Class: Faulty::Storage::Redis
- Inherits:
-
Object
- Object
- Faulty::Storage::Redis
- Defined in:
- lib/faulty/storage/redis.rb
Overview
A storage backend for storing circuit state in Redis.
When using this or any networked backend, be sure to evaluate the risk, and set conservative timeouts so that the circuit storage does not cause cascading failures in your application when evaluating circuits. Always wrap this backend with a FaultTolerantProxy to limit the effect of these types of events.
Defined Under Namespace
Classes: Options
Constant Summary collapse
- ENTRY_SEPARATOR =
Separates the time/status for history entry strings
':'
Instance Attribute Summary collapse
-
#options ⇒ Object
readonly
Returns the value of attribute options.
Instance Method Summary collapse
-
#close(circuit) ⇒ Boolean
Mark a circuit as closed.
-
#entry(circuit, time, success) ⇒ Array<Array>
Add an entry to storage.
-
#fault_tolerant? ⇒ true
Redis storage is not fault-tolerant.
-
#history(circuit) ⇒ Array<Array>
Get the circuit history up to
max_sample_size
. -
#initialize(**options) {|Options| ... } ⇒ Redis
constructor
A new instance of Redis.
-
#list ⇒ Array<String>
List all unexpired circuits.
-
#lock(circuit, state) ⇒ void
Lock a circuit open or closed.
-
#open(circuit, opened_at) ⇒ Boolean
Mark a circuit as open.
-
#reopen(circuit, opened_at, previous_opened_at) ⇒ Boolean
Mark a circuit as reopened.
-
#reset(circuit) ⇒ void
Reset a circuit.
-
#status(circuit) ⇒ Status
Get the status of a circuit.
-
#unlock(circuit) ⇒ void
Unlock a circuit.
Constructor Details
Instance Attribute Details
#options ⇒ Object (readonly)
Returns the value of attribute options.
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# File 'lib/faulty/storage/redis.rb', line 16 def @options end |
Instance Method Details
#close(circuit) ⇒ Boolean
Mark a circuit as closed
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# File 'lib/faulty/storage/redis.rb', line 138 def close(circuit) redis do |r| closed = compare_and_set(r, state_key(circuit), ['open'], 'closed', ex: .circuit_ttl) r.del(entries_key(circuit)) if closed closed end end |
#entry(circuit, time, success) ⇒ Array<Array>
Add an entry to storage
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# File 'lib/faulty/storage/redis.rb', line 96 def entry(circuit, time, success) key = entries_key(circuit) result = pipe do |r| r.sadd(list_key, circuit.name) r.expire(list_key, .circuit_ttl + .list_granularity) if .circuit_ttl r.lpush(key, "#{time}#{ENTRY_SEPARATOR}#{success ? 1 : 0}") r.ltrim(key, 0, .max_sample_size - 1) r.expire(key, .sample_ttl) if .sample_ttl r.lrange(key, 0, -1) end map_entries(result.last) end |
#fault_tolerant? ⇒ true
Redis storage is not fault-tolerant
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# File 'lib/faulty/storage/redis.rb', line 225 def fault_tolerant? false end |
#history(circuit) ⇒ Array<Array>
Get the circuit history up to max_sample_size
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# File 'lib/faulty/storage/redis.rb', line 210 def history(circuit) entries = redis { |r| r.lrange(entries_key(circuit), 0, -1) } map_entries(entries).reverse end |
#list ⇒ Array<String>
List all unexpired circuits
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# File 'lib/faulty/storage/redis.rb', line 218 def list redis { |r| r.sunion(*all_list_keys) } end |
#lock(circuit, state) ⇒ void
This method returns an undefined value.
Lock a circuit open or closed
The circuit_ttl does not apply to locks
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# File 'lib/faulty/storage/redis.rb', line 153 def lock(circuit, state) redis { |r| r.set(lock_key(circuit), state) } end |
#open(circuit, opened_at) ⇒ Boolean
Mark a circuit as open
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# File 'lib/faulty/storage/redis.rb', line 114 def open(circuit, opened_at) redis do |r| opened = compare_and_set(r, state_key(circuit), ['closed', nil], 'open', ex: .circuit_ttl) r.set(opened_at_key(circuit), opened_at, ex: .circuit_ttl) if opened opened end end |
#reopen(circuit, opened_at, previous_opened_at) ⇒ Boolean
Mark a circuit as reopened
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# File 'lib/faulty/storage/redis.rb', line 127 def reopen(circuit, opened_at, previous_opened_at) redis do |r| compare_and_set(r, opened_at_key(circuit), [previous_opened_at.to_s], opened_at, ex: .circuit_ttl) end end |
#reset(circuit) ⇒ void
This method returns an undefined value.
Reset a circuit
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# File 'lib/faulty/storage/redis.rb', line 171 def reset(circuit) pipe do |r| r.del( entries_key(circuit), opened_at_key(circuit), lock_key(circuit) ) r.set(state_key(circuit), 'closed', ex: .circuit_ttl) end end |
#status(circuit) ⇒ Status
Get the status of a circuit
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# File 'lib/faulty/storage/redis.rb', line 187 def status(circuit) futures = {} pipe do |r| futures[:state] = r.get(state_key(circuit)) futures[:lock] = r.get(lock_key(circuit)) futures[:opened_at] = r.get(opened_at_key(circuit)) futures[:entries] = r.lrange(entries_key(circuit), 0, -1) end Faulty::Status.from_entries( map_entries(futures[:entries].value), state: futures[:state].value&.to_sym || :closed, lock: futures[:lock].value&.to_sym, opened_at: futures[:opened_at].value ? futures[:opened_at].value.to_i : nil, options: circuit. ) end |
#unlock(circuit) ⇒ void
This method returns an undefined value.
Unlock a circuit
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# File 'lib/faulty/storage/redis.rb', line 162 def unlock(circuit) redis { |r| r.del(lock_key(circuit)) } end |