GitHub user cphbrt opened a pull request: https://github.com/apache/beam/pull/3717
[BEAM-2750][BEAM-2751] Implement WholeFileIO Follow this checklist to help us incorporate your contribution quickly and easily: - [x] Make sure there is a [JIRA issue](https://issues.apache.org/jira/projects/BEAM/issues/) filed for the change (usually before you start working on it). Trivial changes like typos do not require a JIRA issue. Your pull request should address just this issue, without pulling in other changes. - [x] Each commit in the pull request should have a meaningful subject line and body. - [x] Format the pull request title like `[BEAM-XXX] Fixes bug in ApproximateQuantiles`, where you replace `BEAM-XXX` with the appropriate JIRA issue. - [x] Write a pull request description that is detailed enough to understand what the pull request does, how, and why. - [ ] Run `mvn clean verify` to make sure basic checks pass. A more thorough check will be performed on your pull request automatically. - [ ] If this contribution is large, please file an Apache [Individual Contributor License Agreement](https://www.apache.org/licenses/icla.pdf). --- ## Narrative WholeFileIO fulfills the requests of [BEAM-2750] and [BEAM-2751] for a way to read and write individual files as individual elements of a PCollection to and from specific filenames. ## Description `WholeFileIO.Read` receives a file pattern (glob) of input files. The file pattern is expanded into a `PCollection` of `ResourceId`s, each pointing to a single file. The bytes at the file location specified by the `ResourceId`s are read in and attached to their originating filename in a `KV`. `WholeFileIO.Write` receives a `PCollection` of `KV`s containing byte arrays and their corresponding filenames. The byte arrays are written to the output directory with their corresponding filename. ## Example Usage This example pipeline will read in files according to a given file glob and write them to the specified output directory unmodified other than "-copy" appended to their filenames. If the input file glob specifies files spread through a directory hierarchy, they will still be written out all into the same flat output directory. Example pipeline: ```java public class WholeFileIOPipeline { public interface FileIOOptions extends PipelineOptions { @Description("File glob of the files to read from") @Validation.Required String getInputFiles(); void setInputFiles(String value); @Description("Path of the directory to write files to") @Validation.Required String getOutputDir(); void setOutputDir(String value); } public static void main(String[] args) { final FileIOOptions options = PipelineOptionsFactory.fromArgs(args).withValidation() .as(FileIOOptions.class); Pipeline p = Pipeline.create(options); PCollection<KV<String, byte[]>> files = p.apply( "Read Bytes and filenames of input files", WholeFileIO.read().from(options.getInputFiles()) ); PCollection<KV<String, byte[]>> renamedFiles = files.apply( ParDo.of( new DoFn<KV<String, byte[]>, KV<String, byte[]>>() { @ProcessElement public void processElement(ProcessContext c) { KV<String, byte[]> file = c.element(); c.output(KV.of(file.getKey() + "-copy", file.getValue())); } } ) ); renamedFiles.apply( "Write Bytes to filenames in Output Directory", WholeFileIO.write().to(options.getOutputDir()) ); p.run().waitUntilFinish(); } } ``` Example command to run example pipeline: ```bash mvn clean compile exec:java -Dexec.mainClass=com.example.WholeFileIOPipeline \ -Dexec.args=" \ --inputFiles=/path/to/input/files/** \ --outputDir=/path/to/output/directory/ \ " \ -Pdirect-runner ``` ## ToDo - [ ] Add comments - [ ] Add unit tests - [ ] Scale test for performance - [ ] Find out if `FileSystems.resolve()` will resolve multiple intermediary directories if a user provides a path that doesn't fully exist yet. (`WholeFileIO -> Write -> expand() -> ParDo -> ResourceId logic`) - [ ] Make sure that the `OutputStream` automatically closes when an `Exception` occurs in `WholeFileIO -> Write -> expand() -> ParDo -> try/catch`. If not, close it in a `finally` statement. You can merge this pull request into a Git repository by running: $ git pull https://github.com/cphbrt/beam master+WholeFileIO Alternatively you can review and apply these changes as the patch at: https://github.com/apache/beam/pull/3717.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #3717 ---- commit 42f8b991512aa01019013d64e167b5e5782f87bf Author: Chris Hebert <chris.hebert-...@digitalreasoning.com> Date: 2017-08-10T19:56:32Z [BEAM-2750][BEAM-2751] Implement WholeFileIO ---- --- If your project is set up for it, you can reply to this email and have your reply appear on GitHub as well. If your project does not have this feature enabled and wishes so, or if the feature is enabled but not working, please contact infrastructure at infrastruct...@apache.org or file a JIRA ticket with INFRA. ---