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前面分析了框架的请求和回复实体的封装，而在进行底层网络通信时，需要进行解包(收到数据)和组包(发送数据)，框架底层使用了dubbo协议，数据序列化方式是json格式，这篇文章我们就重点看看解包和组包的逻辑，这部分逻辑在DubboParser类中完成，这个类定义在dubbo-php-framework-master/common/protocol/fsof/DubboParser.php文件中。
下面代码注释中明确列了dubbo协议的格式，大家在看解包组包逻辑时，对照着协议看会清楚很多。另外组包和解包是个相互的过程，也就是组包是将业务数据（DubboRequest,DubboResponse）按规则拼接为二进制串，而解包是将二进制串按规则解析后set属性到业务数据中（DubboRequest，DubboResponse）。
/**
*
* Dubbo网络协议
* +------------------------------------------------------------------------------------------+
* | 包头（二进制数据 16bit） | 包体 |
* +-----------------------------------------------------------------------------------------+
* | 版本号 | 命令&serialize | 空白 | 包序号| 长度 | 数据 |
* +-----------------------------------------------------------------------------------------+
* | magic(2) | cmd&serialize(1)|(1) |sn(8) | len(4) | data(N)|
* +-----------------------------------------------------------------------------------------+
*
* magic：协议包起始标识, 0xdabb
* --------------------------------------------------------------------------------------------
* cmd：命令类型：FLAG_REQUEST为0x80, FLAG_TWOWAY为0x40, FLAG_EVENT为0x20
* serialize：序列化方案编号：与cmd共用一个字节,采用json,对应dubbo中编号为6
* --------------------------------------------------------------------------------------------
* sn：请求序号，consumer会为每个请求编制一个进程内唯一序号
* ，provider处理完请求后在返回的数据包中会携带该sn号，供consumer判断当前的数据是对应哪个请求
* --------------------------------------------------------------------------------------------*
* len：数据报文长度
* --------------------------------------------------------------------------------------------
* data：数据报文，目前采用json进行序列化
* --------------------------------------------------------------------------------------------
*/
class DubboParser
{
//dubbo协议基本信息
const PACKAGE_HEDA_LEN = 16;
const MAX_RECV_LEN = 1048576;//1024*1024;
const RESPONSE_TCP_SEGMENT_LEN = 1048576;//1*1024*1024;
//fsof协议ver字段，ver字段既指示协议版本信息，也作为magic使用
const DUBBO_PROTOCOL_MAGIC = 0xdabb;
//serialize 方案编号
const DUBBO_PROTOCOL_SERIALIZE_FAST_JSON = 6; //serialization code
//fsof协议包头cmd字段含义
const FLAG_REQUEST = 0x80; //request
const FLAG_TWOWAY = 0x40; //two_way
const FLAG_HEARTBEAT_EVENT = 0x20; //heart_event
const SERIALIZATION_MASK = 0x1f; //serialization_mask
const UPPER_MASK = 0xffffffff00000000;
const LOWER_MASK = 0x00000000ffffffff;
const RESPONSE_WITH_EXCEPTION = 0;
const RESPONSE_VALUE = 1;
const RESPONSE_NULL_VALUE = 2;
private $logger;
public function __construct()
{
$this->logger = \Logger::getLogger(__CLASS__);
}
//将DubboRequest编码为二进制字符串
public function packRequest(DubboRequest &$request)
{
//数据按PHP_EOL的分隔符拼接
$reqData = json_encode($request->getDubboVersion()) . PHP_EOL .
json_encode($request->getService()) . PHP_EOL .
json_encode($request->getVersion()) . PHP_EOL .
json_encode($request->getMethod()) . PHP_EOL ;
$typeStr = "";
for($i=0;$i < count($request->getTypes());$i++){
$typeStr = $typeStr.$request->getTypes()[$i];
}
$reqData = $reqData.json_encode($typeStr) . PHP_EOL;
for ($x = 0; $x < count($request->getParams()); $x++) {
$reqData = $reqData . json_encode($request->getParams()[$x]) . PHP_EOL;
}
$attach = array();
$attach['path'] = $request->getService();
$attach['interface'] = $request->getService();
$attach['group'] = $request->getGroup();
$attach['timeout'] = $request->getTimeout();
$attach['version'] = $request->getVersion();
$request->setAttach($attach);
$reqData = $reqData . json_encode($request->getAttach());
$upper = ($request->getSn() & self::UPPER_MASK) >> 32;
$lower = $request->getSn() & self::LOWER_MASK;
$flag = (self::FLAG_REQUEST | self::DUBBO_PROTOCOL_SERIALIZE_FAST_JSON);
if ($request->isTwoWay()) $flag |= self::FLAG_TWOWAY;
if ($request->isHeartbeatEvent()) $flag |= self::FLAG_HEARTBEAT_EVENT;
//调用PHP的系统函数pack，按格式编码数据
$out = pack("n1C1a1N1N1N1",
self::DUBBO_PROTOCOL_MAGIC,
$flag,
"",
$upper,
$lower,
strlen($reqData));
return $out . $reqData;
}
//解析回复包的头部信息
public function parseResponseHeader(DubboResponse &$response)
{
//头部数据长度为16byte，这里截取16个byte后进行解析
$res_header = substr($response->getFullData(), 0, self::PACKAGE_HEDA_LEN);
$format = 'n1magic/C1flag/C1status/N1upper/N1lower/N1len';
//调用PHP函数按上述格式解析数据
$_arr = unpack($format, $res_header);
$response->setStatus($_arr['status']);
$response->setSn($_arr["upper"] << 32 | $_arr["lower"]);
$flag = $_arr["flag"];
if (($flag & self::FLAG_HEARTBEAT_EVENT) != 0)
{
$response->setHeartbeatEvent(true);
}
$response->setSerialization($flag & self::DUBBO_PROTOCOL_SERIALIZE_FAST_JSON);
$response->setLen($_arr["len"]);
return $response;
}
//解包回复包的body部分
public function parseResponseBody(DubboResponse &$response)
{
//从第16byte开始的所有数据当前body部分
$_data = substr($response->getFullData(), self::PACKAGE_HEDA_LEN);
$response->setResponseBody($_data);
$dataArr = array();
//数据不为空时，按PHP_EOL分隔符拆分数据
if ($_data){
$dataArr = explode(PHP_EOL,$_data);
}
if ($response->getStatus() == DubboResponse::OK)
{
if ($response->isHeartbeatEvent())
{
$response->setResult(json_decode($dataArr[0], true));
} else
{
switch ($dataArr[0])
{
case self::RESPONSE_NULL_VALUE:
break;
case self::RESPONSE_VALUE:
$response->setResult(json_decode($dataArr[1], true));
break;
case self::RESPONSE_WITH_EXCEPTION:
$exception = json_decode($dataArr[1], true);
if(is_array($exception) && array_key_exists('message', $exception)){
throw new \Exception($exception['message']);
}else if(is_string($exception)){
throw new \Exception($exception);
}else{
throw new \Exception("provider occur error");
}
break;
default:
return false;
}
}
return $response;
} else {
throw new \Exception(json_decode($dataArr[0], true));
}
}
//解包请求包的头部部分
public function parseRequestHeader(DubboRequest &$request)
{
$_data = substr($request->getFullData(), 0, self::PACKAGE_HEDA_LEN);
$format = 'n1magic/C1flag/C1blank/N1upper/N1lower/N1len';
$_arr = unpack($format, $_data);
$flag = $_arr['flag'];
$request->setTwoWay(($flag & self::FLAG_TWOWAY) != 0);
if (($flag & self::FLAG_HEARTBEAT_EVENT) != 0)
{
$request->setHeartbeatEvent(true);
}
$request->setSerialization($flag & self::DUBBO_PROTOCOL_SERIALIZE_FAST_JSON);
$request->setSn($_arr['upper'] << 32 | $_arr['lower']);
$request->setDataLen($_arr['len']);
$request->setRequestLen($request->getDataLen() + self::PACKAGE_HEDA_LEN);
return $request;
}
//解包请求包的body部分
public function parseRequestBody(DubboRequest &$request)
{
if ($request->getSerialization() != self::DUBBO_PROTOCOL_SERIALIZE_FAST_JSON)
{
$this->logger->error("unknown serialization type :" . $request->getSerialization());
return false;
}
$cliData = substr($request->getFullData(), self::PACKAGE_HEDA_LEN);
if ($cliData)
{
if ($request->isHeartbeatEvent())
{
//心跳请求,不需要数据回送
} else
{
$dataArr = explode(PHP_EOL, $cliData);
$request->setDubboVersion(json_decode($dataArr[0], true));
$request->setService(json_decode($dataArr[1], true));
$request->setVersion(json_decode($dataArr[2], true));
$methodName = json_decode($dataArr[3],true);
if ($methodName == "\$invoke")
{
//泛化调用
$request->setMethod(json_decode($dataArr[5],true));
$request->setParams(json_decode($dataArr[7],true));
$attach = json_decode($dataArr[8],true);
} else
{
//非泛化调用
$request->setMethod($methodName);
$paramTypes = json_decode($dataArr[4], true);
if ($paramTypes == "")
{
//调用没有参数的方法
$request->setTypes(NULL);
$request->setParams(NULL);
$attach = json_decode($dataArr[5],true);
} else
{
$typeArr = explode(";", $paramTypes);
$typeArrLen = count($typeArr);
$request->setParamNum($typeArrLen - 1);
$params = array();
for ($i = 0; $i < $typeArrLen - 1; $i++) {
$params[$i] = json_decode($dataArr[5 + $i],true);
}
$request->setParams($params);
$attach = json_decode($dataArr[5 + ($typeArrLen - 1)],true);
}
}
$request->setAttach($attach);
if (array_key_exists('group', $attach))
{
$request->setGroup($attach['group']);
}
return $request;
}
}
return false;
}
//组包回复包部分
public function packResponse(DubboResponse &$response)
{
if ($response->getStatus() != DubboResponse::OK) {
$resData = json_encode($response->getErrorMsg()) ;
} else {
if($response->getErrorMsg() != NULL && $response->getErrorMsg() != ""){
$resData = json_encode(self::RESPONSE_WITH_EXCEPTION) . PHP_EOL . json_encode($response->getErrorMsg());
}else if ($response->getResult() == NULL) {
$resData = json_encode(self::RESPONSE_NULL_VALUE);
} else {
$resData = json_encode(self::RESPONSE_VALUE) . PHP_EOL . json_encode($response->getResult());
}
}
$resData = $resData.PHP_EOL;
$upper = ($response->getSn() & self::UPPER_MASK) >> 32;
$lower = $response->getSn() & self::LOWER_MASK;
$flag = self::DUBBO_PROTOCOL_SERIALIZE_FAST_JSON;
if ($response->isHeartbeatEvent()) {
$flag |= self::FLAG_HEARTBEAT_EVENT;
}
$out = pack("n1C1C1N1N1N1",
self::DUBBO_PROTOCOL_MAGIC,
$flag,
$response->getStatus(),
$upper,
$lower,
strlen($resData));
return $out . $resData;
}
//判断是否是业务回包，这里判断逻辑也比较简单，非心跳类的包都当做业务包处理。
public function isNormalResponse(DubboResponse $response)
{
return !($response->isHeartbeatEvent());
}
//判断是否是业务请求包
public function isNormalRequest(DubboRequest $request)
{
return !($request->isHeartbeatEvent());
}
public function isOneWayRequest(DubboRequest $request)
{
return !($request->isTwoWay());
}
//心跳请求包
public function isHearBeatRequest(DubboRequest $request)
{
return $request->isHeartbeatEvent();
}
//心跳回复包
public function isHearBeatResponse(DubboResponse $response)
{
return $response->isHeartbeatEvent();
}
//请求在队列中的时间，这个主要是做监控用的
public static function getReqInQueueTime(DubboRequest $request)
{
$ret = 0;
if (!empty($request->reqInfo)) {
$ret = isset($request->reqInfo['inqueue_time']) ? $request->reqInfo['inqueue_time'] : 0;
}
return $ret;
}
}