CHANGELOG.md

Unreleased

New Features

• #1178 batches and transactions are now unified for subscribers.
• #1231 Tree::get_zero_copy allows for reading a value directly in-place without making an IVec first.
• #1250 the global print_profile function has been added which is enabled when compiling with the metrics feature.
• #1254 IVec data will now always have an alignment of 8, which may enable interesting architecture-specific use cases.
• #1307 & #1315 Db::contains_tree can be used to see if a Tree with a given name already exists.

Improvements

• #1214 a new slab-style storage engine has been added which replaces the previous file-per-blob technique for storing large pages.
• #1231 tree nodes now get merged into a single-allocation representation that is able to dynamically avoid various overheads, resulting in significant efficiency improvements.

Breaking Changes

• #1400 Bump MSRV to 1.57.
• #1399 Thread support is now required on all platforms.
• #1135 The "no_metrics" anti-feature has been replaced with the "metrics" positive feature.
• #1178 the Event enum has become a unified struct that allows subscribers to iterate over each (Tree, key, optional value) involved in single key operations, batches, or transactions in a unified way.
• #1178 the Event::key method has been removed in favor of the new more comprehensive iter method.
• #1214 The deprecated Config::build method has been removed.
• #1248 The deprecated Tree::set method has been removed.
• #1248 The deprecated Tree::del method has been removed.
• #1250 The Config::print_profile_on_drop method has been removed in favor of the global print_profile function.
• #1252 The deprecated Db::open method has been removed.
• #1252 The deprecated Config::segment_cleanup_skew method has been removed.
• #1252 The deprecated Config::segment_cleanup_threshold method has been removed.
• #1252 The deprecated Config::snapshot_path method has been removed.
• #1253 The IVec::subslice method has been removed.
• #1275 Keys and values are now limited to 128gb on 64-bit platforms and 512mb on 32-bit platforms.
• #1281 Config's cache_capacity is now a usize, as u64 doesn't make sense for things that must fit in memory anyway.
• #1314 Subscriber::next_timeout now requires a mutable self reference.
• #1349 The "measure_allocs" feature has been removed.
• #1354 Error has been modified to be Copy, removing all heap-allocated variants.

Bug Fixes

• #1202 Fix a space leak where blobs were not removed when replaced by another blob.
• #1229 the powerful ALICE crash consistency tool has been used to discover several crash vulnerabilities, now fixed.

0.34.7

Bug Fixes

• #1314 Fix a bug in Subscriber's Future impl.

0.34.6

Improvements

• documentation improved

0.34.5

Improvements

• #1164 widen some trait bounds on trees and batches

0.34.4

New Features

• #1151 Send is implemented for Iter
• #1167 added Tree::first and Tree::last functions to retrieve the first or last items in a Tree, unless the Tree is empty.

Bug Fixes

• #1159 dropping a Db instance will no-longer prematurely shut-down the background flusher thread.
• #1168 fixed an issue that was causing panics during recovery in 32-bit code.
• #1170 when encountering corrupted storage data, the recovery process will panic less often.

0.34.3

New Features

• #1146 added TransactionalTree::generate_id

0.34.2

Improvements

• #1133 transactions and writebatch performance has been significantly improved by removing a bottleneck in the atomic batch stability tracking code.

0.34.1

New Features

• #1136 Added the TransactionalTree::flush method to flush the underlying database after the transaction commits and before the transaction returns.

0.34

Improvements

• #1132 implemented Fromsled::Error for io::Error to reduce friction in some situations.

Breaking Changes

• #1131 transactions performed on Trees from different Dbs will now safely fail.
• #1131 transactions may now only be performed on tuples of up to 14 elements. For higher numbers, please use slices.

0.33

Breaking Changes

• #1125 the backtrace crate has been made optional, which cuts several seconds off compilation time, but may cause breakage if you interacted with the backtrace field of corruption-related errors.

Bug Fixes

• #1128 Tree::pop_min and Tree::pop_max had a bug where they were not atomic.

0.32.1

New Features

• #1116 IVec::subslice has been added to facilitate creating zero-copy subsliced IVecs that are backed by the same data.

Bug Fixes

• #1120 Fixed a use-after-free caused by missing ref keyword on a Copy type in a pattern match in IVec::as_mut.
• #1108 conversions from Box<[u8]> to IVec are fixed.

0.32

New Features

• #1079 Transactional is now implemented for [&Tree] and [Tree] so you can avoid the previous friction of using tuples, as was necessary previously.
• #1058 The minimum supported Rust version (MSRV) is now 1.39.0.
• #1037 Subscriber now implements Future (non-fused) so prefix watching may now be iterated over via while let Some(event) = (&mut subscriber).await {}

Improvements

• #965 concurrency control is now dynamically enabled for atomic point operations, so that it may be avoided unless transactional functionality is being used in the system. This significantly increases performance for workloads that do not use transactions.
• A number of memory optimizations have been implemented.
• Disk usage has been significantly reduced for many workloads.
• #1016 On 64-bit systems, we can now store 1-2 trillion items.
• #993 Added DerefMut and AsMut<[u8]> for IVec where it works similarly to a Cow, making a private copy if the backing Arc's strong count is not 1.
• #1020 The sled wiki has been moved into the documentation itself, and is accessible through the doc module exported in lib.

Breaking Changes

• #975 Changed the default segment_size from 8m to 512k. This will result in far smaller database files due to better file garbage collection granularity.
• #975 deprecated several Config options that will be removed over time.
• #1000 rearranged some transaction-related imports, and moved them to the transaction module away from the library root to keep the top level docs clean.
• #1015 TransactionalTree::apply_batch now accepts its argument by reference instead of by value.
• Event has been changed to make the inner fields named instead of anonymous.
• #1057 read-only mode has been removed due to not having the resources to properly keep it tested while making progress on high priority issues. This may be correctly implemented in the future if resources permit.
• The conversion between Box<[u8]> and IVec has been temporarily removed. This is re-added in 0.32.1.

0.31

Improvements

• #947 dramatic read and recovery optimizations
• #921 reduced the reliance on locks while performing multithreaded IO on windows.
• #928 use sync_file_range on linux instead of a full fsync for most writes.
• #946 io_uring support changed to the rio crate
• #939 reduced memory consumption during zstd decompression

Breaking Changes

• #927 use SQLite-style varints for serializing u64. This dramatically reduces the written bytes for databases that store small keys and values.
• #943 use varints for most of the fields in message headers, causing an additional large space reduction. combined with #927, these changes reduce bytes written by 68% for workloads writing small items.

0.30.3

• Documentation-only release

0.30.2

New Features

• Added the open function for quickly opening a database at a path with default configuration.

0.30.1

Bugfixes

• Fixed an issue where an idle threadpool worker would spin in a hot loop until work arrived

0.30

Breaking Changes

• Migrated to a new storage format

Bugfixes

• Fixed a bug where cache was not being evicted.
• Fixed a bug with using transactions with compression.

0.29.2

New Features

• The create_new option has been added to Config, allowing the user to specify that a database should only be freshly created, rather than re-opened.

0.29.1

Bugfixes

• Fixed a bug where prefix encoding could be incorrectly handled when merging nodes together.

0.29

New Features

• The Config::open method has been added to give Config a similar feel to std's fs::OpenOptions. The Config::build and Db::start methods are now deprecated in favor of calling Config::open directly.
• A checksum method has been added to Tree and Db for use in verifying backups and migrations.
• Transactions may now involve up to 69 different tables. Nice.
• The TransactionError::Abort variant has had a generic member added that can be returned as a way to return information from a manually-aborted transaction. An abort helper function has been added to reduce the boiler- plate required to return aborted results.

Breaking Changes

• The ConfigBuilder structure has been removed in favor of a simplified Config structure with the same functionality.
• The way that sled versions are detected at initialization time is now independent of serde.
• The cas method is deprecated in favor of the new compare_and_swap method which now returns the proposed value that failed to be applied.
• Tree nodes now have constant prefix encoding lengths.
• The io_buf_size configurable renamed to segment_size.
• The io_buf_size configurable method has been removed from ConfigBuilder. This can be manually set by setting the attribute directly on the ConfigBuilder, but this is discouraged. Additionally, this must now be a power of 2.
• The page_consolidation_threshold method has been removed from ConfigBuilder, and this is now a constant of 10.

0.28

Breaking Changes

• Iter no longer has a lifetime parameter.
• Db::open_tree now returns a Tree instead of an Arc<Tree>. Tree now has an inner type that uses an Arc, so you don't need to think about it.

Bug Fixes

• A bug with prefix encoding has been fixed that led to nodes with keys longer than 256 bytes being stored incorrectly, which led to them being inaccessible and also leading to infinite loops during iteration.
• Several cases of incorrect unsafe code were removed from the sled crate. No bugs are known to have been encountered, but they may have resulted in incorrect optimizations in future refactors.

0.27

Breaking Changes

• Event::Set has been renamed to Event::Insert and Event::Del has been renamed to Event::Remove. These names better align with the methods of BTreeMap from the standard library.

Bug Fixes

• A deadlock was possible in very high write volume situations when the segment accountant lock was taken by all IO threads while a task was blocked trying to submit a file truncation request to the threadpool while holding the segment accountant lock.

New Features

• flush_async has been added to perform time-intensive flushing in an asynchronous manner, returning a Future.

0.26.1

Improvements

• std::thread is no longer used on platforms other than linux, macos, and windows, which increases portability.

0.26

New Features

• Transactions! You may now call Tree::transaction and perform reads, writes, and deletes within a provided closure with a TransactionalTree argument. This closure may be called multiple times if the transaction encounters a concurrent update in the process of its execution. Transactions may also be used on tuples of Tree objects, where the closure will then be parameterized on TransactionalTree instances providing access to each of the provided Tree instances. This allows you to atomically read and modify multiple Tree instances in a single atomic operation. These transactions are serializable, fully ACID, and optimistic.
• Tree::apply_batch allows you to apply a Batch
• TransactionalTree::apply_batch allow you to apply a Batch from within a transaction.

Breaking Changes

• Tree::batch has been removed. Now you can directly create a Batch with Batch::default() and then apply it to a Tree with Tree::apply_batch or during a transaction using TransactionalTree::apply_batch. This facilitates multi-Tree batches via transactions.
• Event::Merge has been removed, and Tree::merge will now send a complete Event::Set item to be distributed to all listening subscribers.