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bztree.cc
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// Copyright (c) Simon Fraser University. All rights reserved.
// Licensed under the MIT license.
//
// Authors:
// Xiangpeng Hao <[email protected]>
// Tianzheng Wang <[email protected]>
#include "bztree.h"
#include <algorithm>
#include <iostream>
#include <string>
namespace bztree {
#ifdef PMDK
pmwcas::PMDKAllocator *Allocator::allocator_ = nullptr;
#endif
uint64_t global_epoch = 0;
void InternalNode::New(bztree::InternalNode **mem, uint32_t alloc_size) {
#ifdef PMDK
auto addr = reinterpret_cast<uint64_t *>(mem);
auto allocator = Allocator::Get();
allocator->AllocateOffset(addr, alloc_size);
uint64_t offset = (*addr) & ~pmwcas::Descriptor::WordDescriptor::kRecycleFlag;
auto node = allocator->GetDirect<bztree::InternalNode>(offset);
memset(node, 0, alloc_size);
node->header.size = alloc_size;
#else
pmwcas::Allocator::Get()->Allocate(reinterpret_cast<void **>(mem),
alloc_size);
memset(*mem, 0, alloc_size);
(*mem)->header.size = alloc_size;
#endif // PMDK
}
// Create an internal node with a new key and associated child pointers inserted
// based on an existing internal node
void InternalNode::New(InternalNode *src_node, const char *key,
uint32_t key_size, uint64_t left_child_addr,
uint64_t right_child_addr, InternalNode **mem) {
uint32_t alloc_size = src_node->GetHeader()->size +
RecordMetadata::PadKeyLength(key_size) +
sizeof(right_child_addr) + sizeof(RecordMetadata);
#ifdef PMDK
auto addr = reinterpret_cast<uint64_t *>(mem);
auto allocator = Allocator::Get();
allocator->AllocateOffset(addr, alloc_size);
uint64_t offset = (*addr) & ~pmwcas::Descriptor::WordDescriptor::kRecycleFlag;
auto node = allocator->GetDirect<bztree::InternalNode>(offset);
memset(node, 0, alloc_size);
new (node)
InternalNode(alloc_size, src_node, 0, src_node->header.sorted_count, key,
key_size, left_child_addr, right_child_addr);
pmwcas::NVRAM::Flush(alloc_size, node);
#else
pmwcas::Allocator::Get()->Allocate(reinterpret_cast<void **>(mem),
alloc_size);
memset(*mem, 0, alloc_size);
new (*mem)
InternalNode(alloc_size, src_node, 0, src_node->header.sorted_count, key,
key_size, left_child_addr, right_child_addr);
#ifdef PMEM
pmwcas::NVRAM::Flush(alloc_size, *mem);
#endif // PMEM
#endif // PMDK
}
// Create an internal node with a single separator key and two pointers
void InternalNode::New(const char *key, uint32_t key_size,
uint64_t left_child_addr, uint64_t right_child_addr,
InternalNode **mem) {
uint32_t alloc_size = sizeof(InternalNode) +
RecordMetadata::PadKeyLength(key_size) +
sizeof(left_child_addr) + sizeof(right_child_addr) +
sizeof(RecordMetadata) * 2;
#ifdef PMDK
auto addr = reinterpret_cast<uint64_t *>(mem);
auto allocator = Allocator::Get();
allocator->AllocateOffset(addr, alloc_size);
uint64_t offset = (*addr) & ~pmwcas::Descriptor::WordDescriptor::kRecycleFlag;
auto node = allocator->GetDirect<bztree::InternalNode>(offset);
memset(node, 0, alloc_size);
new (node) InternalNode(alloc_size, key, key_size, left_child_addr,
right_child_addr);
pmwcas::NVRAM::Flush(alloc_size, node);
#else
pmwcas::Allocator::Get()->Allocate(reinterpret_cast<void **>(mem),
alloc_size);
memset(*mem, 0, alloc_size);
new (*mem) InternalNode(alloc_size, key, key_size, left_child_addr,
right_child_addr);
#ifdef PMEM
pmwcas::NVRAM::Flush(alloc_size, *mem);
#endif // PMEM
#endif // PMDK
}
// Create an internal node with keys and pointers in the provided range from an
// existing source node
void InternalNode::New(InternalNode *src_node, uint32_t begin_meta_idx,
uint32_t nr_records, const char *key, uint32_t key_size,
uint64_t left_child_addr, uint64_t right_child_addr,
InternalNode **new_node, uint64_t left_most_child_addr) {
// Figure out how large the new node will be
uint32_t alloc_size = sizeof(InternalNode);
if (begin_meta_idx > 0) {
// Will not copy from the first element (dummy key), so add it here
alloc_size += src_node->record_metadata[0].GetTotalLength();
alloc_size += sizeof(RecordMetadata);
}
assert(nr_records > 0);
for (uint32_t i = begin_meta_idx; i < begin_meta_idx + nr_records; ++i) {
RecordMetadata meta = src_node->record_metadata[i];
alloc_size += meta.GetTotalLength();
alloc_size += sizeof(RecordMetadata);
}
// Add the new key, if provided
if (key) {
ALWAYS_ASSERT(key_size > 0);
alloc_size += (RecordMetadata::PadKeyLength(key_size) + sizeof(uint64_t) +
sizeof(RecordMetadata));
}
#ifdef PMDK
auto addr = reinterpret_cast<uint64_t *>(new_node);
auto allocator = Allocator::Get();
allocator->AllocateOffset(addr, alloc_size);
uint64_t offset = (*addr) & ~pmwcas::Descriptor::WordDescriptor::kRecycleFlag;
auto node = allocator->GetDirect<bztree::InternalNode>(offset);
memset(node, 0, alloc_size);
new (node) InternalNode(alloc_size, src_node, begin_meta_idx, nr_records,
key, key_size, left_child_addr, right_child_addr,
left_most_child_addr);
pmwcas::NVRAM::Flush(alloc_size, node);
#else
pmwcas::Allocator::Get()->Allocate(reinterpret_cast<void **>(new_node),
alloc_size);
memset(*new_node, 0, alloc_size);
new (*new_node) InternalNode(alloc_size, src_node, begin_meta_idx, nr_records,
key, key_size, left_child_addr, right_child_addr,
left_most_child_addr);
#ifdef PMEM
pmwcas::NVRAM::Flush(alloc_size, *new_node);
#endif // PMEM
#endif // PMDK
}
InternalNode::InternalNode(uint32_t node_size, const char *key,
const uint16_t key_size, uint64_t left_child_addr,
uint64_t right_child_addr)
: BaseNode(false, node_size) {
// Initialize a new internal node with one key only
header.sorted_count = 2; // Includes the null dummy key
header.size = node_size;
// Fill in left child address, with an empty key
uint64_t offset = node_size - sizeof(left_child_addr);
record_metadata[0].FinalizeForInsert(offset, 0, sizeof(left_child_addr));
char *ptr = reinterpret_cast<char *>(this) + offset;
memcpy(ptr, &left_child_addr, sizeof(left_child_addr));
// Fill in right child address, with the separator key
auto padded_key_size = RecordMetadata::PadKeyLength(key_size);
auto total_len = padded_key_size + sizeof(right_child_addr);
offset -= total_len;
record_metadata[1].FinalizeForInsert(offset, key_size, total_len);
ptr = reinterpret_cast<char *>(this) + offset;
memcpy(ptr, key, key_size);
memcpy(ptr + padded_key_size, &right_child_addr, sizeof(right_child_addr));
assert((uint64_t)ptr ==
(uint64_t)this + sizeof(*this) + 2 * sizeof(RecordMetadata));
}
InternalNode::InternalNode(uint32_t node_size, InternalNode *src_node,
uint32_t begin_meta_idx, uint32_t nr_records,
const char *key, const uint16_t key_size,
uint64_t left_child_addr, uint64_t right_child_addr,
uint64_t left_most_child_addr)
: BaseNode(false, node_size) {
ALWAYS_ASSERT(src_node);
__builtin_prefetch((const void *)(src_node), 0, 3);
auto padded_key_size = RecordMetadata::PadKeyLength(key_size);
uint64_t offset = node_size;
bool need_insert_new = key;
uint32_t insert_idx = 0;
// See if we need a new left_most_child_addr, i.e., this must be the new node
// on the right
if (left_most_child_addr) {
offset -= sizeof(uint64_t);
record_metadata[0].FinalizeForInsert(offset, 0, sizeof(uint64_t));
memcpy(reinterpret_cast<char *>(this) + offset, &left_most_child_addr,
sizeof(uint64_t));
++insert_idx;
}
assert(nr_records > 0);
for (uint32_t i = begin_meta_idx; i < begin_meta_idx + nr_records; ++i) {
RecordMetadata meta = src_node->record_metadata[i];
assert(meta.IsVisible());
uint64_t m_payload = 0;
char *m_key = nullptr;
char *m_data = nullptr;
src_node->GetRawRecord(meta, &m_data, &m_key, &m_payload);
auto m_key_size = meta.GetKeyLength();
if (!need_insert_new) {
// New key already inserted, so directly insert the key from src node
assert(meta.GetTotalLength() >= sizeof(uint64_t));
offset -= (meta.GetTotalLength());
record_metadata[insert_idx].FinalizeForInsert(offset, m_key_size,
meta.GetTotalLength());
memcpy(reinterpret_cast<char *>(this) + offset, m_data,
meta.GetTotalLength());
} else {
// Compare the two keys to see which one to insert (first)
auto cmp = KeyCompare(m_key, m_key_size, key, key_size);
ALWAYS_ASSERT(!(cmp == 0 && key_size == m_key_size));
if (cmp > 0) {
assert(insert_idx >= 1);
// Modify the previous key's payload to left_child_addr
auto prev_meta = record_metadata[insert_idx - 1];
memcpy(reinterpret_cast<char *>(this) + prev_meta.GetOffset() +
prev_meta.GetPaddedKeyLength(),
&left_child_addr, sizeof(left_child_addr));
// Now the new separtor key itself
offset -= (padded_key_size + sizeof(right_child_addr));
record_metadata[insert_idx].FinalizeForInsert(
offset, key_size, padded_key_size + sizeof(left_child_addr));
++insert_idx;
memcpy(reinterpret_cast<char *>(this) + offset, key, key_size);
memcpy(reinterpret_cast<char *>(this) + offset + padded_key_size,
&right_child_addr, sizeof(right_child_addr));
offset -= (meta.GetTotalLength());
assert(meta.GetTotalLength() >= sizeof(uint64_t));
record_metadata[insert_idx].FinalizeForInsert(offset, m_key_size,
meta.GetTotalLength());
memcpy(reinterpret_cast<char *>(this) + offset, m_data,
meta.GetTotalLength());
need_insert_new = false;
} else {
assert(meta.GetTotalLength() >= sizeof(uint64_t));
offset -= (meta.GetTotalLength());
record_metadata[insert_idx].FinalizeForInsert(offset, m_key_size,
meta.GetTotalLength());
memcpy(reinterpret_cast<char *>(this) + offset, m_data,
meta.GetTotalLength());
}
}
++insert_idx;
}
if (need_insert_new) {
// The new key-payload pair will be the right-most (largest key) element
uint32_t total_size =
RecordMetadata::PadKeyLength(key_size) + sizeof(uint64_t);
offset -= total_size;
record_metadata[insert_idx].FinalizeForInsert(offset, key_size, total_size);
memcpy(reinterpret_cast<char *>(this) + offset, key, key_size);
memcpy(reinterpret_cast<char *>(this) + offset +
RecordMetadata::PadKeyLength(key_size),
&right_child_addr, sizeof(right_child_addr));
// Modify the previous key's payload to left_child_addr
auto prev_meta = record_metadata[insert_idx - 1];
memcpy(reinterpret_cast<char *>(this) + prev_meta.GetOffset() +
prev_meta.GetPaddedKeyLength(),
&left_child_addr, sizeof(left_child_addr));
++insert_idx;
}
header.size = node_size;
header.sorted_count = insert_idx;
}
// Insert record to this internal node. The node is frozen at this time.
bool InternalNode::PrepareForSplit(
Stack &stack, uint32_t split_threshold, const char *key, uint32_t key_size,
uint64_t left_child_addr, // [key]'s left child pointer
uint64_t right_child_addr, // [key]'s right child pointer
InternalNode **new_node, pmwcas::DescriptorGuard &pd,
pmwcas::DescriptorPool *pool, bool backoff) {
uint32_t data_size = header.size + key_size + sizeof(right_child_addr) +
sizeof(RecordMetadata);
uint32_t new_node_size = sizeof(InternalNode) + data_size;
if (new_node_size < split_threshold) {
// good boy
InternalNode::New(this, key, key_size, left_child_addr, right_child_addr,
new_node);
return true;
}
// After adding a key and pointers the new node would be too large. This
// means we are effectively 'moving up' the tree to do split
// So now we split the node and generate two new internal nodes
ALWAYS_ASSERT(header.sorted_count >= 2);
uint32_t n_left = header.sorted_count >> 1;
auto i_left = pd.ReserveAndAddEntry(
pmwcas::Descriptor::kAllocNullAddress,
reinterpret_cast<uint64_t>(nullptr),
pmwcas::Descriptor::kRecycleNewOnFailure);
auto i_right = pd.ReserveAndAddEntry(
pmwcas::Descriptor::kAllocNullAddress,
reinterpret_cast<uint64_t>(nullptr),
pmwcas::Descriptor::kRecycleNewOnFailure);
uint64_t *ptr_l = pd.GetNewValuePtr(i_left);
uint64_t *ptr_r = pd.GetNewValuePtr(i_right);
// Figure out where the new key will go
auto separator_meta = record_metadata[n_left];
char *separator_key = nullptr;
uint16_t separator_key_size = separator_meta.GetKeyLength();
uint64_t separator_payload = 0;
bool success =
GetRawRecord(separator_meta, nullptr, &separator_key, &separator_payload);
ALWAYS_ASSERT(success);
int cmp = KeyCompare(key, key_size, separator_key, separator_key_size);
if (cmp == 0) {
cmp = key_size - separator_key_size;
}
ALWAYS_ASSERT(cmp != 0);
if (cmp < 0) {
// Should go to left
InternalNode::New(this, 0, n_left, key, key_size, left_child_addr,
right_child_addr,
reinterpret_cast<InternalNode **>(ptr_l), 0);
InternalNode::New(
this, n_left + 1, header.sorted_count - n_left - 1, nullptr, 0, 0, 0,
reinterpret_cast<InternalNode **>(ptr_r), separator_payload);
} else {
InternalNode::New(this, 0, n_left, nullptr, 0, 0, 0,
reinterpret_cast<InternalNode **>(ptr_l), 0);
InternalNode::New(this, n_left + 1, header.sorted_count - n_left - 1, key,
key_size, left_child_addr, right_child_addr,
reinterpret_cast<InternalNode **>(ptr_r),
separator_payload);
}
assert(*ptr_l);
assert(*ptr_r);
uint64_t node_l = *ptr_l & ~pmwcas::Descriptor::WordDescriptor::kRecycleFlag;
uint64_t node_r = *ptr_r & ~pmwcas::Descriptor::WordDescriptor::kRecycleFlag;
// Pop here as if this were a leaf node so that when we get back to the
// original caller, we get stack top as the "parent"
stack.Pop();
// Now get this internal node's real parent
InternalNode *parent = stack.Top() ? stack.Top()->node : nullptr;
if (parent == nullptr) {
// Good!
InternalNode::New(separator_key, separator_key_size, (uint64_t)node_l,
(uint64_t)node_r, new_node);
return true;
}
__builtin_prefetch((const void *)(parent), 0, 2);
// Try to freeze the parent node first
bool frozen_by_me = false;
while (!parent->IsFrozen()) {
frozen_by_me = parent->Freeze(pool);
}
// Someone else froze the parent node and we are told not to compete with
// others (for now)
if (!frozen_by_me && backoff) {
return false;
}
return parent->PrepareForSplit(stack, split_threshold, separator_key,
separator_key_size, (uint64_t)node_l,
(uint64_t)node_r, new_node, pd, pool, backoff);
}
void LeafNode::New(LeafNode **mem, uint32_t node_size) {
#ifdef PMDK
auto addr = reinterpret_cast<uint64_t *>(mem);
auto allocator = Allocator::Get();
allocator->AllocateOffset(addr, node_size);
uint64_t offset = (*addr) & ~pmwcas::Descriptor::WordDescriptor::kRecycleFlag;
auto node = allocator->GetDirect<bztree::InternalNode>(offset);
memset(node, 0, node_size);
new (node) LeafNode(node_size);
pmwcas::NVRAM::Flush(node_size, node);
#else
pmwcas::Allocator::Get()->Allocate(reinterpret_cast<void **>(mem), node_size);
memset(*mem, 0, node_size);
new (*mem) LeafNode(node_size);
#ifdef PMEM
pmwcas::NVRAM::Flush(node_size, *mem);
#endif // PMEM
#endif // PMDK
}
void BaseNode::Dump() {
std::cout << "-----------------------------" << std::endl;
std::cout << " Dumping node: " << this
<< (is_leaf ? " (leaf)" : " (internal)") << std::endl;
std::cout << " Header:\n";
if (is_leaf) {
std::cout << " - free space: "
<< (reinterpret_cast<LeafNode *>(this))->GetFreeSpace()
<< std::endl;
}
std::cout << " - status: 0x" << std::hex << header.status.word << std::endl
<< " (control = 0x"
<< (header.status.word & NodeHeader::StatusWord::kControlMask)
<< std::dec << ", frozen = " << header.status.IsFrozen()
<< ", block size = " << header.status.GetBlockSize()
<< ", delete size = " << header.status.GetDeletedSize()
<< ", record count = " << header.status.GetRecordCount() << ")\n"
<< " - sorted_count: " << header.sorted_count << std::endl;
std::cout << " - size: " << header.size << std::endl;
std::cout << " Record Metadata Array:" << std::endl;
uint32_t n_meta =
std::max<uint32_t>(header.status.GetRecordCount(), header.sorted_count);
for (uint32_t i = 0; i < n_meta; ++i) {
RecordMetadata meta = record_metadata[i];
std::cout << " - record " << i << ": meta = 0x" << std::hex << meta.meta
<< std::endl;
std::cout << std::hex;
std::cout << " (control = 0x"
<< (meta.meta & RecordMetadata::kControlMask) << std::dec
<< ", visible = " << meta.IsVisible()
<< ", offset = " << meta.GetOffset()
<< ", key length = " << meta.GetKeyLength()
<< ", total length = " << meta.GetTotalLength() << std::endl;
}
}
void LeafNode::Dump() {
BaseNode::Dump();
std::cout << " Key-Payload Pairs:" << std::endl;
for (uint32_t i = 0; i < header.status.GetRecordCount(); ++i) {
RecordMetadata meta = record_metadata[i];
if (meta.IsVisible()) {
uint64_t payload = 0;
char *key = nullptr;
GetRawRecord(meta, &key, &payload);
assert(key);
std::string keystr(key, key + meta.GetKeyLength());
std::cout << " - record " << i << ": key = " << keystr
<< ", payload = " << payload << std::endl;
}
}
std::cout << "-----------------------------" << std::endl;
}
void InternalNode::Dump(bool dump_children) {
BaseNode::Dump();
std::cout << " Child pointers and separator keys:" << std::endl;
assert(header.status.GetRecordCount() == 0);
for (uint32_t i = 0; i < header.sorted_count; ++i) {
auto &meta = record_metadata[i];
assert((i == 0 && meta.GetKeyLength() == 0) ||
(i > 0 && meta.GetKeyLength() > 0));
uint64_t right_child_addr = 0;
char *key = nullptr;
GetRawRecord(meta, nullptr, &key, &right_child_addr);
if (key) {
std::string keystr(key, key + meta.GetKeyLength());
std::cout << " || " << keystr << " | ";
}
std::cout << std::hex << "0x" << right_child_addr << std::dec;
}
std::cout << std::endl;
if (dump_children) {
for (uint32_t i = 0; i < header.sorted_count; ++i) {
uint64_t node_addr = *GetPayloadPtr(record_metadata[i]);
#ifdef PMDK
BaseNode *node =
Allocator::Get()->GetDirect<BaseNode>(node_addr);
#else
BaseNode *node = reinterpret_cast<BaseNode *>(node_addr);
#endif
if (node->IsLeaf()) {
(reinterpret_cast<LeafNode *>(node))->Dump();
} else {
(reinterpret_cast<InternalNode *>(node))->Dump(true);
}
}
}
}
ReturnCode LeafNode::Insert(const char *key, uint16_t key_size,
uint64_t payload,
pmwcas::DescriptorPool *pmwcas_pool,
uint32_t split_threshold) {
retry:
NodeHeader::StatusWord expected_status = header.GetStatus();
// If frozon then retry
if (expected_status.IsFrozen()) {
return ReturnCode::NodeFrozen();
}
auto uniqueness = CheckUnique(key, key_size, pmwcas_pool->GetEpoch());
if (uniqueness == Duplicate) {
return ReturnCode::KeyExists();
}
// Check space to see if we need to split the node
auto new_size = LeafNode::GetUsedSpace(expected_status) +
sizeof(RecordMetadata) +
RecordMetadata::PadKeyLength(key_size) + sizeof(payload);
if (new_size >= split_threshold) {
return ReturnCode::NotEnoughSpace();
}
// Now try to reserve space in the free space region using a PMwCAS. Two
// steps: Step 1. Incrementing the record count and block size fields in
// [status] Step 2. Flip the record metadata entry's high order bit and fill
// in global epoch
NodeHeader::StatusWord desired_status = expected_status;
// Block size includes both key and payload sizes
auto padded_key_size = RecordMetadata::PadKeyLength(key_size);
auto total_size = padded_key_size + sizeof(payload);
desired_status.PrepareForInsert(total_size);
// Get the tentative metadata entry (again, make a local copy to work on it)
RecordMetadata *meta_ptr = &record_metadata[expected_status.GetRecordCount()];
RecordMetadata expected_meta = *meta_ptr;
if (!expected_meta.IsVacant()) {
goto retry;
}
RecordMetadata desired_meta;
desired_meta.PrepareForInsert();
// Now do the PMwCAS
auto pd = pmwcas_pool->AllocateDescriptor();
pd.AddEntry(&(&header.status)->word, expected_status.word,
desired_status.word);
pd.AddEntry(&meta_ptr->meta, expected_meta.meta, desired_meta.meta);
if (!pd.MwCAS()) {
goto retry;
}
// Reserved space! Now copy data
// The key size must be padded to 64bit
uint64_t offset = header.size - desired_status.GetBlockSize();
char *ptr = &(reinterpret_cast<char *>(this))[offset];
memcpy(ptr, key, key_size);
memcpy(ptr + padded_key_size, &payload, sizeof(payload));
// Flush the word
#ifdef PMEM
pmwcas::NVRAM::Flush(total_size, ptr);
#endif
retry_phase2:
// Re-check if the node is frozen
if (uniqueness == ReCheck) {
auto new_uniqueness =
RecheckUnique(key, key_size, expected_status.GetRecordCount());
if (new_uniqueness == Duplicate) {
memset(ptr, 0, key_size);
memset(ptr + padded_key_size, 0, sizeof(payload));
offset = 0;
} else if (new_uniqueness == NodeFrozen) {
return ReturnCode::NodeFrozen();
}
}
// Final step: make the new record visible, a 2-word PMwCAS:
// 1. Metadata - set the visible bit and actual block offset
// 2. Status word - set to the initial value read above (s) to detect
// conflicting threads that are trying to set the frozen bit
auto new_meta = desired_meta;
new_meta.FinalizeForInsert(offset, key_size, total_size);
assert(new_meta.GetTotalLength() < 100);
NodeHeader::StatusWord s = header.GetStatus();
if (s.IsFrozen()) {
return ReturnCode::NodeFrozen();
}
auto pd2 = pmwcas_pool->AllocateDescriptor();
pd2.AddEntry(&(&header.status)->word, s.word, s.word);
pd2.AddEntry(&meta_ptr->meta, desired_meta.meta, new_meta.meta);
if (pd2.MwCAS()) {
return ReturnCode::Ok();
} else {
goto retry_phase2;
}
}
LeafNode::Uniqueness LeafNode::CheckUnique(const char *key, uint32_t key_size,
pmwcas::EpochManager *epoch) {
auto metadata = SearchRecordMeta(epoch, key, key_size, nullptr);
if (metadata.IsVacant()) {
return IsUnique;
}
// we need to perform a key compare again
// consider this case:
// a key is inserting when we "SearchRecordMeta"
// when get back, this meta may have finished inserting, so the following if
// will be false however, this key may not be duplicate, so we need to compare
// the key again even if this key is not duplicate, we need to return a
// "Recheck"
if (metadata.IsInserting()) {
return ReCheck;
}
ALWAYS_ASSERT(metadata.IsVisible());
if (KeyCompare(key, key_size, GetKey(metadata), metadata.GetKeyLength()) ==
0) {
return Duplicate;
}
return ReCheck;
}
LeafNode::Uniqueness LeafNode::RecheckUnique(const char *key, uint32_t key_size,
uint32_t end_pos) {
auto current_status = GetHeader()->GetStatus();
if (current_status.IsFrozen()) {
return NodeFrozen;
}
// Linear search on unsorted field
uint32_t linear_end =
std::min<uint32_t>(header.GetStatus().GetRecordCount(), end_pos);
thread_local std::vector<uint32_t> check_idx;
check_idx.clear();
auto check_metadata = [key, key_size, this](
uint32_t i, bool push) -> LeafNode::Uniqueness {
RecordMetadata md = GetMetadata(i);
if (md.IsInserting()) {
if (push) {
check_idx.push_back(i);
}
return ReCheck;
} else if (md.IsVacant() || !md.IsVisible()) {
return IsUnique;
} else {
ALWAYS_ASSERT(md.IsVisible());
auto len = md.GetKeyLength();
if (key_size == len &&
(KeyCompare(key, key_size, GetKey(md), len) == 0)) {
return Duplicate;
}
return IsUnique;
}
};
for (uint32_t i = header.sorted_count; i < linear_end; i++) {
if (check_metadata(i, true) == Duplicate) {
return Duplicate;
}
}
uint32_t need_check = check_idx.size();
while (need_check > 0) {
for (uint32_t i = 0; i < check_idx.size(); ++i) {
auto result = check_metadata(i, false);
if (result == Duplicate) {
return Duplicate;
} else if (result != ReCheck) {
--need_check;
}
}
}
return IsUnique;
}
ReturnCode LeafNode::Update(const char *key, uint16_t key_size,
uint64_t payload,
pmwcas::DescriptorPool *pmwcas_pool) {
retry:
auto old_status = header.GetStatus();
if (old_status.IsFrozen()) {
return ReturnCode::NodeFrozen();
}
RecordMetadata *meta_ptr = nullptr;
auto metadata =
SearchRecordMeta(pmwcas_pool->GetEpoch(), key, key_size, &meta_ptr);
if (metadata.IsVacant()) {
return ReturnCode::NotFound();
} else if (metadata.IsInserting()) {
goto retry;
}
char *record_key = nullptr;
uint64_t record_payload = 0;
GetRawRecord(metadata, &record_key, &record_payload, pmwcas_pool->GetEpoch());
if (payload == record_payload) {
return ReturnCode::Ok();
}
// 1. Update the corresponding payload
// 2. Make sure meta data is not changed
// 3. Make sure status word is not changed
auto pd = pmwcas_pool->AllocateDescriptor();
pd.AddEntry(
reinterpret_cast<uint64_t *>(record_key + metadata.GetPaddedKeyLength()),
record_payload, payload);
pd.AddEntry(&meta_ptr->meta, metadata.meta, metadata.meta);
pd.AddEntry(&(&header.status)->word, old_status.word, old_status.word);
if (!pd.MwCAS()) {
goto retry;
}
return ReturnCode::Ok();
}
RecordMetadata BaseNode::SearchRecordMeta(pmwcas::EpochManager *epoch,
const char *key, uint32_t key_size,
RecordMetadata **out_metadata_ptr,
uint32_t start_pos, uint32_t end_pos,
bool check_concurrency) {
// Binary search on sorted field
for (uint32_t i = 0; i < header.sorted_count; i++) {
RecordMetadata current = GetMetadata(i);
char *current_key = GetKey(current);
assert(current_key || !is_leaf);
auto cmp_result =
KeyCompare(key, key_size, current_key, current.GetKeyLength());
if (cmp_result == 0) {
if (!current.IsVisible()) {
break;
}
if (out_metadata_ptr) {
*out_metadata_ptr = record_metadata + i;
}
return current;
}
}
// Linear search on unsorted field
// uint32_t linear_end =
// std::min<uint32_t>(header.GetStatus().GetRecordCount(), end_pos);
for (uint32_t i = header.sorted_count;
i < header.GetStatus().GetRecordCount(); i++) {
RecordMetadata current = GetMetadata(i);
if (current.IsInserting()) {
if (check_concurrency) {
// Encountered an in-progress insert, recheck later
if (out_metadata_ptr) {
*out_metadata_ptr = record_metadata + i;
}
return current;
} else {
continue;
}
}
if (current.IsVisible()) {
auto current_size = current.GetKeyLength();
if (current_size == key_size &&
KeyCompare(key, key_size, GetKey(current), current_size) == 0) {
if (out_metadata_ptr) {
*out_metadata_ptr = record_metadata + i;
}
return current;
}
}
}
return RecordMetadata{0};
}
ReturnCode LeafNode::Delete(const char *key, uint16_t key_size,
pmwcas::DescriptorPool *pmwcas_pool) {
retry:
NodeHeader::StatusWord old_status = header.GetStatus();
if (old_status.IsFrozen()) {
return ReturnCode::NodeFrozen();
}
RecordMetadata *meta_ptr = nullptr;
auto metadata =
SearchRecordMeta(pmwcas_pool->GetEpoch(), key, key_size, &meta_ptr);
if (metadata.IsVacant()) {
return ReturnCode::NotFound();
} else if (metadata.IsInserting()) {
// FIXME(hao): not mentioned in the paper, should confirm later;
goto retry;
}
auto new_meta = metadata;
new_meta.SetVisible(false);
auto new_status = old_status;
auto old_delete_size = old_status.GetDeletedSize();
new_status.SetDeleteSize(old_delete_size + metadata.GetTotalLength());
auto pd = pmwcas_pool->AllocateDescriptor();
pd.AddEntry(&(&header.status)->word, old_status.word, new_status.word);
pd.AddEntry(&meta_ptr->meta, metadata.meta, new_meta.meta);
if (!pd.MwCAS()) {
goto retry;
}
return ReturnCode::Ok();
}
ReturnCode LeafNode::Read(const char *key, uint16_t key_size, uint64_t *payload,
pmwcas::DescriptorPool *pmwcas_pool) {
auto meta = SearchRecordMeta(pmwcas_pool->GetEpoch(), key, key_size, nullptr,
0, (uint32_t)-1, false);
if (meta.IsVacant()) {
return ReturnCode::NotFound();
}
char *source_addr = (reinterpret_cast<char *>(this) + meta.GetOffset());
*payload = reinterpret_cast<pmwcas::MwcTargetField<uint64_t> *>(
source_addr + meta.GetPaddedKeyLength())
->GetValueProtected();
return ReturnCode::Ok();
}
ReturnCode LeafNode::RangeScanBySize(const char *key1, uint32_t size1,
uint32_t to_scan,
std::list<std::unique_ptr<Record>> *result,
pmwcas::DescriptorPool *pmwcas_pool) {
thread_local std::vector<Record *> tmp_result;
tmp_result.clear();
if (to_scan == 0) {
return ReturnCode::Ok();
}
// Enter a new epoch and copy data
pmwcas::EpochGuard guard(pmwcas_pool->GetEpoch());
// Have to scan all keys
auto count = header.GetStatus().GetRecordCount();
for (uint32_t i = 0; i < count; ++i) {
auto curr_meta = GetMetadata(i);
if (curr_meta.IsVisible()) {
int cmp =
KeyCompare(key1, size1, GetKey(curr_meta), curr_meta.GetKeyLength());
if (cmp <= 0) {
tmp_result.emplace_back(Record::New(curr_meta, this));
}
}
}
std::sort(tmp_result.begin(), tmp_result.end(),
[this](Record *a, Record *b) -> bool {
auto cmp = KeyCompare(a->GetKey(), a->meta.GetKeyLength(),
b->GetKey(), b->meta.GetKeyLength());
return cmp < 0;
});
for (auto item : tmp_result) {
result->emplace_back(item);
}
return ReturnCode::Ok();
}
ReturnCode LeafNode::RangeScanByKey(const char *key1, uint32_t size1,
const char *key2, uint32_t size2,
std::vector<Record *> *result,
pmwcas::DescriptorPool *pmwcas_pool) {
// entering a new epoch and copying the data
pmwcas::EpochGuard guard(pmwcas_pool->GetEpoch());
// scan the sorted fields first
uint32_t i = 0;
auto count = header.GetStatus().GetRecordCount();
while (i < count) {
auto curr_meta = GetMetadata(i);
if (!curr_meta.IsVisible()) {
i += 1;
continue;
}
char *curr_key;
GetRawRecord(curr_meta, &curr_key, nullptr, pmwcas_pool->GetEpoch());
auto range_code = KeyInRange(curr_key, curr_meta.GetKeyLength(), key1,
size1, key2, size2);
if (range_code == 0) {
result->emplace_back(Record::New(curr_meta, this));
} else if (range_code == 1 && i < header.sorted_count) {
// current key is larger than upper bound
// jump to the unsorted field
i = header.sorted_count;
continue;
}
i += 1;
}
std::sort(
result->begin(), result->end(), [this](Record *a, Record *b) -> bool {
auto cmp = BaseNode::KeyCompare(a->GetKey(), a->meta.GetKeyLength(),
b->GetKey(), b->meta.GetKeyLength());
return cmp < 0;
});
return ReturnCode::Ok();
}
bool BaseNode::Freeze(pmwcas::DescriptorPool *pmwcas_pool) {
NodeHeader::StatusWord expected = header.GetStatus();
if (expected.IsFrozen()) {
return false;
}
auto pd = pmwcas_pool->AllocateDescriptor();
pd.AddEntry(&(&header.status)->word, expected.word, expected.Freeze().word);
return pd.MwCAS();
}
LeafNode *LeafNode::Consolidate(pmwcas::DescriptorPool *pmwcas_pool) {
// Freeze the node to prevent new modifications first
if (!Freeze(pmwcas_pool)) {
return nullptr;
}
thread_local std::vector<RecordMetadata> meta_vec;
meta_vec.clear();
SortMetadataByKey(meta_vec, true, pmwcas_pool->GetEpoch());
// Allocate and populate a new node
LeafNode *new_leaf = nullptr;
LeafNode::New(&new_leaf, this->header.size);
new_leaf->CopyFrom(this, meta_vec.begin(), meta_vec.end(),
pmwcas_pool->GetEpoch());
#ifdef PMEM
pmwcas::NVRAM::Flush(this->header.size, new_leaf);
#endif
return new_leaf;
}
uint32_t LeafNode::SortMetadataByKey(std::vector<RecordMetadata> &vec,
bool visible_only,
pmwcas::EpochManager *epoch) {
// Node is frozen at this point
// there should not be any on-going pmwcas
assert(header.status.IsFrozen());
uint32_t total_size = 0;
uint32_t count = header.GetStatus().GetRecordCount();
for (uint32_t i = 0; i < count; ++i) {
// TODO(tzwang): handle deletes
auto meta = record_metadata[i];
if (meta.IsVisible()) {
vec.emplace_back(meta);
total_size += (meta.GetTotalLength());
assert(meta.GetTotalLength());
}
}
// Lambda for comparing two keys
auto key_cmp = [this](RecordMetadata &m1, RecordMetadata &m2) -> bool {
auto l1 = m1.GetKeyLength();
auto l2 = m2.GetKeyLength();
char *k1 = GetKey(m1);
char *k2 = GetKey(m2);
return KeyCompare(k1, l1, k2, l2) < 0;
};
std::sort(vec.begin(), vec.end(), key_cmp);
return total_size;
}
void LeafNode::CopyFrom(LeafNode *node,
std::vector<RecordMetadata>::iterator begin_it,
std::vector<RecordMetadata>::iterator end_it,
pmwcas::EpochManager *epoch) {
// meta_vec is assumed to be in sorted order, insert records one by one
uint32_t offset = this->header.size;
uint16_t nrecords = 0;
for (auto it = begin_it; it != end_it; ++it) {
auto meta = *it;
uint64_t payload = 0;
char *key;
node->GetRawRecord(meta, &key, &payload, epoch);
// Copy data
assert(meta.GetTotalLength() >= sizeof(uint64_t));
uint64_t total_len = meta.GetTotalLength();
assert(offset >= total_len);
offset -= total_len;
char *ptr = &(reinterpret_cast<char *>(this))[offset];
memcpy(ptr, key, total_len);
// Setup new metadata
record_metadata[nrecords].FinalizeForInsert(offset, meta.GetKeyLength(),
total_len);
++nrecords;
}