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https://issues.apache.org/jira/browse/HADOOP-12910?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15320902#comment-15320902
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Tsz Wo Nicholas Sze commented on HADOOP-12910:
----------------------------------------------
Some other ideas:
# Use ListenableFuture. (exteneral dependency)
# Copy & paste ListenableFuture (the license may not permit)
# Copy & paste CompletionStage and CompletableFuture; see the details below.
#3 in more details: Java 8
java.util.concurrent.CompletionStage|CompletableFuture are in [public domain
CC0|http://creativecommons.org/publicdomain/zero/1.0/] so that we may copy them
to org.apache.hadoop.util.concurrent.CompletionStage|CompletableFuture. We may
also need to copy the dependent classes. (Please correct me if I have
misinterpreted the license.)
In branch-2, define a new class, say HadoopCompletableFuture, which implements
Future and org.apache.hadoop.util.concurrent.CompletionStage. The
implementation of HadoopCompletableFuture is simply using
org.apache.hadoop.util.concurrent.CompletableFuture. In trunk,
HadoopCompletableFuture in addition implements
java.util.concurrent.CompletionStage. Then trunk has Java 8 support and is
backward compatible to branch-2. In branch-2, it also has the chaining support
although it does not have the Java 8 language feature such as lambda expression.
{code}
//branch-2
interface HadoopCompletableFuture extends Future,
org.apache.hadoop.util.concurrent.CompletionStage {
}
{code}
{code}
//trunk
interface HadoopCompletableFuture extends Future,
org.apache.hadoop.util.concurrent.CompletionStage,
java.util.concurrent.CompletionStage {
}
{code}
In other words, we copy the Java 8 CompletableFuture related library to
branch-2 since it is in public domain. What do you think?
> Add new FileSystem API to support asynchronous method calls
> -----------------------------------------------------------
>
> Key: HADOOP-12910
> URL: https://issues.apache.org/jira/browse/HADOOP-12910
> Project: Hadoop Common
> Issue Type: New Feature
> Components: fs
> Reporter: Tsz Wo Nicholas Sze
> Assignee: Xiaobing Zhou
> Attachments: HADOOP-12910-HDFS-9924.000.patch,
> HADOOP-12910-HDFS-9924.001.patch, HADOOP-12910-HDFS-9924.002.patch
>
>
> Add a new API, namely FutureFileSystem (or AsynchronousFileSystem, if it is a
> better name). All the APIs in FutureFileSystem are the same as FileSystem
> except that the return type is wrapped by Future, e.g.
> {code}
> //FileSystem
> public boolean rename(Path src, Path dst) throws IOException;
> //FutureFileSystem
> public Future<Boolean> rename(Path src, Path dst) throws IOException;
> {code}
> Note that FutureFileSystem does not extend FileSystem.
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