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/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
#ifndef ITEM_HH
#define ITEM_HH
#include "config.h"
#include <string>
#include <string.h>
#include <stdio.h>
#include <memcached/engine.h>
#include "mutex.hh"
#include "locks.hh"
#include "atomic.hh"
#include "objectregistry.hh"
#include "stats.hh"
/**
* A blob is a minimal sized storage for data up to 2^32 bytes long.
*/
class Blob : public RCValue {
public:
// Constructors.
/**
* Create a new Blob holding the given data.
*
* @param start the beginning of the data to copy into this blob
* @param len the amount of data to copy in
*
* @return the new Blob instance
*/
static Blob* New(const char *start, const size_t len) {
size_t total_len = len + sizeof(Blob);
Blob *t = new (::operator new(total_len)) Blob(start, len);
assert(t->length() == len);
return t;
}
/**
* Create a new Blob holding the contents of the given string.
*
* @param s the string whose contents go into the blob
*
* @return the new Blob instance
*/
static Blob* New(const std::string& s) {
return New(s.data(), s.length());
}
/**
* Create a new Blob pre-filled with the given character.
*
* @param len the size of the blob
*
* @return the new Blob instance
*/
static Blob* New(const size_t len) {
size_t total_len = len + sizeof(Blob);
Blob *t = new (::operator new(total_len)) Blob(len);
assert(t->length() == len);
return t;
}
// Actual accessorish things.
/**
* Get the pointer to the contents of this Blob.
*/
const char* getData() const {
return data;
}
/**
* Get the length of this Blob value.
*/
size_t length() const {
return size;
}
/**
* Get the size of this Blob instance.
*/
size_t getSize() const {
return size + sizeof(Blob);
}
/**
* Get a std::string representation of this blob.
*/
const std::string to_s() const {
return std::string(data, size);
}
// This is necessary for making C++ happy when I'm doing a
// placement new on fairly "normal" c++ heap allocations, just
// with variable-sized objects.
void operator delete(void* p) { ::operator delete(p); }
~Blob() {
ObjectRegistry::onDeleteBlob(this);
}
private:
explicit Blob(const char *start, const size_t len) :
size(static_cast<uint32_t>(len))
{
std::memcpy(data, start, len);
ObjectRegistry::onCreateBlob(this);
}
explicit Blob(const size_t len) :
size(static_cast<uint32_t>(len))
{
ObjectRegistry::onCreateBlob(this);
}
const uint32_t size;
char data[1];
DISALLOW_COPY_AND_ASSIGN(Blob);
};
typedef RCPtr<Blob> value_t;
/**
* The Item structure we use to pass information between the memcached
* core and the backend. Please note that the kvstore don't store these
* objects, so we do have an extra layer of memory copying :(
*/
class Item {
public:
Item(const void* k, const size_t nk, const size_t nb,
const uint32_t fl, const time_t exp, uint64_t theCas = 0,
int64_t i = -1, uint16_t vbid = 0) :
cas(theCas), id(i), exptime(exp), flags(fl), seqno(1), vbucketId(vbid)
{
key.assign(static_cast<const char*>(k), nk);
assert(id != 0);
setData(NULL, nb);
ObjectRegistry::onCreateItem(this);
}
Item(const std::string &k, const uint32_t fl, const time_t exp,
const void *dta, const size_t nb, uint64_t theCas = 0,
int64_t i = -1, uint16_t vbid = 0) :
cas(theCas), id(i), exptime(exp), flags(fl), seqno(1), vbucketId(vbid)
{
key.assign(k);
assert(id != 0);
setData(static_cast<const char*>(dta), nb);
ObjectRegistry::onCreateItem(this);
}
Item(const std::string &k, const uint32_t fl, const time_t exp,
const value_t &val, uint64_t theCas = 0, int64_t i = -1, uint16_t vbid = 0,
uint32_t sno = 1) :
value(val), cas(theCas), id(i), exptime(exp), flags(fl), seqno(sno), vbucketId(vbid)
{
assert(id != 0);
key.assign(k);
ObjectRegistry::onCreateItem(this);
}
Item(const void *k, uint16_t nk, const uint32_t fl, const time_t exp,
const void *dta, const size_t nb, uint64_t theCas = 0,
int64_t i = -1, uint16_t vbid = 0) :
cas(theCas), id(i), exptime(exp), flags(fl), seqno(1), vbucketId(vbid)
{
assert(id != 0);
key.assign(static_cast<const char*>(k), nk);
setData(static_cast<const char*>(dta), nb);
ObjectRegistry::onCreateItem(this);
}
~Item() {
ObjectRegistry::onDeleteItem(this);
}
const char *getData() const {
return value.get() ? value->getData() : NULL;
}
const value_t &getValue() const {
return value;
}
const std::string &getKey() const {
return key;
}
int64_t getId() const {
return id;
}
void setId(int64_t to) {
id = to;
}
int getNKey() const {
return static_cast<int>(key.length());
}
uint32_t getNBytes() const {
return value.get() ? static_cast<uint32_t>(value->length()) : 0;
}
size_t getValMemSize() const {
return value.get() ? value->getSize() : 0;
}
time_t getExptime() const {
return exptime;
}
uint32_t getFlags() const {
return flags;
}
uint64_t getCas() const {
return cas;
}
void setCas() {
cas = nextCas();
}
void setCas(uint64_t ncas) {
cas = ncas;
}
void setValue(const value_t &v) {
value.reset(v);
}
void setFlags(uint32_t f) {
flags = f;
}
void setExpTime(time_t exp_time) {
exptime = exp_time;
}
void fixupJSON(void);
/**
* Append another item to this item
*
* @param item the item to append to this one
* @return true if success
*/
bool append(const Item &item);
/**
* Prepend another item to this item
*
* @param item the item to prepend to this one
* @return true if success
*/
bool prepend(const Item &item);
uint16_t getVBucketId(void) const {
return vbucketId;
}
void setVBucketId(uint16_t to) {
vbucketId = to;
}
/**
* Check if this item is expired or not.
*
* @param asOf the time to be compared with this item's expiry time
* @return true if this item's expiry time < asOf
*/
bool isExpired(time_t asOf) const {
if (getExptime() != 0 && getExptime() < asOf) {
return true;
}
return false;
}
size_t size() {
return sizeof(Item) + key.size() + getValMemSize();
}
uint32_t getSeqno() const {
return seqno;
}
void setSeqno(uint32_t to) {
seqno = to;
}
static void encodeMeta(uint32_t seqno, uint64_t cas, uint32_t length,
uint32_t flags, std::string &dest)
{
uint8_t meta[22];
size_t len = sizeof(meta);
encodeMeta(seqno, cas, length, flags, meta, len);
dest.assign((char*)meta, len);
}
static bool encodeMeta(const Item &itm, uint8_t *dest, size_t &nbytes)
{
return encodeMeta(itm.seqno, itm.cas, itm.getNBytes(), itm.flags,
dest, nbytes);
}
static bool encodeMeta(uint32_t seqno, uint64_t cas, uint32_t length,
uint32_t flags, uint8_t *dest, size_t &nbytes)
{
if (nbytes < 22) {
return false;
}
seqno = htonl(seqno);
cas = htonll(cas);
length = htonl(length);
// flags are stored in network byte order thus no conversion here
dest[0] = 0x01;
dest[1] = 20;
memcpy(dest + 2, &seqno, 4);
memcpy(dest + 6, &cas, 8);
memcpy(dest + 14, &length, 4);
memcpy(dest + 18, &flags, 4);
nbytes = 22;
return true;
}
static bool decodeMeta(const uint8_t *dta, uint32_t &seqno, uint64_t &cas,
uint32_t &length, uint32_t &flags) {
if (*dta != 0x01) {
// Unsupported meta tag
return false;
}
++dta;
if (*dta != 20) {
// Unsupported size
return false;
}
++dta;
memcpy(&seqno, dta, 4);
seqno = ntohl(seqno);
dta += 4;
memcpy(&cas, dta, 8);
cas = ntohll(cas);
dta += 8;
memcpy(&length, dta, 4);
length = ntohl(length);
dta += 4;
// flags are kept in network byte order
memcpy(&flags, dta, 4);
return true;
}
static uint32_t getNMetaBytes() {
return metaDataSize;
}
private:
/**
* Set the item's data. This is only used by constructors, so we
* make it private.
*/
void setData(const char *dta, const size_t nb) {
Blob *data;
if (dta == NULL) {
data = Blob::New(nb);
} else {
data = Blob::New(dta, nb);
}
assert(data);
value.reset(data);
}
value_t value;
std::string key;
uint64_t cas;
int64_t id;
time_t exptime;
uint32_t flags;
uint32_t seqno;
uint16_t vbucketId;
static uint64_t nextCas(void) {
uint64_t ret = gethrtime();
if ((ret & 1000) == 0) {
// we don't have a good enough resolution on the clock
ret |= casCounter++;
if (casCounter > 1000) {
casCounter = 1;
}
}
return ret;
}
static Atomic<uint64_t> casCounter;
static const uint32_t metaDataSize;
DISALLOW_COPY_AND_ASSIGN(Item);
};
#endif
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