Merge pull request #188 from rails/unless-exist

Support unless_exist

app/models/solid_cache/entry.rb

@@ -52,7 +52,7 @@ def lock_and_write(key, &block)
  uncached do
  result = lock.where(key_hash: key_hash_for(key)).pick(:key, :value)
  new_value = block.call(result&.first == key ? result[1] : nil)
- write(key, new_value)
+ write(key, new_value) if new_value
  new_value
  end
  end

lib/solid_cache/store/api.rb

@@ -39,16 +39,27 @@ def read_serialized_entry(key, **options)
  entry_read(key)
  end
 
- def write_entry(key, entry, raw: false, **options)
+ def write_entry(key, entry, raw: false, unless_exist: false, **options)
  payload = serialize_entry(entry, raw: raw, **options)
- # No-op for us, but this writes it to the local cache
- write_serialized_entry(key, payload, raw: raw, **options)
 
- entry_write(key, payload)
+ if unless_exist
+ written = false
+ entry_lock_and_write(key) do |value|
+ if value.nil? || deserialize_entry(value, **options).expired?
+ written = true
+ payload
+ end
+ end
+ else
+ written = entry_write(key, payload)
+ end
+
+ write_serialized_entry(key, payload, raw: raw, returning: written, **options)
+ written
  end
 
- def write_serialized_entry(key, payload, raw: false, unless_exist: false, expires_in: nil, race_condition_ttl: nil, **options)
- true
+ def write_serialized_entry(key, payload, raw: false, unless_exist: false, expires_in: nil, race_condition_ttl: nil, returning: true, **options)
+ returning
  end
 
  def read_serialized_entries(keys)

lib/solid_cache/store/entries.rb

@@ -29,7 +29,9 @@ def entry_clear
 
  def entry_lock_and_write(key, &block)
  writing_key(key, failsafe: :increment) do
- Entry.lock_and_write(key, &block)
+ Entry.lock_and_write(key) do |value|
+ block.call(value).tap { |result| track_writes(1) if result }
+ end
  end
  end
 

test/unit/solid_cache_test.rb

@@ -54,6 +54,17 @@ class SolidCacheTest < ActiveSupport::TestCase
  cache = lookup_store(max_age: 7200)
  assert_equal 7200, cache.max_age
  end
+
+ def test_write_with_unless_exist
+ assert_equal true, @cache.write("foo", 1)
+ assert_equal false, @cache.write("foo", 1, unless_exist: true)
+ end
+
+ def test_write_expired_value_with_unless_exist
+ assert_equal true, @cache.write(1, "aaaa", expires_in: 1.second)
+ travel 2.seconds
+ assert_equal true, @cache.write(1, "bbbb", expires_in: 1.second, unless_exist: true)
+ end
 end
 
 class SolidCacheFailsafeTest < ActiveSupport::TestCase