de.yaacc.share.WatchedCopy Class Reference

The copy fallback with a watchdog. More...

Collaboration diagram for de.yaacc.share.WatchedCopy:

Classes
class	Failure
	The copy failed; getReason() says why.
interface	FileCreator
	Creates the empty target file (before the worker starts, so the caller owns its deletion). More...
interface	Holder
	Holds the finished copy (reopens it as a seekable source). More...
interface	Input
	What is copied. More...
enum	Reason
	Why a copy did not happen. More...

Public Member Functions
	WatchedCopy (long timeoutMillis, int maxStuckWorkers)
PositionalSource	copy (Input input, FileCreator creator, LongSupplier budget, LongSupplier usable, Holder holder) throws Failure
	Copies input into a new file and returns a source that holds it and deletes it when closed.
int	stuckWorkers ()

Detailed Description

The copy fallback with a watchdog.

Plain Java.

BudgetedCopier asks for cancellation only BETWEEN reads, so a provider whose pipe never produces a byte would block the read for ever, on the thread that waits for the copy and while holding the copy slot (and, behind it, the intake gate). Here the copy runs on its own daemon worker (AbandonableCall) and the caller waits at most timeoutMillis. At the deadline the caller, from its own thread, closes the Input (closing a descriptor wakes a blocked libcore read) and the worker's output stream (so a stuck worker does not keep the partial file's blocks allocated after the delete), deletes the partial file, gives the copy slot back and reports Reason#TIMED_OUT, even if the worker stays stuck: it is abandoned. A worker that wakes up later finds out, stops, and cannot leave anything behind: the file was deleted and is only ever opened for writing without creating it, and a held copy it still produces is closed (which deletes the file) instead of being handed out.

One copy at a time (BUSY otherwise); at most maxStuckWorkers abandoned workers at once, beyond that a copy is turned away as busy.

Constructor & Destructor Documentation

WatchedCopy()

de.yaacc.share.WatchedCopy.WatchedCopy	(	long	timeoutMillis,
		int	maxStuckWorkers )

Parameters

timeoutMillis	the longest a copy may take, positive
maxStuckWorkers	abandoned workers allowed to stay alive, at least 1

Member Function Documentation

copy()

PositionalSource de.yaacc.share.WatchedCopy.copy	(	Input	input,
		FileCreator	creator,
		LongSupplier	budget,
		LongSupplier	usable,
		Holder	holder ) throws Failure

Copies input into a new file and returns a source that holds it and deletes it when closed.

Closes input and deletes the file in every failure case.

Parameters

budget	the most bytes the copy may take, evaluated after the slot was taken
usable	the free space on the volume, asked before every chunk

Exceptions

Failure

for every failure

Referenced by de.yaacc.share.SharedFileOpener.copyAndHold().

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stuckWorkers()

int de.yaacc.share.WatchedCopy.stuckWorkers

(

)

Returns

abandoned copy workers that are still alive (for tests and diagnostics)

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The documentation for this class was generated from the following file:

• /github/workspace/yaacc/src/main/java/de/yaacc/share/WatchedCopy.java