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87 linhas
2.9 KiB
87 linhas
2.9 KiB
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include <stdio.h>
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#include "db/dbformat.h"
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#include "port/port.h"
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#include "util/coding.h"
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namespace leveldb {
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static uint64_t PackSequenceAndType(uint64_t seq, ValueType t) {
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assert(seq <= kMaxSequenceNumber);
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assert(t <= kValueTypeForSeek);
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return (seq << 8) | t;
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}
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void AppendInternalKey(std::string* result, const ParsedInternalKey& key) {
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result->append(key.user_key.data(), key.user_key.size());
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PutFixed64(result, PackSequenceAndType(key.sequence, key.type));
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}
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std::string ParsedInternalKey::DebugString() const {
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char buf[50];
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snprintf(buf, sizeof(buf), "' @ %llu : %d",
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(unsigned long long) sequence,
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int(type));
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std::string result = "'";
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result += user_key.ToString();
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result += buf;
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return result;
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}
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const char* InternalKeyComparator::Name() const {
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return "leveldb.InternalKeyComparator";
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}
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int InternalKeyComparator::Compare(const Slice& akey, const Slice& bkey) const {
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// Order by:
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// increasing user key (according to user-supplied comparator)
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// decreasing sequence number
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// decreasing type (though sequence# should be enough to disambiguate)
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int r = user_comparator_->Compare(ExtractUserKey(akey), ExtractUserKey(bkey));
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if (r == 0) {
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const uint64_t anum = DecodeFixed64(akey.data() + akey.size() - 8);
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const uint64_t bnum = DecodeFixed64(bkey.data() + bkey.size() - 8);
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if (anum > bnum) {
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r = -1;
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} else if (anum < bnum) {
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r = +1;
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}
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}
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return r;
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}
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void InternalKeyComparator::FindShortestSeparator(
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std::string* start,
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const Slice& limit) const {
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// Attempt to shorten the user portion of the key
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Slice user_start = ExtractUserKey(*start);
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Slice user_limit = ExtractUserKey(limit);
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std::string tmp(user_start.data(), user_start.size());
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user_comparator_->FindShortestSeparator(&tmp, user_limit);
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if (user_comparator_->Compare(*start, tmp) < 0) {
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// User key has become larger. Tack on the earliest possible
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// number to the shortened user key.
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PutFixed64(&tmp, PackSequenceAndType(kMaxSequenceNumber,kValueTypeForSeek));
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assert(this->Compare(*start, tmp) < 0);
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assert(this->Compare(tmp, limit) < 0);
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start->swap(tmp);
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}
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}
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void InternalKeyComparator::FindShortSuccessor(std::string* key) const {
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Slice user_key = ExtractUserKey(*key);
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std::string tmp(user_key.data(), user_key.size());
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user_comparator_->FindShortSuccessor(&tmp);
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if (user_comparator_->Compare(user_key, tmp) < 0) {
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// User key has become larger. Tack on the earliest possible
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// number to the shortened user key.
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PutFixed64(&tmp, PackSequenceAndType(kMaxSequenceNumber,kValueTypeForSeek));
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assert(this->Compare(*key, tmp) < 0);
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key->swap(tmp);
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}
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}
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}
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