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https://issues.apache.org/jira/browse/HDFS-9368?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15009677#comment-15009677
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Haohui Mai commented on HDFS-9368:
----------------------------------
Looks good to me overall. The patch needs to be rebased towards the latest tip.
{code}
+ssize_t FileHandle::Read(void *buf, size_t nbyte) {
+off_t FileHandle::Seek(off_t offset, Whence whence) {
{code}
Instead of returning -1, these function can return a {{Status}} object that
encapsulates the error code. Then the wrapper in the c binding side would
become:
{code}
static int Error(const Status &stat) {
errno = ...;
return -1;
}
int hdfsSeek(hdfsFS fs, hdfsFile file, tOffset desiredPos) {
Status stat = CheckSystemAndHandle(fs, file);
if (!stat.ok()) {
return Error(stat);
}
int pos = desiredPos;
stat = file->get_impl()->Seek(pos, FileHandle::Whence::SET);
if (!stat.ok()) {
...
}
}
{code}
You can simplify as it needs.
{code}
+ enum Whence {
+ SET = SEEK_SET,
+ CUR = SEEK_CUR,
+ END = SEEK_END,
+ };
{code}
Let's use {{ios_base::seekdir}}
http://www.cplusplus.com/reference/ios/ios_base/seekdir/
{code}
+ FileHandle(InputStream *is) : input_stream_(is), offset_(0){};
{code}
Might make sense to move the inline function to a {{.cc}} file.
{code}
+ unsigned long long get_file_length();
{code}
Can be
{code}
uint64_t get_file_length() const;
{code}
> Implement reads with implicit offset state in libhdfs++
> -------------------------------------------------------
>
> Key: HDFS-9368
> URL: https://issues.apache.org/jira/browse/HDFS-9368
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: hdfs-client
> Reporter: James Clampffer
> Assignee: James Clampffer
> Attachments: HDFS-9368.HDFS-8707.000.patch,
> HDFS-9368.HDFS-8707.001.patch
>
>
> Currently only positional reads are supported. Implement a stateful read
> that keeps track of offset into file. Also expose it in the c bindings as
> hdfsRead.
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