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pigweed / pigweed / pigweed / 2d4016940ecd04d96977a53eeca29b91f593880c / . / pw_kvs / key_value_store.cc
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// Copyright 2020 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#include "pw_kvs/key_value_store.h"
#include <algorithm>
#include <cinttypes>
#include <cstring>
#include <type_traits>
#define PW_LOG_USE_ULTRA_SHORT_NAMES 1
#include "pw_kvs_private/entry.h"
#include "pw_kvs_private/macros.h"
#include "pw_log/log.h"
namespace pw::kvs {
using std::byte;
using std::string_view;
KeyValueStore::KeyValueStore(FlashPartition* partition,
const EntryHeaderFormat& format,
const Options& options)
: partition_(*partition),
entry_header_format_(format),
options_(options),
sectors_(partition_.sector_count()),
last_new_sector_(sectors_.data()),
working_buffer_{} {}
Status KeyValueStore::Init() {
if (kMaxUsableSectors < sectors_.size()) {
CRT("KeyValueStore::kMaxUsableSectors must be at least as large as the "
"number of sectors in the flash partition");
return Status::FAILED_PRECONDITION;
}
if (kMaxUsableSectors > sectors_.size()) {
DBG("KeyValueStore::kMaxUsableSectors is %zu sectors larger than needed",
kMaxUsableSectors - sectors_.size());
}
// Reset the number of occupied key descriptors; we will fill them later.
key_descriptors_.clear();
// TODO: init last_new_sector_ to a random sector. Since the on-flash stored
// information does not allow recovering the previous last_new_sector_ after
// clean start, random is a good second choice.
const size_t sector_size_bytes = partition_.sector_size_bytes();
if (working_buffer_.size() < sector_size_bytes) {
CRT("ERROR: working_buffer_ (%zu bytes) is smaller than sector "
"size (%zu bytes)",
working_buffer_.size(),
sector_size_bytes);
return Status::INVALID_ARGUMENT;
}
DBG("First pass: Read all entries from all sectors");
for (size_t sector_id = 0; sector_id < sectors_.size(); ++sector_id) {
// Track writable bytes in this sector. Updated after reading each entry.
sectors_[sector_id].tail_free_bytes = sector_size_bytes;
const Address sector_address = sector_id * sector_size_bytes;
Address entry_address = sector_address;
for (int num_entries_in_sector = 0;; num_entries_in_sector++) {
DBG("Load entry: sector=%zu, entry#=%d, address=%zu",
sector_id,
num_entries_in_sector,
size_t(entry_address));
if (!AddressInSector(sectors_[sector_id], entry_address)) {
DBG("Fell off end of sector; moving to the next sector");
break;
}
Address next_entry_address;
Status status = LoadEntry(entry_address, &next_entry_address);
if (status == Status::NOT_FOUND) {
DBG("Hit un-written data in sector; moving to the next sector");
break;
}
if (status == Status::DATA_LOSS) {
// It's not clear KVS can make a unilateral decision about what to do
// in corruption cases. It's an application decision, for which we
// should offer some configurability. For now, entirely bail out of
// loading and give up.
//
// Later, scan for remaining valid keys; since it's entirely possible
// that there is a duplicate of the key elsewhere and everything is
// fine. Later, we can wipe and maybe recover the sector.
//
// TODO: Implement rest-of-sector scanning for valid entries.
return Status::DATA_LOSS;
}
TRY(status);
// Entry loaded successfully; so get ready to load the next one.
entry_address = next_entry_address;
// Update of the number of writable bytes in this sector.
sectors_[sector_id].tail_free_bytes =
sector_size_bytes - (entry_address - sector_address);
}
}
DBG("Second pass: Count valid bytes in each sector");
// Initialize the sector sizes.
for (SectorDescriptor& sector : sectors_) {
sector.valid_bytes = 0;
}
// For every valid key, increment the valid bytes for that sector.
for (KeyDescriptor& key_descriptor : key_descriptors_) {
uint32_t sector_id = key_descriptor.address / sector_size_bytes;
Entry header;
TRY(ReadEntryHeader(key_descriptor.address, &header));
sectors_[sector_id].valid_bytes += header.size();
}
initialized_ = true;
return Status::OK;
}
Status KeyValueStore::LoadEntry(Address entry_address,
Address* next_entry_address) {
Entry header;
TRY(ReadEntryHeader(entry_address, &header));
// TODO: Should likely add a "LogHeader" method or similar.
DBG("Header: ");
DBG(" Address = 0x%zx", size_t(entry_address));
DBG(" Magic = 0x%zx", size_t(header.magic()));
DBG(" Checksum = 0x%zx", size_t(header.checksum()));
DBG(" Key length = 0x%zx", size_t(header.key_length()));
DBG(" Value length = 0x%zx", size_t(header.value_length()));
DBG(" Entry size = 0x%zx", size_t(header.size()));
DBG(" Alignment = 0x%zx", size_t(header.alignment_bytes()));
if (HeaderLooksLikeUnwrittenData(header)) {
return Status::NOT_FOUND;
}
// TODO: Handle multiple magics for formats that have changed.
if (header.magic() != entry_header_format_.magic) {
// TODO: It may be cleaner to have some logging helpers for these cases.
CRT("Found corrupt magic: %zx; expecting %zx; at address %zx",
size_t(header.magic()),
size_t(entry_header_format_.magic),
size_t(entry_address));
return Status::DATA_LOSS;
}
// Read the key from flash & validate the entry (which reads the value).
KeyBuffer key_buffer;
TRY(ReadEntryKey(entry_address, header.key_length(), key_buffer.data()));
const string_view key(key_buffer.data(), header.key_length());
TRY(header.VerifyChecksumInFlash(
&partition_, entry_address, entry_header_format_.checksum));
KeyDescriptor key_descriptor(
key,
header.key_version(),
entry_address,
header.deleted() ? KeyDescriptor::kDeleted : KeyDescriptor::kValid);
DBG("Key hash: %zx (%zu)",
size_t(key_descriptor.key_hash),
size_t(key_descriptor.key_hash));
TRY(AppendNewOrOverwriteStaleExistingDescriptor(key_descriptor));
// TODO: Extract this to something like "NextValidEntryAddress".
*next_entry_address = key_descriptor.address + header.size();
return Status::OK;
}
// TODO: This method is the trigger of the O(valid_entries * all_entries) time
// complexity for reading. At some cost to memory, this could be optimized by
// using a hash table instead of scanning, but in practice this should be fine
// for a small number of keys
Status KeyValueStore::AppendNewOrOverwriteStaleExistingDescriptor(
const KeyDescriptor& key_descriptor) {
// With the new key descriptor, either add it to the descriptor table or
// overwrite an existing entry with an older version of the key.
KeyDescriptor* existing_descriptor = FindDescriptor(key_descriptor.key_hash);
if (existing_descriptor) {
if (existing_descriptor->key_version < key_descriptor.key_version) {
// Existing entry is old; replace the existing entry with the new one.
*existing_descriptor = key_descriptor;
} else {
// Otherwise, check for data integrity and leave the existing entry.
if (existing_descriptor->key_version == key_descriptor.key_version) {
ERR("Data loss: Duplicated old(=%zu) and new(=%zu) version",
size_t(existing_descriptor->key_version),
size_t(key_descriptor.key_version));
return Status::DATA_LOSS;
}
DBG("Found stale entry when appending; ignoring");
}
return Status::OK;
}
// Write new entry.
KeyDescriptor* newly_allocated_key_descriptor;
TRY(AppendEmptyDescriptor(&newly_allocated_key_descriptor));
*newly_allocated_key_descriptor = key_descriptor;
return Status::OK;
}
// TODO: Need a better name.
Status KeyValueStore::AppendEmptyDescriptor(KeyDescriptor** new_descriptor) {
if (key_descriptors_.full()) {
// TODO: Is this the right return code?
return Status::RESOURCE_EXHAUSTED;
}
key_descriptors_.emplace_back();
*new_descriptor = &key_descriptors_.back();
return Status::OK;
}
// TODO: Finish.
bool KeyValueStore::HeaderLooksLikeUnwrittenData(const Entry& header) const {
// TODO: This is not correct; it should call through to flash memory.
return header.magic() == 0xffffffff;
}
KeyValueStore::KeyDescriptor* KeyValueStore::FindDescriptor(uint32_t hash) {
for (KeyDescriptor& key_descriptor : key_descriptors_) {
if (key_descriptor.key_hash == hash) {
return &key_descriptor;
}
}
return nullptr;
}
StatusWithSize KeyValueStore::Get(string_view key,
span<byte> value_buffer) const {
TRY_WITH_SIZE(CheckOperation(key));
const KeyDescriptor* key_descriptor;
TRY_WITH_SIZE(FindExistingKeyDescriptor(key, &key_descriptor));
Entry header;
TRY_WITH_SIZE(ReadEntryHeader(key_descriptor->address, &header));
StatusWithSize result = ReadEntryValue(*key_descriptor, header, value_buffer);
if (result.ok() && options_.verify_on_read) {
Status verify_result =
header.VerifyChecksum(entry_header_format_.checksum,
key,
value_buffer.subspan(0, result.size()));
if (!verify_result.ok()) {
std::memset(
value_buffer.subspan(0, result.size()).data(), 0, result.size());
return StatusWithSize(verify_result);
}
return StatusWithSize(verify_result, result.size());
}
return result;
}
Status KeyValueStore::Put(string_view key, span<const byte> value) {
DBG("Writing key/value; key length=%zu, value length=%zu",
key.size(),
value.size());
TRY(CheckOperation(key));
if (value.size() > (1 << 24)) {
// TODO: Reject sizes that are larger than the maximum?
}
KeyDescriptor* key_descriptor;
Status status = FindKeyDescriptor(key, &key_descriptor);
if (status.ok()) {
DBG("Writing over existing entry for key 0x%08" PRIx32 " in sector %zu",
key_descriptor->key_hash,
SectorIndex(SectorFromAddress(key_descriptor->address)));
return WriteEntryForExistingKey(
key_descriptor, KeyDescriptor::kValid, key, value);
}
if (status == Status::NOT_FOUND) {
return WriteEntryForNewKey(key, value);
}
return status;
}
Status KeyValueStore::Delete(string_view key) {
TRY(CheckOperation(key));
KeyDescriptor* key_descriptor;
TRY(FindExistingKeyDescriptor(key, &key_descriptor));
DBG("Writing tombstone for existing key 0x%08" PRIx32 " in sector %zu",
key_descriptor->key_hash,
SectorIndex(SectorFromAddress(key_descriptor->address)));
return WriteEntryForExistingKey(
key_descriptor, KeyDescriptor::kDeleted, key, {});
}
KeyValueStore::iterator& KeyValueStore::iterator::operator++() {
// Skip to the next entry that is valid (not deleted).
while (++index_ < item_.kvs_.key_descriptors_.size() &&
descriptor().deleted()) {
}
return *this;
}
const KeyValueStore::Item& KeyValueStore::iterator::operator*() {
std::memset(item_.key_buffer_.data(), 0, item_.key_buffer_.size());
Entry header;
if (item_.kvs_.ReadEntryHeader(descriptor().address, &header).ok()) {
item_.kvs_.ReadEntryKey(
descriptor().address, header.key_length(), item_.key_buffer_.data());
}
return item_;
}
KeyValueStore::iterator KeyValueStore::begin() const {
size_t i = 0;
// Skip over any deleted entries at the start of the descriptor list.
while (i < key_descriptors_.size() && key_descriptors_[i].deleted()) {
i += 1;
}
return iterator(*this, i);
}
// TODO(hepler): The valid entry count could be tracked in the KVS to avoid the
// need for this for-loop.
size_t KeyValueStore::size() const {
size_t valid_entries = 0;
for (const KeyDescriptor& key_descriptor : key_descriptors_) {
if (!key_descriptor.deleted()) {
valid_entries += 1;
}
}
return valid_entries;
}
StatusWithSize KeyValueStore::ValueSize(std::string_view key) const {
TRY_WITH_SIZE(CheckOperation(key));
const KeyDescriptor* key_descriptor;
TRY_WITH_SIZE(FindExistingKeyDescriptor(key, &key_descriptor));
Entry header;
TRY_WITH_SIZE(ReadEntryHeader(key_descriptor->address, &header));
return StatusWithSize(header.value_length());
}
uint32_t KeyValueStore::HashKey(string_view string) {
uint32_t hash = 0;
uint32_t coefficient = 65599u;
for (char ch : string) {
hash += coefficient * unsigned(ch);
coefficient *= 65599u;
}
return hash;
}
Status KeyValueStore::FixedSizeGet(std::string_view key,
byte* value,
size_t size_bytes) const {
// Ensure that the size of the stored value matches the size of the type.
// Otherwise, report error. This check avoids potential memory corruption.
StatusWithSize result = ValueSize(key);
if (!result.ok()) {
return result.status();
}
if (result.size() != size_bytes) {
DBG("Requested %zu B read, but value is %zu B", size_bytes, result.size());
return Status::INVALID_ARGUMENT;
}
return Get(key, span(value, size_bytes)).status();
}
Status KeyValueStore::CheckOperation(string_view key) const {
if (InvalidKey(key)) {
return Status::INVALID_ARGUMENT;
}
if (!initialized_) {
return Status::FAILED_PRECONDITION;
}
return Status::OK;
}
// Searches for a KeyDescriptor that matches this key and sets *result to point
// to it if one is found.
//
// OK: there is a matching descriptor and *result is set
// NOT_FOUND: there is no descriptor that matches this key, but this key
// has a unique hash (and could potentially be added to the KVS)
// ALREADY_EXISTS: there is no descriptor that matches this key, but the
// key's hash collides with the hash for an existing descriptor
//
Status KeyValueStore::FindKeyDescriptor(string_view key,
const KeyDescriptor** result) const {
char key_buffer[kMaxKeyLength];
const uint32_t hash = HashKey(key);
for (auto& descriptor : key_descriptors_) {
if (descriptor.key_hash == hash) {
TRY(ReadEntryKey(descriptor.address, key.size(), key_buffer));
if (key == string_view(key_buffer, key.size())) {
DBG("Found match for key hash 0x%08" PRIx32, hash);
*result = &descriptor;
return Status::OK;
} else {
WRN("Found key hash collision for 0x%08" PRIx32, hash);
return Status::ALREADY_EXISTS;
}
}
}
return Status::NOT_FOUND;
}
// Searches for a KeyDescriptor that matches this key and sets *result to point
// to it if one is found.
//
// OK: there is a matching descriptor and *result is set
// NOT_FOUND: there is no descriptor that matches this key
//
Status KeyValueStore::FindExistingKeyDescriptor(
string_view key, const KeyDescriptor** result) const {
Status status = FindKeyDescriptor(key, result);
// If the key's hash collides with an existing key or if the key is deleted,
// treat it as if it is not in the KVS.
if (status == Status::ALREADY_EXISTS ||
(status.ok() && (*result)->deleted())) {
return Status::NOT_FOUND;
}
return status;
}
Status KeyValueStore::ReadEntryHeader(Address address, Entry* header) const {
return partition_.Read(address, sizeof(*header), header).status();
}
Status KeyValueStore::ReadEntryKey(Address address,
size_t key_length,
char* key) const {
// TODO: This check probably shouldn't be here; this is like
// checking that the Cortex M's RAM isn't corrupt. This should be
// done at boot time.
// ^^ This argument sometimes comes from Entry::key_value_len,
// which is read directly from flash. If it's corrupted, we shouldn't try
// to read a bunch of extra data.
if (key_length == 0u || key_length > kMaxKeyLength) {
return Status::DATA_LOSS;
}
// The key is immediately after the entry header.
return partition_.Read(address + sizeof(EntryHeader), key_length, key)
.status();
}
StatusWithSize KeyValueStore::ReadEntryValue(
const KeyDescriptor& key_descriptor,
const Entry& header,
span<byte> value) const {
const size_t read_size = std::min(header.value_length(), value.size());
StatusWithSize result = partition_.Read(
key_descriptor.address + sizeof(header) + header.key_length(),
value.subspan(0, read_size));
TRY_WITH_SIZE(result);
if (read_size != header.value_length()) {
return StatusWithSize(Status::RESOURCE_EXHAUSTED, read_size);
}
return StatusWithSize(read_size);
}
Status KeyValueStore::WriteEntryForExistingKey(KeyDescriptor* key_descriptor,
KeyDescriptor::State new_state,
string_view key,
span<const byte> value) {
// Find the original entry and sector to update the sector's valid_bytes.
Entry original_entry;
TRY(ReadEntryHeader(key_descriptor->address, &original_entry));
SectorDescriptor* old_sector = SectorFromAddress(key_descriptor->address);
SectorDescriptor* sector;
TRY(FindOrRecoverSectorWithSpace(
&sector, Entry::size(partition_.alignment_bytes(), key, value)));
DBG("Writing existing entry; found sector: %zu", SectorIndex(sector));
if (old_sector != SectorFromAddress(key_descriptor->address)) {
DBG("Sector for old entry (size %zu) was garbage collected. Old entry "
"relocated to sector %zu",
original_entry.size(),
SectorIndex(SectorFromAddress(key_descriptor->address)));
old_sector = SectorFromAddress(key_descriptor->address);
}
TRY(AppendEntry(sector, key_descriptor, key, value, new_state));
old_sector->RemoveValidBytes(original_entry.size());
return Status::OK;
}
Status KeyValueStore::WriteEntryForNewKey(string_view key,
span<const byte> value) {
if (key_descriptors_.full()) {
WRN("KVS full: trying to store a new entry, but can't. Have %zu entries",
key_descriptors_.size());
return Status::RESOURCE_EXHAUSTED;
}
// Create the KeyDescriptor that will be added to the list. The version and
// address will be set by AppendEntry.
KeyDescriptor key_descriptor(key, 0, 0);
SectorDescriptor* sector;
TRY(FindOrRecoverSectorWithSpace(
&sector, Entry::size(partition_.alignment_bytes(), key, value)));
DBG("Writing new entry; found sector: %zu", SectorIndex(sector));
TRY(AppendEntry(sector, &key_descriptor, key, value, KeyDescriptor::kValid));
// Only add the entry when we are certain the write succeeded.
key_descriptors_.push_back(key_descriptor);
return Status::OK;
}
Status KeyValueStore::RelocateEntry(KeyDescriptor& key_descriptor) {
struct TempEntry {
std::array<char, kMaxKeyLength + 1> key;
std::array<char, sizeof(working_buffer_) - sizeof(key)> value;
};
TempEntry* entry = reinterpret_cast<TempEntry*>(working_buffer_.data());
DBG("Relocating entry"); // TODO: add entry info to the log statement.
// Read the entry to be relocated. Store the header in a local variable and
// store the key and value in the TempEntry stored in the static allocated
// working_buffer_.
Entry header;
TRY(ReadEntryHeader(key_descriptor.address, &header));
TRY(ReadEntryKey(
key_descriptor.address, header.key_length(), entry->key.data()));
string_view key = string_view(entry->key.data(), header.key_length());
StatusWithSize result = ReadEntryValue(
key_descriptor, header, as_writable_bytes(span(entry->value)));
if (!result.status().ok()) {
return Status::INTERNAL;
}
auto value = span(entry->value.data(), result.size());
TRY(header.VerifyChecksum(
entry_header_format_.checksum, key, as_bytes(value)));
SectorDescriptor* old_sector = SectorFromAddress(key_descriptor.address);
// Find a new sector for the entry and write it to the new location.
SectorDescriptor* new_sector;
TRY(FindSectorWithSpace(&new_sector, header.size(), old_sector, true));
TRY(AppendEntry(
new_sector, &key_descriptor, key, as_bytes(value), key_descriptor.state));
// Do the valid bytes accounting for the sector the entry was relocated out
// of.
old_sector->RemoveValidBytes(header.size());
return Status::OK;
}
// Find either an existing sector with enough space that is not the sector to
// skip, or an empty sector. Maintains the invariant that there is always at
// least 1 empty sector unless set to bypass the rule.
Status KeyValueStore::FindSectorWithSpace(
SectorDescriptor** found_sector,
size_t size,
const SectorDescriptor* sector_to_skip,
bool bypass_empty_sector_rule) {
// The last_new_sector_ is the sector that was last selected as the "new empty
// sector" to write to. This last new sector is used as the starting point for
// the next "find a new empty sector to write to" operation. By using the last
// new sector as the start point we will cycle which empty sector is selected
// next, spreading the wear across all the empty sectors and get a wear
// leveling benefit, rather than putting more wear on the lower number
// sectors.
//
// Locally use the sector index for ease of iterating through the sectors. For
// the persistent storage use SectorDescriptor* rather than sector index
// because SectorDescriptor* is the standard way to identify a sector.
size_t last_new_sector_index_ = SectorIndex(last_new_sector_);
size_t start = (last_new_sector_index_ + 1) % sectors_.size();
SectorDescriptor* first_empty_sector = nullptr;
bool at_least_two_empty_sectors = bypass_empty_sector_rule;
DBG("Find sector with %zu bytes available", size);
if (sector_to_skip != nullptr) {
DBG(" Skip sector %zu", SectorIndex(sector_to_skip));
}
if (bypass_empty_sector_rule) {
DBG(" Bypassing empty sector rule");
}
// Look for a partial sector to use with enough space. Immediately use the
// first one of those that is found. While scanning for a partial sector, keep
// track of the first empty sector and if a second sector was seen.
for (size_t j = 0; j < sectors_.size(); j++) {
size_t i = (j + start) % sectors_.size();
SectorDescriptor& sector = sectors_[i];
if (sector_to_skip == &sector) {
DBG(" Skipping the skip sector %zu", i);
continue;
}
DBG(" Examining sector %zu with %hu bytes available",
i,
sector.tail_free_bytes);
if (!SectorEmpty(sector) && sector.HasSpace(size)) {
DBG(" Partially occupied sector %zu with enough space; done!", i);
*found_sector = &sector;
return Status::OK;
}
if (SectorEmpty(sector)) {
if (first_empty_sector == nullptr) {
first_empty_sector = &sector;
} else {
at_least_two_empty_sectors = true;
}
}
}
// If the scan for a partial sector does not find a suitable sector, use the
// first empty sector that was found. Normally it is required to keep 1 empty
// sector after the sector found here, but that rule can be bypassed in
// special circumstances (such as during garbage collection).
if (at_least_two_empty_sectors) {
DBG(" Found a usable empty sector; returning the first found (%zu)",
SectorIndex(first_empty_sector));
last_new_sector_ = first_empty_sector;
*found_sector = first_empty_sector;
return Status::OK;
}
// No sector was found.
DBG(" Unable to find a usable sector");
*found_sector = nullptr;
return Status::RESOURCE_EXHAUSTED;
}
Status KeyValueStore::FindOrRecoverSectorWithSpace(SectorDescriptor** sector,
size_t size) {
Status result = FindSectorWithSpace(sector, size);
if (result == Status::RESOURCE_EXHAUSTED && options_.partial_gc_on_write) {
// Garbage collect and then try again to find the best sector.
TRY(GarbageCollectOneSector());
return FindSectorWithSpace(sector, size);
}
return result;
}
KeyValueStore::SectorDescriptor* KeyValueStore::FindSectorToGarbageCollect() {
SectorDescriptor* sector_candidate = nullptr;
size_t candidate_bytes = 0;
// Step 1: Try to find a sectors with stale keys and no valid keys (no
// relocation needed). If any such sectors are found, use the sector with the
// most reclaimable bytes.
for (auto& sector : sectors_) {
if ((sector.valid_bytes == 0) &&
(RecoverableBytes(sector) > candidate_bytes)) {
sector_candidate = &sector;
candidate_bytes = RecoverableBytes(sector);
}
}
// Step 2: If step 1 yields no sectors, just find the sector with the most
// reclaimable bytes.
if (sector_candidate == nullptr) {
for (auto& sector : sectors_) {
if (RecoverableBytes(sector) > candidate_bytes) {
sector_candidate = &sector;
candidate_bytes = RecoverableBytes(sector);
}
}
}
if (sector_candidate != nullptr) {
DBG("Found sector %zu to Garbage Collect, %zu recoverable bytes",
SectorIndex(sector_candidate),
RecoverableBytes(*sector_candidate));
} else {
DBG("Unable to find sector to garbage collect!");
}
return sector_candidate;
}
Status KeyValueStore::GarbageCollectOneSector() {
DBG("Garbage Collect a single sector");
// Step 1: Find the sector to garbage collect
SectorDescriptor* sector_to_gc = FindSectorToGarbageCollect();
LogSectors();
if (sector_to_gc == nullptr) {
return Status::RESOURCE_EXHAUSTED;
}
// Step 2: Move any valid entries in the GC sector to other sectors
if (sector_to_gc->valid_bytes != 0) {
for (auto& descriptor : key_descriptors_) {
if (AddressInSector(*sector_to_gc, descriptor.address)) {
DBG(" Relocate entry");
TRY(RelocateEntry(descriptor));
}
}
}
if (sector_to_gc->valid_bytes != 0) {
ERR(" Failed to relocate valid entries from sector being garbage "
"collected, %hu valid bytes remain",
sector_to_gc->valid_bytes);
return Status::INTERNAL;
}
// Step 3: Reinitialize the sector
sector_to_gc->tail_free_bytes = 0;
TRY(partition_.Erase(SectorBaseAddress(sector_to_gc), 1));
sector_to_gc->tail_free_bytes = partition_.sector_size_bytes();
DBG(" Garbage Collect complete");
LogSectors();
return Status::OK;
}
Status KeyValueStore::AppendEntry(SectorDescriptor* sector,
KeyDescriptor* key_descriptor,
const string_view key,
span<const byte> value,
KeyDescriptor::State new_state) {
// write header, key, and value
Entry header;
if (new_state == KeyDescriptor::kDeleted) {
header = Entry::Tombstone(entry_header_format_.magic,
entry_header_format_.checksum,
key,
partition_.alignment_bytes(),
key_descriptor->key_version + 1);
} else {
header = Entry::Valid(entry_header_format_.magic,
entry_header_format_.checksum,
key,
value,
partition_.alignment_bytes(),
key_descriptor->key_version + 1);
}
DBG("Appending %zu B entry with key version: %x",
header.size(),
unsigned(header.key_version()));
Address address = NextWritableAddress(sector);
DBG("Appending to address: %#zx", size_t(address));
// Write multiple concatenated buffers and pad the results.
FlashPartition::Output flash(partition_, address);
TRY_ASSIGN(const size_t written,
AlignedWrite<32>(
flash,
header.alignment_bytes(),
{as_bytes(span(&header, 1)), as_bytes(span(key)), value}));
if (options_.verify_on_write) {
TRY(header.VerifyChecksumInFlash(
&partition_, address, entry_header_format_.checksum));
}
key_descriptor->address = address;
key_descriptor->key_version = header.key_version();
key_descriptor->state = new_state;
sector->valid_bytes += written;
sector->RemoveFreeBytes(written);
return Status::OK;
}
void KeyValueStore::LogDebugInfo() {
const size_t sector_size_bytes = partition_.sector_size_bytes();
DBG("====================== KEY VALUE STORE DUMP =========================");
DBG(" ");
DBG("Flash partition:");
DBG(" Sector count = %zu", partition_.sector_count());
DBG(" Sector max count = %zu", kMaxUsableSectors);
DBG(" Sectors in use = %zu", sectors_.size());
DBG(" Sector size = %zu", sector_size_bytes);
DBG(" Total size = %zu", partition_.size_bytes());
DBG(" Alignment = %zu", partition_.alignment_bytes());
DBG(" ");
DBG("Key descriptors:");
DBG(" Entry count = %zu", key_descriptors_.size());
DBG(" Max entry count = %zu", kMaxEntries);
DBG(" ");
DBG(" # hash version address address (hex)");
for (size_t i = 0; i < key_descriptors_.size(); ++i) {
const KeyDescriptor& kd = key_descriptors_[i];
DBG(" |%3zu: | %8zx |%8zu | %8zu | %8zx",
i,
size_t(kd.key_hash),
size_t(kd.key_version),
size_t(kd.address),
size_t(kd.address));
}
DBG(" ");
DBG("Sector descriptors:");
DBG(" # tail free valid has_space");
for (size_t sector_id = 0; sector_id < sectors_.size(); ++sector_id) {
const SectorDescriptor& sd = sectors_[sector_id];
DBG(" |%3zu: | %8zu |%8zu | %s",
sector_id,
size_t(sd.tail_free_bytes),
size_t(sd.valid_bytes),
sd.tail_free_bytes ? "YES" : "");
}
DBG(" ");
// TODO: This should stop logging after some threshold.
// size_t dumped_bytes = 0;
DBG("Sector raw data:");
for (size_t sector_id = 0; sector_id < sectors_.size(); ++sector_id) {
// Read sector data. Yes, this will blow the stack on embedded.
std::array<byte, 500> raw_sector_data; // TODO!!!
StatusWithSize sws =
partition_.Read(sector_id * sector_size_bytes, raw_sector_data);
DBG("Read: %zu bytes", sws.size());
DBG(" base addr offs 0 1 2 3 4 5 6 7");
for (size_t i = 0; i < sector_size_bytes; i += 8) {
DBG(" %3zu %8zx %5zu | %02x %02x %02x %02x %02x %02x %02x %02x",
sector_id,
(sector_id * sector_size_bytes) + i,
i,
static_cast<unsigned int>(raw_sector_data[i + 0]),
static_cast<unsigned int>(raw_sector_data[i + 1]),
static_cast<unsigned int>(raw_sector_data[i + 2]),
static_cast<unsigned int>(raw_sector_data[i + 3]),
static_cast<unsigned int>(raw_sector_data[i + 4]),
static_cast<unsigned int>(raw_sector_data[i + 5]),
static_cast<unsigned int>(raw_sector_data[i + 6]),
static_cast<unsigned int>(raw_sector_data[i + 7]));
// TODO: Fix exit condition.
if (i > 128) {
break;
}
}
DBG(" ");
}
DBG("////////////////////// KEY VALUE STORE DUMP END /////////////////////");
}
void KeyValueStore::LogSectors() const {
DBG("Sector descriptors: count %zu", sectors_.size());
for (auto& sector : sectors_) {
DBG(" - Sector %zu: valid %hu, recoverable %zu, free %hu",
SectorIndex(&sector),
sector.valid_bytes,
RecoverableBytes(sector),
sector.tail_free_bytes);
}
}
void KeyValueStore::LogKeyDescriptor() const {
DBG("Key descriptors: count %zu", key_descriptors_.size());
for (auto& key : key_descriptors_) {
DBG(" - Key: %s, hash %#zx, version %zu, address %#zx",
key.deleted() ? "Deleted" : "Valid",
static_cast<size_t>(key.key_hash),
static_cast<size_t>(key.key_version),
static_cast<size_t>(key.address));
}
}
void KeyValueStore::SectorDescriptor::RemoveValidBytes(size_t size) {
// TODO: add safety check for valid_bytes > size.
if (size > valid_bytes) {
CRT("!!!!!!!!!!!!!!!");
CRT("Remove too many valid bytes!!! remove %zu, only have %hu",
size,
valid_bytes);
valid_bytes = size;
}
valid_bytes -= size;
}
} // namespace pw::kvs