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https://issues.apache.org/jira/browse/HDFS-14478?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sahil Takiar updated HDFS-14478:
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Summary: Add libhdfs APIs for openFile (was: Add libhdfs APIs for
readFully and openFile)
> Add libhdfs APIs for openFile
> -----------------------------
>
> Key: HDFS-14478
> URL: https://issues.apache.org/jira/browse/HDFS-14478
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs-client, libhdfs, native
> Reporter: Sahil Takiar
> Assignee: Sahil Takiar
> Priority: Major
>
> HADOOP-15229 added a "FileSystem builder-based openFile() API" that allows
> specifying configuration values for opening files (similar to HADOOP-14365).
> The {{PositionedReadable#readFully}} APIs have always existed.
> Both of these APIs should be exposed by libhdfs.
> Adding support for {{readFully}} should be straight-forward (a new libhdfs
> API called {{hdfsPreadFully}} whose implementation is similar to
> {{hdfsPread}}).
> Support for {{openFile}} will be a little tricker as it is asynchronous and
> {{FutureDataInputStreamBuilder#build}} returns a {{CompletableFuture}}.
> At a high level, the API for {{openFile}} could look something like this:
> {code:java}
> LIBHDFS_EXTERNAL
> struct hdfsOpenFileBuilder *hdfsOpenFileBuilderAlloc(hdfsFS fs,
> const char *path, int flags);
> LIBHDFS_EXTERNAL
> void hdfsOpenFileBuilderFree(struct hdfsOpenFileBuilder *bld);
> LIBHDFS_EXTERNAL
> struct hdfsOpenFileBuilder *hdfsOpenFileBuilderMust(hdfsFS fs,
> const char *key, const char *value);
> LIBHDFS_EXTERNAL
> struct hdfsOpenFileBuilder *hdfsOpenFileBuilderOpt(hdfsFS fs,
> const char *key, const char *value);
> LIBHDFS_EXTERNAL
> hdfsFileFuture *hdfsOpenFileBuilderBuild(struct hdfsOpenFileBuilder *bld);
> LIBHDFS_EXTERNAL
> void hdfsOpenFileFutureFree(struct hdfsFileFuture *future);
> LIBHDFS_EXTERNAL
> hdfsFile hdfsOpenFileFutureGet(struct hdfsFileFuture *future);
> LIBHDFS_EXTERNAL
> hdfsFile hdfsOpenFileFutureGet(struct hdfsFileFuture *future, int64_t
> timeout, const char* timeUnit);
> LIBHDFS_EXTERNAL
> void hdfsOpenFileFutureCancel(struct hdfsFileFuture *future,
> bool mayInterruptIfRunning);
> {code}
> Instead of exposing all the functionality of {{CompleteableFuture}} libhdfs
> would just expose the functionality of {{Future}}.
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