rocksdb/util/slice.cc

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// 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).
//
// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include <algorithm>
#include "rocksdb/slice_transform.h"
#include "rocksdb/slice.h"
#include "util/string_util.h"
#include <stdio.h>
namespace rocksdb {
namespace {
class FixedPrefixTransform : public SliceTransform {
private:
size_t prefix_len_;
std::string name_;
public:
explicit FixedPrefixTransform(size_t prefix_len)
: prefix_len_(prefix_len),
// Note that if any part of the name format changes, it will require
// changes on options_helper in order to make RocksDBOptionsParser work
// for the new change.
// TODO(yhchiang): move serialization / deserializaion code inside
// the class implementation itself.
name_("rocksdb.FixedPrefix." + ToString(prefix_len_)) {}
virtual const char* Name() const override { return name_.c_str(); }
virtual Slice Transform(const Slice& src) const override {
assert(InDomain(src));
return Slice(src.data(), prefix_len_);
}
virtual bool InDomain(const Slice& src) const override {
return (src.size() >= prefix_len_);
}
virtual bool InRange(const Slice& dst) const override {
return (dst.size() == prefix_len_);
}
virtual bool FullLengthEnabled(size_t* len) const override {
*len = prefix_len_;
return true;
}
virtual bool SameResultWhenAppended(const Slice& prefix) const override {
return InDomain(prefix);
}
};
class CappedPrefixTransform : public SliceTransform {
private:
size_t cap_len_;
std::string name_;
public:
explicit CappedPrefixTransform(size_t cap_len)
: cap_len_(cap_len),
// Note that if any part of the name format changes, it will require
// changes on options_helper in order to make RocksDBOptionsParser work
// for the new change.
// TODO(yhchiang): move serialization / deserializaion code inside
// the class implementation itself.
name_("rocksdb.CappedPrefix." + ToString(cap_len_)) {}
virtual const char* Name() const override { return name_.c_str(); }
virtual Slice Transform(const Slice& src) const override {
assert(InDomain(src));
return Slice(src.data(), std::min(cap_len_, src.size()));
}
virtual bool InDomain(const Slice& /*src*/) const override { return true; }
virtual bool InRange(const Slice& dst) const override {
return (dst.size() <= cap_len_);
}
virtual bool FullLengthEnabled(size_t* len) const override {
*len = cap_len_;
return true;
}
virtual bool SameResultWhenAppended(const Slice& prefix) const override {
return prefix.size() >= cap_len_;
}
};
class NoopTransform : public SliceTransform {
public:
explicit NoopTransform() { }
virtual const char* Name() const override { return "rocksdb.Noop"; }
virtual Slice Transform(const Slice& src) const override { return src; }
virtual bool InDomain(const Slice& /*src*/) const override { return true; }
virtual bool InRange(const Slice& /*dst*/) const override { return true; }
virtual bool SameResultWhenAppended(const Slice& /*prefix*/) const override {
return false;
}
};
}
// 2 small internal utility functions, for efficient hex conversions
// and no need for snprintf, toupper etc...
// Originally from wdt/util/EncryptionUtils.cpp - for ToString(true)/DecodeHex:
char toHex(unsigned char v) {
if (v <= 9) {
return '0' + v;
}
return 'A' + v - 10;
}
// most of the code is for validation/error check
int fromHex(char c) {
// toupper:
if (c >= 'a' && c <= 'f') {
c -= ('a' - 'A'); // aka 0x20
}
// validation
if (c < '0' || (c > '9' && (c < 'A' || c > 'F'))) {
return -1; // invalid not 0-9A-F hex char
}
if (c <= '9') {
return c - '0';
}
return c - 'A' + 10;
}
Slice::Slice(const SliceParts& parts, std::string* buf) {
size_t length = 0;
for (int i = 0; i < parts.num_parts; ++i) {
length += parts.parts[i].size();
}
buf->reserve(length);
for (int i = 0; i < parts.num_parts; ++i) {
buf->append(parts.parts[i].data(), parts.parts[i].size());
}
data_ = buf->data();
size_ = buf->size();
}
// Return a string that contains the copy of the referenced data.
std::string Slice::ToString(bool hex) const {
std::string result; // RVO/NRVO/move
if (hex) {
result.reserve(2 * size_);
for (size_t i = 0; i < size_; ++i) {
unsigned char c = data_[i];
result.push_back(toHex(c >> 4));
result.push_back(toHex(c & 0xf));
}
return result;
} else {
result.assign(data_, size_);
return result;
}
}
// Originally from rocksdb/utilities/ldb_cmd.h
bool Slice::DecodeHex(std::string* result) const {
std::string::size_type len = size_;
if (len % 2) {
// Hex string must be even number of hex digits to get complete bytes back
return false;
}
if (!result) {
return false;
}
result->clear();
result->reserve(len / 2);
for (size_t i = 0; i < len;) {
int h1 = fromHex(data_[i++]);
if (h1 < 0) {
return false;
}
int h2 = fromHex(data_[i++]);
if (h2 < 0) {
return false;
}
result->push_back(static_cast<char>((h1 << 4) | h2));
}
return true;
}
const SliceTransform* NewFixedPrefixTransform(size_t prefix_len) {
return new FixedPrefixTransform(prefix_len);
}
const SliceTransform* NewCappedPrefixTransform(size_t cap_len) {
return new CappedPrefixTransform(cap_len);
}
const SliceTransform* NewNoopTransform() {
return new NoopTransform;
}
} // namespace rocksdb