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session.cpp
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session.cpp
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// session and request processing
//
#include "session.h"
#include <assert.h>
#include <unistd.h>
#include <iostream>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <string.h>
#include <algorithm>
#if !defined(__APPLE__)
#include <endian.h>
#include <byteswap.h>
#endif
using namespace mc;
namespace
{
#if !defined(__APPLE__)
unsigned long long htonll(unsigned long long val)
{
if (__BYTE_ORDER == __BIG_ENDIAN) return (val);
else return __bswap_64(val);
}
unsigned long long ntohll(unsigned long long val)
{
if (__BYTE_ORDER == __BIG_ENDIAN) return (val);
else return __bswap_64(val);
}
#endif
session::buffer make_response_header(const protocol_binary_request_header& h
,unsigned int err, unsigned char extlen, unsigned short keylen, unsigned int body_len)
{
protocol_binary_response_header r;
memset(&r, 0, sizeof(r));
r.response.magic = (uint8_t)PROTOCOL_BINARY_RES;
r.response.opcode = h.request.opcode;
r.response.keylen = (uint16_t)htons((uint16_t)keylen);
r.response.extlen = (uint8_t)extlen;
r.response.datatype = (uint8_t)PROTOCOL_BINARY_RAW_BYTES;
r.response.status = (uint16_t)htons((uint16_t)err);
r.response.bodylen = htonl((uint32_t)body_len);
r.response.opaque = h.request.opaque;
r.response.cas = htonll(h.request.cas);
return session::buffer((unsigned char*)&r, (unsigned char*)&r + sizeof(r));
}
// for logs
/*
void print_header(const protocol_binary_request_header& h)
{
std::clog << "op=" << (unsigned int)h.request.opcode
<< " extlen=" << (unsigned int)h.request.extlen
<< " keylen=" << (unsigned int)h.request.keylen
<< " bodylen=" << (unsigned int)h.request.bodylen
<< " cas=" << (unsigned int)h.request.cas
<< std::endl;
}
*/
}
session::session(int fd, int ctl_pipe, void* user, cache& c)
:fd_(fd)
,ctl_pipe_(ctl_pipe)
,user_(user)
,c_(c)
{
assert(fd_ != -1);
}
session::~session()
{
::close(fd_);
}
bool session::control(buffer b) //control event on the session
{
if (!wctl_.is_active()) {
assert(false);
return false; //must only be write controls for now
}
return continue_write();
}
//returns false if the session is to be closed
bool session::process_chunk(buffer b)
{
static_assert(sizeof(header_.bytes) == sizeof(protocol_binary_request_header), "the compiler doesn't pack the protocol types" );
if (b.empty())
return true;
if (wctl_.is_active()) { //received data while a write is in progress, not good
assert(false);
return false; //will close the session
}
size_t old_size = request_.size();
if (request_.empty()) { //new request?
//check the magic number
if (b[0] != PROTOCOL_BINARY_REQ) {
return false; //close session
}
}
request_.insert(request_.end(), b.begin(), b.end());
//wait for complete header
if (request_.size() < sizeof(protocol_binary_request_header))
return true;
if (old_size < sizeof(header_)) { //got full header
protocol_binary_request_header* h = (protocol_binary_request_header*)(&request_[0]);
memcpy(&header_, h, sizeof(header_));
header_.request.keylen = ntohs(h->request.keylen);
header_.request.bodylen = ntohl(h->request.bodylen);
header_.request.cas = ntohll(h->request.cas);
if (!validate_request())
return false;
}
return handle_request();
}
bool session::handle_request_delete()
{
cache::item item(std::move(request_), header_);
try {
if (!c_.remove(item, header_.request.cas)) {
error_response(PROTOCOL_BINARY_RESPONSE_KEY_EEXISTS);
return true;
}
//generate response
buffer resp = make_response_header(header_, 0, 0, 0, 0);
if (!socket_write(resp.data(), resp.size())) {
return false;
}
}
catch(const std::exception& e) { //some system error
std::cerr << e.what() << std::endl;
return false; //log and disconnect
}
return true;
}
bool session::handle_request_set()
{
cache::item item(std::move(request_), header_);
try {
if (header_.request.cas) {
if (!c_.cas(std::move(item), header_.request.cas)) {
error_response(PROTOCOL_BINARY_RESPONSE_KEY_EEXISTS);
return true;
}
}
else {
c_.set(std::move(item));
}
//generate response
buffer resp = make_response_header(header_, 0, 0, 0, 0);
if (!socket_write(resp.data(), resp.size())) {
return false;
}
}
catch(const std::exception& e) { //some system error
std::cerr << e.what() << std::endl;
return false; //log and disconnect
}
return true;
}
bool session::handle_request_get()
{
typedef uint32_t flag_t;
std::shared_ptr<cache::item> itm;
{ //find item
cache::item req(std::move(request_), header_);
itm = c_.get(req.get_key());
if (!itm) {
error_response(PROTOCOL_BINARY_RESPONSE_KEY_ENOENT);
return true;
}
}
wctl_.item_ = itm;
size_t value_len = itm->get_value_len();
{ //place header and flags
flag_t f = 0;
buffer hdr = make_response_header(header_, 0, sizeof(f), 0, value_len + sizeof(f));
hdr.insert(hdr.end(), (unsigned char*)&f, (unsigned char*)&f+sizeof(f));
size_t first_packet_size = std::min(MAX_WRITE_SIZE, value_len);
const unsigned char *buf = itm->get_data() + itm->h_.request.keylen;
hdr.insert(hdr.end(), buf, buf + first_packet_size);
wctl_.hdr_.swap(hdr);
wctl_.offset_ = first_packet_size;
}
// write the response
if (!continue_write()) {
return false;
}
return true;
}
//the request header is ready by now
bool session::handle_request()
{
//wait for complete packet
if (request_.size() > header_.request.bodylen + sizeof(header_)) { //packet tool large
error_response(PROTOCOL_BINARY_RESPONSE_EINVAL);
return false;
}
else if (request_.size() < header_.request.bodylen + sizeof(header_)) { //wait completion
return true;
}
//got complete packet
bool ret = true;
switch (header_.request.opcode) {
case PROTOCOL_BINARY_CMD_SET:
ret=handle_request_set();
break;
case PROTOCOL_BINARY_CMD_GET:
ret=handle_request_get();
break;
case PROTOCOL_BINARY_CMD_DELETE:
ret=handle_request_delete();
break;
default:
error_response(PROTOCOL_BINARY_RESPONSE_UNKNOWN_COMMAND);
break;
}
reset();
return ret;
}
bool session::validate_request()
{
bool ok = true;
switch (header_.request.opcode) {
case PROTOCOL_BINARY_CMD_SET:
if (header_.request.extlen != 8
|| header_.request.keylen == 0
|| header_.request.bodylen < header_.request.keylen + 8
|| header_.request.keylen > MAX_KEYLEN
) {
error_response(PROTOCOL_BINARY_RESPONSE_EINVAL);
ok = false;
}
if (header_.request.bodylen > MAX_VALUELEN + header_.request.keylen + 8) {
error_response(PROTOCOL_BINARY_RESPONSE_E2BIG);
ok = false;
}
break;
case PROTOCOL_BINARY_CMD_GET:
if (header_.request.extlen != 0
|| header_.request.keylen == 0
|| header_.request.bodylen != header_.request.keylen
) {
error_response(PROTOCOL_BINARY_RESPONSE_EINVAL);
ok = false;
}
break;
case PROTOCOL_BINARY_CMD_DELETE:
if (header_.request.extlen != 0
|| header_.request.keylen == 0
|| header_.request.bodylen != header_.request.keylen
) {
error_response(PROTOCOL_BINARY_RESPONSE_EINVAL);
ok = false;
}
break;
default:
error_response(PROTOCOL_BINARY_RESPONSE_UNKNOWN_COMMAND);
break;
}
return ok;
}
void session::error_response(protocol_binary_response_status err)
{
const char *errstr = nullptr;
switch (err) {
case PROTOCOL_BINARY_RESPONSE_KEY_EEXISTS:
errstr = "Entry exists for key";
break;
case PROTOCOL_BINARY_RESPONSE_KEY_ENOENT:
errstr = "Not found";
break;
case PROTOCOL_BINARY_RESPONSE_EINVAL:
errstr = "Bad parameters";
break;
case PROTOCOL_BINARY_RESPONSE_UNKNOWN_COMMAND:
errstr = "Unsupported command";
break;
case PROTOCOL_BINARY_RESPONSE_E2BIG:
errstr = "Too large";
break;
default:
assert(false);
break;
}
size_t len = 0;
if (errstr)
len = strlen(errstr);
buffer buf = make_response_header(header_, err, 0, 0, len);
if (len)
buf.insert(buf.end(), errstr, errstr + len);
socket_write(&buf[0], buf.size());
reset();
}
bool session::continue_write()
{
if (!wctl_.is_active()) {
assert(false);
return false;
}
//write a chunk
auto pnt = wctl_.next();
size_t len = std::min(MAX_WRITE_SIZE, pnt.second);
if (!len) {
wctl_.reset();
return true;
}
ssize_t cnt = ::write(fd_, pnt.first, len);
if (cnt == -1) {
if (errno != EAGAIN && errno != EWOULDBLOCK) {
std::cerr << "continue write error: fd=" << fd_ << " errno=" << errno << std::endl;
return false;
}
}
else if (!cnt) {
return false;
}
//move pointers
wctl_.move(cnt);
if (!wctl_.is_active()) { //done writing
wctl_.reset();
return true;
}
//schedule a write control event, it'll give an opportunity
//to other sessions handle stuff
mc::sysevent wrtctl(mc::sysevent::session, this);
buffer b = serialize_sysevent(wrtctl);
cnt = ::write(ctl_pipe_, &b[0], b.size());
assert(cnt != -1);
return true;
}
bool session::socket_write(const unsigned char* buf, size_t len)
{
while (len) {
ssize_t cnt = ::write(fd_, buf, len);
if (cnt == -1) {
if (errno != EAGAIN && errno != EWOULDBLOCK) {
std::cerr << "write error: fd=" << fd_ << " errno=" << errno << std::endl;
return false;
}
}
else {
assert(cnt <= len);
len -= cnt;
}
}
return true;
}
void session::reset()
{
request_.clear();
}