Ticket #2497: ms_postgis_begin_to_connect.diff

mappostgis.c

@@ -166 +166 @@
     PQfinish((PGconn*) conn_handle);
 }
 
+/* takes a connection and ensures that it is in a valid transactional state */
+/* performing ROLLBACK and BEGIN on it if necessary */
+int msPOSTGISInitConnection(PGconn *conn)
+{
+  // if connection is in CONNECTION_BAD status, PQreset() it
+  if (PQstatus(conn) == CONNECTION_BAD)
+  {
+    PQreset(conn);
+    if (PQstatus(conn) == CONNECTION_BAD)
+    {
+      msSetError(MS_QUERYERR, "Database connection reports status CONNECTION_BAD even after attempt to PQreset() it.", "msPOSTGISInitConnection()");
+      return MS_FAILURE;
+    }
+  }
+  
+  if (PQtransactionStatus(conn) == PQTRANS_INERROR) // idle, in a failed transaction block
+  {
+      PGresult *rb_res = PQexec(conn, "ROLLBACK");
+      if (!rb_res || PQresultStatus(rb_res) != PGRES_COMMAND_OK) {
+          msSetError(MS_QUERYERR, "Error executing POSTGIS ROLLBACK statement.", "msPOSTGISInitConnection()");
+
+          if(rb_res) {
+              PQclear(rb_res);
+          }
+
+          return MS_FAILURE;
+      }
+      PQclear(rb_res);
+  }
+ 
+  if (PQtransactionStatus(conn) == PQTRANS_IDLE) // idle, but not in a transaction block
+  {
+      PGresult *beg_res = PQexec(conn, "BEGIN");
+      if (!beg_res || PQresultStatus(beg_res) != PGRES_COMMAND_OK) {
+          msSetError(MS_QUERYERR, "Error executing POSTGIS BEGIN statement.", "msPOSTGISInitConnection()");
+  
+          if(beg_res) {
+              PQclear(beg_res);
+          }
+  
+          return MS_FAILURE;
+      }
+      PQclear(beg_res);
+  }
+
+  return MS_SUCCESS;
+}
+
 /*static int gBYTE_ORDER = 0;*/
 
 /* open up a connection to the postgresql database using the connection string in layer->connection */
@@ -250 +298 @@
             return MS_FAILURE;
         }
 
+        /* start a transaction, since it's required by all subsequent (DECLARE CURSOR) queries */
+        if (msPOSTGISInitConnection(layerinfo->conn) != MS_SUCCESS)
+        {
+          return MS_FAILURE;
+        }
+
         msConnPoolRegister(layer, layerinfo->conn, msPOSTGISCloseConnection);
 
         PQsetNoticeProcessor(layerinfo->conn, postresql_NOTICE_HANDLER, (void *) layer);
@@ -486 +540 @@
     free(f_table_name);
     free(columns_wanted);
 
-    /* start transaction required by cursor */
-
-    result = PQexec(layerinfo->conn, "BEGIN");
-    if(!result || PQresultStatus(result) != PGRES_COMMAND_OK) {
-        msSetError(MS_QUERYERR, "Error executing POSTGIS BEGIN statement.", "prepare_database()");
-
-        if(result) {
-            PQclear(result);
-        }
-                if(layerinfo->query_result) {
-                        PQclear(layerinfo->query_result);
-                }
-        layerinfo->query_result = NULL;
-        PQreset(layerinfo->conn);
-
-        free(query_string_0_6);
-
-        return MS_FAILURE;     /* totally screwed */
-    }
-
-    PQclear(result);
-
     /* set enable_seqscan=off not required (already done) */
 
     if(layer->debug) {
@@ -552 +584 @@
             PQclear(result);
         }
         layerinfo->query_result = NULL;
-        PQreset(layerinfo->conn);
+        if (msPOSTGISInitConnection(layerinfo->conn) != MS_SUCCESS)
+        {
+          return MS_FAILURE;
+        }
 
         free(error_message);
         free(query_string_0_6);
@@ -562 +597 @@
 
     PQclear(result);
     layerinfo->query_result = NULL;
-    PQreset(layerinfo->conn);
+    msPOSTGISInitConnection(layerinfo->conn);
 
     /* TODO Rename tmp2 to something meaningful */
     tmp2 = (char *) malloc(149 + strlen(query_string_0_6) + strlen(error_message) + 1);
@@ -643 +678 @@
           PQclear(layerinfo->query_result);
         }
         layerinfo->query_result = NULL;
-        PQreset(layerinfo->conn);
+        msPOSTGISInitConnection(layerinfo->conn);
 
         return MS_FAILURE;
     }
@@ -1202 +1237 @@
     free(geom_column_name);
     free(table_name);
 
-    query_result = PQexec(layerinfo->conn, "BEGIN");
-    if(!query_result || PQresultStatus(query_result) != PGRES_COMMAND_OK) {
-        msSetError(MS_QUERYERR, "Error executing POSTGIS  BEGIN   statement.", "msPOSTGISLayerGetShape()");
-
-        if(query_result) {
-            PQclear(query_result);
-        }
-        PQreset(layerinfo->conn);
-
-        free(query_str);
-
-        return MS_FAILURE;
-    }
-    PQclear(query_result);
-
     query_result = PQexec(layerinfo->conn, query_str);
 
     if(!query_result || PQresultStatus(query_result) != PGRES_COMMAND_OK) {
@@ -1225 +1245 @@
         if(query_result) {
           PQclear(query_result);
         }
-        PQreset(layerinfo->conn);
+        msPOSTGISInitConnection(layerinfo->conn);
 
         free(query_str);
 
@@ -1241 +1261 @@
         if(query_result) {
           PQclear(query_result);
         }
-        PQreset(layerinfo->conn);
+        msPOSTGISInitConnection(layerinfo->conn);
 
         free(query_str);
 
@@ -1312 +1332 @@
                 PQclear(query_result);
 
             query_result = PQexec(layerinfo->conn, "CLOSE mycursor2");
-            if(query_result) {
-                PQclear(query_result);
-            }
 
-            query_result = PQexec(layerinfo->conn, "ROLLBACK");
-            if(!query_result || PQresultStatus(query_result) != PGRES_COMMAND_OK) {
-                msSetError(MS_QUERYERR, "Error executing POSTGIS  BEGIN   statement.", "msPOSTGISLayerGetShape()");
-
-                if(query_result) {
+            if(!query_result || PQresultStatus(query_result) !=  PGRES_COMMAND_OK)
+            {
+                msFreeShape(shape);
+                if (query_result)
+                {
                     PQclear(query_result);
                 }
-                PQreset(layerinfo->conn);
 
-                msFreeShape(shape);
+                if (msPOSTGISInitConnection(layerinfo->conn) != MS_SUCCESS)
+                {
+                    return MS_FAILURE;
+                }
 
+                msSetError(MS_QUERYERR, "Error executing POSTGIS CLOSE statement on query (which returned one or more tuples).", "msPOSTGISLayerGetShape()");
+
                 return MS_FAILURE;
             }
 
@@ -1340 +1361 @@
         PQclear(query_result);
 
         query_result = PQexec(layerinfo->conn, "CLOSE mycursor2");
-        if(query_result) {
-            PQclear(query_result);
-        }
 
-        query_result = PQexec(layerinfo->conn, "ROLLBACK");
-        if(!query_result || PQresultStatus(query_result) != PGRES_COMMAND_OK) {
-            msSetError(MS_QUERYERR, "Error executing POSTGIS  BEGIN   statement.", "msPOSTGISLayerGetShape()");
+        if (!query_result || PQresultStatus(query_result) != PGRES_COMMAND_OK)
+        {
+            if (query_result)
+            {
+              PQclear(query_result);
+            }
 
-            if(query_result) {
-                PQclear(query_result);
+            if (msPOSTGISInitConnection(layerinfo->conn) != MS_SUCCESS)
+            {
+              return MS_FAILURE;
             }
-            PQreset(layerinfo->conn);
 
+            msSetError(MS_QUERYERR, "Error executing POSTGIS CLOSE statement on query (which returned zero tuples).", "msPOSTGISLayerGetShape()");
+
             return MS_FAILURE;
         }