diff options
Diffstat (limited to 'qpid/cpp/src/qpid/client/FlowControl.h')
-rw-r--r-- | qpid/cpp/src/qpid/client/FlowControl.h | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/qpid/cpp/src/qpid/client/FlowControl.h b/qpid/cpp/src/qpid/client/FlowControl.h new file mode 100644 index 0000000000..bff7071b3b --- /dev/null +++ b/qpid/cpp/src/qpid/client/FlowControl.h @@ -0,0 +1,75 @@ +#ifndef QPID_CLIENT_FLOWCONTROL_H +#define QPID_CLIENT_FLOWCONTROL_H + +/* + * + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + * + */ + +#include <qpid/sys/IntegerTypes.h> + +namespace qpid { +namespace client { + +/** + * Flow control works by associating a finite amount of "credit" + * with a subscription. + * + * Credit includes a message count and a byte count. Each message + * received decreases the message count by one, and the byte count by + * the size of the message. Either count can have the special value + * UNLIMITED which is never decreased. + * + * A subscription's credit is exhausted when the message count is 0 or + * the byte count is too small for the next available message. The + * subscription will not receive any further messages until is credit + * is renewed. + * + * In "window mode" credit is automatically renewed when a message is + * completed (which by default happens when it is accepted). In + * non-window mode credit is not automatically renewed, it must be + * explicitly re-set (@see Subscription) + */ +struct FlowControl { + static const uint32_t UNLIMITED=0xFFFFFFFF; + FlowControl(uint32_t messages_=0, uint32_t bytes_=0, bool window_=false) + : messages(messages_), bytes(bytes_), window(window_) {} + + static FlowControl messageCredit(uint32_t messages_) { return FlowControl(messages_,UNLIMITED,false); } + static FlowControl messageWindow(uint32_t messages_) { return FlowControl(messages_,UNLIMITED,true); } + static FlowControl byteCredit(uint32_t bytes_) { return FlowControl(UNLIMITED,bytes_,false); } + static FlowControl byteWindow(uint32_t bytes_) { return FlowControl(UNLIMITED,bytes_,true); } + static FlowControl unlimited() { return FlowControl(UNLIMITED, UNLIMITED, false); } + static FlowControl zero() { return FlowControl(0, 0, false); } + + /** Message credit: subscription can accept up to this many messages. */ + uint32_t messages; + /** Byte credit: subscription can accept up to this many bytes of message content. */ + uint32_t bytes; + /** Window mode. If true credit is automatically renewed as messages are acknowledged. */ + bool window; + + bool operator==(const FlowControl& x) { + return messages == x.messages && bytes == x.bytes && window == x.window; + }; +}; + +}} // namespace qpid::client + +#endif /*!QPID_CLIENT_FLOWCONTROL_H*/ |