In Memory Cache for Ruby

This is a simple Ruby gem for in-memory caching. Read this blog post to understand what Zache is designed for.

First, install it:

gem install zache

Then, use it like this:

require 'zache'
zache = Zache.new
# Expires in 5 minutes
v = zache.get(:count, lifetime: 5 * 60) { expensive_calculation() }

If you omit the lifetime parameter, the key will never expire.

By default Zache is thread-safe. It locks the entire cache on each get call. You can turn that off by using the sync argument:

zache = Zache.new(sync: false)
v = zache.get(:count) { expensive_calculation() }

You may use "dirty" mode, which will return an expired value while calculation is in progress. For example, if you have a value in the cache that's expired, and you call get with a long-running block, the thread waits. If another thread calls get again, that second thread won't wait, but will receive the expired value from the cache. This is a very convenient mode for situations where absolute data accuracy is less important than performance:

zache = Zache.new(dirty: true)
# Or enable dirty mode for a specific get call
value = zache.get(:key, dirty: true) { expensive_calculation() }

You may use "eager" mode with a placeholder value to return immediately while the calculation happens in the background. The cache returns the placeholder instantly and spawns a thread to calculate the actual value. This is useful when you need to avoid blocking while expensive operations complete:

# Returns 0 immediately, calculates in background
value = zache.get(:key, eager: true, placeholder: 0) { expensive_calculation() }

The entire API is documented. Here are some additional useful methods:

# Check if a key exists
zache.exists?(:key)

# Remove a key
zache.remove(:key)

# Remove all keys
zache.remove_all

# Remove keys that match a condition
zache.remove_by { |key| key.to_s.start_with?('temp_') }

# Clean up expired keys
zache.clean

# Check if cache is empty
zache.empty?

Read these guidelines. Make sure your build is green before you contribute your pull request. You will need to have Ruby 2.3+ and Bundler installed. Then:

bundle update
bundle exec rake

If it's clean and you don't see any error messages, submit your pull request.