transaction: Store info about concurrently running transaction

If a transaction run fails because another transaction is running
concurrently, record information about that transaction so it can be
used later to generate a clearer error message.

Author: m-blaha

include/libdnf5/base/transaction.hpp

@@ -23,6 +23,7 @@
 
 #include "transaction_errors.hpp"
 
+#include "libdnf5/base/active_transaction_info.hpp"
 #include "libdnf5/base/base_weak.hpp"
 #include "libdnf5/base/goal_elements.hpp"
 #include "libdnf5/base/log_event.hpp"
@@ -197,6 +198,9 @@ class LIBDNF_API Transaction {
     /// Retrieve captured RPM log messages
     std::vector<std::string> get_rpm_messages();
 
+    /// Retrieve metadat of concurrently running transaction
+    const ActiveTransactionInfo * get_concurrent_transaction() const noexcept;
+
 private:
     friend class TransactionEnvironment;
     friend class TransactionGroup;

libdnf5/base/transaction.cpp

@@ -38,6 +38,7 @@
 #include "transaction_package_impl.hpp"
 #include "utils/string.hpp"
 
+#include "libdnf5/base/active_transaction_info.hpp"
 #include "libdnf5/base/base.hpp"
 #include "libdnf5/common/exception.hpp"
 #include "libdnf5/common/sack/exclude_flags.hpp"
@@ -954,6 +955,8 @@ Transaction::TransactionRunResult Transaction::Impl::_run(
     const std::optional<uint32_t> user_id,
     const std::string & comment,
     const bool test_only) {
+    concurrent_transaction.reset();
+
     // do not allow running a transaction multiple times
     if (history_db_id > 0) {
         return TransactionRunResult::ERROR_RERUN;
@@ -985,6 +988,8 @@ Transaction::TransactionRunResult Transaction::Impl::_run(
 
     TransactionLocker transaction_locker(lock_file_path, info);
     if (!transaction_locker.write_lock()) {
+        auto content = transaction_locker.read_content();
+        concurrent_transaction = std::make_unique<ActiveTransactionInfo>(ActiveTransactionInfo::from_toml(content));
         return TransactionRunResult::ERROR_LOCK;
     }
     transaction_locker.write_transaction_metadata();
@@ -1605,4 +1610,8 @@ void Transaction::set_rpm_messages(std::vector<std::string> && rpm_messages) {
     p_impl->set_rpm_messages(std::move(rpm_messages));
 }
 
+const ActiveTransactionInfo * Transaction::get_concurrent_transaction() const noexcept {
+    return p_impl->concurrent_transaction.get();
+}
+
 }  // namespace libdnf5::base

libdnf5/base/transaction_impl.hpp

@@ -26,6 +26,7 @@
 #endif
 #include "rpm/solv/goal_private.hpp"
 
+#include "libdnf5/base/active_transaction_info.hpp"
 #include "libdnf5/base/transaction.hpp"
 #include "libdnf5/base/transaction_environment.hpp"
 #include "libdnf5/base/transaction_group.hpp"
@@ -158,6 +159,10 @@ class Transaction::Impl {
     std::unordered_map<std::string, transaction::TransactionItemReason> rpm_reason_overrides;
     // Used during transaction replay to verify no extra packages were pulled into the transaction
     std::vector<std::tuple<std::unordered_set<std::string>, GoalJobSettings>> rpm_replays_nevra_cache;
+
+    // If a transaction run fails due to a concurrent transaction,
+    // store information about that concurrent transaction.
+    std::unique_ptr<base::ActiveTransactionInfo> concurrent_transaction{nullptr};
 };