Class: SupportTableCache::MemoryCache

Inherits:
Object
  • Object
show all
Defined in:
lib/support_table_cache/memory_cache.rb

Overview

An optimized cache implementation that can be used when all records can easily fit in memory and are never changed. It is intended for use with small, static support tables only.

This cache will not store nil values. This is to prevent the cache from filling up with cache misses because there is no purging mechanism.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ MemoryCache

Returns a new instance of MemoryCache.



11
12
13
14
 
# File 'lib/support_table_cache/memory_cache.rb', line 11

def initialize
  @cache = {}
  @mutex = Mutex.new
end

Instance Method Details

#clear ⇒ Object 



49
50
51
 
# File 'lib/support_table_cache/memory_cache.rb', line 49

def clear
  @cache.clear
end

#delete(key) ⇒ Object 



45
46
47
 
# File 'lib/support_table_cache/memory_cache.rb', line 45

def delete(key)
  @cache.delete(key)
end

#fetch(key, expires_in: nil) ⇒ Object 



16
17
18
19
20
21
22
23
24
25
 
# File 'lib/support_table_cache/memory_cache.rb', line 16

def fetch(key, expires_in: nil)
  serialized_value, expire_at = @cache[key]
  if serialized_value.nil? || (expire_at && expire_at < Process.clock_gettime(Process::CLOCK_MONOTONIC))
    value = yield if block_given?
    return nil if value.nil?
    write(key, value, expires_in: expires_in)
    serialized_value = Marshal.dump(value)
  end
  Marshal.load(serialized_value)
end

#read(key) ⇒ Object 



27
28
29
 
# File 'lib/support_table_cache/memory_cache.rb', line 27

def read(key)
  fetch(key)
end

#write(key, value, expires_in: nil) ⇒ Object 



31
32
33
34
35
36
37
38
39
40
41
42
43
 
# File 'lib/support_table_cache/memory_cache.rb', line 31

def write(key, value, expires_in: nil)
  return if value.nil?

  if expires_in
    expire_at = Process.clock_gettime(Process::CLOCK_MONOTONIC) + expires_in
  end

  serialized_value = Marshal.dump(value)

  @mutex.synchronize do
    @cache[key] = [serialized_value, expire_at]
  end
end