Open file for reading lazily in CachedCompressedReadBuffer.

dbms/src/Compression/CachedCompressedReadBuffer.cpp

@@ -1,10 +1,10 @@
 #include "CachedCompressedReadBuffer.h"
 
-#include <IO/createReadBufferFromFileBase.h>
 #include <IO/WriteHelpers.h>
-#include <Compression/CompressionInfo.h>
 #include <Compression/LZ4_decompress_faster.h>
 
+#include <utility>
+
 
 namespace DB
 {
@@ -19,7 +19,7 @@ void CachedCompressedReadBuffer::initInput()
 {
     if (!file_in)
     {
-        file_in = createReadBufferFromFileBase(path, estimated_size, aio_threshold, mmap_threshold, buf_size);
+        file_in = file_in_creator();
         compressed_in = file_in.get();
 
         if (profile_callback)
@@ -71,24 +71,12 @@ bool CachedCompressedReadBuffer::nextImpl()
     return true;
 }
 
-
-CachedCompressedReadBuffer::CachedCompressedReadBuffer(std::unique_ptr<ReadBufferFromFileBase> file_in_, UncompressedCache * cache_)
-    : ReadBuffer(nullptr, 0), cache(cache_), file_in(std::move(file_in_)), path(file_in->getFileName()), file_pos(0)
-{
-    compressed_in = file_in.get();
-}
-
-
 CachedCompressedReadBuffer::CachedCompressedReadBuffer(
-    const std::string & path_, UncompressedCache * cache_,
+    const std::string & path_, std::function<std::unique_ptr<ReadBufferFromFileBase>()> file_in_creator_, UncompressedCache * cache_)
-    size_t estimated_size_, size_t aio_threshold_, size_t mmap_threshold_,
+    : ReadBuffer(nullptr, 0), file_in_creator(std::move(file_in_creator_)), cache(cache_), path(path_), file_pos(0)
-    size_t buf_size_)
-    : ReadBuffer(nullptr, 0), cache(cache_), path(path_), buf_size(buf_size_), estimated_size(estimated_size_),
-        aio_threshold(aio_threshold_), mmap_threshold(mmap_threshold_), file_pos(0)
 {
 }
 
-
 void CachedCompressedReadBuffer::seek(size_t offset_in_compressed_file, size_t offset_in_decompressed_block)
 {
     if (owned_cell &&

dbms/src/Compression/CachedCompressedReadBuffer.h

@@ -20,15 +20,11 @@ namespace DB
 class CachedCompressedReadBuffer : public CompressedReadBufferBase, public ReadBuffer
 {
 private:
+    std::function<std::unique_ptr<ReadBufferFromFileBase>()> file_in_creator;
     UncompressedCache * cache;
     std::unique_ptr<ReadBufferFromFileBase> file_in;
 
     const std::string path;
-    size_t buf_size {};
-    size_t estimated_size {};
-    size_t aio_threshold {};
-    size_t mmap_threshold {};
-
     size_t file_pos;
 
     /// A piece of data from the cache, or a piece of read data that we put into the cache.
@@ -42,13 +38,7 @@ private:
     clockid_t clock_type {};
 
 public:
-    CachedCompressedReadBuffer(std::unique_ptr<ReadBufferFromFileBase> file_in, UncompressedCache * cache_);
+    CachedCompressedReadBuffer(const std::string & path, std::function<std::unique_ptr<ReadBufferFromFileBase>()> file_in_creator, UncompressedCache * cache_);
-
-    CachedCompressedReadBuffer(
-        const std::string & path_, UncompressedCache * cache_,
-        size_t estimated_size_, size_t aio_threshold_, size_t mmap_threshold_,
-        size_t buf_size_ = DBMS_DEFAULT_BUFFER_SIZE);
-
 
     void seek(size_t offset_in_compressed_file, size_t offset_in_decompressed_block);
 

dbms/src/Storages/MergeTree/MergeTreeReaderCompact.cpp

@@ -39,10 +39,17 @@ MergeTreeReaderCompact::MergeTreeReaderCompact(
 
     if (uncompressed_cache)
     {
-        auto buffer =
+        auto buffer = std::make_unique<CachedCompressedReadBuffer>(
-            std::make_unique<CachedCompressedReadBuffer>(
+            full_data_path,
-                data_part->disk->readFile(full_data_path, buffer_size, 0, settings.min_bytes_to_use_direct_io, 0),
+            [&]() {
-                uncompressed_cache);
+                return data_part->disk->readFile(
+                    full_data_path,
+                    buffer_size,
+                    0,
+                    settings.min_bytes_to_use_direct_io,
+                    0);
+            },
+            uncompressed_cache);
 
         if (profile_callback_)
             buffer->setProfileCallback(profile_callback_, clock_type_);

dbms/src/Storages/MergeTree/MergeTreeReaderStream.cpp

@@ -79,8 +79,15 @@ MergeTreeReaderStream::MergeTreeReaderStream(
     if (uncompressed_cache)
     {
         auto buffer = std::make_unique<CachedCompressedReadBuffer>(
-            disk->readFile(path_prefix + data_file_extension, buffer_size,
+            path_prefix + data_file_extension,
-                sum_mark_range_bytes, settings.min_bytes_to_use_direct_io, settings.min_bytes_to_use_mmap_io),
+            [&]() {
+                return disk->readFile(
+                    path_prefix + data_file_extension,
+                    buffer_size,
+                    sum_mark_range_bytes,
+                    settings.min_bytes_to_use_direct_io,
+                    settings.min_bytes_to_use_mmap_io);
+            },
             uncompressed_cache);
 
         if (profile_callback)