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vlog.cc
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vlog.cc
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#include "vlog.h"
uint16_t getCrc(uint64_t key, std::string val, uint32_t vlen){
std::vector<unsigned char> data = std::vector<unsigned char>(sizeof(key) + sizeof(vlen) + vlen);
memcpy(data.data(), &key, sizeof(key));
memcpy(data.data() + sizeof(key), &vlen, sizeof(vlen));
memcpy(data.data() + sizeof(key) + sizeof(vlen), val.c_str(), vlen);
return utils::crc16(data);
}
void readCKL(int fd, uint16_t &checkSum, uint64_t &key, uint32_t &len){
if (read(fd, &checkSum, sizeof(checkSum)) < 0){
perror("read checkSum");
}
if (read(fd, &key, sizeof(key)) < 0){
perror("read key");
}
if (read(fd, &len, sizeof(len)) < 0){
perror("read len");
}
}
void readV(int fd, std::string &value, uint32_t len){
if (read(fd, &value[0], len) < 0){
perror("read value");
}
}
void readMagic(int fd, uint8_t &magic){
if (read(fd, &magic, sizeof(magic)) < 0){
perror("read magic");
}
}
Entry::Entry(uint64_t k, std::string val) {
key = k;
value = val;
vlen = val.size();
magic = MAGIC;
checkSum = getCrc(key, value, vlen);
}
VLog::VLog(const std::string &dir) {
this->dir = dir;
int fd = open(dir.c_str(), O_RDWR | O_CREAT, 0644);
if (fd < 0)
{
perror("open");
return;
}
tail = utils::seek_data_block(dir);
uint8_t buffer;
while (true)
{
ssize_t bytesRead = read(fd, &buffer, 1);
if (bytesRead < 0) {
perror("read");
break;
} else if (bytesRead == 0) {
tail = lseek(fd, 0, SEEK_CUR);
break;
}
if (buffer == 0xff) {
// 进行crc校验,如果通过则magic位置为tail位置,否则从现在的magic开始寻找下一个magic,直到校验通过
uint16_t checkSum;
uint64_t key;
uint32_t len;
readCKL(fd, checkSum, key, len);
std::string value = std::string(len, 0);
readV(fd, value, len);
uint16_t crc = getCrc(key, value, len);
tail = lseek(fd, -sizeof(uint8_t)- sizeof(uint16_t) - sizeof(uint64_t) - sizeof(uint32_t) - len, SEEK_CUR);
if (crc == checkSum) {
break;
}
}
}
head = lseek(fd, 0, SEEK_END);
close(fd);
}
void VLog::append(std::map<uint64_t, std::string> all, std::map<uint64_t, uint64_t> &offsets){
int fd = open(dir.c_str(), O_RDWR | O_CREAT, 0644);
if (fd < 0)
{
perror("open");
return;
}
lseek(fd, head, SEEK_SET);
for (auto &kv : all)
{
if (kv.second == DFLAG)
continue;
Entry entry(kv.first, kv.second);
uint64_t size = sizeof(uint8_t) + sizeof(uint16_t) + sizeof(uint64_t) + sizeof(uint32_t) + entry.vlen;
if (write(fd, &entry.magic, sizeof(uint8_t)) < 0){
perror("write magic");
}
if (write(fd, &entry.checkSum, sizeof(uint16_t)) < 0){
perror("write checkSum");
}
if (write(fd, &entry.key, sizeof(uint64_t)) < 0){
perror("write key");
}
if (write(fd, &entry.vlen, sizeof(uint32_t)) < 0){
perror("write vlen");
}
if (write(fd, entry.value.c_str(), entry.vlen) < 0){
perror("write value");
}
offsets[kv.first] = head;
head += size;
}
close(fd);
}
std::string VLog::get(uint64_t offset, uint32_t vlen){
int fd = open(dir.c_str(), O_RDWR, 0644);
if (fd < 0)
{
perror("open");
return "";
}
lseek(fd, offset, SEEK_SET);
uint8_t magic;
readMagic(fd, magic);
if (magic != MAGIC) {
printf("magic: %d\n, offset: %ld\n, vlen: %d\n", magic, offset, vlen);
close(fd);
return "magic error";
}
uint16_t checkSum;
uint64_t key;
uint32_t len;
readCKL(fd, checkSum, key, len);
std::string value = std::string(len, 0);
readV(fd, value, len);
uint16_t crc = getCrc(key, value, len);
if (crc != checkSum) {
close(fd);
return std::to_string(magic) + " " + std::to_string(checkSum) + " " + std::to_string(key) + " " + std::to_string(len) + " " + value;
}
close(fd);
return value;
}
void VLog::gc(std::map<uint64_t, std::pair<std::string, uint64_t>> &kVOff, uint64_t chunk_size, uint64_t &holeOff, uint64_t &len){
int fd = open(dir.c_str(), O_RDWR, 0644);
if (fd < 0)
{
perror("open");
return;
}
lseek(fd, tail, SEEK_SET);
uint64_t offset = tail;
uint64_t oldOffset = tail;
uint64_t total_size = 0;
while (total_size < chunk_size && offset < head)
{
oldOffset = offset;
uint8_t magic;
readMagic(fd, magic);
if (magic != MAGIC) {
break;
}
uint16_t checkSum;
uint64_t key;
uint32_t len;
readCKL(fd, checkSum, key, len);
std::string value = std::string(len, 0);
readV(fd, value, len);
uint16_t crc = getCrc(key, value, len);
offset = lseek(fd, 0, SEEK_CUR);
if (crc != checkSum) {
continue;
}
total_size += (sizeof(uint8_t) + sizeof(uint16_t) + sizeof(uint64_t) + sizeof(uint32_t) + len);
kVOff[key] = std::make_pair(value, oldOffset);
}
holeOff = tail;
tail = offset;
len = total_size;
close(fd);
}