/*
 * Copyright (C) 2011 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package leakcanary

/**
 * [GcTrigger] is used to try triggering garbage collection and enqueuing [KeyedWeakReference] into
 * the associated [java.lang.ref.ReferenceQueue]. The default implementation [Default] comes from
 * AOSP.
 */
fun interface GcTrigger {

  /**
   * Attempts to run garbage collection.
   */
  fun runGc()

  /**
   * Default implementation of [GcTrigger].
   */
  object Default : GcTrigger {
    override fun runGc() {
      // Code taken from AOSP FinalizationTest:
      // https://android.googlesource.com/platform/libcore/+/master/support/src/test/java/libcore/
      // java/lang/ref/FinalizationTester.java
      // System.gc() does not garbage collect every time. Runtime.gc() is
      // more likely to perform a gc.
      Runtime.getRuntime()
        .gc()
      enqueueReferences()
      System.runFinalization()
    }

    private fun enqueueReferences() {
      // Hack. We don't have a programmatic way to wait for the reference queue daemon to move
      // references to the appropriate queues.
      try {
        Thread.sleep(100)
      } catch (e: InterruptedException) {
        throw AssertionError()
      }
    }
  }
}