WIP 3 - Scraper thread safety

gridcoin-community · Aug 28, 2021 · d06dcfe · d06dcfe
1 parent 93de2a9
commit d06dcfe
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Showing 4 changed files with 175 additions and 144 deletions.
diff --git a/src/gridcoin/quorum.cpp b/src/gridcoin/quorum.cpp
@@ -1039,17 +1039,22 @@ class SuperblockValidator
 
             const CScraperManifest_shared_ptr manifest = iter->second;
 
-            LOCK(manifest->cs_manifest);
-
             // If the manifest for the beacon list is now empty, we cannot
             // proceed, but ProjectResolver should always select manifests
             // with a beacon list part:
-            if (manifest->vParts.empty()) {
-                LogPrintf("ValidateSuperblock(): beacon list part missing.");
-                return;
-            }
 
-            convergence.AddPart("BeaconList", manifest->vParts[0]);
+            // Note using fine-grained locking here to avoid lock-order issues and
+            // also to deal with Clang potential false positive below.
+            {
+                LOCK(manifest->cs_manifest);
+
+                if (manifest->vParts.empty()) {
+                    LogPrintf("ValidateSuperblock(): beacon list part missing.");
+                    return;
+                }
+
+                convergence.AddPart("BeaconList", manifest->vParts[0]);
+            }
 
             // Find the offset of the verified beacons project part. Typically
             // this exists at vParts offset 1 when a scraper verified at least
@@ -1058,10 +1063,14 @@ class SuperblockValidator
             const auto verified_beacons_entry_iter = std::find_if(
                 manifest->projects.begin(),
                 manifest->projects.end(),
-                [](const CScraperManifest::dentry& entry) {
+                [manifest](const CScraperManifest::dentry& entry) {
+                    // Clang was giving a false positive on thread safety without this.
+                    LOCK(manifest->cs_manifest);
                     return entry.project == "VerifiedBeacons";
                 });
 
+            LOCK2(CSplitBlob::cs_mapParts, manifest->cs_manifest);
+
             if (verified_beacons_entry_iter == manifest->projects.end()) {
                 LogPrintf("ValidateSuperblock(): verified beacon project missing.");
                 return;
@@ -1074,8 +1083,6 @@ class SuperblockValidator
                 return;
             }
 
-            LOCK(CSplitBlob::cs_mapParts);
-
             convergence.AddPart("VerifiedBeacons", manifest->vParts[part_offset]);
         }
     }; // ProjectCombiner