intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 105 insertions, 0 deletions

diff --git a/library/cpp/blockcodecs/core/common.h b/library/cpp/blockcodecs/core/common.h
new file mode 100644
index 0000000000..f05df4d334
--- /dev/null
+++ b/library/cpp/blockcodecs/core/common.h
@@ -0,0 +1,105 @@
+#pragma once
+
+#include "codecs.h"
+
+#include <util/ysaveload.h>
+#include <util/stream/null.h>
+#include <util/stream/mem.h>
+#include <util/string/cast.h>
+#include <util/string/join.h>
+#include <util/system/align.h>
+#include <util/system/unaligned_mem.h>
+#include <util/generic/hash.h>
+#include <util/generic/cast.h>
+#include <util/generic/buffer.h>
+#include <util/generic/array_ref.h>
+#include <util/generic/singleton.h>
+#include <util/generic/algorithm.h>
+#include <util/generic/mem_copy.h>
+
+namespace NBlockCodecs {
+    struct TDecompressError: public TDataError {
+        TDecompressError(int code) {
+            *this << "cannot decompress (errcode " << code << ")";
+        }
+
+        TDecompressError(size_t exp, size_t real) {
+            *this << "broken input (expected len: " << exp << ", got: " << real << ")";
+        }
+    };
+
+    struct TCompressError: public TDataError {
+        TCompressError(int code) {
+            *this << "cannot compress (errcode " << code << ")";
+        }
+    };
+
+    struct TNullCodec: public ICodec {
+        size_t DecompressedLength(const TData& in) const override {
+            return in.size();
+        }
+
+        size_t MaxCompressedLength(const TData& in) const override {
+            return in.size();
+        }
+
+        size_t Compress(const TData& in, void* out) const override {
+            MemCopy((char*)out, in.data(), in.size());
+
+            return in.size();
+        }
+
+        size_t Decompress(const TData& in, void* out) const override {
+            MemCopy((char*)out, in.data(), in.size());
+
+            return in.size();
+        }
+
+        TStringBuf Name() const noexcept override {
+            return TStringBuf("null");
+        }
+    };
+
+    template <class T>
+    struct TAddLengthCodec: public ICodec {
+        static inline void Check(const TData& in) {
+            if (in.size() < sizeof(ui64)) {
+                ythrow TDataError() << "too small input";
+            }
+        }
+
+        size_t DecompressedLength(const TData& in) const override {
+            Check(in);
+
+            return ReadUnaligned<ui64>(in.data());
+        }
+
+        size_t MaxCompressedLength(const TData& in) const override {
+            return T::DoMaxCompressedLength(in.size()) + sizeof(ui64);
+        }
+
+        size_t Compress(const TData& in, void* out) const override {
+            ui64* ptr = (ui64*)out;
+
+            WriteUnaligned<ui64>(ptr, (ui64) in.size());
+
+            return Base()->DoCompress(!in ? TData(TStringBuf("")) : in, ptr + 1) + sizeof(*ptr);
+        }
+
+        size_t Decompress(const TData& in, void* out) const override {
+            Check(in);
+
+            const auto len = ReadUnaligned<ui64>(in.data());
+
+            if (!len)
+                return 0;
+
+            Base()->DoDecompress(TData(in).Skip(sizeof(len)), out, len);
+            return len;
+        }
+
+        inline const T* Base() const noexcept {
+            return static_cast<const T*>(this);
+        }
+    };
+}