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corobase.cc
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#include "dbcore/rcu.h"
#include "engine.h"
#include "masstree/masstree_scan.hh"
#include "txn.h"
namespace ermia {
#ifdef ADV_COROUTINE
void ConcurrentMasstreeIndex::adv_coro_MultiGet(
transaction *t, std::vector<varstr *> &keys, std::vector<varstr *> &values,
std::vector<ermia::coro::task<bool>> &index_probe_tasks,
std::vector<ermia::coro::task<void>> &get_record_tasks) {
if (!t) {
ermia::epoch_num e = MM::epoch_enter();
ConcurrentMasstree::versioned_node_t sinfo;
std::vector<OID> oids(keys.size());
for (int i = 0; i < keys.size(); ++i) {
oids[i] = INVALID_OID;
index_probe_tasks[i] = masstree_.search(*keys[i], oids[i], e, &sinfo);
index_probe_tasks[i].start();
}
int finished = 0;
while (finished < keys.size()) {
for (auto &t : index_probe_tasks) {
if (t.valid()) {
if (t.done()) {
++finished;
t.destroy();
} else {
t.resume();
}
}
}
}
for (const OID &oid : oids) {
ALWAYS_ASSERT(oid != INVALID_OID);
}
MM::epoch_exit(0, e);
} else {
std::vector<rc_t> rcs(keys.size());
for (int i = 0; i < keys.size(); ++i) {
rcs[i]._val = RC_INVALID;
get_record_tasks[i] = GetRecord(t, rcs[i], *keys[i], *values[i]);
get_record_tasks[i].start();
}
int finished = 0;
while (finished < keys.size()) {
for (auto &task : get_record_tasks) {
if (task.valid()) {
if (task.done()) {
++finished;
task.destroy();
} else {
task.resume();
}
}
}
}
for (const rc_t &rc : rcs) {
ALWAYS_ASSERT(rc._val == RC_TRUE);
}
}
}
#else
void ConcurrentMasstreeIndex::amac_MultiGet(
transaction *t, std::vector<ConcurrentMasstree::AMACState> &requests,
std::vector<varstr *> &values) {
ConcurrentMasstree::versioned_node_t sinfo;
if (!t) {
auto e = MM::epoch_enter();
masstree_.search_amac(requests, e);
MM::epoch_exit(0, e);
} else {
t->ensure_active();
masstree_.search_amac(requests, t->xc->begin_epoch);
if (!config::index_probe_only) {
if (config::amac_version_chain) {
// AMAC style version chain traversal
thread_local std::vector<OIDAMACState> version_requests;
version_requests.clear();
for (auto &s : requests) {
version_requests.emplace_back(s.out_oid);
}
oidmgr->oid_get_version_amac(table_descriptor->GetTupleArray(),
version_requests, t->xc);
uint32_t i = 0;
for (auto &vr : version_requests) {
if (vr.tuple) {
t->DoTupleRead(vr.tuple, values[i++]);
} else if (config::phantom_prot) {
DoNodeRead(t, sinfo.first, sinfo.second);
}
}
} else {
for (uint32_t i = 0; i < requests.size(); ++i) {
auto &r = requests[i];
if (r.out_oid != INVALID_OID) {
auto *tuple = oidmgr->oid_get_version(
table_descriptor->GetTupleArray(), r.out_oid, t->xc);
if (tuple) {
t->DoTupleRead(tuple, values[i]);
} else if (config::phantom_prot) {
DoNodeRead(t, sinfo.first, sinfo.second);
}
}
}
}
}
}
}
void ConcurrentMasstreeIndex::simple_coro_MultiGet(
transaction *t, std::vector<varstr *> &keys, std::vector<varstr *> &values,
std::vector<coroutine_handle<>> &handles) {
ermia::epoch_num e;
if (!t) {
e = MM::epoch_enter();
ConcurrentMasstree::threadinfo ti(e);
ConcurrentMasstree::versioned_node_t sinfo;
OID oid = INVALID_OID;
for (int i = 0; i < keys.size(); ++i) {
handles[i] =
masstree_.search_coro(*keys[i], oid, ti, &sinfo).get_handle();
}
} else {
for (int i = 0; i < keys.size(); ++i) {
handles[i] = coro_GetRecord(t, *keys[i], *values[i]).get_handle();
}
}
int finished = 0;
while (finished < handles.size()) {
for (auto &h : handles) {
if (h) {
if (h.done()) {
++finished;
h.destroy();
h = nullptr;
} else {
h.resume();
}
}
}
}
if (!t) MM::epoch_exit(0, e);
}
ermia::coro::generator<rc_t> ConcurrentMasstreeIndex::coro_GetRecordSV(
transaction *t, const varstr &key, varstr &value, OID *out_oid) {
OID oid = INVALID_OID;
rc_t rc = rc_t{RC_INVALID};
t->ensure_active();
// start: masstree search
ConcurrentMasstree::threadinfo ti(t->xc->begin_epoch);
ConcurrentMasstree::unlocked_tcursor_type lp(*masstree_.get_table(),
key.data(), key.size());
// start: find_unlocked
int match;
key_indexed_position kx;
ConcurrentMasstree::node_base_type *root =
const_cast<ConcurrentMasstree::node_base_type *>(lp.root_);
retry:
// start: reach_leaf
const ConcurrentMasstree::node_base_type *n[2];
ConcurrentMasstree::nodeversion_type v[2];
bool sense;
// Get a non-stale root.
// Detect staleness by checking whether n has ever split.
// The true root has never split.
sense = false;
n[sense] = root;
while (1) {
v[sense] = n[sense]->stable_annotated(ti.stable_fence());
if (!v[sense].has_split()) break;
n[sense] = n[sense]->unsplit_ancestor();
}
// Loop over internal nodes.
while (!v[sense].isleaf()) {
const ConcurrentMasstree::internode_type *in =
static_cast<const ConcurrentMasstree::internode_type *>(n[sense]);
in->prefetch();
co_await suspend_always{};
int kp = ConcurrentMasstree::internode_type::bound_type::upper(lp.ka_, *in);
n[!sense] = in->child_[kp];
if (!n[!sense]) goto retry;
v[!sense] = n[!sense]->stable_annotated(ti.stable_fence());
if (likely(!in->has_changed(v[sense]))) {
sense = !sense;
continue;
}
ConcurrentMasstree::nodeversion_type oldv = v[sense];
v[sense] = in->stable_annotated(ti.stable_fence());
if (oldv.has_split(v[sense]) &&
in->stable_last_key_compare(lp.ka_, v[sense], ti) > 0) {
goto retry;
}
}
lp.v_ = v[sense];
lp.n_ = const_cast<ConcurrentMasstree::leaf_type *>(
static_cast<const ConcurrentMasstree::leaf_type *>(n[sense]));
// end: reach_leaf
forward:
if (lp.v_.deleted()) goto retry;
// lp.n_->prefetch();
// co_await suspend_always{};
lp.perm_ = lp.n_->permutation();
kx = ConcurrentMasstree::leaf_type::bound_type::lower(lp.ka_, lp);
if (kx.p >= 0) {
lp.lv_ = lp.n_->lv_[kx.p];
lp.lv_.prefetch(lp.n_->keylenx_[kx.p]);
co_await suspend_always{};
match = lp.n_->ksuf_matches(kx.p, lp.ka_);
} else
match = 0;
if (lp.n_->has_changed(lp.v_)) {
lp.n_ = lp.n_->advance_to_key(lp.ka_, lp.v_, ti);
goto forward;
}
if (match < 0) {
lp.ka_.shift_by(-match);
root = lp.lv_.layer();
goto retry;
}
// end: find_unlocked
bool found = match;
dbtuple *tuple = nullptr;
if (found) {
oid = lp.value();
// end: masstree search
// start: oid_get_version
oid_array *oa = table_descriptor->GetTupleArray();
TXN::xid_context *visitor_xc = t->xc;
fat_ptr *entry = oa->get(oid);
start_over:
::prefetch((const char *)entry);
co_await suspend_always{};
fat_ptr ptr = volatile_read(*entry);
ASSERT(ptr.asi_type() == 0);
Object *prev_obj = nullptr;
while (ptr.offset()) {
Object *cur_obj = nullptr;
// Must read next_ before reading cur_obj->_clsn:
// the version we're currently reading (ie cur_obj) might be unlinked
// and thus recycled by the memory allocator at any time if it's not
// a committed version. If so, cur_obj->_next will be pointing to some
// other object in the allocator's free object pool - we'll probably
// end up at la-la land if we followed this _next pointer value...
// Here we employ some flavor of OCC to solve this problem:
// the aborting transaction that will unlink cur_obj will update
// cur_obj->_clsn to NULL_PTR, then deallocate(). Before reading
// cur_obj->_clsn, we (as the visitor), first dereference pp to get
// a stable value that "should" contain the right address of the next
// version. We then read cur_obj->_clsn to verify: if it's NULL_PTR
// that means we might have read a wrong _next value that's actually
// pointing to some irrelevant object in the allocator's memory pool,
// hence must start over from the beginning of the version chain.
fat_ptr tentative_next = NULL_PTR;
ASSERT(ptr.asi_type() == 0);
cur_obj = (Object *)ptr.offset();
Object::PrefetchHeader(cur_obj);
co_await suspend_always{};
tentative_next = cur_obj->GetNextVolatile();
ASSERT(tentative_next.asi_type() == 0);
// bool retry = false;
// bool visible = oidmgr->TestVisibility(cur_obj, visitor_xc, retry);
// TestVisibility
{
fat_ptr csn = cur_obj->GetCSN();
if (csn == NULL_PTR) {
// dead tuple that was (or about to be) unlinked, start over
goto start_over;
}
uint16_t asi_type = csn.asi_type();
ALWAYS_ASSERT(asi_type == fat_ptr::ASI_XID ||
asi_type == fat_ptr::ASI_CSN);
if (asi_type == fat_ptr::ASI_XID) { // in-flight
XID holder_xid = XID::from_ptr(csn);
// Dirty data made by me is visible!
if (holder_xid == t->xc->owner) {
ASSERT(!cur_obj->GetNextVolatile().offset() ||
((Object *)cur_obj->GetNextVolatile().offset())
->GetCSN()
.asi_type() == fat_ptr::ASI_CSN);
goto handle_visible;
}
auto *holder = TXN::xid_get_context(holder_xid);
if (!holder) {
goto start_over;
}
auto state = volatile_read(holder->state);
auto owner = volatile_read(holder->owner);
// context still valid for this XID?
if (owner != holder_xid) {
goto start_over;
}
if (state == TXN::TXN_CMMTD) {
ASSERT(volatile_read(holder->end));
ASSERT(owner == holder_xid);
if (holder->end < t->xc->begin) {
goto handle_visible;
}
goto handle_invisible;
}
} else {
// Already committed, now do visibility test
ASSERT(
cur_obj->GetPersistentAddress().asi_type() == fat_ptr::ASI_LOG ||
cur_obj->GetPersistentAddress().asi_type() == fat_ptr::ASI_CHK ||
cur_obj->GetPersistentAddress() == NULL_PTR); // Delete
uint64_t csn_value = CSN::from_ptr(csn).offset();
if (csn_value <= t->xc->begin) {
goto handle_visible;
}
}
goto handle_invisible;
}
handle_visible:
if (out_oid) {
*out_oid = oid;
}
co_return t->DoTupleRead(cur_obj->GetPinnedTuple(), &value);
handle_invisible:
ptr = tentative_next;
prev_obj = cur_obj;
}
}
co_return {RC_FALSE};
}
ermia::coro::generator<rc_t> ConcurrentMasstreeIndex::coro_GetRecord(
transaction *t, const varstr &key, varstr &value, OID *out_oid) {
OID oid = INVALID_OID;
rc_t rc = rc_t{RC_INVALID};
t->ensure_active();
// start: masstree search
ConcurrentMasstree::threadinfo ti(t->xc->begin_epoch);
ConcurrentMasstree::unlocked_tcursor_type lp(*masstree_.get_table(),
key.data(), key.size());
// start: find_unlocked
int match;
key_indexed_position kx;
ConcurrentMasstree::node_base_type *root =
const_cast<ConcurrentMasstree::node_base_type *>(lp.root_);
retry:
// start: reach_leaf
const ConcurrentMasstree::node_base_type *n[2];
ConcurrentMasstree::nodeversion_type v[2];
bool sense;
// Get a non-stale root.
// Detect staleness by checking whether n has ever split.
// The true root has never split.
sense = false;
n[sense] = root;
while (1) {
v[sense] = n[sense]->stable_annotated(ti.stable_fence());
if (!v[sense].has_split()) break;
n[sense] = n[sense]->unsplit_ancestor();
}
// Loop over internal nodes.
while (!v[sense].isleaf()) {
const ConcurrentMasstree::internode_type *in =
static_cast<const ConcurrentMasstree::internode_type *>(n[sense]);
in->prefetch();
co_await suspend_always{};
int kp = ConcurrentMasstree::internode_type::bound_type::upper(lp.ka_, *in);
n[!sense] = in->child_[kp];
if (!n[!sense]) goto retry;
// const ConcurrentMasstree::internode_type* in2 = static_cast<const
// ConcurrentMasstree::internode_type*>(n[!sense]); in2->prefetch(); co_await
// suspend_always{};
v[!sense] = n[!sense]->stable_annotated(ti.stable_fence());
if (likely(!in->has_changed(v[sense]))) {
sense = !sense;
continue;
}
ConcurrentMasstree::nodeversion_type oldv = v[sense];
v[sense] = in->stable_annotated(ti.stable_fence());
if (oldv.has_split(v[sense]) &&
in->stable_last_key_compare(lp.ka_, v[sense], ti) > 0) {
goto retry;
}
}
lp.v_ = v[sense];
lp.n_ = const_cast<ConcurrentMasstree::leaf_type *>(
static_cast<const ConcurrentMasstree::leaf_type *>(n[sense]));
// end: reach_leaf
forward:
if (lp.v_.deleted()) goto retry;
// XXX(tzwang): already working on this node, no need to prefetch+yield again?
// lp.n_->prefetch();
// co_await suspend_always{};
lp.perm_ = lp.n_->permutation();
kx = ConcurrentMasstree::leaf_type::bound_type::lower(lp.ka_, lp);
if (kx.p >= 0) {
lp.lv_ = lp.n_->lv_[kx.p];
lp.lv_.prefetch(lp.n_->keylenx_[kx.p]);
co_await suspend_always{};
match = lp.n_->ksuf_matches(kx.p, lp.ka_);
} else
match = 0;
if (lp.n_->has_changed(lp.v_)) {
lp.n_ = lp.n_->advance_to_key(lp.ka_, lp.v_, ti);
goto forward;
}
if (match < 0) {
lp.ka_.shift_by(-match);
root = lp.lv_.layer();
goto retry;
}
// end: find_unlocked
bool found = match;
dbtuple *tuple = nullptr;
if (found) {
oid = lp.value();
// end: masstree search
// start: oid_get_version
oid_array *oa = table_descriptor->GetTupleArray();
TXN::xid_context *visitor_xc = t->xc;
fat_ptr *entry = oa->get(oid);
start_over:
::prefetch((const char *)entry);
co_await suspend_always{};
fat_ptr ptr = volatile_read(*entry);
ASSERT(ptr.asi_type() == 0);
Object *prev_obj = nullptr;
while (ptr.offset()) {
Object *cur_obj = nullptr;
// Must read next_ before reading cur_obj->_clsn:
// the version we're currently reading (ie cur_obj) might be unlinked
// and thus recycled by the memory allocator at any time if it's not
// a committed version. If so, cur_obj->_next will be pointing to some
// other object in the allocator's free object pool - we'll probably
// end up at la-la land if we followed this _next pointer value...
// Here we employ some flavor of OCC to solve this problem:
// the aborting transaction that will unlink cur_obj will update
// cur_obj->_clsn to NULL_PTR, then deallocate(). Before reading
// cur_obj->_clsn, we (as the visitor), first dereference pp to get
// a stable value that "should" contain the right address of the next
// version. We then read cur_obj->_clsn to verify: if it's NULL_PTR
// that means we might have read a wrong _next value that's actually
// pointing to some irrelevant object in the allocator's memory pool,
// hence must start over from the beginning of the version chain.
fat_ptr tentative_next = NULL_PTR;
ASSERT(ptr.asi_type() == 0);
cur_obj = (Object *)ptr.offset();
// Object::PrefetchHeader(cur_obj);
// co_await suspend_always{};
tentative_next = cur_obj->GetNextVolatile();
ASSERT(tentative_next.asi_type() == 0);
// bool retry = false;
// bool visible = oidmgr->TestVisibility(cur_obj, visitor_xc, retry);
{
fat_ptr csn = cur_obj->GetCSN();
if (csn == NULL_PTR) {
// dead tuple that was (or about to be) unlinked, start over
goto start_over;
}
uint16_t asi_type = csn.asi_type();
ALWAYS_ASSERT(asi_type == fat_ptr::ASI_XID ||
asi_type == fat_ptr::ASI_CSN);
if (asi_type == fat_ptr::ASI_XID) { // in-flight
XID holder_xid = XID::from_ptr(csn);
// Dirty data made by me is visible!
if (holder_xid == t->xc->owner) {
ASSERT(!cur_obj->GetNextVolatile().offset() ||
((Object *)cur_obj->GetNextVolatile().offset())
->GetCSN()
.asi_type() == fat_ptr::ASI_CSN);
goto handle_visible;
}
auto *holder = TXN::xid_get_context(holder_xid);
if (!holder) {
goto start_over;
}
auto state = volatile_read(holder->state);
auto owner = volatile_read(holder->owner);
// context still valid for this XID?
if (owner != holder_xid) {
goto start_over;
}
if (state == TXN::TXN_CMMTD) {
ASSERT(volatile_read(holder->end));
ASSERT(owner == holder_xid);
if (holder->end < t->xc->begin) {
goto handle_visible;
}
goto handle_invisible;
}
} else {
// Already committed, now do visibility test
ASSERT(
cur_obj->GetPersistentAddress().asi_type() == fat_ptr::ASI_LOG ||
cur_obj->GetPersistentAddress().asi_type() == fat_ptr::ASI_CHK ||
cur_obj->GetPersistentAddress() == NULL_PTR); // Delete
uint64_t csn_value = CSN::from_ptr(csn).offset();
if (csn_value <= t->xc->begin) {
goto handle_visible;
}
}
goto handle_invisible;
}
handle_visible:
if (out_oid) {
*out_oid = oid;
}
co_return t->DoTupleRead(cur_obj->GetPinnedTuple(), &value);
handle_invisible:
ptr = tentative_next;
prev_obj = cur_obj;
}
}
co_return {RC_FALSE};
}
ermia::coro::generator<rc_t> ConcurrentMasstreeIndex::coro_UpdateRecord(
transaction *t, const varstr &key, varstr &value) {
// For primary index only
ALWAYS_ASSERT(IsPrimary());
// Search for OID
OID oid = INVALID_OID;
rc_t rc = rc_t{RC_INVALID};
ConcurrentMasstree::versioned_node_t sinfo;
t->ensure_active();
// start: masstree search
ConcurrentMasstree::threadinfo ti(t->xc->begin_epoch);
ConcurrentMasstree::unlocked_tcursor_type lp(*masstree_.get_table(),
key.data(), key.size());
// start: find_unlocked
int match;
key_indexed_position kx;
ConcurrentMasstree::node_base_type *root =
const_cast<ConcurrentMasstree::node_base_type *>(lp.root_);
retry:
// start: reach_leaf
const ConcurrentMasstree::node_base_type *n[2];
ConcurrentMasstree::nodeversion_type v[2];
bool sense;
sense = false;
n[sense] = root;
while (1) {
v[sense] = n[sense]->stable_annotated(ti.stable_fence());
if (!v[sense].has_split()) break;
n[sense] = n[sense]->unsplit_ancestor();
}
// Loop over internal nodes.
while (!v[sense].isleaf()) {
const ConcurrentMasstree::internode_type *in =
static_cast<const ConcurrentMasstree::internode_type *>(n[sense]);
in->prefetch();
co_await suspend_always{};
int kp = ConcurrentMasstree::internode_type::bound_type::upper(lp.ka_, *in);
n[!sense] = in->child_[kp];
if (!n[!sense]) goto retry;
v[!sense] = n[!sense]->stable_annotated(ti.stable_fence());
if (likely(!in->has_changed(v[sense]))) {
sense = !sense;
continue;
}
ConcurrentMasstree::nodeversion_type oldv = v[sense];
v[sense] = in->stable_annotated(ti.stable_fence());
if (oldv.has_split(v[sense]) &&
in->stable_last_key_compare(lp.ka_, v[sense], ti) > 0) {
goto retry;
}
}
lp.v_ = v[sense];
lp.n_ = const_cast<ConcurrentMasstree::leaf_type *>(
static_cast<const ConcurrentMasstree::leaf_type *>(n[sense]));
// end: reach_leaf
forward:
if (lp.v_.deleted()) goto retry;
// lp.n_->prefetch();
// co_await suspend_always{};
lp.perm_ = lp.n_->permutation();
kx = ConcurrentMasstree::leaf_type::bound_type::lower(lp.ka_, lp);
if (kx.p >= 0) {
lp.lv_ = lp.n_->lv_[kx.p];
lp.lv_.prefetch(lp.n_->keylenx_[kx.p]);
co_await suspend_always{};
match = lp.n_->ksuf_matches(kx.p, lp.ka_);
} else
match = 0;
if (lp.n_->has_changed(lp.v_)) {
lp.n_ = lp.n_->advance_to_key(lp.ka_, lp.v_, ti);
goto forward;
}
if (match < 0) {
lp.ka_.shift_by(-match);
root = lp.lv_.layer();
goto retry;
}
// end: find_unlocked
if (match) {
oid = lp.value();
}
sinfo =
ConcurrentMasstree::versioned_node_t(lp.node(), lp.full_version_value());
// end: masstree search
if (match) {
// By default we don't do coroutine prefetch-yield here for updates,
// assuming it's part of an RMW (most cases) which means the data is
// probably in cache anyway. This may not be true however for blind updates.
#ifndef CORO_UPDATE_VERSION_CHAIN
rc = t->Update(table_descriptor, oid, &key, &value);
#else
oid_array *tuple_array = table_descriptor->GetTupleArray();
FID tuple_fid = table_descriptor->GetTupleFid();
fat_ptr new_obj_ptr = NULL_PTR;
fat_ptr prev_obj_ptr = NULL_PTR;
Object *new_object = nullptr;
start_over:
auto *ptr = tuple_array->get(oid);
::prefetch((const char *)ptr);
co_await suspend_always{};
fat_ptr head = volatile_read(*ptr);
ASSERT(head.asi_type() == 0);
Object *old_desc = (Object *)head.offset();
ASSERT(old_desc);
ASSERT(head.size_code() != INVALID_SIZE_CODE);
Object::PrefetchHeader(old_desc);
co_await suspend_always{};
dbtuple *version = (dbtuple *)old_desc->GetPayload();
bool overwrite = false;
auto csn = old_desc->GetCSN();
if (csn == NULL_PTR) {
// stepping on an unlinked version?
goto start_over;
} else if (csn.asi_type() == fat_ptr::ASI_XID) {
/* Grab the context for this XID. If we're too slow,
the context might be recycled for a different XID,
perhaps even *while* we are reading the
context. Copy everything we care about and then
(last) check the context's XID for a mismatch that
would indicate an inconsistent read. If this
occurs, just start over---the version we cared
about is guaranteed to have a LSN now.
*/
auto holder_xid = XID::from_ptr(csn);
XID updater_xid = volatile_read(t->xid);
// in-place update case (multiple updates on the same record by same
// transaction)
if (holder_xid == updater_xid) {
overwrite = true;
goto install;
}
TXN::xid_context *holder = TXN::xid_get_context(holder_xid);
if (not holder) {
#ifndef NDEBUG
auto t = old_desc->GetCSN().asi_type();
ASSERT(t == fat_ptr::ASI_CSN || oid_get(oa, o) != head);
#endif
goto start_over;
}
ASSERT(holder);
auto state = volatile_read(holder->state);
auto owner = volatile_read(holder->owner);
holder = NULL; // use cached values instead!
// context still valid for this XID?
if (unlikely(owner != holder_xid)) {
goto start_over;
}
ASSERT(holder_xid != updater_xid);
if (state == TXN::TXN_CMMTD) {
// Allow installing a new version if the tx committed (might
// still hasn't finished post-commit). Note that the caller
// (ie do_tree_put) should look at the clsn field of the
// returned version (prev) to see if this is an overwrite
// (ie xids match) or not (xids don't match).
ASSERT(holder_xid != updater_xid);
goto install;
}
prev_obj_ptr = NULL_PTR;
goto check_prev;
}
// check dirty writes
else {
ASSERT(csn.asi_type() == fat_ptr::ASI_CSN);
#ifndef RC
// First updater wins: if some concurrent tx committed first,
// I have to abort. Same as in Oracle. Otherwise it's an isolation
// failure: I can modify concurrent transaction's writes.
if (CSN::from_ptr(csn).offset() >= t->xc->begin) {
prev_obj_ptr = NULL_PTR;
goto check_prev;
}
#endif
goto install;
}
install:
// remove uncommitted overwritten version
// (tx's repetitive updates, keep the latest one only)
// Note for this to be correct we shouldn't allow multiple txs
// working on the same tuple at the same time.
new_obj_ptr = Object::Create(&value, false, t->xc->begin_epoch);
ASSERT(new_obj_ptr.asi_type() == 0);
new_object = (Object *)new_obj_ptr.offset();
new_object->SetCSN(t->xc->owner.to_ptr());
if (overwrite) {
new_object->SetNextPersistent(old_desc->GetNextPersistent());
new_object->SetNextVolatile(old_desc->GetNextVolatile());
// I already claimed it, no need to use cas then
volatile_write(ptr->_ptr, new_obj_ptr._ptr);
__sync_synchronize();
prev_obj_ptr = head;
goto check_prev;
} else {
fat_ptr pa = old_desc->GetPersistentAddress();
while (pa == NULL_PTR) {
pa = old_desc->GetPersistentAddress();
}
new_object->SetNextPersistent(pa);
new_object->SetNextVolatile(head);
if (__sync_bool_compare_and_swap(&ptr->_ptr, head._ptr,
new_obj_ptr._ptr)) {
// Succeeded installing a new version, now only I can modify the
// chain, try recycle some objects
if (config::enable_gc) {
MM::gc_version_chain(ptr);
}
prev_obj_ptr = head;
goto check_prev;
} else {
MM::deallocate(new_obj_ptr);
}
}
prev_obj_ptr = NULL_PTR;
check_prev:
Object *prev_obj = (Object *)prev_obj_ptr.offset();
if (prev_obj) { // succeeded
Object::PrefetchHeader(prev_obj);
co_await suspend_always{};
dbtuple *tuple = ((Object *)new_obj_ptr.offset())->GetPinnedTuple();
ASSERT(tuple);
dbtuple *prev = prev_obj->GetPinnedTuple();
ASSERT((uint64_t)prev->GetObject() == prev_obj_ptr.offset());
ASSERT(xc);
#ifdef SSI
// TODO
#endif
#ifdef SSN
// TODO
#endif
// read prev's clsn first, in case it's a committing XID, the clsn's state
// might change to ASI_LOG anytime
ASSERT((uint64_t)prev->GetObject() == prev_obj_ptr.offset());
fat_ptr prev_csn = prev->GetObject()->GetCSN();
fat_ptr prev_persistent_ptr = NULL_PTR;
if (prev_csn.asi_type() == fat_ptr::ASI_XID and
XID::from_ptr(prev_csn) == t->xid) {
// updating my own updates!
// prev's prev: previous *committed* version
ASSERT(((Object *)prev_obj_ptr.offset())->GetAllocateEpoch() ==
xc->begin_epoch);
prev_persistent_ptr = prev_obj->GetNextPersistent();
// FIXME(tzwang): 20190210: seems the deallocation here is too early,
// causing readers to not find any visible version. Fix this together
// with GC later.
// MM::deallocate(prev_obj_ptr);
} else { // prev is committed (or precommitted but in post-commit now)
// head
#if defined(SSI) || defined(SSN) || defined(MVOCC)
// TODO
#endif
t->add_to_write_set(tuple_array->get(oid));
prev_persistent_ptr = prev_obj->GetPersistentAddress();
}
ASSERT(tuple->GetObject()->GetCSN().asi_type() == fat_ptr::ASI_XID);
ASSERT(oidmgr->oid_get_version(tuple_fid, oid, xc) == tuple);
ASSERT(log);
// FIXME(tzwang): mark deleted in all 2nd indexes as well?
// The varstr also encodes the pdest of the overwritten version.
// FIXME(tzwang): the pdest of the overwritten version doesn't belong to
// varstr.
value.ptr = prev_persistent_ptr;
ASSERT(is_delete ||
(value.ptr.offset() && value.ptr.asi_type() == fat_ptr::ASI_LOG));
// log the whole varstr so that recovery can figure out the real size
// of the tuple, instead of using the decoded (larger-than-real) size.
size_t data_size = value.size() + sizeof(varstr);
auto size_code = encode_size_aligned(data_size);
t->log->log_update(tuple_fid, oid,
fat_ptr::make((void *)&value, size_code),
DEFAULT_ALIGNMENT_BITS,
tuple->GetObject()->GetPersistentAddressPtr());
if (config::log_key_for_update) {
auto key_size = align_up(key.size() + sizeof(varstr));
auto key_size_code = encode_size_aligned(key_size);
t->log->log_update_key(tuple_fid, oid,
fat_ptr::make((void *)&key, key_size_code),
DEFAULT_ALIGNMENT_BITS);
}
rc = rc_t{RC_TRUE};
} else { // somebody else acted faster than we did
rc = rc_t{RC_ABORT_SI_CONFLICT};
}
#endif // CORO_UPDATE_VERSION_CHAIN
} else {
rc = rc_t{RC_ABORT_INTERNAL};
}
co_return rc;
}
ermia::coro::generator<bool> ConcurrentMasstreeIndex::coro_InsertOID(
transaction *t, const varstr &key, OID oid) {
ASSERT((char *)key.data() == (char *)&key + sizeof(varstr));
t->ensure_active();
// start: InsertIfAbsent
ConcurrentMasstree::insert_info_t ins_info;
// strat: insert_if_absent
ermia::ConcurrentMasstree::insert_info_t *insert_info = &ins_info;
// Recovery will give a null xc, use epoch 0 for the memory allocated
epoch_num e = 0;
if (t->xc) e = t->xc->begin_epoch;
ConcurrentMasstree::threadinfo ti(e);
ConcurrentMasstree::tcursor_type lp(*masstree_.get_table(), key.data(),
key.size());
// start: find_insert
// start: find_locked
ConcurrentMasstree::node_base_type *root =
const_cast<ConcurrentMasstree::node_base_type *>(lp.root_);
ConcurrentMasstree::nodeversion_type version;
ConcurrentMasstree::permuter_type perm;
retry:
// start: reach_leaf
const ConcurrentMasstree::node_base_type *n[2];
ConcurrentMasstree::nodeversion_type v[2];
bool sense;
// Get a non-stale root.
// Detect staleness by checking whether n has ever split.
// The true root has never split.
sense = false;
n[sense] = root;
while (1) {
v[sense] = n[sense]->stable_annotated(ti.stable_fence());
if (!v[sense].has_split()) break;
n[sense] = n[sense]->unsplit_ancestor();
}
// Loop over internal nodes.
while (!v[sense].isleaf()) {
const ConcurrentMasstree::internode_type *in =
static_cast<const ConcurrentMasstree::internode_type *>(n[sense]);
in->prefetch();
co_await suspend_always{};
int kp = ConcurrentMasstree::internode_type::bound_type::upper(lp.ka_, *in);
n[!sense] = in->child_[kp];
if (!n[!sense]) goto retry;
v[!sense] = n[!sense]->stable_annotated(ti.stable_fence());
if (likely(!in->has_changed(v[sense]))) {
sense = !sense;
continue;
}
ConcurrentMasstree::nodeversion_type oldv = v[sense];
v[sense] = in->stable_annotated(ti.stable_fence());
if (oldv.has_split(v[sense]) &&
in->stable_last_key_compare(lp.ka_, v[sense], ti) > 0) {
goto retry;
}
}
version = v[sense];
lp.n_ = const_cast<ConcurrentMasstree::leaf_type *>(
static_cast<const ConcurrentMasstree::leaf_type *>(n[sense]));
// end: reach_leaf
forward:
if (version.deleted()) goto retry;
// lp.n_->prefetch();
// co_await suspend_always{};
perm = lp.n_->permutation();
fence();
lp.kx_ = ConcurrentMasstree::leaf_type::bound_type::lower(lp.ka_, *lp.n_);
if (lp.kx_.p >= 0) {
ConcurrentMasstree::leafvalue_type lv = lp.n_->lv_[lp.kx_.p];
lv.prefetch(lp.n_->keylenx_[lp.kx_.p]);
co_await suspend_always{};
lp.state_ = lp.n_->ksuf_matches(lp.kx_.p, lp.ka_);
if (lp.state_ < 0 && !lp.n_->has_changed(version) &&
!lv.layer()->has_split()) {
lp.ka_.shift_by(-lp.state_);
root = lv.layer();
goto retry;
}
} else
lp.state_ = 0;
lp.n_->lock(version, ti.lock_fence(tc_leaf_lock));
if (lp.n_->has_changed(version) || lp.n_->permutation() != perm) {
lp.n_->unlock();
lp.n_ = lp.n_->advance_to_key(lp.ka_, version, ti);
goto forward;
} else if (unlikely(lp.state_ < 0)) {
lp.ka_.shift_by(-lp.state_);
lp.n_->lv_[lp.kx_.p] = root =
lp.n_->lv_[lp.kx_.p].layer()->unsplit_ancestor();
lp.n_->unlock();
goto retry;
} else if (unlikely(lp.n_->deleted_layer())) {
lp.ka_.unshift_all();
root = const_cast<ConcurrentMasstree::node_base_type *>(lp.root_);
goto retry;
}
// end: find_locked
lp.original_n_ = lp.n_;
lp.original_v_ = lp.n_->full_unlocked_version_value();
bool found = true;
// maybe we found it
if (lp.state_) {
found = true;
} else {
// otherwise mark as inserted but not present