Problem

You are writing an automation script against the Databricks REST API and need to collect all items from a paginated endpoint while respecting rate limits. Implement a function that processes a predefined sequence of page responses, retries rate-limited pages with exponential backoff, and returns the final ordered result.

Formal Specification

Implement fetch_all_items(responses, max_retries).

• responses is a list of page response objects in the order they are encountered.
• Each response is a dictionary with:
  • page: integer page number
  • status: integer HTTP-like status code (200 or 429)
  • items: list of integers, present when status == 200
  • next_page: integer or null, present when status == 200
  • retry_after: integer seconds, present when status == 429
• Return a dictionary with:
  • items: all fetched items in page order
  • total_wait: total simulated wait time from retries
  • attempts: number of processed responses

If a page returns 429, retry the same page later. The wait added for the k-th retry of that page is retry_after * 2^(k-1). If any page exceeds max_retries, return {"items": [], "total_wait": -1, "attempts": attempts_so_far}.

Examples

Example 1 Input: responses = [{"page":1,"status":200,"items":[1,2],"next_page":2},{"page":2,"status":429,"retry_after":3},{"page":2,"status":200,"items":[3],"next_page":null}], max_retries = 2 Output: {"items":[1,2,3],"total_wait":3,"attempts":3} Explanation: Page 2 is rate-limited once, then succeeds.

Example 2 Input: responses = [{"page":1,"status":429,"retry_after":2},{"page":1,"status":429,"retry_after":2}], max_retries = 1 Output: {"items":[],"total_wait":-1,"attempts":2} Explanation: Page 1 exceeds the allowed retry count.

Constraints

• 1 <= len(responses) <= 10^5
• 1 <= page <= 10^5
• 0 <= len(items) <= 10^3
• 1 <= retry_after <= 10^4
• Responses are valid and correspond to the next required page or a retry of the current page.