Creates a new license request latency metric

Previously, we did not have a license request latency metric. This is a
notable limitation in our metrics. This adds a metric that captures the
timing between a GenerateKeyRequest and an AddKey operation.

Bug: 72994956
Test: New unit tests. Google Play
Change-Id: If99c187399c02f9b5d4c355732af7588bbbefb11

libwvdrmengine/cdm/core/src/cdm_session.cpp

@@ -324,7 +324,23 @@ CdmResponseType CdmSession::RestoreUsageSession(
   return KEY_ADDED;
 }
 
+// This is a thin wrapper that initiates the latency metric.
 CdmResponseType CdmSession::GenerateKeyRequest(
+    const InitializationData& init_data, CdmLicenseType license_type,
+    const CdmAppParameterMap& app_parameters, CdmKeyRequest* key_request) {
+  CdmResponseType result = GenerateKeyRequestInternal(
+      init_data, license_type, app_parameters, key_request);
+  // Note that GenerateReleaseRequest and GenerateRenewalRequest will initialize
+  // the timer themselves. This is duplicate because there are duplicate paths
+  // for calling GenerateReleaseRequest and GenerateRenewalRequest.
+  if (result == KEY_MESSAGE) {
+    key_request_type_ = key_request->type;
+    license_request_latency_.Start(); // Start or restart timer.
+  }
+  return result;
+}
+
+CdmResponseType CdmSession::GenerateKeyRequestInternal(
     const InitializationData& init_data, CdmLicenseType license_type,
     const CdmAppParameterMap& app_parameters,
     CdmKeyRequest* key_request) {
@@ -410,8 +426,15 @@ CdmResponseType CdmSession::GenerateKeyRequest(
   }
 }
 
-// AddKey() - Accept license response and extract key info.
+// This thin wrapper allows us to update metrics.
 CdmResponseType CdmSession::AddKey(const CdmKeyResponse& key_response) {
+  CdmResponseType sts = AddKeyInternal(key_response);
+  UpdateRequestLatencyTiming(sts);
+  return sts;
+}
+
+// AddKeyInternal() - Accept license response and extract key info.
+CdmResponseType CdmSession::AddKeyInternal(const CdmKeyResponse& key_response) {
   if (!initialized_) {
     LOGE("CdmSession::AddKey: not initialized");
     return NOT_INITIALIZED_ERROR;
@@ -602,6 +625,8 @@ CdmResponseType CdmSession::GenerateRenewalRequest(
   if (is_offline_) {
     offline_key_renewal_request_ = key_request->message;
   }
+  key_request_type_ = key_request->type;
+  license_request_latency_.Start(); // Start or restart timer.
   return KEY_MESSAGE;
 }
 
@@ -613,6 +638,10 @@ CdmResponseType CdmSession::RenewKey(const CdmKeyResponse& key_response) {
   }
   CdmResponseType sts =
       license_parser_->HandleKeyUpdateResponse(true, key_response);
+
+  // Record the timing on success.
+  UpdateRequestLatencyTiming(sts);
+
   if (sts != KEY_ADDED) return (sts == KEY_ERROR) ? RENEW_KEY_ERROR_1 : sts;
 
   if (is_offline_) {
@@ -630,6 +659,7 @@ CdmResponseType CdmSession::GenerateReleaseRequest(
     return NOT_INITIALIZED_ERROR;
   }
   is_release_ = true;
+  license_request_latency_.Clear();
   CdmResponseType status = license_parser_->PrepareKeyUpdateRequest(
       false, app_parameters_, usage_table_header_ == NULL ? NULL : this,
       &key_request->message, &key_request->url);
@@ -658,6 +688,10 @@ CdmResponseType CdmSession::GenerateReleaseRequest(
         return RELEASE_USAGE_INFO_FAILED;
     }
   }
+
+  key_request_type_ = key_request->type;
+  license_request_latency_.Start(); // Start or restart timer.
+
   return KEY_MESSAGE;
 }
 
@@ -669,6 +703,9 @@ CdmResponseType CdmSession::ReleaseKey(const CdmKeyResponse& key_response) {
   }
   CdmResponseType sts =
       license_parser_->HandleKeyUpdateResponse(false, key_response);
+  // Record the timing on success.
+  UpdateRequestLatencyTiming(sts);
+
   if (sts != KEY_ADDED) return (sts == KEY_ERROR) ? RELEASE_KEY_ERROR : sts;
 
   if (is_offline_ || has_provider_session_token()) {
@@ -1046,6 +1083,14 @@ bool CdmSession::UpdateUsageInfo() {
       usage_data);
 }
 
+void CdmSession::UpdateRequestLatencyTiming(CdmResponseType sts) {
+  if (sts == KEY_ADDED && license_request_latency_.IsStarted()) {
+    metrics_->cdm_session_license_request_latency_ms_.Record(
+        license_request_latency_.AsMs(), key_request_type_);
+  }
+  license_request_latency_.Clear();
+}
+
 // For testing only - takes ownership of pointers
 
 void CdmSession::set_license_parser(CdmLicense* license_parser) {