Megatest

             (guarded-proc               ;; to avoid collision
              (lambda args
                (let* ((res (condition-case
                             (apply proc args)
                             [x () (cons EXCEPTION-SYMBOL x)])))
                 (mutex-unlock! cxt-mutex)
                 (if (and (pair? res) (eq? (car res) EXCEPTION))
                     (abort (cdr res))
                     res)))))
        (guarded-proc cxt)))))
        
(define *db-keys* #f)

(define *configinfo*   #f)   ;; raw results from setup, includes toppath and table from megatest.config
(define *runconfigdat* #f)   ;; run configs data

  ;;  (begin
  ;;    (debug:print 0 *default-log-port* "Remote failed for " proc " " params " exn="exn)
  ;;    (apply (eval (string->symbol procstr)) params))
  ;;  ;; (if *runremote*
  ;;  ;;    (apply (eval (string->symbol (conc "remote:" procstr))) params)
  ;;  (apply (eval (string->symbol procstr)) params)))

;; retry an operation (depends on srfi-18)
;; ==================
;; idea here is to avoid spending time on coding retrying something.  Trying to be generic here.
;;
;; Exception handling:
;; -------------------
;; if evaluating the thunk results in exception, it will be retried.
;; on last try, if final-failure-returns-actual is true, the exception will be re-thrown to caller.
;;
;; look at options below #!key to see how to configure behavior
;;
;;
(define (retry-thunk
         the-thunk
         #!key ;;;; options below
         (accept-result?   (lambda (x) x)) ;; retry if predicate applied to thunk's result is false 
         (retries                       4) ;; how many tries
         (failure-value                #f) ;; return this on final failure, unless following option is enabled:
         (final-failure-returns-actual #f) ;; on failure, on the last try, just return the result, not failure-value

         (retry-delay                 0.1) ;; delay between tries
         (back-off-factor               1) ;; multiply retry-delay by this factor on retry
         (random-delay                0.1) ;; add a random portion of this value to wait

         (chatty                       #f) ;; print status as we go, for debugging.
         )
  
  (when chatty (print) (print "Entered retry-thunk") (print "-=-=-=-=-=-"))
  (let* ((guarded-thunk ;; we are guarding the thunk against exceptions.  We will record whether result of evaluation is an exception or a regular result.
          (lambda ()
           (let* ((EXCEPTION (gensym)) ;; using gensym to avoid potential collision
                  (res
                   (condition-case
                    (the-thunk) ;; this is what we are guarding the execution of
                    [x () (cons EXCEPTION x)]
                    )))
             (cond
              ((and (pair? res) (eq? (car res) EXCEPTION))
               (if chatty
                   (print " - the-thunk threw exception >"(cdr res)"<"))
               (cons 'exception (cdr res)))
               (else
                (if chatty
                    (print " - the-thunk returned result >"res"<"))
                (cons 'regular-result res)))))))
    
    (let loop ((guarded-res (guarded-thunk))
               (retries-left retries)
               (fail-wait retry-delay))
      (if chatty (print "   =========="))
      (let* ((wait-time (+ fail-wait (+ (* fail-wait back-off-factor)
                                        (* random-delay
                                           (/ (random 1024) 1024) ))))
             (res-type (car guarded-res))
             (res-value (cdr guarded-res)))
        (cond
         ((and (eq? res-type 'regular-result) (accept-result? res-value))
                   (if chatty (print " + return result that satisfied accept-result? >"res-value"<"))
                   res-value)

         ((> retries-left 0)
          (if chatty (print " - sleep "wait-time))
          (thread-sleep! wait-time)
          (if chatty (print " + retry ["retries-left" tries left]"))
          (loop (guarded-thunk)
                (sub1 retries-left)
                wait-time))
         
         ((eq? res-type 'regular-result)
          (if final-failure-returns-actual
              (begin
                (if chatty (print " + last try failed- return the result >"res-value"<"))
                res-value)
              (begin
                (if chatty (print " + last try failed- return canned failure value >"failure-value"<"))
              failure-value)))
         
         (else ;; no retries left; result was not accepted and res-type can only be 'exception
          (if final-failure-returns-actual 
              (begin
                (if chatty (print " + last try failed with exception- re-throw it >"res-value"<"))
                (abort res-value)); re-raise the exception. TODO: find a way for call-history to show as though from entry to this function
              (begin
                (if chatty (print " + last try failed with exception- return canned failure value >"failure-value"<"))
                failure-value))))))))


(define (rpc-transport:server-shutdown server-id rpc:listener #!key (from-on-exit #f))
  (on-exit (lambda () #t)) ;; turn off on-exit stuff
  ;;(tcp-close rpc:listener) ;; gotta exit nicely
  ;;(tasks:bb-server-set-state! server-id "stopped")

      (vector-set! vec 5 (current-seconds))
      (begin
	(print-call-chain (current-error-port))
	(debug:print-error 0 *default-log-port* "call to rpc-transport:server-dat-update-last-access with non-vector!!"))))


(define *api-exec-ht* (make-hash-table))
(define *api-exec-mutex* (make-mutex))
;; let's see if caching the rpc stub curbs thread-profusion on server side
(define (rpc-transport:get-api-exec iface port)
  (mutex-lock! *api-exec-mutex*)
  (let* ((lu (hash-table-ref/default *api-exec-ht* (cons iface  port) #f)))
    (if lu
        (begin
          (mutex-unlock! *api-exec-mutex*)
          lu)
        (let ((res (rpc:procedure 'api-exec iface port)))
          (hash-table-set! *api-exec-ht* (cons iface port) res)
          (mutex-unlock! *api-exec-mutex*)
          res))))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; this client-side procedure makes rpc call to server and returns result
;;
(define (rpc-transport:client-api-send-receive run-id serverdat cmd params #!key (numretries 3))
  ;;(BB> "entered rpc-transport:client-api-send-receive with run-id="run-id " serverdat="serverdat" cmd="cmd" params="params" numretries="numretries)

                                       ;;(vector #t (run-remote cmd params))
                                       (vector 'success (api-exec cmd params))
                                       [x (exn i/o net) (vector 'comms-fail (conc "communications fail ["(->string x)"]") x)]
                                       [x () (vector 'other-fail "other fail ["(->string x)"]" x)]))
                                    chatty: #f
                                    accept-result?: (lambda(x)
                                                      (and (vector? x) (vector-ref x 0)))
                                    retries: 8
                                    back-off-factor: 1.5
                                    random-wait: 0.2
                                    retry-delay: 0.1
                                    final-failure-returns-actual: #t))
                         ;;(BB> "HEY res="res)
                         res
                         ))

	 (thread-join! th1)
	 (thread-terminate! th2)
         ;;(BB> "alt got res="res)
	 (debug:print-info 11 *default-log-port* "got res=" res)
	 (if (vector? res)
             (case (vector-ref res 0)
               ((success) (vector #t (vector-ref res 1)))
               (
                (comms-fail other-fail)
                ;;(comms-fail) 
                (debug:print 0 *default-log-port* "WARNING: comms failure for rpc request >>"res"<<")
                ;;(debug:print 0 *default-log-port* " message: " ((condition-property-accessor 'exn 'message) exn))
                (vector #f (vector-ref res 1)))
               (else
                (debug:print-error 0 *default-log-port* "error occured at server, info=" (vector-ref res 1))
                (debug:print 0 *default-log-port* " client call chain:")
                (print-call-chain (current-error-port))