DD::Image::Image_Cache Class Reference

#include <ImageCache.h>

Public Member Functions
void	rescan_disk_cache ()
void	touch_root ()
void	initialize (const std::string &path, int sizegb)
bool	is_active ()
	True if there has not been a failure and size is non-zero.
bool	is_read ()
	True if read() has been called and thus it has loaded map.
bool	is_written ()
	True if write() has been called and it created cache directories.
void	remove_oldest_files (int targetblocks)
void	remove_all_files ()
bool	remove (const DD::Image::Hash &)
void	print ()
ImageCacheReadI *	open (const DD::Image::Hash &, bool onlyInMemory=false)
	ImageCacheReadI cache files.
ImageCacheWriteI *	create (const DD::Image::Hash &)
	ImageCacheWriteI cache files.
bool	has_file (const DD::Image::Hash &)
std::string	filename (const DD::Image::Hash &)
void	add_file (const DD::Image::Hash &, off_t size)
bool	hasInMemory (const DD::Image::Hash &hash)
	Return true if the file for the given hash is in the in-memory ImageCache cache.
size_t	fileSize (const DD::Image::Hash &hash)
	Get the size of the file on disk, or 0 if absent.

Static Public Member Functions
static Image_Cache &	mainCache ()
static void	setMaxMemoryCache (size_t usage)
	Set the maximum number of bytes for the in-memory ImageCache cache.
static size_t	getMaxMemoryCache ()
	Get the maximum size (in bytes) for the in-memory ImageCache cache.
static void	clearMemoryCache ()
	Clear the in-memory cache of ImageCache files.
static void	waitEmpty ()

Detailed Description

Manages a large LRU cache of files on disk. The files are identified by a DD::Image::Hash. The caller is responsible for the data in the files.

Member Function Documentation

mainCache()

Image_Cache & Image_Cache::mainCache ( )

static

Return the cache used by the Nuke viewer. You probably want to reuse this for any caching unless you actually have an api for the user to name and allocate space for a different cache.

Referenced by DD::Image::ViewerCache::BoxPresent(), DD::Image::ViewerCache::preload(), and DD::Image::ViewerCache::read_from_cache().

initialize()

void Image_Cache::initialize	(	const std::string &	path,
		int	sizegb
	)

Set the base directory filename and the size in gigabytes.

A blank filename or zero size will deactivate the cache so that it does not do anything (call remove_all_files() first if you really want the disk space released).

remove_oldest_files()

void Image_Cache::remove_oldest_files

(

int

targetblocks

)

iterate over the age map note: 'age' isn't really age, higher numbers are newer, lower numbers are older

References DD::Image::Lock::lock(), and DD::Image::Lock::unlock().

remove()

bool Image_Cache::remove

(

const DD::Image::Hash &

hash

)

Remove the file (if it exists) for the given hash. This is a good idea if you attempt to read it and then determine that the data is no good, perhaps an obsolete version of the data. Returns true if has_file() was true.

References DD::Image::Lock::lock(), remove(), and DD::Image::Lock::unlock().

Referenced by DD::Image::ViewerCache::read_from_cache(), and remove().

open()

ImageCacheReadI * Image_Cache::open	(	const DD::Image::Hash &	hash,
		bool	onlyInMemory = false
	)

ImageCacheReadI cache files.

Open a file of cached data.

Allocates and returns a pointer to a data structure that you must pass to the read() and close() methods. Returns NULL if the cached data does not exist.

read it all in at once, and put it into a memory buffer. put this into a Write, and then add that to the cache and arrange a WriteRead to point at that.

Referenced by DD::Image::ViewerCache::BoxPresent(), and DD::Image::ViewerCache::read_from_cache().

create()

ImageCacheWriteI * Image_Cache::create

(

const DD::Image::Hash &

hash

)

ImageCacheWriteI cache files.

Create (or replace) an existing cache file. size must be the number of bytes you will write. The file will not appear in the cache until the close() method is done.

References is_active().