Thread-safe memory-block helper

[jamoore]

A thread-safe helper should be written that will allow tests to check out large chunks of memory that it hopes to use. The total size of the memory should default to the available JVM memory but should be configurable. The size take on each checkout, as well as how long to wait (if at all) should also be configurable. In pseudo-code:

  public final static long oneGB = 1024 * 1024 * 1024;

  Helper helper = new Helper();
  // Optionally: helper = new Helper(4 * oneGB);
  try {
    Memory memory = helper.acquireBytes(oneGB);
    // Optionally:
    // helper.acquireBytes(oneGB, 1000, TimeUnits.MILLISECONDS);


    // Possibly long-running processing here, but try to acquire
    // and free the memory as close to its usage as possible.


  } finally {
    memory.free();
  }

See:

• ​https://github.com/openmicroscopy/bioformats/pull/718#issuecomment-25457178
• ​http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CountDownLatch.html#await(long, java.util.concurrent.TimeUnit?)