RAII class for the PGresult*

include/cache.h

@@ -253,12 +253,35 @@ class SQLiteCache: public GenericCache
  explicit operator bool() const { return db != nullptr; }
 };
 
-class PostgreSQLCache: public GenericCache
+class PostgreSQLHelpers
 {
- static bool regdest;
+ static constexpr time_t postgresepoch = 946648800;
+
+ class PGResultRAIIDT
+ {
+  public:
+  // TODO: make static
+  void operator()(PGresult* res) { PQclear(res); }
+ };
 
+ protected:
  PostgreSQLConnection conn;
 
+ // Convert Postgres binary representation of timestamp to Unix epoch seconds. Microseconds ignored
+ static time_t raw2epoch(time_t raw) { return Invert(raw) / 1000000 + postgresepoch; }
+
+ // Convert Unix epoch time to Postres binary representation
+ static time_t epoch2raw(time_t epoch) { return Invert((epoch - postgresepoch) * 1000000); }
+
+ class PGresultRAII: public std::unique_ptr<PGresult, PGResultRAIIDT>
+ {
+  public:
+  PGresultRAII() = default;
+  PGresultRAII(PGresult* res): std::unique_ptr<PGresult, PGResultRAIIDT>(res) {}
+
+  operator PGresult*() const { return get(); }
+ };
+
  bool CheckCon() const
  {
   if(!*this) return false;
@@ -270,14 +293,27 @@ class PostgreSQLCache: public GenericCache
  template<class D> static D Invert(D d)
  {
   using michlib::int1;
-  if(sizeof(D) <= 1) return d;
-  D     out;
-  int1* pout = pointer_cast<int1*>(&out);
-  int1* pin  = pointer_cast<int1*>(&d);
-  for(size_t i = 0; i < sizeof(D); i++) pout[sizeof(D) - i - 1] = pin[i];
+  D out;
+  Invert(&d, &out, sizeof(D));
   return out;
  }
 
+ static void Invert(const void* src, void* dst, size_t sz)
+ {
+  if(sz == 0) return;
+  const int1* pin  = pointer_cast<const int1*>(src);
+  int1*       pout = pointer_cast<int1*>(dst);
+  for(size_t i = 0; i < sz; i++) pout[sz - i - 1] = pin[i];
+ }
+
+ public:
+ explicit operator bool() const { return conn != nullptr; }
+};
+
+class PostgreSQLCache: public GenericCache, public PostgreSQLHelpers
+{
+ static bool regdest;
+
  public:
  bool Init()
  {
@@ -285,31 +321,20 @@ class PostgreSQLCache: public GenericCache
 
   if(!regdest)
   {
+   PGresultRAII res;
+
    // Create table
+   res = PQexec(conn, "SET client_min_messages=WARNING;");
+   res = PQexec(conn, "CREATE TABLE IF NOT EXISTS cache(key TEXT PRIMARY KEY NOT NULL, value BYTEA, exptime TIMESTAMP(0) NOT NULL);");
+   if(PQresultStatus(res) != PGRES_COMMAND_OK)
    {
-    auto* res = PQexec(conn, "SET client_min_messages=WARNING;");
-    PQclear(res);
-   }
-   {
-    auto* res = PQexec(conn, "CREATE TABLE IF NOT EXISTS cache(key TEXT PRIMARY KEY NOT NULL, value BYTEA, exptime TIMESTAMP(0) NOT NULL);");
-    if(PQresultStatus(res) != PGRES_COMMAND_OK)
-    {
-     michlib::errmessage(PQresStatus(PQresultStatus(res)));
-     michlib::errmessage(PQerrorMessage(conn));
-    }
-    PQclear(res);
-   }
-   {
-    auto* res = PQexec(conn, "SET client_min_messages=NOTICE;");
-    PQclear(res);
+    michlib::errmessage(PQresStatus(PQresultStatus(res)));
+    michlib::errmessage(PQerrorMessage(conn));
    }
 
-   conn.AddDestructor(
-       [](PostgreSQLConnection::DBType conn)
-       {
-        auto* res = PQexec(conn, "DELETE FROM cache WHERE exptime<localtimestamp;");
-        PQclear(res);
-       });
+   res = PQexec(conn, "SET client_min_messages=NOTICE;");
+
+   conn.AddDestructor([](PostgreSQLConnection::DBType conn) { PGresultRAII res = PQexec(conn, "DELETE FROM cache WHERE exptime<localtimestamp;"); });
 
    regdest = true;
   }
@@ -323,21 +348,19 @@ class PostgreSQLCache: public GenericCache
   auto          interval  = michlib::int_cast<michlib::int8>(ttl);
   michlib::int8 rinterval = Invert(interval);
   const char*   params[]  = {key.Buf(), value.Buf(), pointer_cast<const char*>(&rinterval)};
-  int           plens[]   = {int_cast<int>(key.Len()), int_cast<int>(value.Len()), 8};
+  int           plens[]   = {int_cast<int>(key.Len()), int_cast<int>(value.Len()), sizeof(rinterval)};
   int           pfor[]    = {0, 1, 1};
 
-  auto* res = PQexecParams(conn,
-                           "INSERT INTO cache(key,value,exptime) VALUES($1,$2,localtimestamp + ($3::bigint ||' seconds')::interval)"
-                           "ON CONFLICT(key) DO UPDATE SET value=EXCLUDED.value, exptime=EXCLUDED.exptime;",
-                           3, nullptr, params, plens, pfor, 1);
+  PGresultRAII res = PQexecParams(conn,
+                                  "INSERT INTO cache(key,value,exptime) VALUES($1,$2,localtimestamp + ($3::bigint ||' seconds')::interval)"
+                                  "ON CONFLICT(key) DO UPDATE SET value=EXCLUDED.value, exptime=EXCLUDED.exptime;",
+                                  3, nullptr, params, plens, pfor, 1);
   if(PQresultStatus(res) != PGRES_COMMAND_OK)
   {
    michlib::errmessage(PQresStatus(PQresultStatus(res)));
    michlib::errmessage(PQerrorMessage(conn));
-   PQclear(res);
    return false;
   }
-  PQclear(res);
   return true;
  }
 
@@ -349,28 +372,21 @@ class PostgreSQLCache: public GenericCache
   int         plens[]  = {int_cast<int>(key.Len())};
   int         pfor[]   = {0};
 
-  auto* res = PQexecParams(conn, "SELECT value from cache WHERE key=$1::text AND exptime>localtimestamp;", 1, nullptr, params, plens, pfor, 1);
+  PGresultRAII res = PQexecParams(conn, "SELECT value from cache WHERE key=$1::text AND exptime>localtimestamp;", 1, nullptr, params, plens, pfor, 1);
   if(PQresultStatus(res) != PGRES_TUPLES_OK)
   {
    michlib::errmessage(PQresStatus(PQresultStatus(res)));
    michlib::errmessage(PQerrorMessage(conn));
-   PQclear(res);
    return {"", false};
   }
   else if(PQntuples(res) == 0)
-  {
-   PQclear(res);
    return {"", false};
-  }
 
   MString val(PQgetvalue(res, 0, 0), PQgetlength(res, 0, 0));
-  PQclear(res);
   return {std::move(val), true};
  }
 
  virtual ~PostgreSQLCache() override = default;
-
- explicit operator bool() const { return conn != nullptr; }
 };
 
 inline GenericCache* CreateCache(const MString& cachedesc)