[HADOOP-19199] Include FileStatus when opening a file from FileSystem

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 3.4.0
• Component/s: fs
• Labels: pull-request-available
• Assignee: Unassigned
• Reporter: Oliver Caballero Alvarez
• Created: 08/Jun/24 11:07
• Updated: 21/Aug/24 14:07
• Resolved: 10/Jun/24 14:07

Description

The FileSystem abstract class prevents that if you have information about the FileStatus of a file, you use it to open that file, which means that in the implementations of the open method, they have to request the FileStatus of the same file again, making unnecessary requests.

A very clear example is seen in today's latest version of the parquet-hadoop implementation, where:

https://github.com/apache/parquet-java/blob/apache-parquet-1.14.0/parquet-hadoop/src/main/java/org/apache/parquet/hadoop/util/HadoopInputFile.java

Although to create the implementation you had to consult the file to know its FileStatus, when opening it only the path is included, since the FileSystem implementation is the only thing it allows you to do. This implies that the implementation will surely, in its open function, verify that the file exists or what information the file has and perform the same operation again to collect the FileStatus.

 

This would simply be resolved by taking the latest current version:

 

https://github.com/apache/hadoop/blob/release-3.4.0-RC3/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java

and including the following:

 

  public FSDataInputStream open(FileStatus f) throws IOException

{         return this.open(f.getPath(), this.getConf().getInt("io.file.buffer.size", 4096));     }

 

This would imply that it is backward compatible with all current Filesystems, but since it is in the implementation it could be used when this information is already known.

 

 

 

 

Issue Links

• depends upon: PARQUET-2493 HadoopInputFile to pass down FileStatus when opening file.
• depends upon: HADOOP-19200 Reduce the number of headObject when opening a file with the s3 file system
• depends upon: SPARK-48571 Reduce the number of accesses to S3 object storage
• duplicates: HADOOP-15229 Add FileSystem builder-based openFile() API to match createFile(); S3A to implement S3 Select through this API.
• relates to: HADOOP-19131 WrappedIO to export modern filesystem/statistics APIs in a reflection friendly form
• relates to: HADOOP-19200 Reduce the number of headObject when opening a file with the s3 file system
• links to: GitHub Pull Request #6877