given up on resurrecting the container, cf #giveUpIO, the method throws FILE_IO_INTERRUPTED.

Parameters

e:Exception

the exception we saw during IO

stealthMode:boolean

true if the thread doing IO in stealth mode

Exceptions

StandardException:

InterruptDetectedException and normal error policy

Return the FileChannel for the specified StorageRandomAccessFile if it is a RandomAccessFile. Otherwise, return null.

Parameters

file:StorageRandomAccessFile

the file to get the channel for

Returns:FileChannel

a FileChannel if file is an instance of RandomAccessFile, null otherwise

Return the file channel for the current value of the fileData field. If fileData doesn't support file channels, return null.

Callers of this method must synchronize on the container object since two shared fields (fileData and ourChannel) are accessed.

Returns:FileChannel

a FileChannel object, if supported, or null

This method handles what to do when, during a NIO operation we receive a ClosedChannelException. Note the specialization hierarchy:

ClosedChannelException -> AsynchronousCloseException -> ClosedByInterruptException

If e is a ClosedByInterruptException, we normally start container recovery, i.e. we need to reopen the random access file so we get get a new interruptible channel and continue IO.

If e is a AsynchronousCloseException or a plain ClosedChannelException, the behavior depends of stealthMode:

If stealthMode == false, the method will wait for another thread tp finish recovering the IO channel before returning.

If stealthMode == true, the method throws InterruptDetectedException, allowing retry at a higher level in the code. The reason for this is that we sometimes need to release monitors on objects needed by the recovery thread.

Parameters

e:ClosedChannelException

Should be an instance of ClosedChannelException.

stealthMode:boolean

If true, do retry at a higher level

retries:int

Give up waiting for another thread to reopen the channel when retries reaches 0. Only applicable if stealthMode == false.

Exceptions

StandardException:

standard error policy, incl. when we give up waiting for another thread to reopen channel

InterruptDetectedException:

if retry at higher level is required stealthMode == true.

Attempts to fill buf completely from start until it's full.

FileChannel has no readFull() method, so we roll our own.

Parameters

dstBuffer:ByteBuffer

buffer to read into

srcChannel:FileChannel

channel to read from

position:long

file position from where to read

Exceptions

IOException:

if an I/O error occurs while reading

StandardException:

If thread is interrupted.

Read a page into the supplied array.

override of RAFContainer#readPage

MT - thread safe

Parameters

pageNumber:long

the page number to read data from, or -1 (called from getEmbryonicPage)

pageData:byte[]

the buffer to read data into

offset:long

-1 normally (not used since offset is computed from pageNumber), but used if pageNumber == -1 (getEmbryonicPage)

Exceptions

IOException:

exception reading page

StandardException:

Standard Derby error policy

Use this when the thread has received a ClosedByInterruptException (or, prior to JDK 1.7 it may also be AsynchronousCloseException - a bug) exception during IO and its interruped flag is also set. This makes this thread a likely candicate to do container recovery, unless another thread started it already, cf. return value.

Parameters

whence:String

caller site (debug info)

stealthMode:boolean

don't update threadsInPageIO if true

Returns:boolean

true if we did recovery, false if we saw someone else do it and abstained

When the existing channel (ourChannel) has been closed due to interrupt, we need to reopen the underlying RAF to get a fresh channel so we can resume IO.

Attempts to write buf completely from start until end, at the given position in the destination fileChannel.

FileChannel has no writeFull() method, so we roll our own.

Parameters

srcBuffer:ByteBuffer

buffer to write

dstChannel:FileChannel

channel to write to

position:long

file position to start writing at

Exceptions

IOException:

if an I/O error occurs while writing

StandardException:

If thread is interrupted.