[S2GRAPH-257] SafeUpdateCache#withCache method incorrect behavior

• Type: Bug
• Status: To Do
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.1.0, 0.2.0
• Component/s: s2core
• Assignee: Daewon Jeong
• Reporter: Daewon Jeong
• Created: 25/Apr/20 18:24
• Updated: 26/Apr/20 03:06

Description

The SafeUpdateCache Class needs to change the value in another thread when requesting the value from the cache instance.

With the above operation, the current thread should not be blocked.

However, due to the bug in the line below, the lazy value is evaluated unintentionally, causing the forground thread to block.

 

https://github.com/apache/incubator-s2graph/blob/07a5af39a5a52aad2e61c34d685fe00a6bb8e2cc/s2core/src/main/scala/org/apache/s2graph/core/utils/SafeUpdateCache.scala#L158

 

 

def withCache[T <: AnyRef](key: String,
                             broadcast: Boolean,
                             cacheTTLInSecs: Option[Int] = None,
                             onEvict: AnyRef => Unit = defaultOnEvict)(op: => T): T = {
...
...
        if (running) cachedVal
        else {
          val value = op // Bug on this line: value must be declared as lazy val
          Future(value)(executionContext) onComplete {
            case Failure(ex) =>
              put(key, cachedVal, false)
              logger.error(s"withCache update failed: $cacheKey", ex)
            case Success(newValue) =>

              put(key, newValue, broadcast = (broadcast && newValue != cachedVal))
              onEvict(cachedVal)

              cachedVal match {
                case None =>
                case _ => logger.info(s"withCache update success: $cacheKey")
              }
          }

          cachedVal
        }
      }
    }
  }