github.com/mna/redisc

redisc

Package redisc implements a redis cluster client built on top of the redigo package. See the documentation for details.

Installation

$ go get [-u] [-t] github.com/mna/redisc

Releases

• v1.4.0 : Improve the reliability of the refresh of cluster mapping for edge cases where no nodes are known anymore (thanks to @ljfuyuan).

• v1.3.2 : Export the HashSlots constant to make it nicer to write the Cluster.LayoutRefresh function signature.

• v1.3.1 : Fix closing/releasing of connections used in Cluster.EachNode.

• v1.3.0 : Add Cluster.EachNode to call a function with a connection for each known node in the cluster (e.g. to run diagnostics commands on each node or to collect all keys in a cluster); add optional Cluster function field BgError to receive notification of errors happening in background topology refreshes and on closing of RetryConn after following a redirection to a new connection; add optional Cluster function field LayoutRefresh to receive the old and new cluster slot mappings to server address(es); prevent unnecessary cluster layout refreshes when the internal mapping is the same as the redirection error; better handling of closed Cluster; move CI to Github Actions; drop support for old Go versions (currently tested on 1.15+); enable more static analysis/linters; refactor tests to create less separate clusters and run faster.

• v1.2.0 : Use Go modules, fix a failing test due to changed error message on Redis 6.

• v1.1.7 : Do not bind to a random node if Do is called without a command and the connection is not already bound (thanks to @tysonmote).

• v1.1.6 : Append the actual error messages when a refresh returns "all nodes failed" error.

• v1.1.5 : Add Cluster.PoolWaitTime to configure the time to wait on a connection from a pool with MaxActive > 0 and Wait set to true (thanks to @iwanbk).

• v1.1.4 : Add Conn.DoWithTimeout and Conn.ReceiveWithTimeout to match redigo's ConnWithTimeout interface (thanks to @letsfire).

• v1.1.3 : Fix handling of ASK replies in RetryConn.

• v1.1.2 : Remove mention that StartupNodes in Cluster struct needs to be master nodes (it can be replicas). Add supporting test.

• v1.1.1 : Fix CI tests.

• v1.1.0 : This release builds with the github.com/gomodule/redigo package (the new import path of redigo, which also has a breaking change in its v2.0.0, the PMessage type has been removed and consolidated into Message).

• v1.0.0 : This release builds with the github.com/garyburd/redigo package, which - according to its readme - will not be maintained anymore, having moved to github.com/gomodule/redigo for future development. As such, redisc will not be updated with the old redigo package, this version was created only to avoid causing issues to users of redisc.

Documentation

The code documentation is the canonical source for documentation.

The design goal of redisc is to be as compatible as possible with the redigo package. As such, the Cluster type can be used as a drop-in replacement to a redis.Pool when moving from a standalone Redis to a Redis Cluster setup, and the connections returned by the cluster implement redigo's redis.Conn interface. The package offers additional features specific to dealing with a cluster that may be needed for more advanced scenarios.

The main features are:

• Drop-in replacement for redis.Pool (the Cluster type implements the same Get and Close method signatures).
• Connections are redis.Conn interfaces and use the redigo package to execute commands, redisc only handles the cluster part.
• Support for all cluster-supported commands including scripting, transactions and pub-sub (within the limitations imposed by Redis Cluster).
• Support for READONLY/READWRITE commands to allow reading data from replicas.
• Client-side smart routing, automatically keeps track of which node holds which key slots.
• Automatic retry of MOVED, ASK and TRYAGAIN errors when desired, via RetryConn.
• Manual handling of redirections and retries when desired, via IsTryAgain and ParseRedir.
• Automatic detection of the node to call based on the command's first parameter (assumed to be the key).
• Explicit selection of the node to call via BindConn when needed.
• Support for optimal batch calls via SplitBySlot.

Note that to make efficient use of Redis Cluster, some upfront work is usually required. A good understanding of Redis Cluster is highly recommended and the official Redis website has good documentation that covers this. In particular, Migrating to Redis Cluster will help understand how straightforward (or not) the migration may be for your specific case.

Alternatives

• redis-go-cluster.
• radix v1 provides a cluster package.
• radix v2 provides a cluster package.

Support

There are a number of ways you can support the project:

• Use it, star it, build something with it, spread the word!
• Raise issues to improve the project (note: doc typos and clarifications are issues too!)
  • Please search existing issues before opening a new one - it may have already been adressed.
• Pull requests: please discuss new code in an issue first, unless the fix is really trivial.
  • Make sure new code is tested.
  • Be mindful of existing code - PRs that break existing code have a high probability of being declined, unless it fixes a serious issue.
• Sponsor the developer
  • See the Github Sponsor button at the top of the repo on github

License

The BSD 3-Clause license.