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120 rivejä
3.8 KiB
120 rivejä
3.8 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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std::string InternalKey::DebugString() const {
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std::string result;
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ParsedInternalKey parsed;
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if (ParseInternalKey(rep_, &parsed)) {
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result = parsed.DebugString();
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} else {
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result = "(bad)";
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result.append(EscapeString(rep_));
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}
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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 (tmp.size() < user_start.size() &&
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user_comparator_->Compare(user_start, tmp) < 0) {
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// User key has become shorter physically, but larger logically.
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// Tack on the earliest possible 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 (tmp.size() < user_key.size() &&
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user_comparator_->Compare(user_key, tmp) < 0) {
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// User key has become shorter physically, but larger logically.
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// Tack on the earliest possible 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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LookupKey::LookupKey(const Slice& user_key, SequenceNumber s) {
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size_t usize = user_key.size();
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size_t needed = usize + 13; // A conservative estimate
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char* dst;
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if (needed <= sizeof(space_)) {
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dst = space_;
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} else {
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dst = new char[needed];
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}
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start_ = dst;
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dst = EncodeVarint32(dst, usize + 8);
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kstart_ = dst;
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memcpy(dst, user_key.data(), usize);
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dst += usize;
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EncodeFixed64(dst, PackSequenceAndType(s, kValueTypeForSeek));
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dst += 8;
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end_ = dst;
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}
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} // namespace leveldb
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