ProbabilitySampler: avoid copying trace_id. (#397)

g-easy · web-flow · commit 64567d52fc58 · 2019-10-08T14:38:09.000+11:00
diff --git a/opencensus/trace/internal/sampler.cc b/opencensus/trace/internal/sampler.cc
@@ -39,8 +39,7 @@ uint64_t CalculateThreshold(double probability) {
 }
 
 uint64_t CalculateThresholdFromBuffer(const TraceId& trace_id) {
-  uint8_t buf[TraceId::kSize];
-  trace_id.CopyTo(buf);
+  const uint8_t* buf = reinterpret_cast<const uint8_t*>(trace_id.Value());
   uint64_t res = 0;
   // We only use the first 8 bytes of TraceId.
   for (int i = 0; i < 8; ++i) {

Original file line number	Diff line number	Diff line change
`@@ -39,8 +39,7 @@ uint64_t CalculateThreshold(double probability) {`
`39`	`39`	`}`
`40`	`40`
`41`	`41`	`uint64_t CalculateThresholdFromBuffer(const TraceId& trace_id) {`
`42`		`- uint8_t buf[TraceId::kSize];`
`43`		`- trace_id.CopyTo(buf);`
	`42`	`+ const uint8_t* buf = reinterpret_cast<const uint8_t*>(trace_id.Value());`
`44`	`43`	`uint64_t res = 0;`
`45`	`44`	`// We only use the first 8 bytes of TraceId.`
`46`	`45`	`for (int i = 0; i < 8; ++i) {`