org.neo4j.io.pagecache

Interface PageSwapper

public interface PageSwapper

Implementation note: These methods must NEVER swallow a thread-interrupt. If the thread is interrupted when these methods are called, or gets interrupted while they are executing, then they must either throw an InterruptedException, or leave the interrupted-status flag alone.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Close and release all resources associated with the file underlying this PageSwapper.
void	evicted(long pageId, Page page) Notification that a page has been evicted, used to clean up state in structures outside the page table.
File	file() Get the file that this PageSwapper represents.
void	force() Synchronise all writes done by this PageSwapper, with the underlying storage device.
long	getLastPageId() Get the filePageId of the last page in the concrete file.
int	read(long filePageId, Page page) Read the page with the given filePageId, from the concrete file on the file system, into the given page.
int	write(long filePageId, Page page) Write the contents of the given page, to the concrete file on the file system, at the located indicated by the given filePageId.

Method Detail

read

int read(long filePageId,
       Page page)
         throws IOException

Read the page with the given filePageId, from the concrete file on the file system, into the given page. This should be implemented using the Page.swapIn(org.neo4j.io.fs.StoreChannel, long, int) method. Returns the number of bytes read in from the file. May be zero if the requested page was beyond the end of the file. If less than the file page size, then the rest of the page will contain zeros. Note: It is possible for the channel to be asynchronously closed while this operation is taking place. For instance, if the current thread is interrupted. If this happens, then the implementation must reopen the channel and the operation must be retried.

Throws:

IOException

write

int write(long filePageId,
        Page page)
          throws IOException

Write the contents of the given page, to the concrete file on the file system, at the located indicated by the given filePageId. This should be implemented using the Page.swapOut(org.neo4j.io.fs.StoreChannel, long, int) method. Returns the number of bytes written to the file. Note: It is possible for the channel to be asynchronously closed while this operation is taking place. For instance, if the current thread is interrupted. If this happens, then implementation must reopen the channel and the operation must be retried.

Throws:

IOException

evicted

void evicted(long pageId,
           Page page)

Notification that a page has been evicted, used to clean up state in structures outside the page table.

file

File file()

Get the file that this PageSwapper represents.

close

void close()
           throws IOException

Close and release all resources associated with the file underlying this PageSwapper.

Throws:

IOException

force

void force()
           throws IOException

Synchronise all writes done by this PageSwapper, with the underlying storage device.

Throws:

IOException

getLastPageId

long getLastPageId()
                   throws IOException

Get the filePageId of the last page in the concrete file.

Throws:

IOException