360 lines
17 KiB
Scheme
360 lines
17 KiB
Scheme
(module dispatch-servlets mzscheme
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(require (lib "url.ss" "net")
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(lib "unitsig.ss")
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(lib "list.ss"))
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(require "dispatch.ss"
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"web-server-structs.ss"
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"connection-manager.ss"
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"configuration-structures.ss"
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"response.ss"
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"request-parsing.ss"
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"servlet-tables.ss"
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"servlet.ss"
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"sig.ss"
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"timer.ss"
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"util.ss")
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(provide interface-version
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gen-dispatcher)
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(define interface-version 'v1)
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(define (gen-dispatcher host-info config:instances config:scripts config:scripts-lock config:make-servlet-namespace)
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;; ************************************************************
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;; ************************************************************
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;; SERVING SERVLETS
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;; servlet-content-producer: connection request host -> void
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(define (servlet-content-producer conn req host-info)
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(let ([meth (request-method req)])
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(if (eq? meth 'head)
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(output-response/method
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conn
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(make-response/full
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200 "Okay" (current-seconds) TEXT/HTML-MIME-TYPE
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'() (list "ignored"))
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meth)
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(let ([uri (request-uri req)])
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(set-request-bindings/raw!
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req
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(read-bindings/handled conn meth uri (request-headers req)
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host-info))
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(cond
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[(continuation-url? uri)
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=> (lambda (k-ref)
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(invoke-servlet-continuation conn req k-ref host-info))]
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[else
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(servlet-content-producer/path conn req host-info uri)])))))
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;; read-bindings/handled: connection symbol url headers host -> (listof (list (symbol string))
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;; read the bindings and handle any exceptions
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(define (read-bindings/handled conn meth uri headers host-info)
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(with-handlers ([exn? (lambda (e)
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(output-response/method
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conn
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;((responders-protocol (host-responders host-info))
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; (exn-message e))
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((responders-servlet-loading (host-responders
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host-info))
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uri e)
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meth)
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'())])
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(read-bindings conn meth uri headers)))
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;; servlet-content-producer/path: connection request host url -> void
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;; This is not a continuation url so the loading behavior is determined
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;; by the url path. Build the servlet path and then load the servlet
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(define (servlet-content-producer/path conn req host-info uri)
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(with-handlers (;; couldn't find the servlet
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[exn:fail:filesystem:exists:servlet?
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(lambda (the-exn)
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(output-response/method
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conn
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((responders-file-not-found (host-responders
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host-info))
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(request-uri req))
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(request-method req)))]
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;; servlet won't load (e.g. syntax error)
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[(lambda (x) #t)
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(lambda (the-exn)
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(output-response/method
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conn
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((responders-servlet-loading (host-responders
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host-info)) uri
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the-exn)
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(request-method req)))])
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(let ([sema (make-semaphore 0)]
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[last-inst (thread-cell-ref current-servlet-instance)])
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(let/cc suspend
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(let* ([servlet-custodian (make-servlet-custodian)]
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[inst (create-new-instance!
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config:instances servlet-custodian
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(make-execution-context
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conn req (lambda () (suspend #t)))
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sema
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(start-timer 0 void))]
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[real-servlet-path (url-path->path
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(paths-servlet (host-paths host-info))
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(url-path->string (url-path uri)))]
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[servlet-exit-handler (make-servlet-exit-handler inst)])
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(parameterize ([current-directory (get-servlet-base-dir real-servlet-path)]
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[current-custodian servlet-custodian]
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[exit-handler servlet-exit-handler])
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(thread-cell-set! current-servlet-instance inst)
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(let-values (;; timer thread must be within the dynamic extent of
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;; servlet custodian
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[(time-bomb) (start-timer (timeouts-default-servlet
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(host-timeouts host-info))
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(lambda ()
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(servlet-exit-handler #f)))]
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;; any resources (e.g. threads) created when the
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;; servlet is loaded should be within the dynamic
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;; extent of the servlet custodian
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[(servlet-program servlet-namespace) (cached-load real-servlet-path)])
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(parameterize ([current-namespace servlet-namespace])
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(set-servlet-instance-timer! inst time-bomb)
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(with-handlers ([(lambda (x) #t)
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(make-servlet-exception-handler inst host-info)])
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;; Two possibilities:
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;; - module servlet. start : Request -> Void handles
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;; output-response via send/finish, etc.
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;; - unit/sig or simple xexpr servlet. These must produce a
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;; response, which is then output by the server.
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;; Here, we do not know if the servlet was a module,
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;; unit/sig, or Xexpr; we do know whether it produces a
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;; response.
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(let ([r (servlet-program req)])
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(when (response? r)
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(send/back r)))))))))
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(thread-cell-set! current-servlet-instance last-inst)
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(semaphore-post sema))))
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;; make-servlet-exit-handler: servlet-instance -> alpha -> void
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;; exit handler for a servlet
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(define (make-servlet-exit-handler inst)
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(lambda (x)
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(remove-instance! config:instances inst)
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(kill-connection!
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(execution-context-connection
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(servlet-instance-context inst)))
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(custodian-shutdown-all (servlet-instance-custodian inst))))
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;; make-servlet-exception-handler: host -> exn -> void
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;; This exception handler traps all unhandled servlet exceptions
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;; * Must occur within the dynamic extent of the servlet
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;; custodian since several connection custodians will typically
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;; be shutdown during the dynamic extent of a continuation
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;; * Use the connection from the current-servlet-context in case
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;; the exception is raised while invoking a continuation.
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;; * Use the suspend from the servlet-instanct-context which is
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;; closed over the current tcp ports which may need to be
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;; closed for an http 1.0 request.
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;; * Also, suspend will post to the semaphore so that future
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;; requests won't be blocked.
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;; * This fixes PR# 7066
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(define (make-servlet-exception-handler inst host-info)
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(lambda (the-exn)
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(let* ([ctxt (servlet-instance-context inst)]
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[req (execution-context-request ctxt)]
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[resp ((responders-servlet (host-responders
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host-info))
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(request-uri req)
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the-exn)])
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;; Don't handle twice
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(with-handlers ([exn:fail? (lambda (exn) (void))])
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(output-response/method
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(execution-context-connection ctxt)
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resp (request-method req)))
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((execution-context-suspend ctxt)))))
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;; path -> path
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;; The actual servlet's parent directory.
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(define (get-servlet-base-dir servlet-path)
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(let loop ((path servlet-path))
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(let-values ([(base name must-be-dir?) (split-path path)])
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(if must-be-dir?
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(or (and (directory-exists? path) path)
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(loop base))
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(or (and (directory-exists? base) base)
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(loop base))))))
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;; invoke-servlet-continuation: connection request continuation-reference
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;; host -> void
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;; pull the continuation out of the table and apply it
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(define (invoke-servlet-continuation conn req k-ref host-info)
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(with-handlers ([exn:servlet-instance?
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(lambda (the-exn)
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(output-response/method
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conn
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((responders-file-not-found (host-responders
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host-info))
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(request-uri req))
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(request-method req)))]
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[exn:servlet-continuation?
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(lambda (the-exn)
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(output-response/method
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conn
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((responders-file-not-found (host-responders
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host-info))
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(request-uri req))
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(request-method req)))])
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(let* ([last-inst (thread-cell-ref current-servlet-instance)]
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[inst
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(hash-table-get config:instances (first k-ref)
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(lambda ()
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(raise
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(make-exn:servlet-instance
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"" (current-continuation-marks)))))]
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[k-table
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(servlet-instance-k-table inst)])
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(let/cc suspend
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; We don't use call-with-semaphore or dynamic-wind because we
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; always call a continuation. The exit-handler above ensures that
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; the post is done.
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(semaphore-wait (servlet-instance-mutex inst))
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(thread-cell-set! current-servlet-instance inst)
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(set-servlet-instance-context!
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inst
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(make-execution-context
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conn req (lambda () (suspend #t))))
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(increment-timer (servlet-instance-timer inst)
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(timeouts-default-servlet
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(host-timeouts host-info)))
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(let ([k*salt
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(hash-table-get k-table (second k-ref)
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(lambda ()
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(raise
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(make-exn:servlet-continuation
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"" (current-continuation-marks)))))])
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(if (= (second k*salt) (third k-ref))
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((first k*salt) req)
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(raise
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(make-exn:servlet-continuation
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"" (current-continuation-marks))))))
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(thread-cell-set! current-servlet-instance last-inst)
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(semaphore-post (servlet-instance-mutex inst))
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)))
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;; ************************************************************
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;; ************************************************************
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;; Paul's ugly loading code:
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(define make-cache-entry cons)
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(define cache-entry-servlet car)
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(define cache-entry-namespace cdr)
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;; cached-load : str -> script, namespace
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;; timestamps are no longer checked for performance. The cache must be explicitly
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;; refreshed (see dispatch).
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(define (cached-load name)
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(let ([e
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; First try to get the cache entry
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(hash-table-get
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(unbox config:scripts)
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name
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(lambda ()
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; Then try to update the cache entry
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(call-with-semaphore
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config:scripts-lock
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(lambda ()
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(hash-table-get (unbox config:scripts) name
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(lambda ()
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(reload-servlet-script name)))))))])
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(values (cache-entry-servlet e)
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(cache-entry-namespace e))))
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;; exn:i/o:filesystem:servlet-not-found =
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;; (make-exn:fail:filesystem:exists:servlet str continuation-marks str sym)
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(define-struct (exn:fail:filesystem:exists:servlet
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exn:fail:filesystem:exists) ())
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;; reload-servlet-script : str -> cache-entry
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;; The servlet is not cached in the servlet-table, so reload it from the filesystem.
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(define (reload-servlet-script servlet-filename)
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(cond
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[(load-servlet/path servlet-filename)
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=> (lambda (entry)
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; This is only called from cached-load, so config:scripts is locked
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(hash-table-put! (unbox config:scripts)
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servlet-filename
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entry)
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entry)]
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[else
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(raise (make-exn:fail:filesystem:exists:servlet
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(string->immutable-string (format "Couldn't find ~a" servlet-filename))
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(current-continuation-marks) ))]))
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;; load-servlet/path path -> (union #f cache-entry)
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;; given a string path to a filename attempt to load a servlet
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;; A servlet-file will contain either
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;;;; A signed-unit-servlet
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;;;; A module servlet, currently only 'v1
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;;;;;; (XXX: I don't know what 'typed-model-split-store0 was, so it was removed.)
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;;;; A response
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(define (load-servlet/path a-path)
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(parameterize ([current-namespace (config:make-servlet-namespace)])
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(and (file-exists? a-path)
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(let ([s (load/use-compiled a-path)])
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(cond
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;; signed-unit servlet
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; MF: I'd also like to test that s has the correct import signature.
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[(unit/sig? s)
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(make-cache-entry (lambda (initial-request)
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(invoke-unit/sig s servlet^))
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(current-namespace))]
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; FIX - reason about exceptions from dynamic require (catch and report if not already)
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;; module servlet
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[(void? s)
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(let* ([module-name `(file ,(path->string a-path))]
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[version (dynamic-require module-name 'interface-version)])
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(case version
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[(v1)
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(let ([timeout (dynamic-require module-name 'timeout)]
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[start (dynamic-require module-name 'start)])
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(make-cache-entry
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(lambda (initial-request)
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(adjust-timeout! timeout)
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(start initial-request))
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(current-namespace)))]
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[else
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(raise (format "unknown servlet version ~e" version))]))]
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;; response
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[(response? s)
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(letrec ([go (lambda ()
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(begin
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(set! go (lambda () (load/use-compiled a-path)))
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s))])
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(make-cache-entry (lambda (initial-request) (go))
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(current-namespace)))]
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[else
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(raise 'load-servlet/path "Loading ~e produced ~n~e~n instead of a servlet." a-path s)])))))
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(define servlet-bin?
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(let ([svt-bin-re (regexp "^/servlets(;id.*\\*.*\\*.*)?/.*")])
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(lambda (str)
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(regexp-match svt-bin-re str))))
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;; return dispatcher
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(lambda (conn req)
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(let-values ([(uri method path) (decompose-request req)])
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(cond [(string=? "/conf/refresh-servlets" path)
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;; more here - this is broken - only out of date or specifically mentioned
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;; scripts should be flushed. This destroys persistent state!
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(call-with-semaphore config:scripts-lock
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(lambda ()
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(set-box! config:scripts (make-hash-table 'equal))))
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(output-response/method
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conn
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((responders-servlets-refreshed (host-responders host-info)))
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method)]
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[(servlet-bin? path)
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(adjust-connection-timeout!
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conn
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(timeouts-servlet-connection (host-timeouts host-info)))
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;; more here - make timeouts proportional to size of bindings
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(servlet-content-producer conn req host-info)]
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[else
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(next-dispatcher)]))))) |