Retry a function call with exponential backoff

Retries a zero-argument function up to max_attempts times. On failure, waits with exponential backoff before retrying.

Usage

retry(
  fn,
  max_attempts = getOption("refinitiv_max_retries", 2L),
  backoff = 0.5,
  on_failure = c("stop", "NA")
)

Arguments

fn: A zero-argument function to execute. Wrap your call in function() your_call() before passing.
max_attempts: Maximum number of attempts (including the first). Defaults to getOption("refinitiv_max_retries", 2L).
backoff: Initial backoff time in seconds. Doubles after each failure, default = 0.5.
on_failure: What to do when all attempts are exhausted. "stop" (default) throws an error containing the last failure message. "NA" issues a warning and returns NA — use this inside chunked_download() where per-chunk success is tracked externally.

Value

The return value of fn() on success.

Details

retry() is the client-side retry layer. It guards against transient network errors and unexpected exceptions.

Inside chunked_download(): Use retry(fn, max_attempts = 1L, on_failure = "NA") so that retry() acts solely as an error-to-NA converter. The coordinator owns the full retry lifecycle (jittered exponential backoff between rounds, per-chunk tracking).

Standalone callers (e.g., rd_GetESG): Use the default max_attempts (or configure via the refinitiv_max_retries option) for direct retrying with exponential backoff.

It is distinct from two other retry/polling mechanisms in the package:

httr2::req_retry() inside send_json_request() handles HTTP-level transient errors (429 Too Many Requests, 503 Service Unavailable) transparently during httr2::req_perform().
The server polling loop in send_json_request() handles LSEG-specific JSON responses: async ticket/estimated-duration polling and retriable error codes (2504, 500, 400).

Examples

# Succeeds immediately:
Refinitiv:::retry(function() sum(1, 1))
#> [1] 2

# Fails and retries, then gives up:
if (FALSE) { # \dontrun{
retry(function() sum(1, "a"), max_attempts = 2)
} # }