module LockAndCache

Lock and cache using redis!

Most caching libraries don't do locking, meaning that >1 process can be calculating a cached value at the same time. Since you presumably cache things because they cost CPU, database reads, or money, doesn't it make sense to lock while caching?

Constants

DEFAULT_HEARTBEAT_EXPIRES
DEFAULT_MAX_LOCK_WAIT
VERSION

Public Class Methods

cache_storage() click to toggle source

@return [Redis] The redis connection used for cached value storage

# File lib/lock_and_cache.rb, line 41
def LockAndCache.cache_storage
  @cache_storage
end
cache_storage=(redis_connection) click to toggle source

@param redis_connection [Redis] A redis connection to be used for cached value storage

# File lib/lock_and_cache.rb, line 35
def LockAndCache.cache_storage=(redis_connection)
  raise "only redis for now" unless redis_connection.class.to_s == 'Redis'
  @cache_storage = redis_connection
end
cached?(*key_parts) click to toggle source

Check if a key is cached already

@note Standalone mode. See also “context mode,” where you mix LockAndCache into a class and call it from within its methods.

# File lib/lock_and_cache.rb, line 107
def LockAndCache.cached?(*key_parts)
  key = LockAndCache::Key.new key_parts
  key.cached?
end
clear(*key_parts) click to toggle source

Clear a single key

@note Standalone mode. See also “context mode,” where you mix LockAndCache into a class and call it from within its methods.

# File lib/lock_and_cache.rb, line 91
def LockAndCache.clear(*key_parts)
  key = LockAndCache::Key.new key_parts
  key.clear
end
flush_cache() click to toggle source

Flush LockAndCache's cached value storage.

@note If you are sharing a redis database, it will clear it…

@note If you want to clear a single key, try `LockAndCache.clear(key)` (standalone mode) or `#lock_and_cache_clear(method_id, *key_parts)` in context mode.

# File lib/lock_and_cache.rb, line 60
def LockAndCache.flush_cache
  cache_storage.flushdb
end
flush_locks() click to toggle source

Flush LockAndCache's lock storage.

@note If you are sharing a redis database, it will clear it…

@note If you want to clear a single key, try `LockAndCache.clear(key)` (standalone mode) or `#lock_and_cache_clear(method_id, *key_parts)` in context mode.

# File lib/lock_and_cache.rb, line 69
def LockAndCache.flush_locks
  lock_storage.flushdb
end
heartbeat_expires() click to toggle source

@private

# File lib/lock_and_cache.rb, line 134
def LockAndCache.heartbeat_expires
  @heartbeat_expires || DEFAULT_HEARTBEAT_EXPIRES
end
heartbeat_expires=(seconds) click to toggle source

@param seconds [Numeric] How often a process has to heartbeat in order to keep a lock

@note Can be overridden by putting `heartbeat_expires:` in your call to `#lock_and_cache`

# File lib/lock_and_cache.rb, line 127
def LockAndCache.heartbeat_expires=(seconds)
  memo = seconds.to_f
  raise "heartbeat_expires must be greater than 2 seconds" unless memo >= 2
  @heartbeat_expires = memo
end
lock_and_cache(*key_parts_and_options, &blk) click to toggle source

Lock and cache based on a key.

@param key_parts [*] Parts that should be used to construct a key.

@note Standalone mode. See also “context mode,” where you mix LockAndCache into a class and call it from within its methods.

@note A single hash arg is treated as a cache key, e.g. `LockAndCache.lock_and_cache(foo: :bar, expires: 100)` will be treated as a cache key of `foo: :bar, expires: 100` (which is probably wrong!!!). Try `LockAndCache.lock_and_cache({ foo: :bar }, expires: 100)` instead. This is the opposite of context mode.

# File lib/lock_and_cache.rb, line 80
def LockAndCache.lock_and_cache(*key_parts_and_options, &blk)
  options = (key_parts_and_options.last.is_a?(Hash) && key_parts_and_options.length > 1) ? key_parts_and_options.pop : {}
  raise "need a cache key" unless key_parts_and_options.length > 0
  key = LockAndCache::Key.new key_parts_and_options
  action = LockAndCache::Action.new key, options, blk
  action.perform
end
lock_storage() click to toggle source

@return [Redis] The redis connection used for lock and cached value storage

# File lib/lock_and_cache.rb, line 30
def LockAndCache.lock_storage
  @lock_storage
end
lock_storage=(redis_connection) click to toggle source

@param redis_connection [Redis] A redis connection to be used for lock storage

# File lib/lock_and_cache.rb, line 24
def LockAndCache.lock_storage=(redis_connection)
  raise "only redis for now" unless redis_connection.class.to_s == 'Redis'
  @lock_storage = redis_connection
end
locked?(*key_parts) click to toggle source

Check if a key is locked

@note Standalone mode. See also “context mode,” where you mix LockAndCache into a class and call it from within its methods.

# File lib/lock_and_cache.rb, line 99
def LockAndCache.locked?(*key_parts)
  key = LockAndCache::Key.new key_parts
  key.locked?
end
logger() click to toggle source

@return [Logger] The logger.

# File lib/lock_and_cache.rb, line 51
def LockAndCache.logger
  @logger
end
logger=(logger) click to toggle source

@param logger [Logger] A logger.

# File lib/lock_and_cache.rb, line 46
def LockAndCache.logger=(logger)
  @logger = logger
end
max_lock_wait() click to toggle source

@private

# File lib/lock_and_cache.rb, line 120
def LockAndCache.max_lock_wait
  @max_lock_wait || DEFAULT_MAX_LOCK_WAIT
end
max_lock_wait=(seconds) click to toggle source

@param seconds [Numeric] Maximum wait time to get a lock

@note Can be overridden by putting `max_lock_wait:` in your call to `#lock_and_cache`

# File lib/lock_and_cache.rb, line 115
def LockAndCache.max_lock_wait=(seconds)
  @max_lock_wait = seconds.to_f
end

Public Instance Methods

lock_and_cache(*key_parts_and_options, &blk) click to toggle source

Lock and cache a method given key parts.

The cache key will automatically include the class name of the object calling it (the context!) and the name of the method it is called from.

@param key_parts_and_options [*] Parts that you want to include in the lock and cache key. If the last element is a Hash, it will be treated as options.

@return The cached value (possibly newly calculated).

@note Subject mode - this is expected to be called on an object whose class has LockAndCache mixed in. See also standalone mode.

@note A single hash arg is treated as an options hash, e.g. `lock_and_cache(expires: 100)` will be treated as options `expires: 100`. This is the opposite of standalone mode.

# File lib/lock_and_cache.rb, line 165
def lock_and_cache(*key_parts_and_options, &blk)
  options = key_parts_and_options.last.is_a?(Hash) ? key_parts_and_options.pop : {}
  key = LockAndCache::Key.new key_parts_and_options, context: self, caller: caller
  action = LockAndCache::Action.new key, options, blk
  action.perform
end
lock_and_cache_clear(method_id, *key_parts) click to toggle source

Clear a lock and cache given exactly the method and exactly the same arguments

@note Subject mode - this is expected to be called on an object whose class has LockAndCache mixed in. See also standalone mode.

# File lib/lock_and_cache.rb, line 149
def lock_and_cache_clear(method_id, *key_parts)
  key = LockAndCache::Key.new key_parts, context: self, method_id: method_id
  key.clear
end
lock_and_cache_locked?(method_id, *key_parts) click to toggle source

Check if a method is locked on an object.

@note Subject mode - this is expected to be called on an object whose class has LockAndCache mixed in. See also standalone mode.

# File lib/lock_and_cache.rb, line 141
def lock_and_cache_locked?(method_id, *key_parts)
  key = LockAndCache::Key.new key_parts, context: self, method_id: method_id
  key.locked?
end