import org.apache.cassandra.db.Directories.DataDirectory; //导入依赖的package包/类
private List<Directories.DataDirectoryCandidate> getWriteableDirectories(DataDirectory[] dataDirectories, long writeSize)
{
    // copied from Directories.getWriteableLocation(long)
    List<Directories.DataDirectoryCandidate> candidates = new ArrayList<>();

    long totalAvailable = 0L;

    for (DataDirectory dataDir : dataDirectories)
        {
            Directories.DataDirectoryCandidate candidate = new Directories.DataDirectoryCandidate(dataDir);
            // exclude directory if its total writeSize does not fit to data directory
            if (candidate.availableSpace < writeSize)
                continue;
            candidates.add(candidate);
            totalAvailable += candidate.availableSpace;
        }

    Directories.sortWriteableCandidates(candidates, totalAvailable);

    return candidates;
}
 

import org.apache.cassandra.db.Directories.DataDirectory; //导入依赖的package包/类
public static Closeable markDirectoriesUnwriteable(ColumnFamilyStore cfs)
{
    try
    {
        for ( ; ; )
        {
            DataDirectory dir = cfs.getDirectories().getWriteableLocation(1);
            BlacklistedDirectories.maybeMarkUnwritable(cfs.getDirectories().getLocationForDisk(dir));
        }
    }
    catch (IOError e)
    {
        // Expected -- marked all directories as unwritable
    }
    return () -> BlacklistedDirectories.clearUnwritableUnsafe();
}
 

import org.apache.cassandra.db.Directories.DataDirectory; //导入依赖的package包/类
@Test
public void testDiskFailurePolicy_best_effort()
{
    DiskFailurePolicy origPolicy = DatabaseDescriptor.getDiskFailurePolicy();
    
    try 
    {
        DatabaseDescriptor.setDiskFailurePolicy(DiskFailurePolicy.best_effort);
        // Fake a Directory creation failure
        if (Directories.dataDirectories.length > 0)
        {
            String[] path = new String[] {KS, "bad"};
            File dir = new File(Directories.dataDirectories[0].location, StringUtils.join(path, File.separator));
            FileUtils.handleFSError(new FSWriteError(new IOException("Unable to create directory " + dir), dir));
        }

        for (DataDirectory dd : Directories.dataDirectories)
        {
            File file = new File(dd.location, new File(KS, "bad").getPath());
            assertTrue(BlacklistedDirectories.isUnwritable(file));
        }
    } 
    finally 
    {
        DatabaseDescriptor.setDiskFailurePolicy(origPolicy);
    }
}
 

import org.apache.cassandra.db.Directories.DataDirectory; //导入依赖的package包/类
@Test
public void testDiskFailurePolicy_best_effort()
{
    DiskFailurePolicy origPolicy = DatabaseDescriptor.getDiskFailurePolicy();

    try
    {
        DatabaseDescriptor.setDiskFailurePolicy(DiskFailurePolicy.best_effort);
        // Fake a Directory creation failure
        if (Directories.dataDirectories.length > 0)
        {
            String[] path = new String[] {KS, "bad"};
            File dir = new File(Directories.dataDirectories[0].location, StringUtils.join(path, File.separator));
            FileUtils.handleFSError(new FSWriteError(new IOException("Unable to create directory " + dir), dir));
        }

        for (DataDirectory dd : Directories.dataDirectories)
        {
            File file = new File(dd.location, new File(KS, "bad").getPath());
            assertTrue(BlacklistedDirectories.isUnwritable(file));
        }
    } 
    finally 
    {
        DatabaseDescriptor.setDiskFailurePolicy(origPolicy);
    }
}