Reporting a special status for queries exceeding the large result limit(6)

Author: iagaponenko

src/czar/HttpCzarQueryModule.cc

@@ -227,55 +227,69 @@ void HttpCzarQueryModule::_dumpQueryInfo(string const& func, SubmitResult const&
 
 json HttpCzarQueryModule::_waitAndExtractResult(SubmitResult const& submitResult,
                                                 http::BinaryEncodingMode binaryEncoding, bool async) const {
-    if (!(submitResult.status != "COMPLETED" || submitResult.status != "EXECUTING")) {
-        throw http::Error(context() + __func__, submitResult.errorMessage);
-    }
-    // Block the current thread before the query will finish or fail.
-    string const messageSelectQuery =
-            "SELECT chunkId, code, message, severity+0, timeStamp FROM " + submitResult.messageTable;
     auto const conn =
             sql::SqlConnectionFactory::make(cconfig::CzarConfig::instance()->getMySqlResultConfig());
-    sql::SqlResults messageQueryResults;
-    sql::SqlErrorObject messageQueryErr;
-    if (!conn->runQuery(messageSelectQuery, messageQueryResults, messageQueryErr)) {
-        _dropTable(submitResult.messageTable);
-        _dropTable(submitResult.resultTable);
-        string const msg = "failed query=" + messageSelectQuery + " err=" + messageQueryErr.printErrMsg();
-        error(__func__, msg);
-        throw http::Error(context() + __func__, msg);
-    }
+    if (async) {
+        // For the async queries the result table is not going to be ready
+        // until the query is completed. The caller should wait for the query
+        // to finish before calling this method.
+        if (submitResult.status != "COMPLETED") {
+            throw http::Error(context() + __func__,
+                              "queryId=" + to_string(submitResult.queryId) +
+                                      " is still executing or it has failed, status=" + submitResult.status);
+        }
 
-    // Read thе message table to see if the user query suceeded or failed
-    vector<string> chunkId;
-    vector<string> code;
-    vector<string> message;
-    vector<string> severity;
-    sql::SqlErrorObject messageProcessErr;
-    if (!messageQueryResults.extractFirst4Columns(chunkId, code, message, severity, messageProcessErr)) {
-        messageQueryResults.freeResults();
+        // For the async queries the message table (if it still exists) is not used.
         _dropTable(submitResult.messageTable);
-        _dropTable(submitResult.resultTable);
-        string const msg = "failed to extract results of query=" + messageSelectQuery +
-                           " err=" + messageProcessErr.printErrMsg();
-        error(__func__, msg);
-        throw http::Error(context() + __func__, msg);
-    }
-    string errorMsg;
-    for (size_t i = 0; i < chunkId.size(); ++i) {
-        if (stoi(code[i]) > 0) {
-            errorMsg += "[chunkId=" + chunkId[i] + " code=" + code[i] + " message=" + message[i] +
-                        " severity=" + severity[i] + "], ";
+    } else {
+        // The sync queries are required to wait on the message table to be unlocked
+        // before proceeding to the result table. The message table is expected to be ready
+        // at any point of time after the query has been submitted. If the query is still
+        // executing the thread will block until the query is completed or failed.
+        string const messageSelectQuery =
+                "SELECT chunkId, code, message, severity+0, timeStamp FROM " + submitResult.messageTable;
+        sql::SqlResults messageQueryResults;
+        sql::SqlErrorObject messageQueryErr;
+        if (!conn->runQuery(messageSelectQuery, messageQueryResults, messageQueryErr)) {
+            _dropTable(submitResult.messageTable);
+            _dropTable(submitResult.resultTable);
+            string const msg = "failed query=" + messageSelectQuery + " err=" + messageQueryErr.printErrMsg();
+            error(__func__, msg);
+            throw http::Error(context() + __func__, msg);
+        }
+
+        // Read thе message table to see if the user query suceeded or failed
+        vector<string> chunkId;
+        vector<string> code;
+        vector<string> message;
+        vector<string> severity;
+        sql::SqlErrorObject messageProcessErr;
+        if (!messageQueryResults.extractFirst4Columns(chunkId, code, message, severity, messageProcessErr)) {
+            messageQueryResults.freeResults();
+            _dropTable(submitResult.messageTable);
+            _dropTable(submitResult.resultTable);
+            string const msg = "failed to extract results of query=" + messageSelectQuery +
+                               " err=" + messageProcessErr.printErrMsg();
+            error(__func__, msg);
+            throw http::Error(context() + __func__, msg);
+        }
+        string errorMsg;
+        for (size_t i = 0; i < chunkId.size(); ++i) {
+            if (stoi(code[i]) > 0) {
+                errorMsg += "[chunkId=" + chunkId[i] + " code=" + code[i] + " message=" + message[i] +
+                            " severity=" + severity[i] + "], ";
+            }
+        }
+        if (!errorMsg.empty()) {
+            messageQueryResults.freeResults();
+            _dropTable(submitResult.messageTable);
+            _dropTable(submitResult.resultTable);
+            error(__func__, errorMsg);
+            throw http::Error(context() + __func__, errorMsg);
         }
-    }
-    if (!errorMsg.empty()) {
         messageQueryResults.freeResults();
         _dropTable(submitResult.messageTable);
-        _dropTable(submitResult.resultTable);
-        error(__func__, errorMsg);
-        throw http::Error(context() + __func__, errorMsg);
     }
-    messageQueryResults.freeResults();
-    _dropTable(submitResult.messageTable);
 
     // Read a result set from the result table, package it into the JSON object
     // and sent it back to a user.
@@ -302,9 +316,9 @@ json HttpCzarQueryModule::_waitAndExtractResult(SubmitResult const& submitResult
     json rowsJson = _rowsToJson(resultQueryResults, schemaJson, binaryEncoding);
     resultQueryResults.freeResults();
 
-    // Note that the result table of the asynchronously submitted queries
-    // is now explicitly deleted by the caller after the result has been extracted.
-    // Otherwise the table will be automatically garbage collected by Czar after
+    // Note that the result table of the asynchronously submitted queries is required to be
+    // explicitly deleted by the caller after the result has been extracted. If this is not
+    // done by the user the table will be automatically garbage collected by Czar after
     // a certain period of time.
     if (!async) {
         _dropTable(submitResult.resultTable);