The way getFileStores() is used poses problems in a containerized application

[Dennis]

I don't understand why the following doesn't use Files.getFileStore(this.file.toPath()). This retrieves the overlay correctly but the current implementation doesn't, which prevents the creation of a persisted chronicle map.

Chronicle-Map/src/main/java/net/openhft/chronicle/hash/impl/VanillaChronicleHash.java

Lines 1100 to 1113 in 79e6e29

 private void fallocate(long mappingOffsetInFile, long length) throws IOException { 
     FileSystem fileSystem = file.toPath().getFileSystem(); 
  
     long maxSize = 0; 
     for (FileStore fileStore : fileSystem.getFileStores()) { 
         long unallocatedSpace = fileStore.getUnallocatedSpace(); 
         if (unallocatedSpace > length * 11 / 10) { 
             PosixFallocate.fallocate(raf.getFD(), mappingOffsetInFile, length); 
             return; 
         } 
         maxSize = Math.max(maxSize, unallocatedSpace); 
     } 
     throw new IOException("Not enough space to fallocate " + (length >> 20) + " MiB to " + fileSystem.getRootDirectories().iterator().next() + " unallocated was " + (maxSize >> 20) + " MiB"); 
 } 

[Jerry Shea]

Fixed by #519