From ff29856d80c1c3778cc99a35ed8f2ba8c642d37f Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Wed, 9 Apr 2025 15:16:31 +1200 Subject: [PATCH v2 2/4] Improve read_stream.c program flow. Commit 55918f79 removed the space-based reason for calling read_stream_look_ahead() at the top and bottom of read_stream_next_buffer(). Commit 7ea8cd15 removed the need to call it with a different flag in each spot. We can delete a couple of dozen lines and just call it at the top now. That's much tidier, but also required for a later patch that reorders the queue. --- src/backend/storage/aio/read_stream.c | 29 +++++---------------------- 1 file changed, 5 insertions(+), 24 deletions(-) diff --git a/src/backend/storage/aio/read_stream.c b/src/backend/storage/aio/read_stream.c index 0d3dd65bfed..a98213d4df2 100644 --- a/src/backend/storage/aio/read_stream.c +++ b/src/backend/storage/aio/read_stream.c @@ -909,28 +909,12 @@ read_stream_next_buffer(ReadStream *stream, void **per_buffer_data) } #endif - if (unlikely(stream->pinned_buffers == 0)) + /* Look ahead and check for end of stream. */ + read_stream_look_ahead(stream); + if (stream->pinned_buffers == 0) { - Assert(stream->oldest_buffer_index == stream->next_buffer_index); - - /* End of stream reached? */ - if (stream->distance == 0) - return InvalidBuffer; - - /* - * The usual order of operations is that we look ahead at the bottom - * of this function after potentially finishing an I/O and making - * space for more, but if we're just starting up we'll need to crank - * the handle to get started. - */ - read_stream_look_ahead(stream); - - /* End of stream reached? */ - if (stream->pinned_buffers == 0) - { - Assert(stream->distance == 0); - return InvalidBuffer; - } + Assert(stream->distance == 0); + return InvalidBuffer; } /* Grab the oldest pinned buffer and associated per-buffer data. */ @@ -1022,9 +1006,6 @@ read_stream_next_buffer(ReadStream *stream, void **per_buffer_data) /* Advance oldest buffer, with wrap-around. */ read_stream_advance_buffer(stream, &stream->oldest_buffer_index); - /* Prepare for the next call. */ - read_stream_look_ahead(stream); - #ifndef READ_STREAM_DISABLE_FAST_PATH /* See if we can take the fast path for all-cached scans next time. */ if (stream->ios_in_progress == 0 && -- 2.39.5