ilooner commented on a change in pull request #1296: DRILL-5365: Prevent plugin
config from changing default fs. Make DrillFileSystem Immutable.
URL: https://github.com/apache/drill/pull/1296#discussion_r203902329
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/store/dfs/DrillFileSystem.java
##########
@@ -65,46 +62,105 @@
import com.google.common.collect.Maps;
/**
- * DrillFileSystem is the wrapper around the actual FileSystem implementation.
+ * DrillFileSystem is the wrapper around the actual FileSystem implementation.
The {@link DrillFileSystem} is
+ * immutable.
*
* If {@link org.apache.drill.exec.ops.OperatorStats} are provided it returns
an instrumented FSDataInputStream to
* measure IO wait time and tracking file open/close operations.
*/
public class DrillFileSystem extends FileSystem implements OpenFileTracker {
static final org.slf4j.Logger logger =
org.slf4j.LoggerFactory.getLogger(DrillFileSystem.class);
private final static boolean TRACKING_ENABLED =
AssertionUtil.isAssertionsEnabled();
+ private final static DrillFileSystemCache CACHE = new DrillFileSystemCache();
+ public static final String FS_DEFAULT_NAME = "fs.default.name";
public static final String UNDERSCORE_PREFIX = "_";
public static final String DOT_PREFIX = ".";
private final ConcurrentMap<DrillFSDataInputStream, DebugStackTrace>
openedFiles = Maps.newConcurrentMap();
+ private final Configuration fsConf;
private final FileSystem underlyingFs;
private final OperatorStats operatorStats;
private final CompressionCodecFactory codecFactory;
+ private boolean initialized = false;
+
public DrillFileSystem(Configuration fsConf) throws IOException {
this(fsConf, null);
}
public DrillFileSystem(Configuration fsConf, OperatorStats operatorStats)
throws IOException {
- this.underlyingFs = FileSystem.get(fsConf);
+ // Configuration objects are mutable, and the underlying FileSystem object
may directly use a passed in Configuration.
+ // In order to avoid scenarios where a Configuration can change after a
DrillFileSystem is created, we make a copy
+ // of the Configuration.
+ this.fsConf = new Configuration(fsConf);
+ normalize(fsConf);
Review comment:
Thanks for showing me this, never knew about it.
I think setDeprecateProperties does some of what we need, but would still
have a problem. Consider the following input and output mappings for
setDeprecateProperties.
(fs.default.name: val1 ) -> (fs.default.name: val1 )
(fs.default.name: val1, fs.defaultFS: val2 ) -> (fs.default.name: val1,
fs.defaultFS: val2 )
(fs.default.name: val1, fs.defaultFS: val1 ) -> (fs.default.name: val1,
fs.defaultFS: val1 )
Ideally we would want all this outputs to be the same and we would want a
warning if our given config has different values for fs.default.name and
fs.defaultFS.
The normalize method handles this cases. I am trying to think of a way to
use setDeprecateProperties to replace some of the existing code in normalize.
But I can't think of a way to use setDeprecateProperties with the extra case
handling to make the code any simpler than what it is now.
If you have any ideas on a way we could use setDeprecateProperties and
handle the other cases described above more simply than the current normalize
method, let me know and I will do it. Otherwise if we can't think of anything
now, I'd prefer to keep the normalize method as is.
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