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fix: sampler now samples correctly #100
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Sampler was not adhering to the configured propability when not ALWAYS or NEVER. Issue was that the Sampler was using Number.MAX_VALUE, which uses 1024-bits. There were two issues with this approach: 1. The MAX_VALUE is NOT considered a "safe integer" and thus there are side effects during manipulation. 2. The `shouldSample` method was only comparing the idUpperBound (based on 1024-bits of data) to the lower 16 characters (64-bits) of a trace, which was resulting in the configured probabilty not being respected. We now us a 52-bit number, which falls within the "safe integer" range (53-bits) and is able to be fully represented by a 13-diget hex value. This allows the value to: 1. Be safely algorithmically manipulated without side effects. 2. Be easily compared to the lower 52-bits (13 characters) of a traceId. The tests have been updated to perform validation of traceIds that should and should not be sampled given a probability.
The zpages tests were relying on the fact that the sampler was broken, they have now been configured to always sample to make sure the tests pass.
kjin
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Aug 23, 2018
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@justindsmith Thanks! |
kjin
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Aug 24, 2018
Sampler was not adhering to the configured propability when not ALWAYS or NEVER. Issue was that the Sampler was using Number.MAX_VALUE, which uses 1024-bits. There were two issues with this approach: 1. The MAX_VALUE is NOT considered a "safe integer" and thus there are side effects during manipulation. 2. The `shouldSample` method was only comparing the idUpperBound (based on 1024-bits of data) to the lower 16 characters (64-bits) of a trace, which was resulting in the configured probabilty not being respected. We now us a 52-bit number, which falls within the "safe integer" range (53-bits) and is able to be fully represented by a 13-diget hex value. This allows the value to: 1. Be safely algorithmically manipulated without side effects. 2. Be easily compared to the lower 52-bits (13 characters) of a traceId. The tests have been updated to perform validation of traceIds that should and should not be sampled given a probability.
kjin
pushed a commit
to kjin/opencensus-node
that referenced
this pull request
Aug 24, 2018
Sampler was not adhering to the configured propability when not ALWAYS or NEVER. Issue was that the Sampler was using Number.MAX_VALUE, which uses 1024-bits. There were two issues with this approach: 1. The MAX_VALUE is NOT considered a "safe integer" and thus there are side effects during manipulation. 2. The `shouldSample` method was only comparing the idUpperBound (based on 1024-bits of data) to the lower 16 characters (64-bits) of a trace, which was resulting in the configured probabilty not being respected. We now us a 52-bit number, which falls within the "safe integer" range (53-bits) and is able to be fully represented by a 13-diget hex value. This allows the value to: 1. Be safely algorithmically manipulated without side effects. 2. Be easily compared to the lower 52-bits (13 characters) of a traceId. The tests have been updated to perform validation of traceIds that should and should not be sampled given a probability.
kjin
pushed a commit
to kjin/opencensus-node
that referenced
this pull request
Aug 24, 2018
Sampler was not adhering to the configured propability when not ALWAYS or NEVER. Issue was that the Sampler was using Number.MAX_VALUE, which uses 1024-bits. There were two issues with this approach: 1. The MAX_VALUE is NOT considered a "safe integer" and thus there are side effects during manipulation. 2. The `shouldSample` method was only comparing the idUpperBound (based on 1024-bits of data) to the lower 16 characters (64-bits) of a trace, which was resulting in the configured probabilty not being respected. We now us a 52-bit number, which falls within the "safe integer" range (53-bits) and is able to be fully represented by a 13-diget hex value. This allows the value to: 1. Be safely algorithmically manipulated without side effects. 2. Be easily compared to the lower 52-bits (13 characters) of a traceId. The tests have been updated to perform validation of traceIds that should and should not be sampled given a probability.
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Sampler was not adhering to the configured propability when not ALWAYS or
NEVER. Issue was that the Sampler was using Number.MAX_VALUE, which uses
1024-bits. There were two issues with this approach:
effects during manipulation.
shouldSamplemethod was only comparing the idUpperBound (based on1024-bits of data) to the lower 16 characters (64-bits) of a trace, which
was resulting in the configured probabilty not being respected.
We now us a 52-bit number, which falls within the "safe integer" range (53-bits)
and is able to be fully represented by a 13-diget hex value. This allows the
value to:
The tests have been updated to perform validation of traceIds that should and
should not be sampled given a probability.
fixes #99