Provides methods for creating, maintaining, and securing the disk cache. More...

Inheritance diagram for ImageResizer.Plugins.DiskCache.DiskCache:

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Collaboration diagram for ImageResizer.Plugins.DiskCache.DiskCache:

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Public Member Functions
	DiskCache ()
	Creates a disk cache in the /imagecache folder More...

	DiskCache (string virtualDir)
	Creates a DiskCache instance at the specified location. Must be installed as a plugin to be operational. More...

void	LoadSettings (Config c)
	Uses the defaults from the resizing.diskcache section in the specified configuration. Throws an invalid operation exception if the DiskCache is already started. More...

IPlugin	Install (Config c)
	Loads the settings from 'c', starts the cache, and registers the plugin. Will throw an invalidoperationexception if already started. More...

bool	Uninstall (Config c)
	Uninstalls the plugin. Should reverse all changes made during Install More...

bool	IsConfigurationValid ()
	Returns true if the configured settings are valid and .NET (not NTFS) permissions will work. More...

bool	Start ()
	Attempts to start the DiskCache using the current settings. Returns true if succesful or if already started. Returns false on a configuration error. Called by Install() More...

bool	Stop ()
	Returns true if stopped succesfully. Cannot be restarted More...

bool	CanProcess (HttpContext current, IResponseArgs e)
	Returns false if the cache is unable to process the request. If false, the caller should fall back to a different cache More...

void	Process (HttpContext context, IResponseArgs e)
	Must update the cache if needed, then either rewrite, redirect or serve the cached data. More...

CacheResult	Process (IResponseArgs e)

IEnumerable< IIssue >	GetIssues ()

Protected Member Functions
void	BeforeSettingChanged ()
	Throws an exception if the class is already modified More...

bool	HasFileIOPermission ()
	Returns true if .NET permissions allow writing to the cache directory. Does not check NTFS permissions. More...

bool	HasNTFSPermission ()

string	GetExecutingUser ()

Protected Attributes
int	cacheAccessTimeout = 15000

string	virtualDir = HostingEnvironment.ApplicationVirtualPath.TrimEnd('/') + "/imagecache"

ILogger	log = null

CustomDiskCache	cache = null

CleanupManager	cleaner = null

WebConfigWriter	writer = null

readonly object	_startSync = new object()

volatile bool	_started = false

Properties
int	Subfolders `[get, set]`
	Controls how many subfolders to use for disk caching. Rounded to the next power of to. (1->2, 3->4, 5->8, 9->16, 17->32, 33->64, 65->128,129->256,etc.) NTFS does not handle more than 8,000 files per folder well. Larger folders also make cleanup more resource-intensive. Defaults to 32, which combined with the default setting of 400 images per folder, allows for scalability to 12,800 actively used image versions. For example, given a desired cache size of 100,000 items, this should be set to 256. More...

bool	Enabled `[get, set]`
	Allows disk caching to be disabled for debuginng purposes. Defaults to true. More...

bool	AutoClean `[get, set]`
	If true, items from the cache folder will be automatically 'garbage collected' if the cache size limits are exceeded. Defaults to false. More...

CleanupStrategy	CleanupStrategy `[get, set]`
	Only relevant when AutoClean=true. Settings about how background cache cleanup are performed. It is best not to modify these settings. There are very complicated and non-obvious factors involved in their choice. More...

int	CacheAccessTimeout `[get, set]`
	How many milliseconds to wait for a cached item to be available. Values below 0 are set to 0. Defaults to 15 seconds. Actual time spent waiting may be 2 or 3x this value, if multiple layers of synchronization require a wait. More...

bool	HashModifiedDate `[get, set]`
	If true, when a source file is changed, a new file will be created instead of overwriting the old cached file. This helps prevent file lock contention on high-traffic servers. Defaults to true. Do NOT set this to false in a Web Garden or if you have overlapped recycle enabled, as you may risk having occasional failed requests due to write contention by separate proccesses. Changes the hash function, so you should delete the cache folder whenever this setting is modified. More...

bool	AsyncWrites `[get, set]`
	If true, writes to the disk cache will be performed outside the request thread, allowing responses to return to the client quicker. More...

int	AsyncBufferSize `[get, set]`
	If more than this amount of memory (in bytes) is currently allocated by queued writes, the request will be processed synchronously instead of asynchronously. More...

string	VirtualCacheDir `[get, set]`
	Sets the location of the cache directory. Can be a virtual path (like /App/imagecache) or an application-relative path (like ~/imagecache, the default). Relative paths are assummed to be relative to the application root. All values are converted to virtual path format upon assignment (/App/imagecache) Will throw an InvalidOperationException if changed after the plugin is installed. More...

string	PhysicalCacheDir `[get]`
	Returns the physical path of the cache directory specified in VirtualCacheDir. More...

ILogger	Logger `[get]`

bool	Started `[get]`
	Returns true if the DiskCache instance is operational. More...

Properties inherited from ImageResizer.Configuration.Logging.ILoggerProvider
ILogger	Logger `[get]`

Detailed Description

Provides methods for creating, maintaining, and securing the disk cache.

Definition at line 36 of file DiskCache.cs.

Constructor & Destructor Documentation

ImageResizer.Plugins.DiskCache.DiskCache.DiskCache ( )

inline

Creates a disk cache in the /imagecache folder

Definition at line 162 of file DiskCache.cs.

162 {}

ImageResizer.Plugins.DiskCache.DiskCache.DiskCache ( string virtualDir )

inline

Creates a DiskCache instance at the specified location. Must be installed as a plugin to be operational.

Parameters

virtualDir

Definition at line 168 of file DiskCache.cs.

                                            {
             VirtualCacheDir = virtualDir;
         }

Member Function Documentation

void ImageResizer.Plugins.DiskCache.DiskCache.BeforeSettingChanged ( )

inlineprotected

Throws an exception if the class is already modified

Definition at line 155 of file DiskCache.cs.

                                               {
             if (_started) throw new InvalidOperationException("DiskCache settings may not be adjusted after it is started.");
         }

bool ImageResizer.Plugins.DiskCache.DiskCache.CanProcess	(	HttpContext	current,
		IResponseArgs	e
	)

inline

Returns false if the cache is unable to process the request. If false, the caller should fall back to a different cache

Parameters

current
e

Implements ImageResizer.Caching.ICache.

Definition at line 288 of file DiskCache.cs.

                                                                      {
             //Disk caching will 'pass on' caching requests if 'cache=no'.
             if (((ResizeSettings)e.RewrittenQuerystring).Cache == ServerCacheMode.No) return false;
             return Started;//Add support for nocache
         }

bool ImageResizer.Plugins.DiskCache.DiskCache.HasFileIOPermission ( )

inlineprotected

Returns true if .NET permissions allow writing to the cache directory. Does not check NTFS permissions.

Returns

Definition at line 234 of file DiskCache.cs.

                                              {
             FileIOPermission writePermission = new FileIOPermission(FileIOPermissionAccess.AllAccess,new string[]{PhysicalCacheDir, Path.Combine(PhysicalCacheDir,"web.config")});
             return SecurityManager.IsGranted(writePermission);
         }

IPlugin ImageResizer.Plugins.DiskCache.DiskCache.Install ( Config c )

inline

Loads the settings from 'c', starts the cache, and registers the plugin. Will throw an invalidoperationexception if already started.

Parameters

c

Returns

Implements ImageResizer.Plugins.IPlugin.

Definition at line 195 of file DiskCache.cs.

                                          {
             if (c.get("diskcache.logging", false)) {
                 if (c.Plugins.LogManager != null) 
                     log = c.Plugins.LogManager.GetLogger("ImageResizer.Plugins.DiskCache");
                 else 
                     c.Plugins.LoggingAvailable += delegate(ILogManager mgr) {
                         if (log != null) log = c.Plugins.LogManager.GetLogger("ImageResizer.Plugins.DiskCache");
                     };
             }
             LoadSettings(c);
             Start();
             c.Pipeline.AuthorizeImage += Pipeline_AuthorizeImage;
             c.Plugins.add_plugin(this);
             return this;
         }

bool ImageResizer.Plugins.DiskCache.DiskCache.IsConfigurationValid ( )

inline

Returns true if the configured settings are valid and .NET (not NTFS) permissions will work.

Returns

Definition at line 227 of file DiskCache.cs.

                                           {
             return !string.IsNullOrEmpty(VirtualCacheDir) && this.Enabled && HasFileIOPermission();
         }

void ImageResizer.Plugins.DiskCache.DiskCache.LoadSettings ( Config c )

inline

Uses the defaults from the resizing.diskcache section in the specified configuration. Throws an invalid operation exception if the DiskCache is already started.

Definition at line 175 of file DiskCache.cs.

                                           {
             Subfolders = c.get("diskcache.subfolders", Subfolders);
             Enabled = c.get("diskcache.enabled", Enabled);
             AutoClean = c.get("diskcache.autoClean", AutoClean);
             VirtualCacheDir = c.get("diskcache.dir", VirtualCacheDir);
             HashModifiedDate = c.get("diskcache.hashModifiedDate", HashModifiedDate);
             CacheAccessTimeout = c.get("diskcache.cacheAccessTimeout", CacheAccessTimeout);
             AsyncBufferSize = c.get("diskcache.asyncBufferSize", AsyncBufferSize);
             AsyncWrites = c.get("diskcache.asyncWrites", AsyncWrites);
             CleanupStrategy.LoadFrom(c.getNode("cleanupStrategy"));
         }

void ImageResizer.Plugins.DiskCache.DiskCache.Process	(	HttpContext	current,
		IResponseArgs	e
	)

inline

Must update the cache if needed, then either rewrite, redirect or serve the cached data.

Parameters

current
e

Implements ImageResizer.Caching.ICache.

Definition at line 295 of file DiskCache.cs.

                                                                   {
 
             CacheResult r = Process(e);
             context.Items["FinalCachedFile"] = r.PhysicalPath;
 
             if (r.Data == null) {
 
                 //Calculate the virtual path
                 string virtualPath = VirtualCacheDir.TrimEnd('/') + '/' + r.RelativePath.Replace('\\', '/').TrimStart('/');
 
                 //Rewrite to cached, resized image.
                 context.RewritePath(virtualPath, false);
             } else {
                 //Remap the response args writer to use the existing stream.
                 ((ResponseArgs)e).ResizeImageToStream = delegate(Stream s) {
                     ((MemoryStream)r.Data).WriteTo(s);
                 };
                 context.RemapHandler(new NoCacheHandler(e));
             }
         }

bool ImageResizer.Plugins.DiskCache.DiskCache.Start ( )

inline

Attempts to start the DiskCache using the current settings. Returns true if succesful or if already started. Returns false on a configuration error. Called by Install()

Definition at line 254 of file DiskCache.cs.

                             {
             if (!IsConfigurationValid()) return false;
             lock (_startSync) {
                 if (_started) return true;
                 if (!IsConfigurationValid()) return false;
 
                 //Init the writer.
                 writer = new WebConfigWriter(this,PhysicalCacheDir);
                 //Init the inner cache
                 cache = new CustomDiskCache(this, PhysicalCacheDir, Subfolders, HashModifiedDate,AsyncBufferSize);
                 //Init the cleanup strategy
                 if (AutoClean && cleanupStrategy == null) cleanupStrategy = new CleanupStrategy(); //Default settings if null
                 //Init the cleanup worker
                 if (AutoClean) cleaner = new CleanupManager(this, cache, cleanupStrategy);
                 //If we're running with subfolders, enqueue the cache root for cleanup (after the 5 minute delay)
                 //so we don't eternally 'skip' files in the root or in other unused subfolders (since only 'accessed' subfolders are ever cleaned ). 
                 if (cleaner != null) cleaner.CleanAll();
 
                 if (log != null) log.Info("DiskCache started successfully.");
                 //Started successfully
                 _started = true;
                 return true;
             }
         }

bool ImageResizer.Plugins.DiskCache.DiskCache.Stop ( )

inline

Returns true if stopped succesfully. Cannot be restarted

Returns

Definition at line 282 of file DiskCache.cs.

                            {
             if (cleaner != null) cleaner.Dispose();
             cleaner = null;
             return true;
         }

bool ImageResizer.Plugins.DiskCache.DiskCache.Uninstall ( Config c )

inline

Uninstalls the plugin. Should reverse all changes made during Install

Parameters

c

Returns

Implements ImageResizer.Plugins.IPlugin.

Definition at line 216 of file DiskCache.cs.

                                         {
             c.Plugins.remove_plugin(this);
             c.Pipeline.AuthorizeImage -= Pipeline_AuthorizeImage;
             return this.Stop();
         }

Property Documentation

int ImageResizer.Plugins.DiskCache.DiskCache.AsyncBufferSize

getset

If more than this amount of memory (in bytes) is currently allocated by queued writes, the request will be processed synchronously instead of asynchronously.

Definition at line 117 of file DiskCache.cs.

bool ImageResizer.Plugins.DiskCache.DiskCache.AsyncWrites

getset

If true, writes to the disk cache will be performed outside the request thread, allowing responses to return to the client quicker.

Definition at line 107 of file DiskCache.cs.

bool ImageResizer.Plugins.DiskCache.DiskCache.AutoClean

getset

If true, items from the cache folder will be automatically 'garbage collected' if the cache size limits are exceeded. Defaults to false.

Definition at line 65 of file DiskCache.cs.

int ImageResizer.Plugins.DiskCache.DiskCache.CacheAccessTimeout

getset

How many milliseconds to wait for a cached item to be available. Values below 0 are set to 0. Defaults to 15 seconds. Actual time spent waiting may be 2 or 3x this value, if multiple layers of synchronization require a wait.

Definition at line 85 of file DiskCache.cs.

CleanupStrategy ImageResizer.Plugins.DiskCache.DiskCache.CleanupStrategy

getset

Only relevant when AutoClean=true. Settings about how background cache cleanup are performed. It is best not to modify these settings. There are very complicated and non-obvious factors involved in their choice.

Definition at line 74 of file DiskCache.cs.

bool ImageResizer.Plugins.DiskCache.DiskCache.Enabled

getset

Allows disk caching to be disabled for debuginng purposes. Defaults to true.

Definition at line 54 of file DiskCache.cs.

bool ImageResizer.Plugins.DiskCache.DiskCache.HashModifiedDate

getset

If true, when a source file is changed, a new file will be created instead of overwriting the old cached file. This helps prevent file lock contention on high-traffic servers. Defaults to true. Do NOT set this to false in a Web Garden or if you have overlapped recycle enabled, as you may risk having occasional failed requests due to write contention by separate proccesses. Changes the hash function, so you should delete the cache folder whenever this setting is modified.

Definition at line 98 of file DiskCache.cs.

string ImageResizer.Plugins.DiskCache.DiskCache.PhysicalCacheDir

get

Returns the physical path of the cache directory specified in VirtualCacheDir.

Definition at line 145 of file DiskCache.cs.

bool ImageResizer.Plugins.DiskCache.DiskCache.Started

get

Returns true if the DiskCache instance is operational.

Definition at line 249 of file DiskCache.cs.

int ImageResizer.Plugins.DiskCache.DiskCache.Subfolders

getset

Controls how many subfolders to use for disk caching. Rounded to the next power of to. (1->2, 3->4, 5->8, 9->16, 17->32, 33->64, 65->128,129->256,etc.) NTFS does not handle more than 8,000 files per folder well. Larger folders also make cleanup more resource-intensive. Defaults to 32, which combined with the default setting of 400 images per folder, allows for scalability to 12,800 actively used image versions. For example, given a desired cache size of 100,000 items, this should be set to 256.

Definition at line 45 of file DiskCache.cs.

string ImageResizer.Plugins.DiskCache.DiskCache.VirtualCacheDir

getset

Sets the location of the cache directory. Can be a virtual path (like /App/imagecache) or an application-relative path (like ~/imagecache, the default). Relative paths are assummed to be relative to the application root. All values are converted to virtual path format upon assignment (/App/imagecache) Will throw an InvalidOperationException if changed after the plugin is installed.

Definition at line 131 of file DiskCache.cs.

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

C:/Users/nathanael/Documents/resizer/Plugins/DiskCache/DiskCache.cs

Public Member Functions

Protected Member Functions

Protected Attributes

Properties

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Property Documentation