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time.interval_elapsed_ratio

FLOATtime.interval_elapsed_ratioTIMErefTIMEstartTIMEend

Available inall subroutines.

Returns the proportion of time between start and end that has elapsed at the reference time, as a number between 0 and 1.

Example

sub vcl_miss {
    declare local var.ratio FLOAT;
    set var.ratio = time.interval_elapsed_ratio(now,
        std.time("2025-01-01 00:00:00", now),
        std.time("2026-01-01 00:00:00", now));


    if (var.ratio >= req.digest.ratio) {
        // Request is eligible for A/B test
    }
}

Note that req.digest.ratio is not meaningful in vcl_recv since the digest is not yet computed, but you can use fastly.hash to acheive similar results.

sub vcl_recv {
    declare local var.ratio FLOAT;
    set var.ratio = time.interval_elapsed_ratio(now,
        std.time("2025-01-01 00:00:00", now),
        std.time("2026-01-01 00:00:00", now));


    declare local var.current_ratio FLOAT = fastly.hash(req.url, 0, 0, 1024);
    set var.current_ratio /= 1024.0;


    if (var.ratio >= var.current_ratio) {
        // Request is eligible for A/B test
    }
}
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