refine code for kakfa request/response, string/bytes.

@@ -27,6 +27,7 @@
 using namespace std;
 
 #include <srs_kernel_error.hpp>
+#include <srs_core_autofree.hpp>
 
 #ifdef SRS_AUTO_KAFKA
 
@@ -36,6 +37,15 @@ SrsKafkaString::SrsKafkaString()
     data = NULL;
 }
 
+SrsKafkaString::SrsKafkaString(string v)
+{
+    size = (int16_t)v.length();
+    
+    srs_assert(size > 0);
+    data = new char[size];
+    memcpy(data, v.data(), size);
+}
+
 SrsKafkaString::~SrsKafkaString()
 {
     srs_freep(data);
@@ -62,6 +72,15 @@ SrsKafkaBytes::SrsKafkaBytes()
     data = NULL;
 }
 
+SrsKafkaBytes::SrsKafkaBytes(const char* v, int nb_v)
+{
+    size = (int16_t)nb_v;
+    
+    srs_assert(size > 0);
+    data = new char[size];
+    memcpy(data, v, size);
+}
+
 SrsKafkaBytes::~SrsKafkaBytes()
 {
     srs_freep(data);
@@ -175,7 +194,7 @@ int SrsKafkaResponseHeader::total_size()
     return 4 + size;
 }
 
-SrsKafkaMessage::SrsKafkaMessage()
+SrsKafkaRawMessage::SrsKafkaRawMessage()
 {
     offset = 0;
     message_size = 0;
@@ -186,7 +205,7 @@ SrsKafkaMessage::SrsKafkaMessage()
     value = new SrsKafkaBytes();
 }
 
-SrsKafkaMessage::~SrsKafkaMessage()
+SrsKafkaRawMessage::~SrsKafkaRawMessage()
 {
     srs_freep(key);
     srs_freep(value);
@@ -198,14 +217,30 @@ SrsKafkaMessageSet::SrsKafkaMessageSet()
 
 SrsKafkaMessageSet::~SrsKafkaMessageSet()
 {
-    vector<SrsKafkaMessage*>::iterator it;
+    vector<SrsKafkaRawMessage*>::iterator it;
     for (it = messages.begin(); it != messages.end(); ++it) {
-        SrsKafkaMessage* message = *it;
+        SrsKafkaRawMessage* message = *it;
         srs_freep(message);
     }
     messages.clear();
 }
 
+SrsKafkaRequest::SrsKafkaRequest()
+{
+}
+
+SrsKafkaRequest::~SrsKafkaRequest()
+{
+}
+
+SrsKafkaResponse::SrsKafkaResponse()
+{
+}
+
+SrsKafkaResponse::~SrsKafkaResponse()
+{
+}
+
 SrsKafkaTopicMetadataRequest::SrsKafkaTopicMetadataRequest()
 {
     header.set_api_key(SrsKafkaApiKeyMetadataRequest);
@@ -215,6 +250,19 @@ SrsKafkaTopicMetadataRequest::~SrsKafkaTopicMetadataRequest()
 {
 }
 
+void SrsKafkaTopicMetadataRequest::add_topic(string topic)
+{
+    topics.append(new SrsKafkaString(topic));
+}
+
+SrsKafkaTopicMetadataResponse::SrsKafkaTopicMetadataResponse()
+{
+}
+
+SrsKafkaTopicMetadataResponse::~SrsKafkaTopicMetadataResponse()
+{
+}
+
 SrsKafkaProtocol::SrsKafkaProtocol(ISrsProtocolReaderWriter* io)
 {
     skt = io;
@@ -224,7 +272,7 @@ SrsKafkaProtocol::~SrsKafkaProtocol()
 {
 }
 
-int SrsKafkaProtocol::send_and_free_message(SrsKafkaMessage* msg)
+int SrsKafkaProtocol::send_and_free_message(SrsKafkaRequest* msg)
 {
     int ret = ERROR_SUCCESS;
     
@@ -247,6 +295,11 @@ int SrsKafkaClient::fetch_metadata(string topic)
 {
     int ret = ERROR_SUCCESS;
     
+    SrsKafkaTopicMetadataRequest* req = new SrsKafkaTopicMetadataRequest();
+    SrsAutoFree(SrsKafkaTopicMetadataRequest, req);
+    
+    req->add_topic(topic);
+    
     // TODO: FIXME: implements it.
     
     return ret;

@@ -64,6 +64,7 @@ private:
     char* data;
 public:
     SrsKafkaString();
+    SrsKafkaString(std::string v);
     virtual ~SrsKafkaString();
 public:
     virtual bool null();
@@ -83,6 +84,7 @@ private:
     char* data;
 public:
     SrsKafkaBytes();
+    SrsKafkaBytes(const char* v, int nb_v);
     virtual ~SrsKafkaBytes();
 public:
     virtual bool null();
@@ -269,7 +271,7 @@ public:
  * the kafka message in message set.
  * @see https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-Messagesets
  */
-struct SrsKafkaMessage
+struct SrsKafkaRawMessage
 {
 // metadata.
 public:
@@ -313,8 +315,8 @@ public:
      */
     SrsKafkaBytes* value;
 public:
-    SrsKafkaMessage();
-    virtual ~SrsKafkaMessage();
+    SrsKafkaRawMessage();
+    virtual ~SrsKafkaRawMessage();
 };
 
 /**
@@ -324,13 +326,33 @@ public:
 class SrsKafkaMessageSet
 {
 private:
-    std::vector<SrsKafkaMessage*> messages;
+    std::vector<SrsKafkaRawMessage*> messages;
 public:
     SrsKafkaMessageSet();
     virtual ~SrsKafkaMessageSet();
 };
 
 /**
+ * the kafka request message, for protocol to send.
+ */
+class SrsKafkaRequest
+{
+public:
+    SrsKafkaRequest();
+    virtual ~SrsKafkaRequest();
+};
+
+/**
+ * the kafka response message, for protocol to recv.
+ */
+class SrsKafkaResponse
+{
+public:
+    SrsKafkaResponse();
+    virtual ~SrsKafkaResponse();
+};
+
+/**
  * request the metadata from broker.
  * This API answers the following questions:
  *      What topics exist?
@@ -344,20 +366,30 @@ public:
  *
  * @see https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-MetadataAPI
  */
-class SrsKafkaTopicMetadataRequest
+class SrsKafkaTopicMetadataRequest : public SrsKafkaRequest
 {
 private:
     SrsKafkaRequestHeader header;
-    SrsKafkaArray<SrsKafkaString*> request;
+    SrsKafkaArray<SrsKafkaString*> topics;
 public:
     SrsKafkaTopicMetadataRequest();
     virtual ~SrsKafkaTopicMetadataRequest();
+public:
+    virtual void add_topic(std::string topic);
 };
 
-class SrsKafkaTopicMetadataResponse
+/**
+ * response for the metadata request from broker.
+ * The response contains metadata for each partition, 
+ * with partitions grouped together by topic. This 
+ * metadata refers to brokers by their broker id. 
+ * The brokers each have a host and port.
+ * @see https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-MetadataResponse
+ */
+class SrsKafkaTopicMetadataResponse : public SrsKafkaResponse
 {
 private:
-    SrsKafkaRequestHeader header;
+    SrsKafkaResponseHeader header;
 public:
     SrsKafkaTopicMetadataResponse();
     virtual ~SrsKafkaTopicMetadataResponse();
@@ -378,7 +410,7 @@ public:
      * write the message to kafka server.
      * @param msg the msg to send. user must not free it again.
      */
-    virtual int send_and_free_message(SrsKafkaMessage* msg);
+    virtual int send_and_free_message(SrsKafkaRequest* msg);
 };
 
 /**