Package net.adoptopenjdk.icedteaweb.resources

Class ResourceTracker

  • public class ResourceTracker
extends java.lang.Object
    This class tracks the downloading of various resources of a JNLP file to local files in the cache. It can be used to download icons, jnlp and extension files, jars, and jardiff files using the version based protocol or any file using the basic download protocol (jardiff and version not implemented yet).

    The resource tracker can be configured to prefetch resources, which are downloaded in the order added to the media tracker.

    Multiple threads are used to download and cache resources that are actively being waited for (blocking a caller) or those that have been started downloading by calling the startDownload method. Resources that are prefetched are downloaded one at a time and only if no other trackers have requested downloads. This allows the tracker to start downloading many items without using many system resources, but still quickly download items as needed.

    Version:
    $Revision: 1.22 $

    • Field Detail

      • LOG

        private static final Logger LOG

      • resources

        private final java.util.Map<UrlKey,​Resource> resources
        the resources known about by this resource tracker

      • prefetch

        private final boolean prefetch
        whether to download parts before requested

    • Constructor Detail

      • ResourceTracker

        public ResourceTracker()
        Creates a resource tracker that does not prefetch resources.

      • ResourceTracker

        public ResourceTracker​(boolean prefetch)
        Creates a resource tracker that does not prefetch resources.

      • ResourceTracker

        public ResourceTracker​(boolean prefetch,
                       DownloadOptions downloadOptions,
                       UpdatePolicy updatePolicy)
        Creates a resource tracker.
        Parameters:
        prefetch - whether to download resources before requested.

    • Method Detail

      • addResource

        public void addResource​(java.net.URL location,
                        VersionString version)

      • addResource

        public void addResource​(java.net.URL location,
                        VersionString version,
                        UpdatePolicy updatePolicy)
        Add a resource identified by the specified location and version. The tracker only downloads one version of a given resource per instance (ie cannot download both versions 1 and 2 of a resource in the same tracker).
        Parameters:
        location - the location of the resource
        version - the resource version
        updatePolicy - whether to check for updates if already in cache

      • addToResources

        private boolean addToResources​(Resource resource)
        Returns:
        true if no resource with the given URL is currently tracked.

      • startDownloadingIfPrefetch

        private void startDownloadingIfPrefetch​(Resource resource)

      • removeResource

        public void removeResource​(java.net.URL location)
        Removes a resource from the tracker. This method is useful to allow memory to be reclaimed, but calling this method is not required as resources are reclaimed when the tracker is collected.
        Parameters:
        location - location of resource to be removed
        Throws:
        IllegalResourceDescriptorException - if the resource is not being tracked

      • getCacheURL

        public java.net.URL getCacheURL​(java.net.URL location)
        Returns a URL pointing to the cached location of the resource, or the resource itself if it is a non-cacheable resource.

        If the resource has not downloaded yet, the method will block until it has been transferred to the cache.

        Parameters:
        location - the resource location
        Returns:
        the resource, or null if it could not be downloaded
        Throws:
        IllegalResourceDescriptorException - if the resource is not being tracked
        See Also:
        CacheUtil.isCacheable(java.net.URL)

      • getCacheFile

        public java.io.File getCacheFile​(java.net.URL location)
        Returns a file containing the downloaded resource. If the resource is non-cacheable then null is returned unless the resource is a local file (the original file is returned).

        If the resource has not downloaded yet, the method will block until it has been transferred to the cache.

        Parameters:
        location - the resource location
        Returns:
        a local file containing the resource, or null
        Throws:
        IllegalResourceDescriptorException - if the resource is not being tracked
        See Also:
        CacheUtil.isCacheable(java.net.URL)

      • getCacheFile

        private static java.io.File getCacheFile​(Resource resource)

      • waitForResources

        public void waitForResources​(java.net.URL... urls)
                      throws java.lang.InterruptedException
        Wait for a group of resources to be downloaded and made available locally.
        Parameters:
        urls - the resources to wait for
        Throws:
        java.lang.InterruptedException - if thread is interrupted
        IllegalResourceDescriptorException - if the resource is not being tracked

      • getAmountRead

        public long getAmountRead​(java.net.URL location)
        Returns the number of bytes downloaded for a resource.
        Parameters:
        location - the resource location
        Returns:
        the number of bytes transferred
        Throws:
        IllegalResourceDescriptorException - if the resource is not being tracked

      • checkResource

        public boolean checkResource​(java.net.URL location)
        Returns whether a resource is available for use (ie, can be accessed with the getCacheFile method).
        Parameters:
        location - the resource location
        Returns:
        resource availability
        Throws:
        IllegalResourceDescriptorException - if the resource is not being tracked

      • getTotalSize

        public long getTotalSize​(java.net.URL location)
        Returns the number of total size in bytes of a resource, or -1 it the size is not known.
        Parameters:
        location - the resource location
        Returns:
        the number of bytes, or -1
        Throws:
        IllegalResourceDescriptorException - if the resource is not being tracked

      • getResources

        private Resource[] getResources​(java.net.URL[] urls)

      • waitForCompletion

        private void waitForCompletion​(Resource... resources)
        Wait for some resources.
        Parameters:
        resources - the resources to wait for
        Throws:
        java.lang.InterruptedException - if another thread interrupted the wait

      • getConfiguredThreadCount

        private int getConfiguredThreadCount()

      • triggerDownloadFor

        private java.util.concurrent.Future<Resource> triggerDownloadFor​(Resource resource,
                                                                 java.util.concurrent.Executor downloadExecutor)

      • addDownloadListener

        public void addDownloadListener​(java.net.URL resourceUrl,
                                java.net.URL[] allResources,
                                DownloadServiceListener listener)

      • getPercentageDownloaded

        private int getPercentageDownloaded​(java.net.URL[] allResources)