At Mon, 25 May 2020 07:44:09 +0900, Michael Paquier <mich...@paquier.xyz> wrote in > Hi all, > > I have been playing with the new APIs of xlogreader.h, and while > merging some of my stuff with 13, I found the handling around > ->seg.ws_file overcomplicated and confusing as it is necessary for a > plugin to manipulate directly the fd of an opened segment in the WAL > segment open/close callbacks.
That depends on where we draw responsibility border, or who is responsible to the value of ws_file. I think that this API change was assuming the callbacks having full-knowledge of the xlogreader struct and are responsible to maintain related struct members, and I agree to that direction. > Wouldn't it be cleaner to limit the exposition of ->seg.ws_file to the > user if possible? There are cases like a WAL sender where you cannot > do that, but something that came to my mind is to make > WALSegmentOpenCB return the fd of the opened segment, and pass down the > fd to close to WALSegmentCloseCB. Then xlogreader.c is in charge of > resetting the field when a segment is closed. > > Any thoughts? If we are going to hide the struct from the callbacks, we shouldn't pass to the callbacks a pointer to the complete XLogReaderState struct. regards. -- Kyotaro Horiguchi NTT Open Source Software Center