make threadpool a class object

reporting/PostgresBackend.cpp

@@ -411,17 +411,15 @@ std::vector<TransactionAndMetadata>
 PostgresBackend::fetchTransactions(
     std::vector<ripple::uint256> const& hashes) const
 {
-    PgQuery pgQuery(pgPool_);
+    std::vector<TransactionAndMetadata> results;
-    pgQuery("SET statement_timeout TO 10000");
+    constexpr bool doAsync = true;
-    std::stringstream sql;
+    if (doAsync)
-    bool first = true;
+    {
         auto start = std::chrono::system_clock::now();
-    boost::asio::thread_pool pool{hashes.size()};
         auto end = std::chrono::system_clock::now();
         auto duration = ((end - start).count()) / 1000000000.0;
-    BOOST_LOG_TRIVIAL(info)
+        BOOST_LOG_TRIVIAL(info) << __func__ << " created threadpool. took "
-        << __func__ << " created threadpool. took " << std::to_string(duration);
+                                << std::to_string(duration);
-    std::vector<TransactionAndMetadata> results;
         results.resize(hashes.size());
         std::condition_variable cv;
         std::mutex mtx;
@@ -429,16 +427,14 @@ PostgresBackend::fetchTransactions(
         for (size_t i = 0; i < hashes.size(); ++i)
         {
             auto const& hash = hashes[i];
-        boost::asio::post([this,
+            boost::asio::post(
-                           &hash,
+                pool_, [this, &hash, &results, &numRemaining, &cv, &mtx, i]() {
-                           &results,
+                    BOOST_LOG_TRIVIAL(debug)
-                           &numRemaining,
+                        << __func__ << " getting txn = " << i;
-                           &cv,
-                           &mtx,
-                           i]() {
                     PgQuery pgQuery(pgPool_);
                     std::stringstream sql;
-            sql << "SELECT transaction,metadata,ledger_seq FROM transactions "
+                    sql << "SELECT transaction,metadata,ledger_seq FROM "
+                           "transactions "
                            "WHERE HASH = \'\\x"
                         << ripple::strHex(hash) << "\'";
 
@@ -463,9 +459,43 @@ PostgresBackend::fetchTransactions(
         duration = ((end2 - end).count()) / 1000000000.0;
         BOOST_LOG_TRIVIAL(info)
             << __func__ << " fetched " << std::to_string(hashes.size())
-        << " transactions. took " << std::to_string(duration);
+            << " transactions with threadpool. took "
+            << std::to_string(duration);
+    }
+    else
+    {
+        PgQuery pgQuery(pgPool_);
+        pgQuery("SET statement_timeout TO 10000");
+        std::stringstream sql;
+        for (size_t i = 0; i < hashes.size(); ++i)
+        {
+            auto const& hash = hashes[i];
+            sql << "SELECT transaction,metadata,ledger_seq FROM "
+                   "transactions "
+                   "WHERE HASH = \'\\x"
+                << ripple::strHex(hash) << "\'";
+            if (i + 1 < hashes.size())
+                sql << " UNION ALL ";
+        }
+        auto start = std::chrono::system_clock::now();
+        auto res = pgQuery(sql.str().data());
+        auto end = std::chrono::system_clock::now();
+        auto duration = ((end - start).count()) / 1000000000.0;
+        BOOST_LOG_TRIVIAL(info)
+            << __func__ << " fetched " << std::to_string(hashes.size())
+            << " transactions with union all. took "
+            << std::to_string(duration);
+        if (size_t numRows = checkResult(res, 3))
+        {
+            for (size_t i = 0; i < numRows; ++i)
+                results.push_back(
+                    {res.asUnHexedBlob(i, 0),
+                     res.asUnHexedBlob(i, 1),
+                     res.asBigInt(i, 2)});
+        }
+    }
     return results;
-}  // namespace Backend
+}
 
 std::vector<Blob>
 PostgresBackend::fetchLedgerObjects(

reporting/PostgresBackend.h

@@ -15,6 +15,7 @@ private:
     std::shared_ptr<PgPool> pgPool_;
     mutable PgQuery writeConnection_;
     mutable bool abortWrite_ = false;
+    mutable boost::asio::thread_pool pool_{200};
 
 public:
     PostgresBackend(boost::json::object const& config);