1 files changed, 179 insertions, 0 deletions
diff --git a/src/rocksdb/db/blob_index.h b/src/rocksdb/db/blob_index.h
new file mode 100644
index 000000000..483a7b97b
--- /dev/null
+++ b/src/rocksdb/db/blob_index.h
@@ -0,0 +1,179 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+#pragma once
+#ifndef ROCKSDB_LITE
+
+#include <sstream>
+#include <string>
+
+#include "rocksdb/options.h"
+#include "util/coding.h"
+#include "util/string_util.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+// BlobIndex is a pointer to the blob and metadata of the blob. The index is
+// stored in base DB as ValueType::kTypeBlobIndex.
+// There are three types of blob index:
+//
+//    kInlinedTTL:
+//      +------+------------+---------------+
+//      | type | expiration | value         |
+//      +------+------------+---------------+
+//      | char | varint64   | variable size |
+//      +------+------------+---------------+
+//
+//    kBlob:
+//      +------+-------------+----------+----------+-------------+
+//      | type | file number | offset   | size     | compression |
+//      +------+-------------+----------+----------+-------------+
+//      | char | varint64    | varint64 | varint64 | char        |
+//      +------+-------------+----------+----------+-------------+
+//
+//    kBlobTTL:
+//      +------+------------+-------------+----------+----------+-------------+
+//      | type | expiration | file number | offset   | size     | compression |
+//      +------+------------+-------------+----------+----------+-------------+
+//      | char | varint64   | varint64    | varint64 | varint64 | char        |
+//      +------+------------+-------------+----------+----------+-------------+
+//
+// There isn't a kInlined (without TTL) type since we can store it as a plain
+// value (i.e. ValueType::kTypeValue).
+class BlobIndex {
+ public:
+  enum class Type : unsigned char {
+    kInlinedTTL = 0,
+    kBlob = 1,
+    kBlobTTL = 2,
+    kUnknown = 3,
+  };
+
+  BlobIndex() : type_(Type::kUnknown) {}
+
+  bool IsInlined() const { return type_ == Type::kInlinedTTL; }
+
+  bool HasTTL() const {
+    return type_ == Type::kInlinedTTL || type_ == Type::kBlobTTL;
+  }
+
+  uint64_t expiration() const {
+    assert(HasTTL());
+    return expiration_;
+  }
+
+  const Slice& value() const {
+    assert(IsInlined());
+    return value_;
+  }
+
+  uint64_t file_number() const {
+    assert(!IsInlined());
+    return file_number_;
+  }
+
+  uint64_t offset() const {
+    assert(!IsInlined());
+    return offset_;
+  }
+
+  uint64_t size() const {
+    assert(!IsInlined());
+    return size_;
+  }
+
+  Status DecodeFrom(Slice slice) {
+    static const std::string kErrorMessage = "Error while decoding blob index";
+    assert(slice.size() > 0);
+    type_ = static_cast<Type>(*slice.data());
+    if (type_ >= Type::kUnknown) {
+      return Status::Corruption(
+          kErrorMessage,
+          "Unknown blob index type: " + ToString(static_cast<char>(type_)));
+    }
+    slice = Slice(slice.data() + 1, slice.size() - 1);
+    if (HasTTL()) {
+      if (!GetVarint64(&slice, &expiration_)) {
+        return Status::Corruption(kErrorMessage, "Corrupted expiration");
+      }
+    }
+    if (IsInlined()) {
+      value_ = slice;
+    } else {
+      if (GetVarint64(&slice, &file_number_) && GetVarint64(&slice, &offset_) &&
+          GetVarint64(&slice, &size_) && slice.size() == 1) {
+        compression_ = static_cast<CompressionType>(*slice.data());
+      } else {
+        return Status::Corruption(kErrorMessage, "Corrupted blob offset");
+      }
+    }
+    return Status::OK();
+  }
+
+  std::string DebugString(bool output_hex) const {
+    std::ostringstream oss;
+
+    if (IsInlined()) {
+      oss << "[inlined blob] value:" << value_.ToString(output_hex);
+    } else {
+      oss << "[blob ref] file:" << file_number_ << " offset:" << offset_
+          << " size:" << size_;
+    }
+
+    if (HasTTL()) {
+      oss << " exp:" << expiration_;
+    }
+
+    return oss.str();
+  }
+
+  static void EncodeInlinedTTL(std::string* dst, uint64_t expiration,
+                               const Slice& value) {
+    assert(dst != nullptr);
+    dst->clear();
+    dst->reserve(1 + kMaxVarint64Length + value.size());
+    dst->push_back(static_cast<char>(Type::kInlinedTTL));
+    PutVarint64(dst, expiration);
+    dst->append(value.data(), value.size());
+  }
+
+  static void EncodeBlob(std::string* dst, uint64_t file_number,
+                         uint64_t offset, uint64_t size,
+                         CompressionType compression) {
+    assert(dst != nullptr);
+    dst->clear();
+    dst->reserve(kMaxVarint64Length * 3 + 2);
+    dst->push_back(static_cast<char>(Type::kBlob));
+    PutVarint64(dst, file_number);
+    PutVarint64(dst, offset);
+    PutVarint64(dst, size);
+    dst->push_back(static_cast<char>(compression));
+  }
+
+  static void EncodeBlobTTL(std::string* dst, uint64_t expiration,
+                            uint64_t file_number, uint64_t offset,
+                            uint64_t size, CompressionType compression) {
+    assert(dst != nullptr);
+    dst->clear();
+    dst->reserve(kMaxVarint64Length * 4 + 2);
+    dst->push_back(static_cast<char>(Type::kBlobTTL));
+    PutVarint64(dst, expiration);
+    PutVarint64(dst, file_number);
+    PutVarint64(dst, offset);
+    PutVarint64(dst, size);
+    dst->push_back(static_cast<char>(compression));
+  }
+
+ private:
+  Type type_ = Type::kUnknown;
+  uint64_t expiration_ = 0;
+  Slice value_;
+  uint64_t file_number_ = 0;
+  uint64_t offset_ = 0;
+  uint64_t size_ = 0;
+  CompressionType compression_ = kNoCompression;
+};
+
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // ROCKSDB_LITE