Method toString

src/Deferred.java:1394–1434

Returns a helpful string representation of this Deferred. The string returned is built in O(N) where N is the number of callbacks currently in the chain. The string isn't built entirely atomically, so it can appear to show this Deferred in a slightly inconsistent

()

   * especially if this is in the fast-path of your application.
   */
  public String toString() {
    final int state = this.state;  // volatile access before reading result.
    final Object result = this.result;
    final String str;
    if (result == null) {
      str = "null";
    } else if (result instanceof Deferred) {  // Nested Deferreds
      str = "Deferred@" + result.hashCode();  // are hard to read.
    } else {
      str = result.toString();
    }

    // We can't easily estimate how much space we'll need for the callback
    // chains, so let's just make sure we have enough space for all the static
    // cruft and the result, and double that to avoid the first re-allocation.
    // If result is a very long string, we may end up wasting some space, but
    // it's not likely to happen and even less likely to be a problem.
    final StringBuilder buf = new StringBuilder((9 + 10 + 7 + 7
                                                 + str.length()) * 2);
    buf.append("Deferred@").append(super.hashCode())
      .append("(state=").append(stateString(state))
      .append(", result=").append(str)
      .append(", callback=");
    synchronized (this) {
      if (callbacks == null || next_callback == last_callback) {
        buf.append("<none>, errback=<none>");
      } else {
        for (int i = next_callback; i < last_callback; i += 2) {
          buf.append(callbacks[i]).append(" -> ");
        }
        buf.setLength(buf.length() - 4);  // Remove the extra " -> ".
        buf.append(", errback=");
        for (int i = next_callback + 1; i < last_callback; i += 2) {
          buf.append(callbacks[i]).append(" -> ");
        }
        buf.setLength(buf.length() - 4);  // Remove the extra " -> ".
      }
    }
    buf.append(')');
    return buf.toString();
  }

  private static String stateString(final int state) {
    switch (state) {