bug 1450630 - use DataStorage in main thread only r=mcmanus

Move the TRR blacklist check to the main thread, and since it is now
done a little later and for each separate request, make sure to only do
the telemetry counting for one of the record types (A) so that we don't
count them twice.

MozReview-Commit-ID: BgvU4TzrpCq

--HG--
extra : rebase_source : 304bc75a6f22963b51e89034de1b30506337b6ec

netwerk/dns/TRR.cpp

@@ -140,6 +140,22 @@ TRR::SendHTTPRequest()
     return NS_ERROR_FAILURE;
   }
 
+  if ((mType == TRRTYPE_A) || (mType == TRRTYPE_AAAA)) {
+    // let NS resolves skip the blacklist check
+    if (gTRRService->IsTRRBlacklisted(mHost, mPB, true)) {
+      if (mType == TRRTYPE_A) {
+        // count only blacklist for A records to avoid double counts
+        Telemetry::Accumulate(Telemetry::DNS_TRR_BLACKLISTED, true);
+      }
+      // not really an error but no TRR is issued
+      return NS_ERROR_UNKNOWN_HOST;
+    } else {
+      if (mType == TRRTYPE_A) {
+        Telemetry::Accumulate(Telemetry::DNS_TRR_BLACKLISTED, false);
+      }
+    }
+  }
+
   nsresult rv;
   nsCOMPtr<nsIIOService> ios(do_GetIOService(&rv));
   NS_ENSURE_SUCCESS(rv, rv);

netwerk/dns/TRRService.cpp

@@ -384,13 +384,6 @@ bool
 TRRService::IsTRRBlacklisted(const nsACString &aHost, bool privateBrowsing,
                              bool aParentsToo) // false if domain
 {
-  if (mClearTRRBLStorage) {
-    if (mTRRBLStorage) {
-      mTRRBLStorage->Clear();
-    }
-    mClearTRRBLStorage = false;
-  }
-
   if (mMode == MODE_TRRONLY) {
     return false; // might as well try
   }
@@ -408,6 +401,15 @@ TRRService::IsTRRBlacklisted(const nsACString &aHost, bool privateBrowsing,
     return false;
   }
 
+  // Only use the Storage API in the main thread
+  MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
+
+  if (mClearTRRBLStorage) {
+    mTRRBLStorage->Clear();
+    mClearTRRBLStorage = false;
+    return false; // just cleared!
+  }
+
   int32_t dot = aHost.FindChar('.');
   if ((dot == kNotFound) && aParentsToo) {
     // Only if a full host name. Domains can be dotless to be able to

netwerk/dns/nsHostResolver.cpp

@@ -1114,15 +1114,6 @@ nsHostResolver::TrrLookup(nsHostRecord *aRec, TRR *pushedTRR)
     rec->mTRRSuccess = 0; // bump for each successful TRR response
     rec->mTrrAUsed = nsHostRecord::INIT;
     rec->mTrrAAAAUsed = nsHostRecord::INIT;
-
-    if (gTRRService && gTRRService->IsTRRBlacklisted(rec->host, rec->pb, true)) {
-        Telemetry::Accumulate(Telemetry::DNS_TRR_BLACKLISTED, true);
-        MOZ_ASSERT(!rec->mTRRUsed);
-        // not really an error but no TRR is issued
-        return NS_ERROR_UNKNOWN_HOST;
-    }
-    Telemetry::Accumulate(Telemetry::DNS_TRR_BLACKLISTED, false);
-
     rec->mTrrStart = TimeStamp::Now();
     rec->mTRRUsed = true; // this record gets TRR treatment