SERVER-106166 Don't append Inf to FTDC for totalAvailableTokens (#37181)

GitOrigin-RevId: f86ad3fa0cfca39ef06115133cb2121ff942b683

Author: erin2722

jstests/noPassthrough/connection_establishment_server_params.js

@@ -18,6 +18,7 @@ function getIngressConnectionEstablishmentMaxQueueDepthDefault(mongo) {
 // Check the default values are used if not set explicitly
 let mongo = MongoRunner.runMongod();
 const maxInt32 = Math.pow(2, 31) - 1;
+const maxInt64 = Math.pow(2, 63) - 1;
 
 let ingressConnectionEstablishmentRatePerSecDefault =
     getIngressConnectionEstablishmentRatePerSec(mongo);
@@ -27,10 +28,10 @@ let ingressConnectionEstablishmentBurstCapacitySecsDefault =
     getingressConnectionEstablishmentBurstCapacitySecs(mongo);
 assert.eq(ingressConnectionEstablishmentBurstCapacitySecsDefault, Number.MAX_VALUE);
 
-// There are infinite tokens available by default.
+// There are infinite tokens available by default, and we append that as INT64_MAX.
 let availableTokens =
     mongo.adminCommand({serverStatus: 1}).queues.ingressSessionEstablishment.totalAvailableTokens;
-assert.eq(availableTokens, Infinity);
+assert.eq(availableTokens, maxInt64);
 
 let ingressConnectionEstablishmentMaxQueueDepthDefault =
     getIngressConnectionEstablishmentMaxQueueDepthDefault(mongo);

src/mongo/db/admission/rate_limiter.cpp

@@ -194,7 +194,11 @@ void RateLimiter::appendStats(BSONObjBuilder* bob) const {
     if (const auto avg = stats().averageTimeQueuedMicros.get()) {
         bob->append("averageTimeQueuedMicros", *avg);
     }
-    bob->append("totalAvailableTokens", tokensAvailable());
+
+    // FTDC consumers may not handle infinity, and so we append INT64_MAX instead.
+    bob->append("totalAvailableTokens",
+                static_cast<double>(std::min(static_cast<long double>(INT64_MAX),
+                                             static_cast<long double>(tokensAvailable()))));
 }
 
 double RateLimiter::tokensAvailable() const {