Dalli Changelog
=====================

Unreleased
==========

5.0.5
==========

Performance:

- Batch multi-key commands into a single write to reduce packet overhead (#1107)
  - With `TCP_NODELAY` set on sockets, each `write` call emits a separate packet; the meta protocol was calling `write` up to 3 times per key in multi-key operations (`get_multi`, `set_multi`, `delete_multi`), significantly increasing network traffic compared to the old binary protocol
  - Multi-key request paths now buffer all per-key commands into a single binary string and flush once; single-key paths combine the write and flush into one `flushed_write` call
  - Thanks to Jean Boussier for this contribution

- Avoid repeated `RUBY_ENGINE` checks on every socket read (#1103)
  - Moved the JRuby branch from a runtime `if` inside `ConnectionManager#read` to a class-level conditional method definition, so the check happens once at load time rather than on every read call
  - Thanks to Jean Boussier for this contribution

- Eliminate per-call array allocations in `ResponseProcessor` (#1104)
  - Token sets passed to `error_on_unexpected!` (e.g. `[VA, EN, HD]`) were allocated as new arrays on every invocation; replaced with frozen constants defined once at class load time
  - Thanks to Jean Boussier for this contribution

- Avoid string copies when building request commands in `RequestFormatter` (#1106)
  - Changed `cmd + TERMINATOR` to `cmd << TERMINATOR`; since `cmd` is always a mutable string, the in-place append avoids copying the entire command string just to append two bytes
  - Thanks to Jean Boussier for this contribution

5.0.4
==========

Bug fixes:

- Fix `string_fastpath` flag collision with compression (#1099)
  - `ValueSerializer::FLAG_UTF8` and `ValueCompressor::FLAG_COMPRESSED` were both `0x2`, causing `Dalli::UnmarshalError` on any UTF-8 string written with `string_fastpath: true` when compression is enabled, and silent encoding corruption for binary strings
  - Introduces `Dalli::Flags` to centralise bit flag constants; UTF8 is reassigned to `0x4`
  - Adds regression test covering short/long UTF-8, binary, and cross-client read scenarios
  - Thanks to Jean Boussier and Mikael Henriksson for the fix and regression test

- Fix client-level `string_fastpath: true` being silently ignored (#1101)
  - `Dalli::Client.new(servers, string_fastpath: true)` had no effect; the fast path was only taken when `string_fastpath: true` was passed as a per-request option on each `set` call
  - Per-request option continues to take precedence over the client-level setting in both directions

5.0.3
==========

Performance:

- Eliminate double array allocation in `Client#perform` (#1093)
  - Changed method signature from `perform(*all_args)` with destructuring to `perform(op, key, *args)`, letting Ruby decompose arguments directly without intermediate array allocations
  - Reduces benchmark time by ~39% across all Dalli operations (get, set, delete, etc.)
  - Thanks to Sam Obeid for this contribution

Features:

- Support `connect_timeout:` keyword argument with `resolv-replace` >= 0.2.0, which now correctly forwards keyword arguments through its `TCPSocket` patch (#1096)

- Add `Dalli::Instrumentation.disable!` to allow disabling OpenTelemetry instrumentation at runtime (#1088)
  - Also exposes `Dalli::Instrumentation.tracer=` for setting a custom tracer

5.0.2
==========

Performance:

- Add single-server fast path for `get_multi`, `set_multi`, and `delete_multi` (#1077)
  - When only one memcached server is configured, bypass the `Pipelined*` machinery (IO.select, response buffering, server grouping) and issue all quiet meta requests inline followed by a noop terminator
  - `get_multi` shows ~1.5x improvement at 10 keys and ~1.75x at 100–500 keys compared to the `PipelinedGetter` path
  - Thanks to Dan Mayer (Shopify) for this contribution

Development:

- Add `bin/benchmark_branch` script for benchmarking against the current branch

5.0.1
==========

Performance:

- Reduce object allocations in pipelined get response processing (#1072, #1078)
  - Offset-based `ResponseBuffer`: track a read offset instead of slicing a new string after every parsed response; compact only when the consumed portion exceeds 4KB and more than half the buffer
  - Inline response processor parsing: avoid intermediate array allocations from `split`-based header parsing
  - Block-based `pipeline_next_responses`: yield `(key, value, cas)` directly when a block is given, avoiding per-call Hash allocation
  - `PipelinedGetter`: replace Hash-based socket-to-server mapping with linear scan (faster for typical 1-5 server counts); use `Process.clock_gettime(CLOCK_MONOTONIC)` instead of `Time.now`
- Add cross-version benchmark script (`bin/compare_versions`) for reproducible performance comparisons across Dalli versions

Bug Fixes:

- Rescue `IOError` in connection manager `write`/`flush` methods (#1075)
  - Prevents unhandled exceptions when a connection is closed mid-operation
  - Thanks to Graham Cooper (Shopify) for this fix

Development:

- Add `rubocop-thread_safety` for detecting thread-safety issues (#1076)
- Add CONTRIBUTING.md with AI contribution policy (#1074)

5.0.0
==========

**Breaking Changes:**

- **Removed binary protocol** - The meta protocol is now the only supported protocol
  - The `:protocol` option is no longer used
  - Requires memcached 1.6+ (for meta protocol support)
  - Users on older memcached versions must upgrade or stay on Dalli 4.x

- **Removed SASL authentication** - The meta protocol does not support authentication
  - Use network-level security (firewall rules, VPN) or memcached's TLS support instead
  - Users requiring SASL authentication must stay on Dalli 4.x with binary protocol

- **Ruby 3.3+ required** - Dropped support for Ruby 3.1 and 3.2
  - Ruby 3.2 reached end-of-life in March 2026
  - JRuby remains supported

Performance:

- **~7% read performance improvement** (CRuby only)
  - Use native `IO#read` instead of custom `readfull` implementation
  - Enabled by Ruby 3.3's `IO#timeout=` support
  - JRuby continues to use `readfull` for compatibility

OpenTelemetry:

- Migrate to stable OTel semantic conventions (#1070)
  - `db.system` renamed to `db.system.name`
  - `db.operation` renamed to `db.operation.name`
  - `server.address` now contains hostname only; `server.port` is a separate integer attribute
  - `get_with_metadata` and `fetch_with_lock` now include `server.address`/`server.port`
- Add `db.query.text` span attribute with configurable modes
  - `:otel_db_statement` option: `:include`, `:obfuscate`, or `nil` (default: omitted)
- Add `peer.service` span attribute
  - `:otel_peer_service` option for logical service naming

Internal:

- Simplified protocol directory structure: moved `lib/dalli/protocol/meta/*` to `lib/dalli/protocol/`
- Removed deprecated binary protocol files and SASL authentication code
- Removed `require 'set'` (autoloaded in Ruby 3.3+)

4.3.3
==========

Performance:

- Reduce object allocations in pipelined get response processing (#1072)
  - Offset-based `ResponseBuffer`: track a read offset instead of slicing a new string after every parsed response; compact only when the consumed portion exceeds 4KB and more than half the buffer
  - Inline response processor parsing: avoid intermediate array allocations from `split`-based header parsing in both binary and meta protocols
  - Block-based `pipeline_next_responses`: yield `(key, value, cas)` directly when a block is given, avoiding per-call Hash allocation
  - `PipelinedGetter`: replace Hash-based socket-to-server mapping with linear scan (faster for typical 1-5 server counts); use `Process.clock_gettime(CLOCK_MONOTONIC)` instead of `Time.now`
- Add cross-version benchmark script (`bin/compare_versions`) for reproducible performance comparisons across Dalli versions

Bug Fixes:

- Skip OTel integration tests when meta protocol is unavailable (#1072)

4.3.2
==========

OpenTelemetry:

- Migrate to stable OTel semantic conventions
  - `db.system` renamed to `db.system.name`
  - `db.operation` renamed to `db.operation.name`
  - `server.address` now contains hostname only; `server.port` is a separate integer attribute
  - `get_with_metadata` and `fetch_with_lock` now include `server.address`/`server.port`
- Add `db.query.text` span attribute with configurable modes
  - `:otel_db_statement` option: `:include`, `:obfuscate`, or `nil` (default: omitted)
- Add `peer.service` span attribute
  - `:otel_peer_service` option for logical service naming

4.3.1
==========

Bug Fixes:

- Fix socket compatibility with gems that monkey-patch TCPSocket (#996, #1012)
  - Gems like `socksify` and `resolv-replace` modify `TCPSocket#initialize`, breaking Ruby 3.0+'s `connect_timeout:` keyword argument
  - Detection now uses parameter signature checking instead of gem-specific method detection
  - Falls back to `Timeout.timeout` when monkey-patching is detected
  - Detection result is cached for performance

- Fix network retry bug with `socket_max_failures: 0` (#1065)
  - Previously, setting `socket_max_failures: 0` could still cause retries due to error handling
  - Introduced `RetryableNetworkError` subclass to distinguish retryable vs non-retryable errors
  - `down!` now raises non-retryable `NetworkError`, `reconnect!` raises `RetryableNetworkError`
  - Thanks to Graham Cooper (Shopify) for this fix

- Fix "character class has duplicated range" Ruby warning (#1067)
  - Fixed regex in `KeyManager::VALID_NAMESPACE_SEPARATORS` that caused warnings on newer Ruby versions
  - Thanks to Hartley McGuire for this fix

Improvements:

- Add StrictWarnings test helper to catch Ruby warnings early (#1067)

- Use bulk attribute setter for OpenTelemetry spans (#1068)
  - Reduces lock acquisitions when setting span attributes
  - Thanks to Robert Laurin (Shopify) for this optimization

- Fix double recording of exceptions on OpenTelemetry spans (#1069)
  - OpenTelemetry's `in_span` method already records exceptions and sets error status automatically
  - Removed redundant explicit exception recording that caused exceptions to appear twice in traces
  - Thanks to Robert Laurin (Shopify) for this fix

4.3.0
==========

New Features:

- Add `namespace_separator` option to customize the separator between namespace and key (#1019)
  - Default is `:` for backward compatibility
  - Must be a single non-alphanumeric character (e.g., `:`, `/`, `|`, `.`)
  - Example: `Dalli::Client.new(servers, namespace: 'myapp', namespace_separator: '/')`

Bug Fixes:

- Fix architecture-dependent struct timeval packing for socket timeouts (#1034)
  - Detects correct pack format for time_t and suseconds_t on each platform
  - Fixes timeout issues on architectures with 64-bit time_t

- Fix get_multi hanging with large key counts (#776, #941)
  - Add interleaved read/write for pipelined gets to prevent socket buffer deadlock
  - For batches over 10,000 keys per server, requests are now sent in chunks

- **Breaking:** Enforce string-only values in raw mode (#1022)
  - `set(key, nil, raw: true)` now raises `MarshalError` instead of storing `""`
  - `set(key, 123, raw: true)` now raises `MarshalError` instead of storing `"123"`
  - This matches the behavior of client-level `raw: true` mode
  - To store counters, use string values: `set('counter', '0', raw: true)`

CI:

- Add TruffleRuby to CI test matrix (#988)

4.2.0
==========

Performance:

- Buffered I/O: Use `socket.sync = false` with explicit flush to reduce syscalls for pipelined operations
- get_multi optimizations: Use Set for O(1) server tracking lookups
- Raw mode optimization: Skip bitflags request in meta protocol when in raw mode (saves 2 bytes per request)

New Features:

- OpenTelemetry tracing support: Automatically instruments operations when OpenTelemetry SDK is present
  - Zero overhead when OpenTelemetry is not loaded
  - Traces `get`, `set`, `delete`, `get_multi`, `set_multi`, `delete_multi`, `get_with_metadata`, and `fetch_with_lock`
  - Spans include `db.system: memcached` and `db.operation` attributes
  - Single-key operations include `server.address` attribute
  - Multi-key operations include `db.memcached.key_count` attribute
  - `get_multi` spans include `db.memcached.hit_count` and `db.memcached.miss_count` for cache efficiency metrics
  - Exceptions are automatically recorded on spans with error status

4.1.0
==========

New Features:

- Add `set_multi` for efficient bulk set operations using pipelined requests
- Add `delete_multi` for efficient bulk delete operations using pipelined requests
- Add `fetch_with_lock` for thundering herd protection using meta protocol's vivify/recache flags (requires memcached 1.6+)
- Add thundering herd protection support to meta protocol (requires memcached 1.6+):
  - `N` (vivify) flag for creating stubs on cache miss
  - `R` (recache) flag for winning recache race when TTL is below threshold
  - Response flags `W` (won recache), `X` (stale), `Z` (lost race)
  - `delete_stale` method for marking items as stale instead of deleting
- Add `get_with_metadata` for advanced cache operations with metadata retrieval (requires memcached 1.6+):
  - Returns hash with `:value`, `:cas`, `:won_recache`, `:stale`, `:lost_recache`
  - Optional `:return_hit_status` returns `:hit_before` (true/false for previous access)
  - Optional `:return_last_access` returns `:last_access` (seconds since last access)
  - Optional `:skip_lru_bump` prevents LRU update on access
  - Optional `:vivify_ttl` and `:recache_ttl` for thundering herd protection

Deprecations:

- Binary protocol is deprecated and will be removed in Dalli 5.0. Use `protocol: :meta` instead (requires memcached 1.6+)
- SASL authentication is deprecated and will be removed in Dalli 5.0. Consider using network-level security or memcached's TLS support

4.0.1
==========

- Add `:raw` client option to skip serialization entirely, returning raw byte strings
- Handle `OpenSSL::SSL::SSLError` in connection manager

4.0.0
==========

BREAKING CHANGES:

- Require Ruby 3.1+ (dropped support for Ruby 2.6, 2.7, and 3.0)
- Removed `Dalli::Server` deprecated alias - use `Dalli::Protocol::Binary` instead
- Removed `:compression` option - use `:compress` instead
- Removed `close_on_fork` method - use `reconnect_on_fork` instead

Other changes:

- Add security warning when using default Marshal serializer (silence with `silence_marshal_warning: true`)
- Add defense-in-depth input validation for stats command arguments
- Add `string_fastpath` option to skip serialization for simple strings (byroot)
- Meta protocol set performance improvement (danmayer)
- Fix connection_pool 3.0 compatibility for Rack session store
- Fix session recovery after deletion (stengineering0)
- Fix cannot read response data included terminator `\r\n` when use meta protocol (matsubara0507)
- Support SERVER_ERROR response from Memcached as per the [memcached spec](https://github.com/memcached/memcached/blob/e43364402195c8e822bb8f88755a60ab8bbed62a/doc/protocol.txt#L172) (grcooper)
- Update Socket timeout handling to use Socket#timeout= when available (nickamorim)
- Serializer: reraise all .load errors as UnmarshalError (olleolleolle)
- Reconnect gracefully when a fork is detected instead of crashing (PatrickTulskie)
- Update CI to test against memcached 1.6.40

3.2.8
==========

- Handle IO::TimeoutError when establishing connection (eugeneius)
- Drop dependency on base64 gem (Earlopain)
- Address incompatibility with resolv-replace (y9v)
- Add rubygems.org metadata (m-nakamura145)

3.2.7
==========

- Fix cascading error when there's an underlying network error in a pipelined get (eugeneius)
- Ruby 3.4/head compatibility by adding base64 to gemspec (tagliala)
- Add Ruby 3.3 to CI (m-nakamura145)
- Use Socket's connect_timeout when available, and pass timeout to the socket's send and receive timeouts (mlarraz)

3.2.6
==========

- Rescue IO::TimeoutError raised by Ruby since 3.2.0 on blocking reads/writes (skaes)
- Fix rubydoc link (JuanitoFatas)

3.2.5
==========

- Better handle memcached requests being interrupted by Thread#raise or Thread#kill (byroot)
- Unexpected errors are no longer treated as `Dalli::NetworkError`, including errors raised by `Timeout.timeout` (byroot)

3.2.4
==========

- Cache PID calls for performance since glibc no longer caches in recent versions (byroot)
- Preallocate the read buffer in Socket#readfull (byroot)

3.2.3
==========

- Sanitize CAS inputs to ensure additional commands are not passed to memcached (xhzeem / petergoldstein)
- Sanitize input to flush command to ensure additional commands are not passed to memcached (xhzeem / petergoldstein)
- Namespaces passed as procs are now evaluated every time, as opposed to just on initialization (nrw505)
- Fix missing require of uri in ServerConfigParser (adam12)
- Fix link to the CHANGELOG.md file in README.md (rud)

3.2.2
==========

- Ensure apps are resilient against old session ids (kbrock)

3.2.1
==========

- Fix null replacement bug on some SASL-authenticated services (veritas1)

3.2.0
==========

- BREAKING CHANGE: Remove protocol_implementation client option (petergoldstein)
- Add protocol option with meta implementation (petergoldstein)

3.1.6
==========

- Fix bug with cas/cas! with "Not found" value (petergoldstein)
- Add Ruby 3.1 to CI (petergoldstein)
- Replace reject(&:nil?) with compact (petergoldstein)

3.1.5
==========

- Fix bug with get_cas key with "Not found" value (petergoldstein)
- Replace should return nil, not raise error, on miss (petergoldstein)

3.1.4
==========

- Improve response parsing performance (byroot)
- Reorganize binary protocol parsing a bit (petergoldstein)
- Fix handling of non-ASCII keys in get_multi (petergoldstein)

3.1.3
==========

- Restore falsey behavior on delete/delete_cas for nonexistent key (petergoldstein)

3.1.2
==========

- Make quiet? / multi? public on Dalli::Protocol::Binary (petergoldstein)

3.1.1
==========

- Add quiet support for incr, decr, append, depend, and flush (petergoldstein)
- Additional refactoring to allow reuse of connection behavior (petergoldstein)
- Fix issue in flush such that it wasn't passing the delay argument to memcached (petergoldstein)

3.1.0
==========

- BREAKING CHANGE: Update Rack::Session::Dalli to inherit from Abstract::PersistedSecure.  This will invalidate existing sessions (petergoldstein)
- BREAKING CHANGE: Use of unsupported operations in a multi block now raise an error. (petergoldstein)
- Extract PipelinedGetter from Dalli::Client (petergoldstein)
- Fix SSL socket so that it works with pipelined gets (petergoldstein)
- Additional refactoring to split classes (petergoldstein)

3.0.6
==========

- Fix regression in SASL authentication response parsing (petergoldstein)

3.0.5
==========

- Add Rubocop and fix most outstanding issues (petergoldstein)
- Extract a number of classes, to simplify the largest classes (petergoldstein)
- Ensure against socket corruption if an error occurs in a multi block (petergoldstein)

3.0.4
==========

- Clean connections and retry after NetworkError in get_multi (andrejbl)
- Internal refactoring and cleanup (petergoldstein)

3.0.3
==========

- Restore ability for `compress` to be disabled on a per request basis (petergoldstein)
- Fix broken image in README (deining)
- Use bundler-cache in CI (olleolleolle)
- Remove the OpenSSL extensions dependency (petergoldstein)
- Add Memcached 1.5.x to the CI matrix
- Updated compression documentation (petergoldstein)

3.0.2
==========

- Restore Windows compatibility (petergoldstein)
- Add JRuby to CI and make requisite changes (petergoldstein)
- Clarify documentation for supported rubies (petergoldstein)

3.0.1
==========

- Fix syntax error that prevented inclusion of Dalli::Server (ryanfb)
- Restore with method required by ActiveSupport::Cache::MemCacheStore

3.0.0
==========
- BREAKING CHANGES:

  * Removes :dalli_store.
    Use Rails' official :mem_cache_store instead.
    https://guides.rubyonrails.org/caching_with_rails.html
  * Attempting to store a larger value than allowed by memcached used to
    print a warning and truncate the value. This now raises an error to
    prevent silent data corruption.
  * Compression now defaults to `true` for large values (greater than 4KB).
    This is intended to minimize errors due to the previous note.
  * Errors marshalling values now raise rather than just printing an error.
  * The Rack session adapter has been refactored to remove support for thread-unsafe
    configurations. You will need to include the `connection_pool` gem in
    your Gemfile to ensure session operations are thread-safe.
  * When using namespaces, the algorithm for calculating truncated keys was
    changed.  Non-truncated keys and truncated keys for the non-namespace
    case were left unchanged.

- Raise NetworkError when multi response gets into corrupt state (mervync, #783)
- Validate servers argument (semaperepelitsa, petergoldstein, #776)
- Enable SSL support (bdunne, #775)
- Add gat operation (tbeauvais, #769)
- Removes inline native code, use Ruby 2.3+ support for bsearch instead. (mperham)
- Switch repo to Github Actions and upgrade Ruby versions (petergoldstein, bdunne, Fryguy)
- Update benchmark test for Rubyprof changes (nateberkopec)
- Remove support for the `kgio` gem, it is not relevant in Ruby 2.3+. (mperham)
- Remove inline native code, use Ruby 2.3+ support for bsearch instead. (mperham)


2.7.11
==========
- DEPRECATION: :dalli_store will be removed in Dalli 3.0.
  Use Rails' official :mem_cache_store instead.
  https://guides.rubyonrails.org/caching_with_rails.html
- Add new `digest_class` option to Dalli::Client [#724]
- Don't treat NameError as a network error [#728]
- Handle nested comma separated server strings (sambostock)

2.7.10
==========
- Revert frozen string change (schneems)
- Advertise supports_cached_versioning? in DalliStore (schneems)
- Better detection of fork support, to allow specs to run under Truffle Ruby (deepj)
- Update logging for over max size to log as error (aeroastro)

2.7.9
==========
- Fix behavior for Rails 5.2+ cache_versioning (GriwMF)
- Ensure fetch provides the key to the fallback block as an argument (0exp)
- Assorted performance improvements (schneems)

2.7.8
==========
- Rails 5.2 compatibility (pbougie)
- Fix Session Cache compatibility (pixeltrix)

2.7.7
==========
- Support large cache keys on fetch multi (sobrinho)
- Not found checks no longer trigger the result's equality method (dannyfallon)
- Use SVG build badges (olleolleolle)
- Travis updates (junaruga, tiarly, petergoldstein)
- Update default down_retry_delay (jaredhales)
- Close kgio socket after IO.select timeouts
- Documentation updates (tipair)
- Instrument DalliStore errors with instrument_errors configuration option. (btatnall)

2.7.6
==========
- Rails 5.0.0.beta2 compatibility (yui-knk, petergoldstein)
- Add cas!, a variant of the #cas method that yields to the block whether or not the key already exist (mwpastore)
- Performance improvements (nateberkopec)
- Add Ruby 2.3.0 to support matrix (tricknotes)

2.7.5
==========

- Support rcvbuff and sndbuff byte configuration. (btatnall)
- Add `:cache_nils` option to support nil values in `DalliStore#fetch` and `Dalli::Client#fetch` (wjordan, #559)
- Log retryable server errors with 'warn' instead of 'info' (phrinx)
- Fix timeout issue with Dalli::Client#get_multi_yielder (dspeterson)
- Escape namespaces with special regexp characters (Steven Peckins)
- Ensure LocalCache supports the `:raw` option and Entry unwrapping (sj26)
- Ensure bad ttl values don't cause Dalli::RingError (eagletmt, petergoldstein)
- Always pass namespaced key to instrumentation API (kaorimatz)
- Replace use of deprecated TimeoutError with Timeout::Error (eagletmt)
- Clean up gemspec, and use Bundler for loading (grosser)
- Dry up local cache testing (grosser)

2.7.4
==========

- Restore Windows compatibility (dfens, #524)

2.7.3
==========

- Assorted spec improvements
- README changes to specify defaults for failover and compress options (keen99, #470)
- SASL authentication changes to deal with Unicode characters (flypiggy, #477)
- Call to_i on ttl to accomodate ActiveSupport::Duration (#494)
- Change to implicit blocks for performance (glaucocustodio, #495)
- Change to each_key for performance (jastix, #496)
- Support stats settings - (dterei, #500)
- Raise DallError if hostname canno be parsed (dannyfallon, #501)
- Fix instrumentation for falsey values (AlexRiedler, #514)
- Support UNIX socket configurations (r-stu31, #515)

2.7.2
==========

- The fix for #423 didn't make it into the released 2.7.1 gem somehow.

2.7.1
==========

- Rack session will check if servers are up on initialization (arthurnn, #423)
- Add support for IPv6 addresses in hex form, ie: "[::1]:11211" (dplummer, #428)
- Add symbol support for namespace (jingkai #431)
- Support expiration intervals longer than 30 days (leonid-shevtsov #436)

2.7.0
==========

- BREAKING CHANGE:
  Dalli::Client#add and #replace now return a truthy value, not boolean true or false.
- Multithreading support with dalli\_store:
  Use :pool\_size to create a pool of shared, threadsafe Dalli clients in Rails:
```ruby
    config.cache_store = :dalli_store, "cache-1.example.com", "cache-2.example.com", :compress => true, :pool_size => 5, :expires_in => 300
```
  This will ensure the Rails.cache singleton does not become a source of contention.
  **PLEASE NOTE** Rails's :mem\_cache\_store does not support pooling as of
Rails 4.0.  You must use :dalli\_store.

- Implement `version` for retrieving version of connected servers [dterei, #384]
- Implement `fetch_multi` for batched read/write [sorentwo, #380]
- Add more support for safe updates with multiple writers: [philipmw, #395]
  `require 'dalli/cas/client'` augments Dalli::Client with the following methods:
  * Get value with CAS:            `[value, cas] = get_cas(key)`
                                   `get_cas(key) {|value, cas| ...}`
  * Get multiple values with CAS:  `get_multi_cas(k1, k2, ...) {|value, metadata| cas = metadata[:cas]}`
  * Set value with CAS:            `new_cas = set_cas(key, value, cas, ttl, options)`
  * Replace value with CAS:        `replace_cas(key, new_value, cas, ttl, options)`
  * Delete value with CAS:         `delete_cas(key, cas)`
- Fix bug with get key with "Not found" value [uzzz, #375]

2.6.4
=======

- Fix ADD command, aka `write(unless_exist: true)` (pitr, #365)
- Upgrade test suite from mini\_shoulda to minitest.
- Even more performance improvements for get\_multi (xaop, #331)

2.6.3
=======

- Support specific stats by passing `:items` or `:slabs` to `stats` method [bukhamseen]
- Fix 'can't modify frozen String' errors in `ActiveSupport::Cache::DalliStore` [dblock]
- Protect against objects with custom equality checking [theron17]
- Warn if value for key is too large to store [locriani]

2.6.2
=======

- Properly handle missing RubyInline

2.6.1
=======

- Add optional native C binary search for ring, add:

gem 'RubyInline'

  to your Gemfile to get a 10% speedup when using many servers.
  You will see no improvement if you are only using one server.

- More get_multi performance optimization [xaop, #315]
- Add lambda support for cache namespaces [joshwlewis, #311]

2.6.0
=======

- read_multi optimization, now checks local_cache [chendo, #306]
- Re-implement get_multi to be non-blocking [tmm1, #295]
- Add `dalli` accessor to dalli_store to access the underlying
Dalli::Client, for things like `get_multi`.
- Add `Dalli::GzipCompressor`, primarily for compatibility with nginx's HttpMemcachedModule using `memcached_gzip_flag`

2.5.0
=======

- Don't escape non-ASCII keys, memcached binary protocol doesn't care. [#257]
- :dalli_store now implements LocalCache [#236]
- Removed lots of old session_store test code, tests now all run without a default memcached server [#275]
- Changed Dalli ActiveSupport adapter to always attempt instrumentation [brianmario, #284]
- Change write operations (add/set/replace) to return false when value is too large to store [brianmario, #283]
- Allowing different compressors per client [naseem]

2.4.0
=======
- Added the ability to swap out the compressed used to [de]compress cache data [brianmario, #276]
- Fix get\_multi performance issues with lots of memcached servers [tmm1]
- Throw more specific exceptions [tmm1]
- Allowing different types of serialization per client [naseem]

2.3.0
=======
- Added the ability to swap out the serializer used to [de]serialize cache data [brianmario, #274]

2.2.1
=======

- Fix issues with ENV-based connections. [#266]
- Fix problem with SessionStore in Rails 4.0 [#265]

2.2.0
=======

- Add Rack session with\_lock helper, for Rails 4.0 support [#264]
- Accept connection string in the form of a URL (e.g., memcached://user:pass@hostname:port) [glenngillen]
- Add touch operation [#228, uzzz]

2.1.0
=======

- Add Railtie to auto-configure Dalli when included in Gemfile [#217, steveklabnik]

2.0.5
=======

- Create proper keys for arrays of objects passed as keys [twinturbo, #211]
- Handle long key with namespace [#212]
- Add NODELAY to TCP socket options [#206]

2.0.4
=======

- Dalli no longer needs to be reset after Unicorn/Passenger fork [#208]
- Add option to re-raise errors rescued in the session and cache stores. [pitr, #200]
- DalliStore#fetch called the block if the cached value == false [#205]
- DalliStore should have accessible options [#195]
- Add silence and mute support for DalliStore [#207]
- Tracked down and fixed socket corruption due to Timeout [#146]

2.0.3
=======

- Allow proper retrieval of stored `false` values [laserlemon, #197]
- Allow non-ascii and whitespace keys, only the text protocol has those restrictions [#145]
- Fix DalliStore#delete error-handling [#196]

2.0.2
=======

- Fix all dalli\_store operations to handle nil options [#190]
- Increment and decrement with :initial => nil now return nil (lawrencepit, #112)

2.0.1
=======

- Fix nil option handling in dalli\_store#write [#188]

2.0.0
=======

- Reimplemented the Rails' dalli\_store to remove use of
  ActiveSupport::Cache::Entry which added 109 bytes overhead to every
  value stored, was a performance bottleneck and duplicated a lot of
  functionality already in Dalli.  One benchmark went from 4.0 sec to 3.0
  sec with the new dalli\_store. [#173]
- Added reset\_stats operation [#155]
- Added support for configuring keepalive on TCP connections to memcached servers (@bianster, #180)

Notes:

  * data stored with dalli\_store 2.x is NOT backwards compatible with 1.x.
    Upgraders are advised to namespace their keys and roll out the 2.x
    upgrade slowly so keys do not clash and caches are warmed.
    `config.cache_store = :dalli_store, :expires_in => 24.hours.to_i, :namespace => 'myapp2'`
  * data stored with plain Dalli::Client API is unchanged.
  * removed support for dalli\_store's race\_condition\_ttl option.
  * removed support for em-synchrony and unix socket connection options.
  * removed support for Ruby 1.8.6
  * removed memcache-client compability layer and upgrade documentation.


1.1.5
=======

- Coerce input to incr/decr to integer via #to\_i [#165]
- Convert test suite to minitest/spec (crigor, #166)
- Fix encoding issue with keys [#162]
- Fix double namespacing with Rails and dalli\_store. [#160]

1.1.4
=======

- Use 127.0.0.1 instead of localhost as default to avoid IPv6 issues
- Extend DalliStore's :expires\_in when :race\_condition\_ttl is also used.
- Fix :expires\_in option not propogating from DalliStore to Client, GH-136
- Added support for native Rack session store.  Until now, Dalli's
  session store has required Rails.  Now you can use Dalli to store
  sessions for any Rack application.

    require 'rack/session/dalli'
    use Rack::Session::Dalli, :memcache_server => 'localhost:11211', :compression => true

1.1.3
=======

- Support Rails's autoloading hack for loading sessions with objects
  whose classes have not be required yet, GH-129
- Support Unix sockets for connectivity.  Shows a 2x performance
  increase but keep in mind they only work on localhost. (dfens)

1.1.2
=======

- Fix incompatibility with latest Rack session API when destroying
  sessions, thanks @twinge!

1.1.1
=======

v1.1.0 was a bad release.  Yanked.

1.1.0
=======

- Remove support for Rails 2.3, add support for Rails 3.1
- Fix socket failure retry logic, now you can restart memcached and Dalli won't complain!
- Add support for fibered operation via em-synchrony (eliaslevy)
- Gracefully handle write timeouts, GH-99
- Only issue bug warning for unexpected StandardErrors, GH-102
- Add travis-ci build support (ryanlecompte)
- Gracefully handle errors in get_multi (michaelfairley)
- Misc fixes from crash2burn, fphilipe, igreg, raggi

1.0.5
=======

- Fix socket failure retry logic, now you can restart memcached and Dalli won't complain!

1.0.4
=======

- Handle non-ASCII key content in dalli_store
- Accept key array for read_multi in dalli_store
- Fix multithreaded race condition in creation of mutex

1.0.3
=======

- Better handling of application marshalling errors
- Work around jruby IO#sysread compatibility issue


1.0.2
=======

 - Allow browser session cookies (blindsey)
 - Compatibility fixes (mwynholds)
 - Add backwards compatibility module for memcache-client, require 'dalli/memcache-client'.  It makes
   Dalli more compatible with memcache-client and prints out a warning any time you do something that
   is no longer supported so you can fix your code.

1.0.1
=======

 - Explicitly handle application marshalling bugs, GH-56
 - Add support for username/password as options, to allow multiple bucket access
   from the same Ruby process, GH-52
 - Add support for >1MB values with :value_max_bytes option, GH-54 (r-stu31)
 - Add support for default TTL, :expires_in, in Rails 2.3. (Steven Novotny)
   config.cache_store = :dalli_store, 'localhost:11211', {:expires_in => 4.hours}


1.0.0
=======

Welcome gucki as a Dalli committer!

 - Fix network and namespace issues in get_multi (gucki)
 - Better handling of unmarshalling errors (mperham)

0.11.2
=======

 - Major reworking of socket error and failover handling (gucki)
 - Add basic JRuby support (mperham)

0.11.1
======

 - Minor fixes, doc updates.
 - Add optional support for kgio sockets, gives a 10-15% performance boost.

0.11.0
======

Warning: this release changes how Dalli marshals data.  I do not guarantee compatibility until 1.0 but I will increment the minor version every time a release breaks compatibility until 1.0.

IT IS HIGHLY RECOMMENDED YOU FLUSH YOUR CACHE BEFORE UPGRADING.

 - multi() now works reentrantly.
 - Added new Dalli::Client option for default TTLs, :expires_in, defaults to 0 (aka forever).
 - Added new Dalli::Client option, :compression, to enable auto-compression of values.
 - Refactor how Dalli stores data on the server.  Values are now tagged
   as "marshalled" or "compressed" so they can be automatically deserialized
   without the client having to know how they were stored.

0.10.1
======

 - Prefer server config from environment, fixes Heroku session store issues (thanks JoshMcKin)
 - Better handling of non-ASCII values (size -> bytesize)
 - Assert that keys are ASCII only

0.10.0
======

Warning: this release changed how Rails marshals data with Dalli.  Unfortunately previous versions double marshalled values.  It is possible that data stored with previous versions of Dalli will not work with this version.

IT IS HIGHLY RECOMMENDED YOU FLUSH YOUR CACHE BEFORE UPGRADING.

 - Rework how the Rails cache store does value marshalling.
 - Rework old server version detection to avoid a socket read hang.
 - Refactor the Rails 2.3 :dalli\_store to be closer to :mem\_cache\_store.
 - Better documentation for session store config (plukevdh)

0.9.10
----

 - Better server retry logic (next2you)
 - Rails 3.1 compatibility (gucki)


0.9.9
----

 - Add support for *_multi operations for add, set, replace and delete.  This implements
   pipelined network operations; Dalli disables network replies so we're not limited by
   latency, allowing for much higher throughput.

    dc = Dalli::Client.new
    dc.multi do
      dc.set 'a', 1
      dc.set 'b', 2
      dc.set 'c', 3
      dc.delete 'd'
    end
 - Minor fix to set the continuum sorted by value (kangster)
 - Implement session store with Rails 2.3.  Update docs.

0.9.8
-----

 - Implement namespace support
 - Misc fixes


0.9.7
-----

 - Small fix for NewRelic integration.
 - Detect and fail on older memcached servers (pre-1.4).

0.9.6
-----

 - Patches for Rails 3.0.1 integration.

0.9.5
-----

 - Major design change - raw support is back to maximize compatibility with Rails
 and the increment/decrement operations.  You can now pass :raw => true to most methods
 to bypass (un)marshalling.
 - Support symbols as keys (ddollar)
 - Rails 2.3 bug fixes


0.9.4
-----

 - Dalli support now in rack-bug (http://github.com/brynary/rack-bug), give it a try!
 - Namespace support for Rails 2.3 (bpardee)
 - Bug fixes


0.9.3
-----

 - Rails 2.3 support (beanieboi)
 - Rails SessionStore support
 - Passenger integration
 - memcache-client upgrade docs, see Upgrade.md


0.9.2
----

 - Verify proper operation in Heroku.


0.9.1
----

 - Add fetch and cas operations (mperham)
 - Add incr and decr operations (mperham)
 - Initial support for SASL authentication via the MEMCACHE_{USERNAME,PASSWORD} environment variables, needed for Heroku (mperham)

0.9.0
-----

 - Initial gem release.
