We limit the maximum number of concurrent connections that a client can make the proxy. The quota is implemented as a (thread-safe) map of client certificate hash to available number of connections. When a new connection is made, we decrement the availability counter by one. When the counter hits zero, no more connections can be made and any new connection from the same client is terminated by the proxy.
Currently, the counter is incremented when a connection is terminated, including connections that are terminated *because* the quota is reached (i. e. the connections for which the counter is not decremented because the counter is already zero). This means that the first time the quota is reached, the next connection is dropped, the counter is incremented to 1 and new connections can be made again, bypassing the quota. This process can be repeated to achieve, theoretically, infinite quota.
This CL fixes this bug by only incrementing the counter, upon connection termination, for connections that have decremented the counter in the first place.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=217231593
1. Moved code for the GCP proxy to where the [] proxy code used to live.
3. Corrected reference to the GCP proxy location.
4. Misc changes to make ErrorProne and various tools happy.
+diekmann to LGTM terraform whitelist change.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=213630560
When a quota request is rejected, increment the metric counter by one.
Also makes both frontend and backend metrics singleton because all the fields they have a static.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=185146804
The quota handler terminates connections when quota is exceeded.
The next CL will add instrumentation for quota related metrics.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=185042675
