Filesystem list call with prefix is slow in large containers

When the filesystem blobstore is used, running the following code takes very long if there are a lot of files in the container:

    ListContainerOptions options = new ListContainerOptions();

    options.prefix("test-container-subdirectory/");

    Set<? extends StorageMetadata> results =
      blobStore.list("test-container",options);

See the attached Java source file JCLOUDS1488.java for the full code.

On my system, running the attached Java code takes over 10 seconds to list a single file if there are 500,000 files in the container outside that prefix.

Output from the attached code:

Number of blobs listed: 1
First listed blob: test-container-subdirectory/file-to-list
Time it took to list the blobs: 13256 ms

A more general version of this problem was reported previously in JCLOUDS-1371.