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1 | /** |
2 | * A MergeOperator for rocksdb that implements string append. | |
3 | * @author Deon Nicholas (dnicholas@fb.com) | |
4 | * Copyright 2013 Facebook | |
5 | */ | |
6 | ||
7 | #include "stringappend.h" | |
8 | ||
7c673cae FG |
9 | #include <assert.h> |
10 | ||
1e59de90 TL |
11 | #include <memory> |
12 | ||
7c673cae | 13 | #include "rocksdb/merge_operator.h" |
1e59de90 TL |
14 | #include "rocksdb/slice.h" |
15 | #include "rocksdb/utilities/options_type.h" | |
7c673cae FG |
16 | #include "utilities/merge_operators.h" |
17 | ||
f67539c2 | 18 | namespace ROCKSDB_NAMESPACE { |
1e59de90 TL |
19 | namespace { |
20 | static std::unordered_map<std::string, OptionTypeInfo> | |
21 | stringappend_merge_type_info = { | |
22 | #ifndef ROCKSDB_LITE | |
23 | {"delimiter", | |
24 | {0, OptionType::kString, OptionVerificationType::kNormal, | |
25 | OptionTypeFlags::kNone}}, | |
26 | #endif // ROCKSDB_LITE | |
27 | }; | |
28 | } // namespace | |
7c673cae FG |
29 | // Constructor: also specify the delimiter character. |
30 | StringAppendOperator::StringAppendOperator(char delim_char) | |
1e59de90 TL |
31 | : delim_(1, delim_char) { |
32 | RegisterOptions("Delimiter", &delim_, &stringappend_merge_type_info); | |
33 | } | |
34 | ||
35 | StringAppendOperator::StringAppendOperator(const std::string& delim) | |
36 | : delim_(delim) { | |
37 | RegisterOptions("Delimiter", &delim_, &stringappend_merge_type_info); | |
7c673cae FG |
38 | } |
39 | ||
40 | // Implementation for the merge operation (concatenates two strings) | |
11fdf7f2 | 41 | bool StringAppendOperator::Merge(const Slice& /*key*/, |
7c673cae | 42 | const Slice* existing_value, |
11fdf7f2 TL |
43 | const Slice& value, std::string* new_value, |
44 | Logger* /*logger*/) const { | |
7c673cae FG |
45 | // Clear the *new_value for writing. |
46 | assert(new_value); | |
47 | new_value->clear(); | |
48 | ||
49 | if (!existing_value) { | |
50 | // No existing_value. Set *new_value = value | |
1e59de90 | 51 | new_value->assign(value.data(), value.size()); |
7c673cae FG |
52 | } else { |
53 | // Generic append (existing_value != null). | |
54 | // Reserve *new_value to correct size, and apply concatenation. | |
1e59de90 TL |
55 | new_value->reserve(existing_value->size() + delim_.size() + value.size()); |
56 | new_value->assign(existing_value->data(), existing_value->size()); | |
57 | new_value->append(delim_); | |
7c673cae FG |
58 | new_value->append(value.data(), value.size()); |
59 | } | |
60 | ||
61 | return true; | |
62 | } | |
63 | ||
7c673cae FG |
64 | std::shared_ptr<MergeOperator> MergeOperators::CreateStringAppendOperator() { |
65 | return std::make_shared<StringAppendOperator>(','); | |
66 | } | |
67 | ||
1e59de90 TL |
68 | std::shared_ptr<MergeOperator> MergeOperators::CreateStringAppendOperator( |
69 | char delim_char) { | |
11fdf7f2 TL |
70 | return std::make_shared<StringAppendOperator>(delim_char); |
71 | } | |
72 | ||
1e59de90 TL |
73 | std::shared_ptr<MergeOperator> MergeOperators::CreateStringAppendOperator( |
74 | const std::string& delim) { | |
75 | return std::make_shared<StringAppendOperator>(delim); | |
76 | } | |
77 | ||
f67539c2 | 78 | } // namespace ROCKSDB_NAMESPACE |