don't create strands for cache download. output cache info in server_info

src/backend/SimpleCache.cpp

@@ -1,7 +1,7 @@
 #include <backend/SimpleCache.h>
 namespace Backend {
 uint32_t
-SimpleCache::latestLedgerSequence()
+SimpleCache::latestLedgerSequence() const
 {
     std::shared_lock lck{mtx_};
     return latestSeq_;
@@ -91,12 +91,12 @@ SimpleCache::setFull()
 }
 
 bool
-SimpleCache::isFull()
+SimpleCache::isFull() const
 {
     return full_;
 }
 size_t
-SimpleCache::size()
+SimpleCache::size() const
 {
     std::shared_lock lck{mtx_};
     return map_.size();

src/backend/SimpleCache.h

@@ -49,14 +49,14 @@ public:
     setFull();
 
     uint32_t
-    latestLedgerSequence();
+    latestLedgerSequence() const;
 
     // whether the cache has all data for the most recent ledger
     bool
-    isFull();
+    isFull() const;
 
     size_t
-    size();
+    size() const;
 };
 
 }  // namespace Backend

src/etl/ReportingETL.cpp

@@ -937,9 +937,8 @@ ReportingETL::loadCache(uint32_t seq)
     {
         std::optional<ripple::uint256> start = cursors[i];
         std::optional<ripple::uint256> end = cursors[i + 1];
-        cacheDownloadStrands_.emplace_back(ioContext_);
         boost::asio::spawn(
-            cacheDownloadStrands_.back(),
+            ioContext_,
             [this, seq, start, end, numRemaining](
                 boost::asio::yield_context yield) {
                 std::optional<ripple::uint256> cursor = start;
@@ -948,7 +947,7 @@ ReportingETL::loadCache(uint32_t seq)
                     auto res =
                         Backend::retryOnTimeout([this, seq, &cursor, &yield]() {
                             return backend_->fetchLedgerPage(
-                                cursor, seq, 256, yield);
+                                cursor, seq, 256, false, yield);
                         });
                     backend_->cache().update(res.objects, seq, true);
                     if (!res.cursor || (end && *(res.cursor) > *end))

src/etl/ReportingETL.h

@@ -67,8 +67,6 @@ private:
     /// ledgers are published in order
     boost::asio::io_context::strand publishStrand_;
 
-    std::vector<boost::asio::io_context::strand> cacheDownloadStrands_;
-
     /// Mechanism for communicating with ETL sources. ETLLoadBalancer wraps an
     /// arbitrary number of ETL sources and load balances ETL requests across
     /// those sources.

src/rpc/handlers/ServerInfo.cpp

@@ -29,6 +29,11 @@ doServerInfo(Context const& context)
         info["counters"] = boost::json::object{};
         info["counters"].as_object()["rpc"] = context.counters.report();
     }
+    auto& cache = (response["cache"] = boost::json::object{}).as_object();
+    cache["size"] = context.backend->cache().size();
+    cache["is_full"] = context.backend->cache().isFull();
+    cache["latest_ledger_seq"] =
+        context.backend->cache().latestLedgerSequence();
 
     auto serverInfoRippled = context.balancer->forwardToRippled(
         context.params, context.clientIp, context.yield);