ddtrace/tracer: add sample_rate_limit field to startup log. #1230
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We want to know when the sample rate limit is in effect and what its value is. This commit adds that information to the tracer's startup log.
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Added some |
| // true if rules sampling is enabled. If not present it returns math.NaN() and false. | ||
| func (rs *rulesSampler) limit() (float64, bool) { | ||
| if rs.enabled() { | ||
| return float64(rs.limiter.limiter.Limit()), true |
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We should be OK without nil checks here. Other places throughout the rulesSampler code assume these fields are not nil and all of the constructors populate them.
If we ever changed rulesSampler to allow nil members, we would be unlikely to miss this line, since it lives within the rulesSampler methods.
| @@ -280,12 +280,16 @@ func newRateLimiter() *rateLimiter { | |||
| } | |||
| } | |||
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| func (rs *rulesSampler) enabled() bool { | |||
| if rs.enabled() { | ||
| return float64(rs.limiter.limiter.Limit()), true | ||
| } | ||
| return math.NaN(), false |
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This works, but to remove complexity, I would probably return -1, false in this case. Then 284 can just be rs.globalRate >= 0. Unless the rate can actually be negative, which would be surprising.
Don't have a strong preference though.
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-1 would probably be a better choice, however we already use NaN in various places in the sampler and elsewhere as the canonical "not present" float64 value so I would like to stay consistent.
We want to know when the sample rate limit is in effect and what its value
is. This commit adds that information to the tracer's startup log.