Squashed 'src/rocksdb/' content from commit 224932d

git-subtree-dir: src/rocksdb
git-subtree-split: 224932d4d0b561712107d747c662df181c39644d

table/plain_table_key_coding.h

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+//  Copyright (c) 2013, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+
+#pragma once
+#ifndef ROCKSDB_LITE
+
+#include "rocksdb/slice.h"
+#include "db/dbformat.h"
+
+namespace rocksdb {
+
+class WritableFile;
+struct ParsedInternalKey;
+
+// Helper class to write out a key to an output file
+// Actual data format of the key is documented in plain_table_factory.h
+class PlainTableKeyEncoder {
+ public:
+  explicit PlainTableKeyEncoder(EncodingType encoding_type,
+                                uint32_t user_key_len,
+                                const SliceTransform* prefix_extractor,
+                                size_t index_sparseness)
+      : encoding_type_((prefix_extractor != nullptr) ? encoding_type : kPlain),
+        fixed_user_key_len_(user_key_len),
+        prefix_extractor_(prefix_extractor),
+        index_sparseness_((index_sparseness > 1) ? index_sparseness : 1),
+        key_count_for_prefix(0) {}
+  // key: the key to write out, in the format of internal key.
+  // file: the output file to write out
+  // offset: offset in the file. Needs to be updated after appending bytes
+  //         for the key
+  // meta_bytes_buf: buffer for extra meta bytes
+  // meta_bytes_buf_size: offset to append extra meta bytes. Will be updated
+  //                      if meta_bytes_buf is updated.
+  Status AppendKey(const Slice& key, WritableFile* file, uint64_t* offset,
+                   char* meta_bytes_buf, size_t* meta_bytes_buf_size);
+
+  // Return actual encoding type to be picked
+  EncodingType GetEncodingType() { return encoding_type_; }
+
+ private:
+  EncodingType encoding_type_;
+  uint32_t fixed_user_key_len_;
+  const SliceTransform* prefix_extractor_;
+  const size_t index_sparseness_;
+  size_t key_count_for_prefix;
+  IterKey pre_prefix_;
+};
+
+// A helper class to decode keys from input buffer
+// Actual data format of the key is documented in plain_table_factory.h
+class PlainTableKeyDecoder {
+ public:
+  explicit PlainTableKeyDecoder(EncodingType encoding_type,
+                                uint32_t user_key_len,
+                                const SliceTransform* prefix_extractor)
+      : encoding_type_(encoding_type),
+        prefix_len_(0),
+        fixed_user_key_len_(user_key_len),
+        prefix_extractor_(prefix_extractor),
+        in_prefix_(false) {}
+  // Find the next key.
+  // start: char array where the key starts.
+  // limit: boundary of the char array
+  // parsed_key: the output of the result key
+  // internal_key: if not null, fill with the output of the result key in
+  //               un-parsed format
+  // bytes_read: how many bytes read from start. Output
+  // seekable: whether key can be read from this place. Used when building
+  //           indexes. Output.
+  Status NextKey(const char* start, const char* limit,
+                 ParsedInternalKey* parsed_key, Slice* internal_key,
+                 size_t* bytes_read, bool* seekable = nullptr);
+  EncodingType encoding_type_;
+  uint32_t prefix_len_;
+  uint32_t fixed_user_key_len_;
+  Slice saved_user_key_;
+  IterKey cur_key_;
+  const SliceTransform* prefix_extractor_;
+  bool in_prefix_;
+
+ private:
+  Status NextPlainEncodingKey(const char* start, const char* limit,
+                              ParsedInternalKey* parsed_key,
+                              Slice* internal_key, size_t* bytes_read,
+                              bool* seekable = nullptr);
+  Status NextPrefixEncodingKey(const char* start, const char* limit,
+                               ParsedInternalKey* parsed_key,
+                               Slice* internal_key, size_t* bytes_read,
+                               bool* seekable = nullptr);
+};
+
+}  // namespace rocksdb
+
+#endif  // ROCKSDB_LITE