Measure connect latency in microseconds instead of milliseconds

Summary:
Just to make sure I don't break anything: zbgsed `conn_lat_ms` https://fburl.com/code/tb1z7zvy and I don't see anything.

NOTE: I'm going to make post in traffeed.

This will later be used to define new latency metrics more accurately where latency metric will be everything minus connection creation time.

While this change might looks huge it's just simple move from millis to micros

Reviewed By: kwaugh

Differential Revision: D59735786

fbshipit-source-id: 2d2ed585c64ed848e39850ee48431d19dbaf593d

proxygen/lib/http/HQConnector.cpp

@@ -22,11 +22,11 @@ using namespace fizz::client;
 
 namespace proxygen {
 
-std::chrono::milliseconds HQConnector::timeElapsed() {
+std::chrono::microseconds HQConnector::timeElapsed() {
  if (timePointInitialized(connectStart_)) {
- return millisecondsSince(connectStart_);
+ return microsecondsSince(connectStart_);
  }
- return std::chrono::milliseconds(0);
+ return std::chrono::microseconds(0);
 }
 
 void HQConnector::reset() {

proxygen/lib/http/HQConnector.h

@@ -77,7 +77,7 @@ class HQConnector : public HQSession::ConnectCallback {
  std::shared_ptr<quic::QuicTransportStatsCallback>
  quicTransportStatsCallback = nullptr);
 
- std::chrono::milliseconds timeElapsed();
+ std::chrono::microseconds timeElapsed();
 
  bool isBusy() const {
  return (session_ != nullptr);

proxygen/lib/http/HTTPConnector.cpp

@@ -96,11 +96,11 @@ void HTTPConnector::connectSSL(EventBase* eventBase,
  this, connectAddr, timeoutMs.count(), socketOptions, bindAddr);
 }
 
-std::chrono::milliseconds HTTPConnector::timeElapsed() {
+std::chrono::microseconds HTTPConnector::timeElapsed() {
  if (timePointInitialized(connectStart_)) {
- return millisecondsSince(connectStart_);
+ return microsecondsSince(connectStart_);
  }
- return std::chrono::milliseconds(0);
+ return std::chrono::microseconds(0);
 }
 
 // Callback interface

proxygen/lib/http/HTTPConnector.h

@@ -137,7 +137,7 @@ class HTTPConnector : protected folly::AsyncSocket::ConnectCallback {
  * @returns the number of milliseconds since connecting began, or
  * zero if connecting hasn't started yet.
  */
- std::chrono::milliseconds timeElapsed();
+ std::chrono::microseconds timeElapsed();
 
  /**
  * @returns true iff this connector is busy setting up a connection. If

proxygen/lib/utils/Time.h

@@ -108,6 +108,12 @@ inline std::chrono::milliseconds millisecondsSince(
  return millisecondsBetween(getCurrentTime<ClockType>(), t);
 }
 
+template <typename ClockType = SteadyClock>
+inline std::chrono::microseconds microsecondsSince(
+ std::chrono::time_point<ClockType> t) {
+ return microsecondsBetween(getCurrentTime<ClockType>(), t);
+}
+
 template <typename ClockType = SteadyClock>
 inline std::chrono::seconds secondsSince(std::chrono::time_point<ClockType> t) {
  return secondsBetween(getCurrentTime<ClockType>(), t);