diff options
Diffstat (limited to 'src/backend')
| -rw-r--r-- | src/backend/storage/aio/read_stream.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/src/backend/storage/aio/read_stream.c b/src/backend/storage/aio/read_stream.c index 0e7f5557f5c..031fde9f4cb 100644 --- a/src/backend/storage/aio/read_stream.c +++ b/src/backend/storage/aio/read_stream.c @@ -247,12 +247,33 @@ read_stream_start_pending_read(ReadStream *stream) Assert(stream->pinned_buffers + stream->pending_read_nblocks <= stream->max_pinned_buffers); +#ifdef USE_ASSERT_CHECKING /* We had better not be overwriting an existing pinned buffer. */ if (stream->pinned_buffers > 0) Assert(stream->next_buffer_index != stream->oldest_buffer_index); else Assert(stream->next_buffer_index == stream->oldest_buffer_index); + /* + * Pinned buffers forwarded by a preceding StartReadBuffers() call that + * had to split the operation should match the leading blocks of this + * following StartReadBuffers() call. + */ + Assert(stream->forwarded_buffers <= stream->pending_read_nblocks); + for (int i = 0; i < stream->forwarded_buffers; ++i) + Assert(BufferGetBlockNumber(stream->buffers[stream->next_buffer_index + i]) == + stream->pending_read_blocknum + i); + + /* + * Check that we've cleared the queue/overflow entries corresponding to + * the rest of the blocks covered by this read, unless it's the first go + * around and we haven't even initialized them yet. + */ + for (int i = stream->forwarded_buffers; i < stream->pending_read_nblocks; ++i) + Assert(stream->next_buffer_index + i >= stream->initialized_buffers || + stream->buffers[stream->next_buffer_index + i] == InvalidBuffer); +#endif + /* Do we need to issue read-ahead advice? */ flags = stream->read_buffers_flags; if (stream->advice_enabled) @@ -979,6 +1000,19 @@ read_stream_next_buffer(ReadStream *stream, void **per_buffer_data) stream->pending_read_nblocks == 0 && stream->per_buffer_data_size == 0) { + /* + * The fast path spins on one buffer entry repeatedly instead of + * rotating through the whole queue and clearing the entries behind + * it. If the buffer it starts with happened to be forwarded between + * StartReadBuffers() calls and also wrapped around the circular queue + * partway through, then a copy also exists in the overflow zone, and + * it won't clear it out as the regular path would. Do that now, so + * it doesn't need code for that. + */ + if (stream->oldest_buffer_index < stream->io_combine_limit - 1) + stream->buffers[stream->queue_size + stream->oldest_buffer_index] = + InvalidBuffer; + stream->fast_path = true; } #endif |