Bug 1742408 - Add TRR skip reason telemetry that only includes relevant reasons r=nhnt11

Differential Revision: https://phabricator.services.mozilla.com/D131798

netwerk/dns/TRRSkippedReason.h

@@ -51,6 +51,27 @@ enum class TRRSkippedReason : uint32_t {
   ODOH_DECRYPTION_FAILED = 36,  // Failed to decrypt DNS packets.
 };
 
+inline bool IsRelevantTRRSkipReason(TRRSkippedReason aReason) {
+  // - TRR_REQ_MODE_DISABLED - these requests are intentionally skipping TRR.
+  //     These include DNS queries used to bootstrap the TRR connection,
+  //     captive portal checks, connectivity checks, etc.
+  //     Since we don't want to use TRR for these connections, we don't need
+  //     to include them with other relevant skip reasons.
+  // - TRR_DISABLED_FLAG - This reason is used when retrying failed connections,
+  //    sync DNS resolves on the main thread, or requests coming from
+  //    webextensions that choose to skip TRR
+  // - TRR_EXCLUDED - This reason is used when a certain domain is excluded
+  //    from TRR because it is explicitly set by the user, or because it
+  //    is part of the user's DNS suffix list, indicating a host that is likely
+  //    to be on the local network.
+  if (aReason == TRRSkippedReason::TRR_REQ_MODE_DISABLED ||
+      aReason == TRRSkippedReason::TRR_DISABLED_FLAG ||
+      aReason == TRRSkippedReason::TRR_EXCLUDED) {
+    return false;
+  }
+  return true;
+}
+
 }  // namespace net
 }  // namespace mozilla
 

netwerk/dns/nsHostRecord.cpp

@@ -312,6 +312,20 @@ void AddrHostRecord::ResolveComplete() {
                          : Telemetry::TRR_SKIP_REASON_NATIVE_FAILED,
           TRRService::ProviderKey(), static_cast<uint32_t>(mTRRSkippedReason));
     }
+
+    if (IsRelevantTRRSkipReason(mTRRSkippedReason)) {
+      Telemetry::Accumulate(Telemetry::TRR_RELEVANT_SKIP_REASON_TRR_FIRST,
+                            TRRService::ProviderKey(),
+                            static_cast<uint32_t>(mTRRSkippedReason));
+
+      if (!mTRRSuccess) {
+        Telemetry::Accumulate(
+            mNativeSuccess ? Telemetry::TRR_RELEVANT_SKIP_REASON_NATIVE_SUCCESS
+                           : Telemetry::TRR_RELEVANT_SKIP_REASON_NATIVE_FAILED,
+            TRRService::ProviderKey(),
+            static_cast<uint32_t>(mTRRSkippedReason));
+      }
+    }
   }
 
   if (mEffectiveTRRMode == nsIRequest::TRR_FIRST_MODE) {

toolkit/components/telemetry/Histograms.json

@@ -4641,6 +4641,44 @@
     "releaseChannelCollection": "opt-out",
     "description": "When in TRR-first mode, if TRR was skipped and native failed, it lists the reason we may have skipped TRR, keyed by the provider."
   },
+
+  "TRR_RELEVANT_SKIP_REASON_TRR_FIRST": {
+    "record_in_processes": ["main", "socket"],
+    "products": ["firefox"],
+    "alert_emails": ["necko@mozilla.com", "vgosu@mozilla.com"],
+    "expires_in_version": "never",
+    "kind": "enumerated",
+    "keyed": true,
+    "n_values": 50,
+    "bug_numbers": [1649143, 1699523, 1742408],
+    "releaseChannelCollection": "opt-out",
+    "description": "When in TRR-first mode, it lists the reason we may have skipped TRR, keyed by the provider. Does not include requests that intentionally skip TRR."
+  },
+  "TRR_RELEVANT_SKIP_REASON_NATIVE_SUCCESS": {
+    "record_in_processes": ["main", "socket"],
+    "products": ["firefox"],
+    "alert_emails": ["necko@mozilla.com", "vgosu@mozilla.com"],
+    "expires_in_version": "never",
+    "kind": "enumerated",
+    "keyed": true,
+    "n_values": 50,
+    "bug_numbers": [1649143, 1699523, 1742408],
+    "releaseChannelCollection": "opt-out",
+    "description": "When in TRR-first mode, if TRR was skipped and native succeeded, it lists the reason we may have skipped TRR, keyed by the provider. Does not include requests that intentionally skip TRR."
+  },
+  "TRR_RELEVANT_SKIP_REASON_NATIVE_FAILED": {
+    "record_in_processes": ["main", "socket"],
+    "products": ["firefox"],
+    "alert_emails": ["necko@mozilla.com", "vgosu@mozilla.com"],
+    "expires_in_version": "never",
+    "kind": "enumerated",
+    "keyed": true,
+    "n_values": 50,
+    "bug_numbers": [1699523, 1742408],
+    "releaseChannelCollection": "opt-out",
+    "description": "When in TRR-first mode, if TRR was skipped and native failed, it lists the reason we may have skipped TRR, keyed by the provider. Does not include requests that intentionally skip TRR."
+  },
+
   "DNS_TRR_FIRST4": {
     "record_in_processes": ["main", "socket"],
     "products": ["firefox", "fennec"],