Github user keith-turner commented on a diff in the pull request:
https://github.com/apache/accumulo/pull/95#discussion_r60625787
--- Diff:
core/src/main/java/org/apache/accumulo/core/file/FileOperations.java ---
@@ -48,38 +48,295 @@ public static FileOperations getInstance() {
return new DispatchingFileFactory();
}
+ //
+ // Abstract methods (to be implemented by subclasses)
+ //
+
+ protected abstract long getFileSize(GetFileSizeOperation options) throws
IOException;
+
+ protected abstract FileSKVWriter openWriter(OpenWriterOperation options)
throws IOException;
+
+ protected abstract FileSKVIterator openIndex(OpenIndexOperation options)
throws IOException;
+
+ protected abstract FileSKVIterator
openScanReader(OpenScanReaderOperation options) throws IOException;
+
+ protected abstract FileSKVIterator openReader(OpenReaderOperation
options) throws IOException;
+
+ //
+ // File operations
+ //
+
/**
- * Open a reader that will not be seeked giving an initial seek
location. This is useful for file operations that only need to scan data within
a range and do
- * not need to seek. Therefore file metadata such as indexes does not
need to be kept in memory while the file is scanned. Also seek optimizations
like bloom
- * filters do not need to be loaded.
+ * Construct an operation object allowing one to query the size of a
file. <br>
+ * Syntax:
*
+ * <pre>
+ * long size = fileOperations.getFileSize().ofFile(filename, fileSystem,
fsConfiguration).withTableConfiguration(tableConf).execute();
+ * </pre>
*/
+ public GetFileSizeOperation getFileSize() {
+ return new GetFileSizeOperation();
+ }
- public abstract FileSKVIterator openReader(String file, Range range,
Set<ByteSequence> columnFamilies, boolean inclusive, FileSystem fs,
Configuration conf,
- RateLimiter readLimiter, AccumuloConfiguration tableConf) throws
IOException;
+ /**
+ * Construct an operation object allowing one to create a writer for a
file. <br>
+ * Syntax:
+ *
+ * <pre>
+ * FileSKVWriter writer = fileOperations.openWriter()
+ * .ofFile(...)
+ * .withTableConfiguration(...)
+ * .withRateLimiter(...) // optional
+ * .withCompression(...) // optional
+ * .execute();
+ * </pre>
+ */
+ public OpenWriterOperation openWriter() {
+ return new OpenWriterOperation();
+ }
+
+ /**
+ * Construct an operation object allowing one to create an index
iterator for a file. <br>
+ * Syntax:
+ *
+ * <pre>
+ * FileSKVIterator iterator = fileOperations.openIndex()
+ * .ofFile(...)
+ * .withTableConfiguration(...)
+ * .withRateLimiter(...) // optional
+ * .withBlockCache(...) // optional
+ * .execute();
+ * </pre>
+ */
+ public OpenIndexOperation openIndex() {
+ return new OpenIndexOperation();
+ }
- public abstract FileSKVIterator openReader(String file, Range range,
Set<ByteSequence> columnFamilies, boolean inclusive, FileSystem fs,
Configuration conf,
- RateLimiter readLimiter, AccumuloConfiguration tableConf, BlockCache
dataCache, BlockCache indexCache) throws IOException;
+ /**
+ * Construct an operation object allowing one to create a "scan" reader
for a file. Scan readers do not have any optimizations for seeking beyond their
+ * initial position. This is useful for file operations that only need
to scan data within a range and do not need to seek. Therefore file metadata
such as
+ * indexes does not need to be kept in memory while the file is scanned.
Also seek optimizations like bloom filters do not need to be loaded. <br>
+ * Syntax:
+ *
+ * <pre>
+ * FileSKVIterator scanner = fileOperations.openScanReader()
+ * .ofFile(...)
+ * .overRange(...)
+ * .withTableConfiguration(...)
+ * .withRateLimiter(...) // optional
+ * .withBlockCache(...) // optional
+ * .execute();
+ * </pre>
+ */
+ public OpenScanReaderOperation openScanReader() {
+ return new OpenScanReaderOperation();
+ }
/**
- * Open a reader that fully support seeking and also enable any
optimizations related to seeking, like bloom filters.
+ * Construct an operation object allowing one to create a reader for a
file. A reader constructed in this manner fully supports seeking, and also
enables any
+ * optimizations related to seeking (e.g. Bloom filters). <br>
+ * Syntax:
*
+ * <pre>
+ * FileSKVIterator scanner = fileOperations.openReader()
+ * .ofFile(...)
+ * .withTableConfiguration(...)
+ * .withRateLimiter(...) // optional
+ * .withBlockCache(...) // optional
+ * .seekToBeginning(...) // optional
+ * .execute();
+ * </pre>
+ */
+ public OpenReaderOperation openReader() {
+ return new OpenReaderOperation();
+ }
+
+ //
+ // Operation objects.
+ //
+
+ /**
+ * Options common to all FileOperations.
+ */
+ protected static class FileAccessOperation<SubclassType extends
FileAccessOperation<SubclassType>> {
+ private AccumuloConfiguration tableConfiguration;
+
+ private String filename;
+ private FileSystem fs;
+ private Configuration fsConf;
+
+ /** Specify the table configuration defining access to this file. */
+ @SuppressWarnings("unchecked")
+ public SubclassType withTableConfiguration(AccumuloConfiguration
tableConfiguration) {
+ this.tableConfiguration = tableConfiguration;
+ return (SubclassType) this;
+ }
+
+ /** Specify the file this operation should apply to. */
+ @SuppressWarnings("unchecked")
+ public SubclassType ofFile(String filename, FileSystem fs,
Configuration fsConf) {
+ this.filename = filename;
+ this.fs = fs;
+ this.fsConf = fsConf;
+ return (SubclassType) this;
+ }
+
+ public String getFilename() {
+ return filename;
+ }
+
+ public FileSystem getFileSystem() {
+ return fs;
+ }
+
+ public Configuration getConfiguration() {
+ return fsConf;
+ }
+
+ public AccumuloConfiguration getTableConfiguration() {
--- End diff --
Did you consider making table config an argument of `ofFile()`?
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