aio_read doing synchronous stat when size parameter is null about node-rados HOT 6 CLOSED

Yes it's true, if the size is not specified, the async is only partial because of use of rados_stat() is synchronous. However, it permit to read a full object (Anyway asynchronously) without knowing its size. Another possibility would be to make an asynchronous call to rados_stat().
Meanwhile, it would be wise to make this clear in the documentation or examples.

from node-rados.

I looked at doing an asynchronous stat call, but that is not provided by librados so we would need to have our own NanAsyncWorker to do this (which requires a bit more work).

I think if someone wanted to do a full async read in a single call they should manually do a (blocking) ioctx.stat call first to get the length they want to read.

But another problem in the way full read are currently implemented (sync or async) is that it assumes the size of the object doesn't change between the stat call and the read call. I think it would be better to read until EOF is reached, instead of using a stat.

from node-rados.

Yes I understand what you mean. But I'm not sure that there is the notion of EOF in librados for a complete reading.
Otherwise, we can also specify a default size for reading, per example python has default length set to 4096 for sync read : http://ceph.com/docs/master/rados/api/python/#rados.Ioctx.read
That would be the simple way.

from node-rados.

I think you ask to read say 4096 and know its EOF when librados returns less than 4096.

from node-rados.

I will do tests like this.

from node-rados.

Default read size is now 8192.

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