refine config, add comments.

@@ -1431,153 +1431,6 @@ vector<SrsConfDirective*> SrsConfig::get_vhosts()
     return vhosts;
 }
 
-SrsConfDirective* SrsConfig::get_vhost_on_connect(string vhost)
-{
-    SrsConfDirective* conf = get_vhost(vhost);
-
-    if (!conf) { 
-        return NULL;
-    }
-    
-    conf = conf->get("http_hooks");
-    if (!conf) {
-        return NULL;
-    }
-    
-    SrsConfDirective* enabled = conf->get("enabled");
-    if (!enabled || enabled->arg0() != "on") {
-        return NULL;
-    }
-    
-    return conf->get("on_connect");
-}
-
-SrsConfDirective* SrsConfig::get_vhost_on_close(string vhost)
-{
-    SrsConfDirective* conf = get_vhost(vhost);
-
-    if (!conf) { 
-        return NULL;
-    }
-    
-    conf = conf->get("http_hooks");
-    if (!conf) {
-        return NULL;
-    }
-    
-    SrsConfDirective* enabled = conf->get("enabled");
-    if (!enabled || enabled->arg0() != "on") {
-        return NULL;
-    }
-    
-    return conf->get("on_close");
-}
-
-SrsConfDirective* SrsConfig::get_vhost_on_publish(string vhost)
-{
-    SrsConfDirective* conf = get_vhost(vhost);
-
-    if (!conf) { 
-        return NULL;
-    }
-    
-    conf = conf->get("http_hooks");
-    if (!conf) {
-        return NULL;
-    }
-    
-    SrsConfDirective* enabled = conf->get("enabled");
-    if (!enabled || enabled->arg0() != "on") {
-        return NULL;
-    }
-    
-    return conf->get("on_publish");
-}
-
-SrsConfDirective* SrsConfig::get_vhost_on_unpublish(string vhost)
-{
-    SrsConfDirective* conf = get_vhost(vhost);
-
-    if (!conf) { 
-        return NULL;
-    }
-    
-    conf = conf->get("http_hooks");
-    if (!conf) {
-        return NULL;
-    }
-    
-    SrsConfDirective* enabled = conf->get("enabled");
-    if (!enabled || enabled->arg0() != "on") {
-        return NULL;
-    }
-    
-    return conf->get("on_unpublish");
-}
-
-SrsConfDirective* SrsConfig::get_vhost_on_play(string vhost)
-{
-    SrsConfDirective* conf = get_vhost(vhost);
-
-    if (!conf) { 
-        return NULL;
-    }
-    
-    conf = conf->get("http_hooks");
-    if (!conf) {
-        return NULL;
-    }
-    
-    SrsConfDirective* enabled = conf->get("enabled");
-    if (!enabled || enabled->arg0() != "on") {
-        return NULL;
-    }
-    
-    return conf->get("on_play");
-}
-
-SrsConfDirective* SrsConfig::get_vhost_on_stop(string vhost)
-{
-    SrsConfDirective* conf = get_vhost(vhost);
-
-    if (!conf) { 
-        return NULL;
-    }
-    
-    conf = conf->get("http_hooks");
-    if (!conf) {
-        return NULL;
-    }
-    
-    SrsConfDirective* enabled = conf->get("enabled");
-    if (!enabled || enabled->arg0() != "on") {
-        return NULL;
-    }
-    
-    return conf->get("on_stop");
-}
-
-SrsConfDirective* SrsConfig::get_vhost_on_dvr_hss_reap_flv(string vhost)
-{
-    SrsConfDirective* conf = get_vhost(vhost);
-
-    if (!conf) { 
-        return NULL;
-    }
-    
-    conf = conf->get("http_hooks");
-    if (!conf) {
-        return NULL;
-    }
-    
-    SrsConfDirective* enabled = conf->get("enabled");
-    if (!enabled || enabled->arg0() != "on") {
-        return NULL;
-    }
-    
-    return conf->get("on_dvr_hss_reap_flv");
-}
-
 bool SrsConfig::get_vhost_enabled(string vhost)
 {
     SrsConfDirective* vhost_conf = get_vhost(vhost);
@@ -1684,17 +1537,6 @@ double SrsConfig::get_queue_length(string vhost)
     return ::atoi(conf->arg0().c_str());
 }
 
-SrsConfDirective* SrsConfig::get_forward(string vhost)
-{
-    SrsConfDirective* conf = get_vhost(vhost);
-
-    if (!conf) {
-        return NULL;
-    }
-    
-    return conf->get("forward");
-}
-
 SrsConfDirective* SrsConfig::get_refer(string vhost)
 {
     SrsConfDirective* conf = get_vhost(vhost);
@@ -1751,6 +1593,164 @@ int SrsConfig::get_chunk_size(const string &vhost)
     return ::atoi(conf->arg0().c_str());
 }
 
+SrsConfDirective* SrsConfig::get_forward(string vhost)
+{
+    SrsConfDirective* conf = get_vhost(vhost);
+
+    if (!conf) {
+        return NULL;
+    }
+    
+    return conf->get("forward");
+}
+
+SrsConfDirective* SrsConfig::get_vhost_on_connect(string vhost)
+{
+    SrsConfDirective* conf = get_vhost(vhost);
+
+    if (!conf) { 
+        return NULL;
+    }
+    
+    conf = conf->get("http_hooks");
+    if (!conf) {
+        return NULL;
+    }
+    
+    SrsConfDirective* enabled = conf->get("enabled");
+    if (!enabled || enabled->arg0() != "on") {
+        return NULL;
+    }
+    
+    return conf->get("on_connect");
+}
+
+SrsConfDirective* SrsConfig::get_vhost_on_close(string vhost)
+{
+    SrsConfDirective* conf = get_vhost(vhost);
+
+    if (!conf) { 
+        return NULL;
+    }
+    
+    conf = conf->get("http_hooks");
+    if (!conf) {
+        return NULL;
+    }
+    
+    SrsConfDirective* enabled = conf->get("enabled");
+    if (!enabled || enabled->arg0() != "on") {
+        return NULL;
+    }
+    
+    return conf->get("on_close");
+}
+
+SrsConfDirective* SrsConfig::get_vhost_on_publish(string vhost)
+{
+    SrsConfDirective* conf = get_vhost(vhost);
+
+    if (!conf) { 
+        return NULL;
+    }
+    
+    conf = conf->get("http_hooks");
+    if (!conf) {
+        return NULL;
+    }
+    
+    SrsConfDirective* enabled = conf->get("enabled");
+    if (!enabled || enabled->arg0() != "on") {
+        return NULL;
+    }
+    
+    return conf->get("on_publish");
+}
+
+SrsConfDirective* SrsConfig::get_vhost_on_unpublish(string vhost)
+{
+    SrsConfDirective* conf = get_vhost(vhost);
+
+    if (!conf) { 
+        return NULL;
+    }
+    
+    conf = conf->get("http_hooks");
+    if (!conf) {
+        return NULL;
+    }
+    
+    SrsConfDirective* enabled = conf->get("enabled");
+    if (!enabled || enabled->arg0() != "on") {
+        return NULL;
+    }
+    
+    return conf->get("on_unpublish");
+}
+
+SrsConfDirective* SrsConfig::get_vhost_on_play(string vhost)
+{
+    SrsConfDirective* conf = get_vhost(vhost);
+
+    if (!conf) { 
+        return NULL;
+    }
+    
+    conf = conf->get("http_hooks");
+    if (!conf) {
+        return NULL;
+    }
+    
+    SrsConfDirective* enabled = conf->get("enabled");
+    if (!enabled || enabled->arg0() != "on") {
+        return NULL;
+    }
+    
+    return conf->get("on_play");
+}
+
+SrsConfDirective* SrsConfig::get_vhost_on_stop(string vhost)
+{
+    SrsConfDirective* conf = get_vhost(vhost);
+
+    if (!conf) { 
+        return NULL;
+    }
+    
+    conf = conf->get("http_hooks");
+    if (!conf) {
+        return NULL;
+    }
+    
+    SrsConfDirective* enabled = conf->get("enabled");
+    if (!enabled || enabled->arg0() != "on") {
+        return NULL;
+    }
+    
+    return conf->get("on_stop");
+}
+
+SrsConfDirective* SrsConfig::get_vhost_on_dvr_hss_reap_flv(string vhost)
+{
+    SrsConfDirective* conf = get_vhost(vhost);
+
+    if (!conf) { 
+        return NULL;
+    }
+    
+    conf = conf->get("http_hooks");
+    if (!conf) {
+        return NULL;
+    }
+    
+    SrsConfDirective* enabled = conf->get("enabled");
+    if (!enabled || enabled->arg0() != "on") {
+        return NULL;
+    }
+    
+    return conf->get("on_dvr_hss_reap_flv");
+}
+
 bool SrsConfig::get_bw_check_enabled(const string &vhost)
 {
     SrsConfDirective* conf = get_vhost(vhost);

@@ -422,81 +422,103 @@ public:
     */
     virtual std::vector<SrsConfDirective*>  get_vhosts();
     /**
-    * 
+    * whether vhost is enabled
+    * @param vhost, the vhost name.
+    * @return true when vhost is ok; otherwise, false.
     */
     virtual bool                get_vhost_enabled(std::string vhost);
     /**
-    * 
+    * whether vhost is enabled
+    * @param vhost, the vhost directive.
+    * @return true when vhost is ok; otherwise, false.
     */
     virtual bool                get_vhost_enabled(SrsConfDirective* vhost);
     /**
-    * 
+    * whether gop_cache is enabled of vhost.
+    * gop_cache used to cache last gop, for client to fast startup.
+    * @return true when gop_cache is ok; otherwise, false.
     */
-    virtual SrsConfDirective*   get_vhost_on_connect(std::string vhost);
+    virtual bool                get_gop_cache(std::string vhost);
     /**
-    * 
+    * whether atc is enabled of vhost.
+    * atc always use encoder timestamp, SRS never adjust the time.
+    * @return true when atc is ok; otherwise, false.
     */
-    virtual SrsConfDirective*   get_vhost_on_close(std::string vhost);
+    virtual bool                get_atc(std::string vhost);
     /**
-    * 
+    * whether atc_auto is enabled of vhost.
+    * atc_auto used to auto enable atc, when metadata specified the bravo_atc.
+    * @return true when atc_auto is ok; otherwise, false.
     */
-    virtual SrsConfDirective*   get_vhost_on_publish(std::string vhost);
+    virtual bool                get_atc_auto(std::string vhost);
     /**
-    * 
+    * get the time_jitter algorithm.
+    * @return the time_jitter algorithm, defined in SrsRtmpJitterAlgorithm.
     */
-    virtual SrsConfDirective*   get_vhost_on_unpublish(std::string vhost);
+    virtual int                 get_time_jitter(std::string vhost);
     /**
     * 
     */
-    virtual SrsConfDirective*   get_vhost_on_play(std::string vhost);
+    virtual double              get_queue_length(std::string vhost);
     /**
     * 
     */
-    virtual SrsConfDirective*   get_vhost_on_stop(std::string vhost);
+    virtual SrsConfDirective*   get_refer(std::string vhost);
     /**
     * 
     */
-    virtual SrsConfDirective*   get_vhost_on_dvr_hss_reap_flv(std::string vhost);
+    virtual SrsConfDirective*   get_refer_play(std::string vhost);
     /**
     * 
     */
-    virtual bool                get_gop_cache(std::string vhost);
+    virtual SrsConfDirective*   get_refer_publish(std::string vhost);
     /**
     * 
     */
-    virtual bool                get_atc(std::string vhost);
+    virtual int                 get_chunk_size(const std::string& vhost);
+// forward section
+public:
     /**
     * 
     */
-    virtual bool                get_atc_auto(std::string vhost);
+    virtual SrsConfDirective*   get_forward(std::string vhost);
+// http_hooks section
+public:
     /**
-    * 
+    * get the on_connect callbacks of vhost.
+    * @return the on_connect callback directive, the args is the url to callback.
     */
-    virtual int                 get_time_jitter(std::string vhost);
+    virtual SrsConfDirective*   get_vhost_on_connect(std::string vhost);
     /**
-    * 
+    * get the on_close callbacks of vhost.
+    * @return the on_close callback directive, the args is the url to callback.
     */
-    virtual double              get_queue_length(std::string vhost);
+    virtual SrsConfDirective*   get_vhost_on_close(std::string vhost);
     /**
-    * 
+    * get the on_publish callbacks of vhost.
+    * @return the on_publish callback directive, the args is the url to callback.
     */
-    virtual SrsConfDirective*   get_forward(std::string vhost);
+    virtual SrsConfDirective*   get_vhost_on_publish(std::string vhost);
     /**
-    * 
+    * get the on_unpublish callbacks of vhost.
+    * @return the on_unpublish callback directive, the args is the url to callback.
     */
-    virtual SrsConfDirective*   get_refer(std::string vhost);
+    virtual SrsConfDirective*   get_vhost_on_unpublish(std::string vhost);
     /**
-    * 
+    * get the on_play callbacks of vhost.
+    * @return the on_play callback directive, the args is the url to callback.
     */
-    virtual SrsConfDirective*   get_refer_play(std::string vhost);
+    virtual SrsConfDirective*   get_vhost_on_play(std::string vhost);
     /**
-    * 
+    * get the on_stop callbacks of vhost.
+    * @return the on_stop callback directive, the args is the url to callback.
     */
-    virtual SrsConfDirective*   get_refer_publish(std::string vhost);
+    virtual SrsConfDirective*   get_vhost_on_stop(std::string vhost);
     /**
-    * 
+    * get the on_dvr_hss_reap_flv callbacks of vhost.
+    * @return the on_dvr_hss_reap_flv callback directive, the args is the url to callback.
     */
-    virtual int                 get_chunk_size(const std::string& vhost);
+    virtual SrsConfDirective*   get_vhost_on_dvr_hss_reap_flv(std::string vhost);
 // bwct(bandwidth check tool) section
 public:
     /**