structured cache: fix some minor issues (#995)

- Fix double WriteResponse in PUT record failure path; the detail-body branch now short-circuits instead of falling through to a second WriteResponse call
- Return 405 Method Not Allowed for unsupported verbs in the root, namespace, bucket, record, and chunk handlers (previously fell through to no response)
- Clamp exec$/replay-recording thread_count so a bogus query value cannot spawn an unbounded worker pool

## Performance / cleanup

- NamespaceMap now uses TransparentStringHash + std::equal_to<>, so Get/Put/Find/Drop can probe the map with a std::string_view directly instead of constructing a temporary std::string on every request
- Replace insert_or_assign with try_emplace under the exclusive lock in GetNamespace; the find() re-check already guarantees the key is absent, so try_emplace matches intent better

## Reverted

- The earlier change to erase the pinned entry from m_DroppedNamespaces after DropNamespace's post-drop work was reverted: other threads may still hold pointers into a dropped namespace, so tearing it down eagerly is unsafe. Dropped namespaces remain pinned for the lifetime of the process as before.

1 files changed, 16 insertions, 11 deletions

diff --git a/src/zenserver/storage/cache/httpstructuredcache.cpp b/src/zenserver/storage/cache/httpstructuredcache.cpp
index 8ad48225b..4d3673e70 100644
--- a/src/zenserver/storage/cache/httpstructuredcache.cpp
+++ b/src/zenserver/storage/cache/httpstructuredcache.cpp
@@ -437,19 +437,22 @@ HttpStructuredCacheService::HandleRequest(HttpServerRequest& Request)
 
 		std::string RecordPath = UrlDecode(Params.GetValue("path"));
 
-		uint32_t ThreadCount = GetHardwareConcurrency();
+		const uint32_t HardwareConcurrency = GetHardwareConcurrency();
+		const uint32_t MaxThreadCount	   = std::max<uint32_t>(HardwareConcurrency, 16u);
+		uint32_t	   ThreadCount		   = HardwareConcurrency;
 		if (auto Param = Params.GetValue("thread_count"); Param.empty() == false)
 		{
 			if (auto Value = ParseInt<uint64_t>(Param))
 			{
-				ThreadCount = gsl::narrow<uint32_t>(Value.value());
+				ThreadCount = gsl::narrow_cast<uint32_t>(std::min<uint64_t>(Value.value(), MaxThreadCount));
 			}
 		}
+		ThreadCount = std::clamp<uint32_t>(ThreadCount, 1u, MaxThreadCount);
 
 		ZEN_INFO("initiating cache RPC replay using {} threads, from '{}'", ThreadCount, RecordPath);
 
 		std::unique_ptr<cache::IRpcRequestReplayer> Replayer(cache::MakeDiskRequestReplayer(RecordPath, false));
-		ReplayRequestRecorder(RequestContext, *Replayer, ThreadCount < 1 ? 1 : ThreadCount);
+		ReplayRequestRecorder(RequestContext, *Replayer, ThreadCount);
 
 		ZEN_INFO("cache RPC replay COMPLETED");
 
@@ -557,7 +560,7 @@ HttpStructuredCacheService::HandleCacheRequest(HttpServerRequest& Request)
 			break;
 		default:
 			m_CacheStats.BadRequestCount++;
-			break;
+			return Request.WriteResponse(HttpResponseCode::MethodNotAllowed);
 	}
 }
 
@@ -707,7 +710,8 @@ HttpStructuredCacheService::HandleCacheNamespaceRequest(HttpServerRequest& Reque
 			break;
 
 		default:
-			break;
+			m_CacheStats.BadRequestCount++;
+			return Request.WriteResponse(HttpResponseCode::MethodNotAllowed);
 	}
 }
 
@@ -797,7 +801,8 @@ HttpStructuredCacheService::HandleCacheBucketRequest(HttpServerRequest& Request,
 			break;
 
 		default:
-			break;
+			m_CacheStats.BadRequestCount++;
+			return Request.WriteResponse(HttpResponseCode::MethodNotAllowed);
 	}
 }
 
@@ -816,7 +821,8 @@ HttpStructuredCacheService::HandleCacheRecordRequest(HttpServerRequest& Request,
 			break;
 
 		default:
-			break;
+			m_CacheStats.BadRequestCount++;
+			return Request.WriteResponse(HttpResponseCode::MethodNotAllowed);
 	}
 }
 
@@ -1216,8 +1222,6 @@ HttpStructuredCacheService::HandlePutCacheRecord(HttpServerRequest& Request, con
 	}
 
 	auto WriteFailureResponse = [&Request](const ZenCacheStore::PutResult& PutResult) {
-		ZEN_UNUSED(PutResult);
-
 		HttpResponseCode ResponseCode = HttpResponseCode::InternalServerError;
 		switch (PutResult.Status)
 		{
@@ -1231,7 +1235,7 @@ HttpStructuredCacheService::HandlePutCacheRecord(HttpServerRequest& Request, con
 
 		if (PutResult.Details)
 		{
-			Request.WriteResponse(ResponseCode, PutResult.Details);
+			return Request.WriteResponse(ResponseCode, PutResult.Details);
 		}
 		return Request.WriteResponse(ResponseCode);
 	};
@@ -1507,7 +1511,8 @@ HttpStructuredCacheService::HandleCacheChunkRequest(HttpServerRequest& Request,
 			HandlePutCacheChunk(Request, Ref, PolicyFromUrl);
 			break;
 		default:
-			break;
+			m_CacheStats.BadRequestCount++;
+			return Request.WriteResponse(HttpResponseCode::MethodNotAllowed);
 	}
 }