Add support for after commit triggers (#136)

src/query/interpreter.cpp

@@ -1401,6 +1401,54 @@ void Interpreter::Abort() {
   db_accessor_ = std::nullopt;
 }
 
+namespace {
+void RunTriggersIndividually(const utils::SkipList<Trigger> &triggers, InterpreterContext *interpreter_context) {
+  // Run the triggers
+  for (const auto &trigger : triggers.access()) {
+    spdlog::debug("Executing trigger '{}'", trigger.name());
+    utils::MonotonicBufferResource execution_memory{kExecutionMemoryBlockSize};
+
+    // create a new transaction for each trigger
+    auto storage_acc = interpreter_context->db->Access();
+    DbAccessor db_accessor{&storage_acc};
+
+    try {
+      trigger.Execute(&interpreter_context->plan_cache, &db_accessor, &execution_memory,
+                      *interpreter_context->tsc_frequency, interpreter_context->execution_timeout_sec,
+                      &interpreter_context->is_shutting_down);
+    } catch (const utils::BasicException &exception) {
+      spdlog::warn("Trigger {} failed with exception:\n{}", trigger.name(), exception.what());
+      db_accessor.Abort();
+      continue;
+    }
+
+    auto maybe_constraint_violation = db_accessor.Commit();
+    if (maybe_constraint_violation.HasError()) {
+      const auto &constraint_violation = maybe_constraint_violation.GetError();
+      switch (constraint_violation.type) {
+        case storage::ConstraintViolation::Type::EXISTENCE: {
+          const auto &label_name = db_accessor.LabelToName(constraint_violation.label);
+          MG_ASSERT(constraint_violation.properties.size() == 1U);
+          const auto &property_name = db_accessor.PropertyToName(*constraint_violation.properties.begin());
+          spdlog::warn("Trigger '{}' failed to commit due to existence constraint violation on :{}({})", trigger.name(),
+                       label_name, property_name);
+          break;
+        }
+        case storage::ConstraintViolation::Type::UNIQUE: {
+          const auto &label_name = db_accessor.LabelToName(constraint_violation.label);
+          std::stringstream property_names_stream;
+          utils::PrintIterable(property_names_stream, constraint_violation.properties, ", ",
+                               [&](auto &stream, const auto &prop) { stream << db_accessor.PropertyToName(prop); });
+          spdlog::warn("Trigger '{}' failed to commit due to unique constraint violation on :{}({})", trigger.name(),
+                       label_name, property_names_stream.str());
+          break;
+        }
+      }
+    }
+  }
+}
+}  // namespace
+
 void Interpreter::Commit() {
   // It's possible that some queries did not finish because the user did
   // not pull all of the results from the query.
@@ -1409,6 +1457,16 @@ void Interpreter::Commit() {
   // a query.
   if (!db_accessor_) return;
 
+  // Run the triggers
+  for (const auto &trigger : interpreter_context_->before_commit_triggers.access()) {
+    spdlog::debug("Executing trigger '{}'", trigger.name());
+    utils::MonotonicBufferResource execution_memory{kExecutionMemoryBlockSize};
+    trigger.Execute(&interpreter_context_->plan_cache, &*execution_db_accessor_, &execution_memory,
+                    *interpreter_context_->tsc_frequency, interpreter_context_->execution_timeout_sec,
+                    &interpreter_context_->is_shutting_down);
+  }
+  SPDLOG_DEBUG("Finished executing before commit triggers");
+
   auto maybe_constraint_violation = db_accessor_->Commit();
   if (maybe_constraint_violation.HasError()) {
     const auto &constraint_violation = maybe_constraint_violation.GetError();
@@ -1438,16 +1496,15 @@ void Interpreter::Commit() {
     }
   }
 
-  // Run the triggers
-  for (const auto &trigger : interpreter_context_->triggers.access()) {
-    utils::MonotonicBufferResource execution_memory{kExecutionMemoryBlockSize};
-    trigger.Execute(&interpreter_context_->plan_cache, &*execution_db_accessor_, &execution_memory,
-                    *interpreter_context_->tsc_frequency, interpreter_context_->execution_timeout_sec,
-                    &interpreter_context_->is_shutting_down);
-  }
-
   execution_db_accessor_ = std::nullopt;
   db_accessor_ = std::nullopt;
+
+  background_thread_.AddTask([interpreter_context = this->interpreter_context_] {
+    RunTriggersIndividually(interpreter_context->after_commit_triggers, interpreter_context);
+    SPDLOG_DEBUG("Finished executing after commit triggers");  // NOLINT(bugprone-lambda-function-name)
+  });
+
+  SPDLOG_DEBUG("Finished comitting the transaction");
 }
 
 void Interpreter::AdvanceCommand() {

src/query/interpreter.hpp

@@ -20,6 +20,7 @@
 #include "utils/memory.hpp"
 #include "utils/skip_list.hpp"
 #include "utils/spin_lock.hpp"
+#include "utils/thread_pool.hpp"
 #include "utils/timer.hpp"
 #include "utils/tsc.hpp"
 
@@ -147,8 +148,14 @@ struct PreparedQuery {
  */
 struct InterpreterContext {
   explicit InterpreterContext(storage::Storage *db) : db(db) {
-    // auto triggers_acc = triggers.access();
-    // triggers_acc.insert(Trigger{"Creator", "CREATE (:CREATED)", &ast_cache, &antlr_lock});
+    // {
+    //   auto triggers_acc = before_commit_triggers.access();
+    //   triggers_acc.insert(Trigger{"BeforeCreator", "CREATE (:BEFORE)", &ast_cache, &antlr_lock});
+    // }
+    // {
+    //   auto triggers_acc = after_commit_triggers.access();
+    //   triggers_acc.insert(Trigger{"AfterCreator", "CREATE (:AFTER)", &ast_cache, &antlr_lock});
+    // }
   }
 
   storage::Storage *db;
@@ -171,7 +178,8 @@ struct InterpreterContext {
   utils::SkipList<PlanCacheEntry> plan_cache;
 
   // use a thread safe container
-  utils::SkipList<Trigger> triggers;
+  utils::SkipList<Trigger> before_commit_triggers;
+  utils::SkipList<Trigger> after_commit_triggers;
 };
 
 /// Function that is used to tell all active interpreters that they should stop
@@ -304,6 +312,8 @@ class Interpreter final {
   bool in_explicit_transaction_{false};
   bool expect_rollback_{false};
 
+  utils::ThreadPool background_thread_{1};
+
   PreparedQuery PrepareTransactionQuery(std::string_view query_upper);
   void Commit();
   void AdvanceCommand();

src/query/trigger.hpp

@@ -19,6 +19,8 @@ struct Trigger {
   // NOLINTNEXTLINE (modernize-use-nullptr)
   bool operator<(const std::string &other) const { return name_ < other; }
 
+  const auto &name() const { return name_; }
+
  private:
   std::string name_;
   ParsedQuery parsed_statements_;