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tuple.h
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tuple.h
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#ifndef _NDB_TUPLE_H_
#define _NDB_TUPLE_H_
#include <atomic>
#include <vector>
#include <string>
#include <utility>
#include <limits>
#include <unordered_map>
#include <ostream>
#include <thread>
#include "amd64.h"
#include "core.h"
#include "counter.h"
#include "macros.h"
#include "varkey.h"
#include "util.h"
#include "rcu.h"
#include "thread.h"
#include "spinlock.h"
#include "small_unordered_map.h"
#include "prefetch.h"
#include "ownership_checker.h"
// debugging tool
//#define TUPLE_LOCK_OWNERSHIP_CHECKING
template <template <typename> class Protocol, typename Traits>
class transaction; // forward decl
// XXX: hack
extern std::string (*g_proto_version_str)(uint64_t v);
/**
* A dbtuple is the type of value which we stick
* into underlying (non-transactional) data structures- it
* also contains the memory of the value
*/
struct dbtuple {
friend std::ostream &
operator<<(std::ostream &o, const dbtuple &tuple);
public:
// trying to save space by putting constraints
// on node maximums
typedef uint32_t version_t;
typedef uint16_t node_size_type;
typedef uint64_t tid_t;
typedef uint8_t * record_type;
typedef const uint8_t * const_record_type;
typedef size_t size_type;
typedef std::string string_type;
static const tid_t MIN_TID = 0;
static const tid_t MAX_TID = (tid_t) -1;
// lock ownership helpers- works by recording all tuple
// locks obtained in each transaction, and then when the txn
// finishes, calling AssertAllTupleLocksReleased(), which makes
// sure the current thread is no longer the owner of any locks
// acquired during the txn
#ifdef TUPLE_LOCK_OWNERSHIP_CHECKING
static inline void
TupleLockRegionBegin()
{
ownership_checker<dbtuple, dbtuple>::NodeLockRegionBegin();
}
// is used to signal the end of a tuple lock region
static inline void
AssertAllTupleLocksReleased()
{
ownership_checker<dbtuple, dbtuple>::AssertAllNodeLocksReleased();
}
private:
static inline void
AddTupleToLockRegion(const dbtuple *n)
{
ownership_checker<dbtuple, dbtuple>::AddNodeToLockRegion(n);
}
#endif
private:
static const version_t HDR_LOCKED_MASK = 0x1;
static const version_t HDR_DELETING_SHIFT = 1;
static const version_t HDR_DELETING_MASK = 0x1 << HDR_DELETING_SHIFT;
static const version_t HDR_WRITE_INTENT_SHIFT = 2;
static const version_t HDR_WRITE_INTENT_MASK = 0x1 << HDR_WRITE_INTENT_SHIFT;
static const version_t HDR_MODIFYING_SHIFT = 3;
static const version_t HDR_MODIFYING_MASK = 0x1 << HDR_MODIFYING_SHIFT;
static const version_t HDR_LATEST_SHIFT = 4;
static const version_t HDR_LATEST_MASK = 0x1 << HDR_LATEST_SHIFT;
static const version_t HDR_VERSION_SHIFT = 5;
static const version_t HDR_VERSION_MASK = ((version_t)-1) << HDR_VERSION_SHIFT;
public:
#ifdef TUPLE_MAGIC
class magic_failed_exception: public std::exception {};
static const uint8_t TUPLE_MAGIC = 0x29U;
uint8_t magic;
inline ALWAYS_INLINE void CheckMagic() const
{
if (unlikely(magic != TUPLE_MAGIC)) {
print(1);
// so we can catch it later and print out useful debugging output
throw magic_failed_exception();
}
}
#else
inline ALWAYS_INLINE void CheckMagic() const {}
#endif
// NB(stephentu): ABA problem happens after some multiple of
// 2^(NBits(version_t)-6) concurrent modifications- somewhat low probability
// event, so we let it happen
//
// <-- low bits
// [ locked | deleting | write_intent | modifying | latest | version ]
// [ 0..1 | 1..2 | 2..3 | 3..4 | 4..5 | 5..32 ]
volatile version_t hdr;
#ifdef TUPLE_LOCK_OWNERSHIP_CHECKING
std::thread::id lock_owner;
#endif
// uninterpreted TID
tid_t version;
// small sizes on purpose
node_size_type size; // actual size of record
// (only meaningful is the deleting bit is not set)
node_size_type alloc_size; // max size record allowed. is the space
// available for the record buf
dbtuple *next; // be very careful about traversing this pointer,
// GC is capable of reaping it at certain (well defined)
// points, and will not bother to set it to null
#ifdef TUPLE_CHECK_KEY
// for debugging
std::string key;
void *tree;
#endif
#ifdef CHECK_INVARIANTS
// for debugging
std::atomic<uint64_t> opaque;
#endif
// must be last field
uint8_t value_start[0];
void print(std::ostream &o, unsigned len) const;
private:
// private ctor/dtor b/c we do some special memory stuff
// ctors start node off as latest node
static inline ALWAYS_INLINE node_size_type
CheckBounds(size_type s)
{
INVARIANT(s <= std::numeric_limits<node_size_type>::max());
return s;
}
dbtuple(const dbtuple &) = delete;
dbtuple(dbtuple &&) = delete;
dbtuple &operator=(const dbtuple &) = delete;
// creates a (new) record with a tentative value at MAX_TID
dbtuple(size_type size, size_type alloc_size, bool acquire_lock)
:
#ifdef TUPLE_MAGIC
magic(TUPLE_MAGIC),
#endif
hdr(HDR_LATEST_MASK |
(acquire_lock ? (HDR_LOCKED_MASK | HDR_WRITE_INTENT_MASK) : 0) |
(!size ? HDR_DELETING_MASK : 0))
#ifdef TUPLE_LOCK_OWNERSHIP_CHECKING
, lock_owner()
#endif
, version(MAX_TID)
, size(CheckBounds(size))
, alloc_size(CheckBounds(alloc_size))
, next(nullptr)
#ifdef TUPLE_CHECK_KEY
, key()
, tree(nullptr)
#endif
#ifdef CHECK_INVARIANTS
, opaque(0)
#endif
{
INVARIANT(((char *)this) + sizeof(*this) == (char *) &value_start[0]);
INVARIANT(is_latest());
INVARIANT(size || is_deleting());
++g_evt_dbtuple_creates;
g_evt_dbtuple_bytes_allocated += alloc_size + sizeof(dbtuple);
#ifdef TUPLE_LOCK_OWNERSHIP_CHECKING
if (acquire_lock) {
lock_owner = std::this_thread::get_id();
AddTupleToLockRegion(this);
INVARIANT(is_lock_owner());
}
#endif
COMPILER_MEMORY_FENCE; // for acquire_lock
}
// creates a record at version derived from base
// (inheriting its value).
dbtuple(tid_t version,
struct dbtuple *base,
size_type alloc_size,
bool set_latest)
:
#ifdef TUPLE_MAGIC
magic(TUPLE_MAGIC),
#endif
hdr(set_latest ? HDR_LATEST_MASK : 0)
#ifdef TUPLE_LOCK_OWNERSHIP_CHECKING
, lock_owner()
#endif
, version(version)
, size(base->size)
, alloc_size(CheckBounds(alloc_size))
, next(base->next)
#ifdef TUPLE_CHECK_KEY
, key()
, tree(nullptr)
#endif
#ifdef CHECK_INVARIANTS
, opaque(0)
#endif
{
INVARIANT(size <= alloc_size);
INVARIANT(set_latest == is_latest());
if (base->is_deleting())
mark_deleting();
NDB_MEMCPY(&value_start[0], base->get_value_start(), size);
++g_evt_dbtuple_creates;
g_evt_dbtuple_bytes_allocated += alloc_size + sizeof(dbtuple);
}
// creates a spill record, copying in the *old* value if necessary, but
// setting the size to the *new* value
dbtuple(tid_t version,
const_record_type r,
size_type old_size,
size_type new_size,
size_type alloc_size,
struct dbtuple *next,
bool set_latest,
bool needs_old_value)
:
#ifdef TUPLE_MAGIC
magic(TUPLE_MAGIC),
#endif
hdr((set_latest ? HDR_LATEST_MASK : 0) | (!new_size ? HDR_DELETING_MASK : 0))
#ifdef TUPLE_LOCK_OWNERSHIP_CHECKING
, lock_owner()
#endif
, version(version)
, size(CheckBounds(new_size))
, alloc_size(CheckBounds(alloc_size))
, next(next)
#ifdef TUPLE_CHECK_KEY
, key()
, tree(nullptr)
#endif
#ifdef CHECK_INVARIANTS
, opaque(0)
#endif
{
INVARIANT(!needs_old_value || old_size <= alloc_size);
INVARIANT(new_size <= alloc_size);
INVARIANT(set_latest == is_latest());
INVARIANT(new_size || is_deleting());
if (needs_old_value)
NDB_MEMCPY(&value_start[0], r, old_size);
++g_evt_dbtuple_creates;
g_evt_dbtuple_bytes_allocated += alloc_size + sizeof(dbtuple);
}
friend class rcu;
~dbtuple();
static event_avg_counter g_evt_avg_dbtuple_stable_version_spins;
static event_avg_counter g_evt_avg_dbtuple_lock_acquire_spins;
static event_avg_counter g_evt_avg_dbtuple_read_retries;
public:
enum ReadStatus {
READ_FAILED,
READ_EMPTY,
READ_RECORD,
};
inline void
prefetch() const
{
#ifdef TUPLE_PREFETCH
prefetch_bytes(this, sizeof(*this) + alloc_size);
#endif
}
// gcs *this* instance, ignoring the chain
void gc_this();
inline bool
is_locked() const
{
return IsLocked(hdr);
}
static inline bool
IsLocked(version_t v)
{
return v & HDR_LOCKED_MASK;
}
#ifdef TUPLE_LOCK_OWNERSHIP_CHECKING
inline bool
is_lock_owner() const
{
return std::this_thread::get_id() == lock_owner;
}
#else
inline bool
is_lock_owner() const
{
return true;
}
#endif
inline version_t
lock(bool write_intent)
{
// XXX: implement SPINLOCK_BACKOFF
CheckMagic();
#ifdef ENABLE_EVENT_COUNTERS
unsigned nspins = 0;
#endif
version_t v = hdr;
const version_t lockmask = write_intent ?
(HDR_LOCKED_MASK | HDR_WRITE_INTENT_MASK) :
(HDR_LOCKED_MASK);
while (IsLocked(v) ||
!__sync_bool_compare_and_swap(&hdr, v, v | lockmask)) {
nop_pause();
v = hdr;
#ifdef ENABLE_EVENT_COUNTERS
++nspins;
#endif
}
#ifdef TUPLE_LOCK_OWNERSHIP_CHECKING
lock_owner = std::this_thread::get_id();
AddTupleToLockRegion(this);
INVARIANT(is_lock_owner());
#endif
COMPILER_MEMORY_FENCE;
INVARIANT(IsLocked(hdr));
INVARIANT(!write_intent || IsWriteIntent(hdr));
INVARIANT(!IsModifying(hdr));
#ifdef ENABLE_EVENT_COUNTERS
g_evt_avg_dbtuple_lock_acquire_spins.offer(nspins);
#endif
return hdr;
}
inline void
unlock()
{
CheckMagic();
version_t v = hdr;
bool newv = false;
INVARIANT(IsLocked(v));
INVARIANT(is_lock_owner());
if (IsModifying(v) || IsWriteIntent(v)) {
newv = true;
const version_t n = Version(v);
v &= ~HDR_VERSION_MASK;
v |= (((n + 1) << HDR_VERSION_SHIFT) & HDR_VERSION_MASK);
}
// clear locked + modifying bits
v &= ~(HDR_LOCKED_MASK | HDR_MODIFYING_MASK | HDR_WRITE_INTENT_MASK);
if (newv) {
INVARIANT(!reader_check_version(v));
INVARIANT(!writer_check_version(v));
}
INVARIANT(!IsLocked(v));
INVARIANT(!IsModifying(v));
INVARIANT(!IsWriteIntent(v));
#ifdef TUPLE_LOCK_OWNERSHIP_CHECKING
lock_owner = std::thread::id();
INVARIANT(!is_lock_owner());
#endif
COMPILER_MEMORY_FENCE;
hdr = v;
}
inline bool
is_deleting() const
{
return IsDeleting(hdr);
}
static inline bool
IsDeleting(version_t v)
{
return v & HDR_DELETING_MASK;
}
inline void
mark_deleting()
{
CheckMagic();
// the lock on the latest version guards non-latest versions
INVARIANT(!is_latest() || is_locked());
INVARIANT(!is_latest() || is_lock_owner());
INVARIANT(!is_deleting());
hdr |= HDR_DELETING_MASK;
}
inline void
clear_deleting()
{
CheckMagic();
INVARIANT(is_locked());
INVARIANT(is_lock_owner());
INVARIANT(is_deleting());
hdr &= ~HDR_DELETING_MASK;
}
inline bool
is_modifying() const
{
return IsModifying(hdr);
}
inline void
mark_modifying()
{
CheckMagic();
version_t v = hdr;
INVARIANT(IsLocked(v));
INVARIANT(is_lock_owner());
//INVARIANT(!IsModifying(v)); // mark_modifying() must be re-entrant
v |= HDR_MODIFYING_MASK;
COMPILER_MEMORY_FENCE; // XXX: is this fence necessary?
hdr = v;
COMPILER_MEMORY_FENCE;
}
static inline bool
IsModifying(version_t v)
{
return v & HDR_MODIFYING_MASK;
}
inline bool
is_write_intent() const
{
return IsWriteIntent(hdr);
}
static inline bool
IsWriteIntent(version_t v)
{
return v & HDR_WRITE_INTENT_MASK;
}
inline bool
is_latest() const
{
return IsLatest(hdr);
}
static inline bool
IsLatest(version_t v)
{
return v & HDR_LATEST_MASK;
}
inline void
clear_latest()
{
CheckMagic();
INVARIANT(is_locked());
INVARIANT(is_lock_owner());
INVARIANT(is_latest());
hdr &= ~HDR_LATEST_MASK;
}
static inline version_t
Version(version_t v)
{
return (v & HDR_VERSION_MASK) >> HDR_VERSION_SHIFT;
}
inline version_t
reader_stable_version(bool allow_write_intent) const
{
version_t v = hdr;
#ifdef ENABLE_EVENT_COUNTERS
unsigned long nspins = 0;
#endif
while (IsModifying(v) ||
(!allow_write_intent && IsWriteIntent(v))) {
nop_pause();
v = hdr;
#ifdef ENABLE_EVENT_COUNTERS
++nspins;
#endif
}
COMPILER_MEMORY_FENCE;
#ifdef ENABLE_EVENT_COUNTERS
g_evt_avg_dbtuple_stable_version_spins.offer(nspins);
#endif
return v;
}
/**
* returns true if succeeded, false otherwise
*/
inline bool
try_writer_stable_version(version_t &v, unsigned int spins) const
{
v = hdr;
while (IsWriteIntent(v) && spins--) {
INVARIANT(IsLocked(v));
nop_pause();
v = hdr;
}
const bool ret = !IsWriteIntent(v);
COMPILER_MEMORY_FENCE;
INVARIANT(ret || IsLocked(v));
INVARIANT(!ret || !IsModifying(v));
return ret;
}
inline version_t
unstable_version() const
{
return hdr;
}
inline bool
reader_check_version(version_t version) const
{
COMPILER_MEMORY_FENCE;
// are the versions the same, modulo the
// {locked, write_intent, latest} bits?
const version_t MODULO_BITS =
(HDR_LOCKED_MASK | HDR_WRITE_INTENT_MASK | HDR_LATEST_MASK);
return (hdr & ~MODULO_BITS) == (version & ~MODULO_BITS);
}
inline bool
writer_check_version(version_t version) const
{
COMPILER_MEMORY_FENCE;
return hdr == version;
}
inline ALWAYS_INLINE struct dbtuple *
get_next()
{
return next;
}
inline const struct dbtuple *
get_next() const
{
return next;
}
inline ALWAYS_INLINE void
set_next(struct dbtuple *next)
{
CheckMagic();
this->next = next;
}
inline void
clear_next()
{
CheckMagic();
this->next = nullptr;
}
inline ALWAYS_INLINE uint8_t *
get_value_start()
{
CheckMagic();
return &value_start[0];
}
inline ALWAYS_INLINE const uint8_t *
get_value_start() const
{
return &value_start[0];
}
// worst name ever...
inline bool
is_not_behind(tid_t t) const
{
return version <= t;
}
private:
#ifdef ENABLE_EVENT_COUNTERS
struct scoped_recorder {
scoped_recorder(unsigned long &n) : n(&n) {}
~scoped_recorder()
{
g_evt_avg_dbtuple_read_retries.offer(*n);
}
private:
unsigned long *n;
};
#endif
// written to be non-recursive
template <typename Reader, typename StringAllocator>
static ReadStatus
record_at_chain(
const dbtuple *starting, tid_t t, tid_t &start_t,
Reader &reader, StringAllocator &sa, bool allow_write_intent)
{
#ifdef ENABLE_EVENT_COUNTERS
unsigned long nretries = 0;
scoped_recorder rec(nretries);
#endif
const dbtuple *current = starting;
loop:
INVARIANT(current->version != MAX_TID);
const version_t v = current->reader_stable_version(allow_write_intent);
const struct dbtuple *p;
const bool found = current->is_not_behind(t);
if (found) {
start_t = current->version;
const size_t read_sz = IsDeleting(v) ? 0 : current->size;
if (unlikely(read_sz && !reader(current->get_value_start(), read_sz, sa)))
goto retry;
if (unlikely(!current->reader_check_version(v)))
goto retry;
return read_sz ? READ_RECORD : READ_EMPTY;
} else {
p = current->get_next();
}
if (unlikely(!current->reader_check_version(v)))
goto retry;
if (p) {
current = p;
goto loop;
}
// see note in record_at()
start_t = MIN_TID;
return READ_EMPTY;
retry:
#ifdef ENABLE_EVENT_COUNTERS
++nretries;
#endif
goto loop;
}
// we force one level of inlining, but don't force record_at_chain()
// to be inlined
template <typename Reader, typename StringAllocator>
inline ALWAYS_INLINE ReadStatus
record_at(
tid_t t, tid_t &start_t,
Reader &reader, StringAllocator &sa, bool allow_write_intent) const
{
#ifdef ENABLE_EVENT_COUNTERS
unsigned long nretries = 0;
scoped_recorder rec(nretries);
#endif
if (unlikely(version == MAX_TID)) {
// XXX(stephentu): HACK! we use MAX_TID to indicate a tentative
// "insert"- the actual latest value is empty.
//
// since our system is screwed anyways if we ever reach MAX_TID, this
// is OK for now, but a real solution should exist at some point
start_t = MIN_TID;
return READ_EMPTY;
}
loop:
const version_t v = reader_stable_version(allow_write_intent);
const struct dbtuple *p;
const bool found = is_not_behind(t);
if (found) {
//if (unlikely(!IsLatest(v)))
// return READ_FAILED;
start_t = version;
const size_t read_sz = IsDeleting(v) ? 0 : size;
if (unlikely(read_sz && !reader(get_value_start(), read_sz, sa)))
goto retry;
if (unlikely(!reader_check_version(v)))
goto retry;
return read_sz ? READ_RECORD : READ_EMPTY;
} else {
p = get_next();
}
if (unlikely(!reader_check_version(v)))
goto retry;
if (p)
return record_at_chain(p, t, start_t, reader, sa, allow_write_intent);
// NB(stephentu): if we reach the end of a chain then we assume that
// the record exists as a deleted record.
//
// This is safe because we have been very careful to not garbage collect
// elements along the chain until it is guaranteed that the record
// is superceded by later record in any consistent read. Therefore,
// if we reach the end of the chain, then it *must* be the case that
// the record does not actually exist.
//
// Note that MIN_TID is the *wrong* tid to use here given wrap-around- we
// really should be setting this value to the tid which represents the
// oldest TID possible in the system. But we currently don't implement
// wrap around
start_t = MIN_TID;
return READ_EMPTY;
retry:
#ifdef ENABLE_EVENT_COUNTERS
++nretries;
#endif
goto loop;
}
static event_counter g_evt_dbtuple_creates;
static event_counter g_evt_dbtuple_logical_deletes;
static event_counter g_evt_dbtuple_physical_deletes;
static event_counter g_evt_dbtuple_bytes_allocated;
static event_counter g_evt_dbtuple_bytes_freed;
static event_counter g_evt_dbtuple_spills;
static event_counter g_evt_dbtuple_inplace_buf_insufficient;
static event_counter g_evt_dbtuple_inplace_buf_insufficient_on_spill;
static event_avg_counter g_evt_avg_record_spill_len;
public:
/**
* Read the record at tid t. Returns true if such a record exists, false
* otherwise (ie the record was GC-ed, or other reasons). On a successful
* read, the value @ start_t will be stored in r
*
* NB(stephentu): calling stable_read() while holding the lock
* is an error- this will cause deadlock
*/
template <typename Reader, typename StringAllocator>
inline ALWAYS_INLINE ReadStatus
stable_read(
tid_t t, tid_t &start_t,
Reader &reader, StringAllocator &sa,
bool allow_write_intent) const
{
return record_at(t, start_t, reader, sa, allow_write_intent);
}
inline bool
is_latest_version(tid_t t) const
{
return is_latest() && is_not_behind(t);
}
bool
stable_is_latest_version(tid_t t) const
{
version_t v = 0;
if (!try_writer_stable_version(v, 16))
return false;
// now v is a stable version
INVARIANT(!IsWriteIntent(v));
INVARIANT(!IsModifying(v));
const bool ret = IsLatest(v) && is_not_behind(t);
// only check_version() if the answer would be true- otherwise,
// no point in doing a version check
if (ret && writer_check_version(v))
return true;
else
// no point in retrying, since we know it will fail (since we had a
// version change)
return false;
}
inline bool
latest_value_is_nil() const
{
return is_latest() && size == 0;
}
inline bool
stable_latest_value_is_nil() const
{
version_t v = 0;
if (!try_writer_stable_version(v, 16))
return false;
INVARIANT(!IsWriteIntent(v));
INVARIANT(!IsModifying(v));
const bool ret = IsLatest(v) && size == 0;
if (ret && writer_check_version(v))
return true;
else
return false;
}
struct write_record_ret {
write_record_ret() : head_(), rest_(), forced_spill_() {}
write_record_ret(dbtuple *head, dbtuple* rest, bool forced_spill)
: head_(head), rest_(rest), forced_spill_(forced_spill)
{
INVARIANT(head);
INVARIANT(head != rest);
INVARIANT(!forced_spill || rest);
}
dbtuple *head_;
dbtuple *rest_;
bool forced_spill_;
};
// XXX: kind of hacky, but we do this to avoid virtual
// functions / passing multiple function pointers around
enum TupleWriterMode {
TUPLE_WRITER_NEEDS_OLD_VALUE, // all three args ignored
TUPLE_WRITER_COMPUTE_NEEDED,
TUPLE_WRITER_COMPUTE_DELTA_NEEDED, // last two args ignored
TUPLE_WRITER_DO_WRITE,
TUPLE_WRITER_DO_DELTA_WRITE,
};
typedef size_t (*tuple_writer_t)(TupleWriterMode, const void *, uint8_t *, size_t);
/**
* Always writes the record in the latest (newest) version slot,
* not asserting whether or not inserting r @ t would violate the
* sorted order invariant
*
* ret.first = latest tuple after the write (guaranteed to not be nullptr)
* ret.second = old version of tuple, iff no overwrite (can be nullptr)
*
* Note: if this != ret.first, then we need a tree replacement
*/
template <typename Transaction>
write_record_ret
write_record_at(const Transaction *txn, tid_t t,
const void *v, tuple_writer_t writer)
{
#ifndef DISABLE_OVERWRITE_IN_PLACE
CheckMagic();
INVARIANT(is_locked());
INVARIANT(is_lock_owner());
INVARIANT(is_latest());
INVARIANT(is_write_intent());
const size_t new_sz =
v ? writer(TUPLE_WRITER_COMPUTE_NEEDED, v, get_value_start(), size) : 0;
INVARIANT(!v || new_sz);
INVARIANT(is_deleting() || size);
const size_t old_sz = is_deleting() ? 0 : size;
if (!new_sz)
++g_evt_dbtuple_logical_deletes;
// try to overwrite this record
if (likely(txn->can_overwrite_record_tid(version, t) && old_sz)) {
INVARIANT(!is_deleting());
// see if we have enough space
if (likely(new_sz <= alloc_size)) {
// directly update in place
mark_modifying();
if (v)
writer(TUPLE_WRITER_DO_WRITE, v, get_value_start(), old_sz);
version = t;
size = new_sz;
if (!new_sz)
mark_deleting();
return write_record_ret(this, nullptr, false);
}
//std::cerr
// << "existing: " << g_proto_version_str(version) << std::endl
// << "new : " << g_proto_version_str(t) << std::endl
// << "alloc_size : " << alloc_size << std::endl
// << "new_sz : " << new_sz << std::endl;
// keep this tuple in the chain (it's wasteful, but not incorrect)
// so that cleanup is easier
//
// XXX(stephentu): alloc_spill() should acquire the lock on
// the returned tuple in the ctor, as an optimization
const bool needs_old_value =
writer(TUPLE_WRITER_NEEDS_OLD_VALUE, nullptr, nullptr, 0);
INVARIANT(new_sz);
INVARIANT(v);
dbtuple * const rep =
alloc_spill(t, get_value_start(), old_sz, new_sz,
this, true, needs_old_value);
writer(TUPLE_WRITER_DO_WRITE, v, rep->get_value_start(), old_sz);
INVARIANT(rep->is_latest());
INVARIANT(rep->size == new_sz);
clear_latest();
++g_evt_dbtuple_inplace_buf_insufficient;
// [did not spill because of epochs, need to replace this with rep]
return write_record_ret(rep, this, false);
}
//std::cerr
// << "existing: " << g_proto_version_str(version) << std::endl
// << "new : " << g_proto_version_str(t) << std::endl
// << "alloc_size : " << alloc_size << std::endl
// << "new_sz : " << new_sz << std::endl;
// need to spill
++g_evt_dbtuple_spills;
g_evt_avg_record_spill_len.offer(size);
if (new_sz <= alloc_size && old_sz) {
INVARIANT(!is_deleting());
dbtuple * const spill = alloc(version, this, false);
INVARIANT(!spill->is_latest());
mark_modifying();
set_next(spill);
if (v)
writer(TUPLE_WRITER_DO_WRITE, v, get_value_start(), size);
version = t;
size = new_sz;
if (!new_sz)
mark_deleting();
return write_record_ret(this, spill, true);
}
const bool needs_old_value =
writer(TUPLE_WRITER_NEEDS_OLD_VALUE, nullptr, nullptr, 0);
dbtuple * const rep =
alloc_spill(t, get_value_start(), old_sz, new_sz,
this, true, needs_old_value);
if (v)
writer(TUPLE_WRITER_DO_WRITE, v, rep->get_value_start(), size);
INVARIANT(rep->is_latest());
INVARIANT(rep->size == new_sz);
INVARIANT(new_sz || rep->is_deleting()); // set by alloc_spill()
clear_latest();
++g_evt_dbtuple_inplace_buf_insufficient_on_spill;
return write_record_ret(rep, this, true);
#else
CheckMagic();
INVARIANT(is_locked());
INVARIANT(is_lock_owner());
INVARIANT(is_latest());
INVARIANT(is_write_intent());
const size_t new_sz =
v ? writer(TUPLE_WRITER_COMPUTE_NEEDED, v, get_value_start(), size) : 0;
INVARIANT(!v || new_sz);
INVARIANT(is_deleting() || size);
const size_t old_sz = is_deleting() ? 0 : size;
if (!new_sz)
++g_evt_dbtuple_logical_deletes;
const bool needs_old_value =
writer(TUPLE_WRITER_NEEDS_OLD_VALUE, nullptr, nullptr, 0);
dbtuple * const rep =
alloc_spill(t, get_value_start(), old_sz, new_sz,
this, true, needs_old_value);
if (v)
writer(TUPLE_WRITER_DO_WRITE, v, rep->get_value_start(), size);
INVARIANT(rep->is_latest());
INVARIANT(rep->size == new_sz);
INVARIANT(new_sz || rep->is_deleting()); // set by alloc_spill()
clear_latest();
++g_evt_dbtuple_inplace_buf_insufficient_on_spill;
return write_record_ret(rep, this, true);
#endif
}
// NB: we round up allocation sizes because jemalloc will do this
// internally anyways, so we might as well grab more usable space (really
// just internal vs external fragmentation)
static inline dbtuple *
alloc_first(size_type sz, bool acquire_lock)
{
INVARIANT(sz <= std::numeric_limits<node_size_type>::max());
const size_t max_alloc_sz =
std::numeric_limits<node_size_type>::max() + sizeof(dbtuple);
const size_t alloc_sz =
std::min(