fix(db): fix id generator runtime error

Former-commit-id: fc964ebe4af0d31527b9b6ec01558d84199efbff

cpp/src/db/id_generators.cpp

 #include <chrono>
 #include <assert.h>
+#include <iostream>
 
 #include "id_generators.h"
 
@@ -17,18 +18,17 @@ IDNumber SimpleIDGenerator::getNextIDNumber() {
     return micros * MAX_IDS_PER_MICRO;
 }
 
-IDNumbers&& SimpleIDGenerator::getNextIDNumbers(size_t n) {
+void SimpleIDGenerator::getNextIDNumbers(size_t n, IDNumbers& ids) {
     assert(n < MAX_IDS_PER_MICRO);
     auto now = std::chrono::system_clock::now();
     auto micros = std::chrono::duration_cast<std::chrono::microseconds>(
             now.time_since_epoch()).count();
     micros *= MAX_IDS_PER_MICRO;
 
-    IDNumbers ids = IDNumbers(n);
+    ids.clear();
     for (int pos=0; pos<n; ++pos) {
-        ids[pos] = micros + pos;
+        ids.push_back(micros+pos);
     }
-    return std::move(ids);
 }
 
 

cpp/src/db/id_generators.h

@@ -10,7 +10,7 @@ namespace engine {
 class IDGenerator {
 public:
     virtual IDNumber getNextIDNumber() = 0;
-    virtual IDNumbers&& getNextIDNumbers(size_t n_) = 0;
+    virtual void getNextIDNumbers(size_t n, IDNumbers& ids) = 0;
 
     virtual ~IDGenerator();
 
@@ -20,7 +20,7 @@ public:
 class SimpleIDGenerator : public IDGenerator {
 public:
     virtual IDNumber getNextIDNumber() override;
-    virtual IDNumbers&& getNextIDNumbers(size_t n_) override;
+    virtual void getNextIDNumbers(size_t n, IDNumbers& ids) override;
 
 private:
     const size_t MAX_IDS_PER_MICRO = 1000;