Review fixes

src/Common/ProfileEvents.cpp

@@ -451,8 +451,8 @@ The server successfully detected this situation and will download merged part fr
     M(ThreadPoolReaderPageCacheMissBytes, "Number of bytes read inside ThreadPoolReader when read was not done from page cache and was hand off to thread pool.") \
     M(ThreadPoolReaderPageCacheMissElapsedMicroseconds, "Time spent reading data inside the asynchronous job in ThreadPoolReader - when read was not done from page cache.") \
     \
-    M(AsynchronousReadWaitMicroseconds, "Time spent in waiting for asynchronous reads.") \
-    M(SynchronousReadWaitMicroseconds, "Time spent in waiting for synchronous reads.") \
+    M(AsynchronousReadWaitMicroseconds, "Time spent in waiting for asynchronous reads in asynchronous local read.") \
+    M(SynchronousReadWaitMicroseconds, "Time spent in waiting for synchronous reads in asynchronous local read.") \
     M(AsynchronousRemoteReadWaitMicroseconds, "Time spent in waiting for asynchronous remote reads.") \
     M(SynchronousRemoteReadWaitMicroseconds, "Time spent in waiting for synchronous remote reads.") \
     \

src/Disks/IO/AsynchronousBoundedReadBuffer.cpp

@@ -200,11 +200,12 @@ bool AsynchronousBoundedReadBuffer::nextImpl()
 
         prefetch_future = {};
         prefetch_buffer.swap(memory);
-        last_prefetch_info = {};
 
         if (read_settings.enable_filesystem_read_prefetches_log)
             appendToPrefetchLog(FilesystemPrefetchState::USED, result.size, result.execution_watch);
 
+        last_prefetch_info = {};
+
         ProfileEvents::increment(ProfileEvents::RemoteFSPrefetchedReads);
         ProfileEvents::increment(ProfileEvents::RemoteFSPrefetchedBytes, result.size);
     }

src/Disks/IO/ThreadPoolRemoteFSReader.cpp

@@ -86,8 +86,7 @@ IAsynchronousReader::Result ThreadPoolRemoteFSReader::execute(Request request)
     auto watch = std::make_unique<Stopwatch>(CLOCK_REALTIME);
 
     reader.set(request.buf, request.size);
-    if (request.offset)
-        reader.seek(request.offset, SEEK_SET);
+    reader.seek(request.offset, SEEK_SET);
     if (request.ignore)
         reader.ignore(request.ignore);
 

src/Disks/IO/ThreadPoolRemoteFSReader.h

@@ -38,6 +38,7 @@ public:
     std::shared_ptr<AsyncReadCounters> getReadCounters() const { return async_read_counters; }
 
 private:
+    /// Reader is used for reading only by RemoteFSFileDescriptor.
     SeekableReadBuffer & reader;
     std::shared_ptr<AsyncReadCounters> async_read_counters;
 };