| // 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(FindKeyDescriptor(key, &key_descriptor)); |
| |
| if (key_descriptor->deleted()) { |
| return StatusWithSize(Status::NOT_FOUND); |
| } |
| |
| 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; |
| if (FindKeyDescriptor(key, &key_descriptor).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); |
| } |
| |
| return WriteEntryForNewKey(key, value); |
| } |
| |
| Status KeyValueStore::Delete(string_view key) { |
| TRY(CheckOperation(key)); |
| |
| KeyDescriptor* key_descriptor; |
| TRY(FindKeyDescriptor(key, &key_descriptor)); |
| |
| if (key_descriptor->deleted()) { |
| return Status::NOT_FOUND; |
| } |
| |
| 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(FindKeyDescriptor(key, &key_descriptor)); |
| |
| if (key_descriptor->deleted()) { |
| return StatusWithSize(Status::NOT_FOUND); |
| } |
| |
| 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; |
| } |
| |
| 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; |
| } |
| } |
| } |
| return Status::NOT_FOUND; |
| } |
| |
| 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( |
| §or, 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( |
| §or, 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 == §or) { |
| 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 = §or; |
| return Status::OK; |
| } |
| |
| if (SectorEmpty(sector)) { |
| if (first_empty_sector == nullptr) { |
| first_empty_sector = §or; |
| } 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.ok()) { |
| return result; |
| } |
| if (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 = §or; |
| 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 = §or; |
| 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(§or), |
| 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 |