public void loadServerVariables()

in src/main/core-impl/java/com/mysql/cj/NativeSession.java [455:580]
113 lines of code
25 McCabe index (conditional complexity)

    public void loadServerVariables(Lock lock, String version) {
        if (this.cacheServerConfiguration.getValue()) {
            createConfigCacheIfNeeded(lock);

            Map<String, String> cachedVariableMap = this.serverConfigCache.get(this.hostInfo.getDatabaseUrl());

            if (cachedVariableMap != null) {
                String cachedServerVersion = cachedVariableMap.get(SERVER_VERSION_STRING_VAR_NAME);

                if (cachedServerVersion != null && getServerSession().getServerVersion() != null
                        && cachedServerVersion.equals(getServerSession().getServerVersion().toString())) {
                    Map<String, String> localVariableMap = this.protocol.getServerSession().getServerVariables();
                    Map<String, String> newLocalVariableMap = new HashMap<>();
                    newLocalVariableMap.putAll(cachedVariableMap);
                    newLocalVariableMap.putAll(localVariableMap); // preserving variables already configured on previous session initialization steps
                    this.protocol.getServerSession().setServerVariables(newLocalVariableMap);
                    return;
                }

                this.serverConfigCache.invalidate(this.hostInfo.getDatabaseUrl());
            }
        }

        try {
            if (version != null && version.indexOf('*') != -1) {
                StringBuilder buf = new StringBuilder(version.length() + 10);
                for (int i = 0; i < version.length(); i++) {
                    char c = version.charAt(i);
                    buf.append(c == '*' ? "[star]" : c);
                }
                version = buf.toString();
            }

            String versionComment = this.propertySet.getBooleanProperty(PropertyKey.paranoid).getValue() || version == null ? "" : "/* " + version + " */";

            this.protocol.getServerSession().setServerVariables(new HashMap<>());

            TelemetrySpan span = getTelemetryHandler().startSpan(TelemetrySpanName.LOAD_VARIABLES);
            try (TelemetryScope scope = span.makeCurrent()) {
                span.setAttribute(TelemetryAttribute.DB_SYSTEM, "MySQL");
                span.setAttribute(TelemetryAttribute.DB_NAME, () -> this.hostInfo.getDatabase());
                span.setAttribute(TelemetryAttribute.DB_OPERATION, TelemetryAttribute.OPERATION_SELECT);
                span.setAttribute(TelemetryAttribute.DB_STATEMENT, TelemetryAttribute.OPERATION_SELECT + TelemetryAttribute.STATEMENT_SUFFIX);
                span.setAttribute(TelemetryAttribute.DB_SYSTEM, TelemetryAttribute.DB_SYSTEM_DEFAULT);
                span.setAttribute(TelemetryAttribute.DB_USER, () -> this.hostInfo.getUser());
                span.setAttribute(TelemetryAttribute.THREAD_ID, () -> Thread.currentThread().getId());
                span.setAttribute(TelemetryAttribute.THREAD_NAME, () -> Thread.currentThread().getName());

                if (versionMeetsMinimum(5, 1, 0)) {
                    StringBuilder queryBuf = new StringBuilder(versionComment).append("SELECT");
                    queryBuf.append("  @@session.auto_increment_increment AS auto_increment_increment");
                    queryBuf.append(", @@character_set_client AS character_set_client");
                    queryBuf.append(", @@character_set_connection AS character_set_connection");
                    queryBuf.append(", @@character_set_results AS character_set_results");
                    queryBuf.append(", @@character_set_server AS character_set_server");
                    queryBuf.append(", @@collation_server AS collation_server");
                    queryBuf.append(", @@collation_connection AS collation_connection");
                    queryBuf.append(", @@init_connect AS init_connect");
                    queryBuf.append(", @@interactive_timeout AS interactive_timeout");
                    if (!versionMeetsMinimum(5, 5, 0)) {
                        queryBuf.append(", @@language AS language");
                    }
                    queryBuf.append(", @@license AS license");
                    queryBuf.append(", @@lower_case_table_names AS lower_case_table_names");
                    queryBuf.append(", @@max_allowed_packet AS max_allowed_packet");
                    queryBuf.append(", @@net_write_timeout AS net_write_timeout");
                    queryBuf.append(", @@performance_schema AS performance_schema");
                    if (!versionMeetsMinimum(8, 0, 3)) {
                        queryBuf.append(", @@query_cache_size AS query_cache_size");
                        queryBuf.append(", @@query_cache_type AS query_cache_type");
                    }
                    queryBuf.append(", @@sql_mode AS sql_mode");
                    queryBuf.append(", @@system_time_zone AS system_time_zone");
                    queryBuf.append(", @@time_zone AS time_zone");
                    if (versionMeetsMinimum(8, 0, 3) || versionMeetsMinimum(5, 7, 20) && !versionMeetsMinimum(8, 0, 0)) {
                        queryBuf.append(", @@transaction_isolation AS transaction_isolation");
                    } else {
                        queryBuf.append(", @@tx_isolation AS transaction_isolation");
                    }
                    queryBuf.append(", @@wait_timeout AS wait_timeout");

                    NativePacketPayload resultPacket = (NativePacketPayload) this.protocol
                            .sendCommand(this.commandBuilder.buildComQuery(null, this, queryBuf.toString()), false, 0);
                    Resultset rs = ((NativeProtocol) this.protocol).readAllResults(-1, false, resultPacket, false, null,
                            new ResultsetFactory(Type.FORWARD_ONLY, null));
                    Field[] f = rs.getColumnDefinition().getFields();
                    if (f.length > 0) {
                        ValueFactory<String> vf = new StringValueFactory(this.propertySet);
                        Row r;
                        if ((r = rs.getRows().next()) != null) {
                            for (int i = 0; i < f.length; i++) {
                                String value = r.getValue(i, vf);
                                this.protocol.getServerSession().getServerVariables().put(f[i].getColumnLabel(), value);
                            }
                        }
                    }

                } else {
                    NativePacketPayload resultPacket = (NativePacketPayload) this.protocol
                            .sendCommand(this.commandBuilder.buildComQuery(null, this, versionComment + "SHOW VARIABLES"), false, 0);
                    Resultset rs = ((NativeProtocol) this.protocol).readAllResults(-1, false, resultPacket, false, null,
                            new ResultsetFactory(Type.FORWARD_ONLY, null));
                    ValueFactory<String> vf = new StringValueFactory(this.propertySet);
                    Row r;
                    while ((r = rs.getRows().next()) != null) {
                        this.protocol.getServerSession().getServerVariables().put(r.getValue(0, vf), r.getValue(1, vf));
                    }
                }
            } catch (Throwable t) {
                span.setError(t);
                throw t;
            } finally {
                span.end();
            }

        } catch (IOException e) {
            throw ExceptionFactory.createException(e.getMessage(), e);
        }

        if (this.cacheServerConfiguration.getValue()) {
            this.protocol.getServerSession().getServerVariables().put(SERVER_VERSION_STRING_VAR_NAME, getServerSession().getServerVersion().toString());
            Map<String, String> localVariableMap = new HashMap<>();
            localVariableMap.putAll(this.protocol.getServerSession().getServerVariables());
            this.serverConfigCache.put(this.hostInfo.getDatabaseUrl(), Collections.unmodifiableMap(localVariableMap));
        }
    }