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Rate limit a request by automatically adding a delay

Source: R/req-throttle.R
req_throttle.Rd

Use req_throttle() to ensure that repeated calls to req_perform() never exceed a specified rate.

Usage

req_throttle(req, rate, realm = NULL)

Arguments

req

A httr2 request object.

rate

Maximum rate, i.e. maximum number of requests per second. Usually easiest expressed as a fraction, number_of_requests / number_of_seconds, e.g. 15 requests per minute is 15 / 60.

realm

A string that uniquely identifies the throttle pool to use (throttling limits always apply per pool). If not supplied, defaults to the hostname of the request.

Value

A modified HTTP request.

See also

req_retry() for another way of handling rate-limited APIs.

Examples

# Ensure we never send more than 30 requests a minute
req <- request(example_url()) |>
  req_throttle(rate = 30 / 60)

resp <- req_perform(req)
throttle_status()
#>       realm        last_request
#> 1 127.0.0.1 2024-11-04 18:05:15
resp <- req_perform(req)
#> Waiting 2s for throttling delay ■■■■■■■■■■■■■■■                 
#> Waiting 2s for throttling delay ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■  
throttle_status()
#>       realm        last_request
#> 1 127.0.0.1 2024-11-04 18:05:17