dbms: IO: added test [#METR-2944].

dbms/include/DB/IO/ReadBufferFromFile.h

@@ -16,13 +16,13 @@ private:
 	std::string file_name;
 	
 public:
-	ReadBufferFromFile(const std::string & file_name_, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
+	ReadBufferFromFile(const std::string & file_name_, size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE, int flags = -1,
 		char * existing_memory = NULL, size_t alignment = 0)
 		: ReadBufferFromFileDescriptor(-1, buf_size, existing_memory, alignment), file_name(file_name_)
 	{
 		ProfileEvents::increment(ProfileEvents::FileOpen);
 
-		fd = open(file_name.c_str(), O_RDONLY);
+		fd = open(file_name.c_str(), flags == -1 ? O_RDONLY : flags);
 
 		if (-1 == fd)
 			throwFromErrno("Cannot open file " + file_name, errno == ENOENT ? ErrorCodes::FILE_DOESNT_EXIST : ErrorCodes::CANNOT_OPEN_FILE);

dbms/src/IO/tests/o_direct_and_dirty_pages.cpp

@@ -0,0 +1,45 @@
+#include <string>
+
+#include <iostream>
+
+#include <DB/Core/Types.h>
+#include <DB/IO/WriteHelpers.h>
+#include <DB/IO/ReadHelpers.h>
+#include <DB/IO/WriteBufferFromFile.h>
+#include <DB/IO/ReadBufferFromFile.h>
+
+
+int main(int argc, char ** argv)
+{
+	using namespace DB;
+
+	try
+	{
+		ReadBufferFromFile rand_in("/dev/urandom");
+		unsigned rand = 0;
+		readBinary(rand, rand_in);
+
+		String test = "Hello, world! " + toString(rand);
+
+		{
+			WriteBufferFromFile wb("test", 4096);
+			writeStringBinary(test, wb);
+			wb.next();
+		}
+
+		{
+			ReadBufferFromFile rb("test", 4096, O_RDONLY | O_DIRECT, nullptr, 4096);
+			String res;
+			readStringBinary(res, rb);
+
+			std::cerr << "test: " << test << ", res: " << res << std::endl;
+		}
+	}
+	catch (const Exception & e)
+	{
+		std::cerr << e.what() << ", " << e.displayText() << std::endl;
+		return 1;
+	}
+
+	return 0;
+}

dbms/src/Interpreters/loadMetadata.cpp

@@ -112,7 +112,7 @@ void loadMetadata(Context & context)
 			{
 				static const size_t in_buf_size = 32768;
 				char in_buf[in_buf_size];
-				ReadBufferFromFile in(tables[j], 32768, in_buf);
+				ReadBufferFromFile in(tables[j], 32768, -1, in_buf);
 				WriteBufferFromString out(s);
 				copyData(in, out);
 			}