Class: Philiprehberger::HttpClient::Cache

Inherits:
Object
  • Object
show all
Defined in:
lib/philiprehberger/http_client/cache.rb

Overview

Simple in-memory cache for GET responses. Respects Cache-Control headers (max-age, no-cache, no-store) and supports conditional requests via ETag and Last-Modified headers.

Examples:

cache = Cache.new
cache.store(uri, response)
cached = cache.lookup(uri)

Defined Under Namespace

Classes: CacheEntry

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Cache

Returns a new instance of Cache.



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# File 'lib/philiprehberger/http_client/cache.rb', line 19

def initialize
  @monitor = Monitor.new
  @store = {}
end

Instance Method Details

#clear! ⇒ void

This method returns an undefined value.

Remove all entries from the cache.



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# File 'lib/philiprehberger/http_client/cache.rb', line 81

def clear!
  @monitor.synchronize { @store.clear }
end

#entry_for(uri) ⇒ CacheEntry?

Return the cache entry for conditional request headers. Returns nil if no entry exists (even if expired).

Parameters:

  • uri (URI) —

    the request URI

Returns:



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# File 'lib/philiprehberger/http_client/cache.rb', line 50

def entry_for(uri)
  key = cache_key(uri)
  @monitor.synchronize { @store[key] }
end

#lookup(uri) ⇒ Response?

Look up a cached response for the given URI. Returns nil if not cached or expired.

Parameters:

  • uri (URI) —

    the request URI

Returns:

  • (Response, nil) —

    the cached response or nil



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# File 'lib/philiprehberger/http_client/cache.rb', line 29

def lookup(uri)
  key = cache_key(uri)
  @monitor.synchronize do
    entry = @store[key]
    return nil unless entry

    if expired?(entry)
      # Keep entries with etag/last_modified for conditional requests
      @store.delete(key) unless entry.etag || entry.last_modified
      nil
    else
      entry.response
    end
  end
end

#size ⇒ Integer

Return the number of cached entries.

Returns:

  • (Integer) 


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# File 'lib/philiprehberger/http_client/cache.rb', line 88

def size
  @monitor.synchronize { @store.size }
end

#store(uri, response) ⇒ void

This method returns an undefined value.

Store a response in the cache. Respects Cache-Control: no-store (does not cache).

Parameters:

  • uri (URI) —

    the request URI

  • response (Response) —

    the response to cache



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# File 'lib/philiprehberger/http_client/cache.rb', line 61

def store(uri, response)
  return if no_store?(response)

  key = cache_key(uri)
  cc = parse_cache_control(response)

  entry = CacheEntry.new(
    response: response,
    stored_at: now,
    max_age: cc[:max_age],
    etag: response.headers['etag'],
    last_modified: response.headers['last-modified']
  )

  @monitor.synchronize { @store[key] = entry }
end