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152 行
4.7 KiB
152 行
4.7 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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LargeValueRef LargeValueRef::Make(const Slice& value, CompressionType ctype) {
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LargeValueRef result;
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port::SHA1_Hash(value.data(), value.size(), &result.data[0]);
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EncodeFixed64(&result.data[20], value.size());
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result.data[28] = static_cast<unsigned char>(ctype);
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return result;
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}
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std::string LargeValueRefToFilenameString(const LargeValueRef& h) {
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assert(sizeof(h.data) == LargeValueRef::ByteSize());
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assert(sizeof(h.data) == 29); // So we can hardcode the array size of buf
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static const char tohex[] = "0123456789abcdef";
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char buf[20*2];
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for (int i = 0; i < 20; i++) {
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buf[2*i] = tohex[(h.data[i] >> 4) & 0xf];
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buf[2*i+1] = tohex[h.data[i] & 0xf];
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}
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std::string result = std::string(buf, sizeof(buf));
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result += "-";
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result += NumberToString(h.ValueSize());
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result += "-";
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result += NumberToString(static_cast<uint64_t>(h.compression_type()));
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return result;
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}
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static uint32_t hexvalue(char c) {
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if (c >= '0' && c <= '9') {
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return c - '0';
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} else if (c >= 'A' && c <= 'F') {
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return 10 + c - 'A';
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} else {
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assert(c >= 'a' && c <= 'f');
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return 10 + c - 'a';
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}
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}
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bool FilenameStringToLargeValueRef(const Slice& s, LargeValueRef* h) {
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Slice in = s;
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if (in.size() < 40) {
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return false;
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}
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for (int i = 0; i < 20; i++) {
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if (!isxdigit(in[i*2]) || !isxdigit(in[i*2+1])) {
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return false;
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}
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unsigned char c = (hexvalue(in[i*2])<<4) | hexvalue(in[i*2+1]);
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h->data[i] = c;
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}
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in.remove_prefix(40);
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uint64_t value_size, ctype;
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if (ConsumeChar(&in, '-') &&
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ConsumeDecimalNumber(&in, &value_size) &&
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ConsumeChar(&in, '-') &&
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ConsumeDecimalNumber(&in, &ctype) &&
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in.empty() &&
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(ctype <= kSnappyCompression)) {
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EncodeFixed64(&h->data[20], value_size);
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h->data[28] = static_cast<unsigned char>(ctype);
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return true;
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} else {
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return false;
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}
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}
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}
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