Megatest

(define *send-receive-mutex* (make-mutex)) ;; should have separate mutex per run-id



;; this entry point can decide based on cmd whether to dispatch to old api calls via remote or via ulex
;;
(define (rmt:send-receive cmd rid params #!key (attemptnum 1)(area-dat #f))
  (let* ((areapath      *toppath*);; TODO - resolve from dbstruct to be compatible with multiple areas
	 (runremote     (or area-dat
			    *runremote*)))
    ;; ensure we have a record for our connection for given area
    (if (not runremote)                   ;; can remove this one. should never get here.         
	(begin
	  (set! *runremote* (make-remote))
	  (set! runremote   *runremote*))) ;; new runremote will come from this on next iteration
    
    (if (member cmd '(blah))
      (begin
	(mutex-lock! *send-receive-mutex*)
	(if (not *runremote*)(set! *runremote* (make-remote)))
	(let ((ulex:conn (remote-ulex:conn *runremote*)))
	  (if (not ulex:conn)(remote-ulex:conn-set! *runremote* (rmtmod:setup-ulex *toppath*)))
	  (rmtmod:send-receive-ulex ulex:conn cmd rid params attemptnum area-dat)))
      (rmt:send-receive-orig runremote *rmt-mutex* areapath cmd rid params attemptnum: attemptnum area-dat: area-dat))))

;; RA => e.g. usage (rmt:send-receive 'get-var #f (list varname))
;;
(define (rmt:send-receive-orig runremote rmt-mutex toppath cmd rid params #!key (attemptnum 1)(area-dat #f)) ;; start attemptnum at 1 so the modulo below works as expected

  #;(common:telemetry-log (conc "rmt:"(->string cmd))
                        payload: `((rid . ,rid)
                                   (params . ,params)))
                          
  
  ;; do all the prep locked under the rmt-mutex
  (mutex-lock! *rmt-mutex*)
  
  ;; 1. check if server is started IFF cmd is a write OR if we are not on the homehost, store in runremote
  ;; 2. check the age of the connections. refresh the connection if it is older than timeout-20 seconds.
  ;; 3. do the query, if on homehost use local access
  ;;
  (let* ((start-time    (current-seconds)) ;; snapshot time so all use cases get same value



	 (readonly-mode (rmtmod:calc-ro-mode runremote *toppath*)))







    ;; ensure we have a homehost record
    (if (not (pair? (remote-hh-dat runremote)))  ;; not on homehost
	(thread-sleep! 0.1) ;; since we shouldn't get here, delay a little
	(remote-hh-dat-set! runremote (common:get-homehost)))
    
    ;;(print "BB> readonly-mode is "readonly-mode" dbfile is "dbfile)
    (cond

	   (> (current-seconds) ;; if it has been more than server-timeout seconds since last contact, close this connection and start a new on
	      (+ (http-transport:server-dat-get-last-access (remote-conndat runremote))
		 (remote-server-timeout runremote))))
      (debug:print-info 0 *default-log-port* "Connection to " (remote-server-url runremote) " expired due to no accesses, forcing new connection.")
      (http-transport:close-connections area-dat: runremote)
      (remote-conndat-set! runremote #f) ;; invalidate the connection, thus forcing a new connection.
      (mutex-unlock! *rmt-mutex*)
      (rmt:send-receive-orig  runremote rmt-mutex toppath cmd rid params attemptnum: attemptnum))
     

     ;; on homehost and this is a read
     ((and (not (remote-force-server runremote)) ;; honor forced use of server, i.e. server NOT required
	   (cdr (remote-hh-dat runremote))       ;; on homehost
           (member cmd api:read-only-queries))   ;; this is a read
      (mutex-unlock! *rmt-mutex*)
      (debug:print-info 12 *default-log-port* "rmt:send-receive, case  5")
      (rmt:open-qry-close-locally cmd 0 params))

     ;; on homehost and this is a write, we already have a server, but server has died
     ((and (cdr (remote-hh-dat runremote))           ;; on homehost
           (not (member cmd api:read-only-queries))  ;; this is a write
           (remote-server-url runremote)             ;; have a server
           (not (server:ping (remote-server-url runremote))))  ;; server has died. NOTE: this is not a cheap call! Need better approach.
      (set! *runremote* (make-remote))
      (remote-force-server-set! runremote (common:force-server?))
      (mutex-unlock! *rmt-mutex*)
      (debug:print-info 12 *default-log-port* "rmt:send-receive, case  6")
      (rmt:send-receive-orig  runremote rmt-mutex toppath cmd rid params attemptnum: attemptnum))

     ;; on homehost and this is a write, we already have a server
     ((and (not (remote-force-server runremote))     ;; honor forced use of server, i.e. server NOT required
	   (cdr (remote-hh-dat runremote))           ;; on homehost
           (not (member cmd api:read-only-queries))  ;; this is a write
           (remote-server-url runremote))            ;; have a server
      (mutex-unlock! *rmt-mutex*)

	  (and (not (cdr (remote-hh-dat runremote)))        ;; not on a homehost 
	       (not (remote-conndat runremote))))           ;; and no connection
      (debug:print-info 12 *default-log-port* "rmt:send-receive, case 9, hh-dat: " (remote-hh-dat runremote) " conndat: " (remote-conndat runremote))
      (mutex-unlock! *rmt-mutex*)
      (if (not (server:check-if-running *toppath*)) ;; who knows, maybe one has started up?
	  (server:start-and-wait *toppath*))
      (remote-conndat-set! runremote (rmt:get-connection-info *toppath*)) ;; calls client:setup which calls client:setup-http
      (rmt:send-receive-orig  runremote rmt-mutex toppath cmd rid params attemptnum: attemptnum)) ;; TODO: add back-off timeout as

     ;; all set up if get this far, dispatch the query
     ((and (not (remote-force-server runremote))
	   (cdr (remote-hh-dat runremote))) ;; we are on homehost
      (mutex-unlock! *rmt-mutex*)
      (debug:print-info 12 *default-log-port* "rmt:send-receive, case 10")
      (rmt:open-qry-close-locally cmd (if rid rid 0) params))