Closes the last loop promised in the whitepaper's Future Work: a
node serves its state as an S-expression portal over HTTP, another
node pulls it down with tcp-connect + tcp-recv and materializes the
bindings locally via (eval (read-from-string line)).
examples/portal-http-server.lsp (90 lines):
- Holds some state (counter, my-int, my-list, my-fib, my-str)
- GET /portal → S-expression body: a sequence of (define ...) forms
- GET / → HTML index
- Uses heap-snapshot / heap-restore for O(1) memory on asm
examples/portal-http-client.lsp (90 lines):
- tcp-connect, send HTTP/1.0 GET, receive full response
- Strip headers (walk to first \r\n\r\n)
- Split body by \n, eval each non-empty, non-comment line
- The remote bindings are now live locally
3×3 server/client matrix: all 9 combinations green. Every runtime
hosts, every runtime consumes. The wire format is Scheme source;
no schema, no JSON, no Protobuf.
Prerequisite fix: `eval` semantics aligned across all three impls.
Python and C's `eval` special form previously evaluated its result
in the CALLER's env, so a nested (eval (read-from-string
"(define x 42)")) would install x in the local function scope —
invisible to later top-level code. asm's bi_eval always used the
global env (r14). With this commit, all three impls evaluate the
eval'd result in the global env, matching asm's existing behavior.
Python: uncommonlisp.py leval eval-handler now does `env = env.g`
before continuing the trampoline.
C: c/eval.c SYM_EVAL branch now does `env = env->global`.
asm: no change (already correct).
One pre-existing Python defect surfaced by the client:
`count` is a SRFI-1-style builtin (`d(S('count'), ...)`), so a
local let-loop variable named `count` collides with it in the
inline-cache lookup path and OP_LOOK_ADD1 fires on the builtin
instead of the local. Worked around by renaming the loop
accumulator to `cnt`. Underlying Env.lookup shortcut-to-global
issue is out of scope for this commit.
Regression: 975 tests still green.
120 lines
4.5 KiB
Text
120 lines
4.5 KiB
Text
;;; portal-http-server.lsp — serve S-expression portal bytes over HTTP.
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;;;
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;;; The server holds some state (bindings). On GET /portal it serializes
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;;; those bindings as an S-expression portal (just (define ...) forms)
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;;; and returns them as the HTTP body. A client can (tcp-connect) +
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;;; read, strip the HTTP headers, and evaluate the body — which is
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;;; literally Scheme source.
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;;;
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;;; This closes the loop: continuations / state across machines via
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;;; sockets, using the language itself as the wire format.
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;;;
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;;; Runs byte-identically in Python, C, and asm:
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;;; python3 uncommonlisp.py --fast examples/portal-http-server.lsp
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;;; ./c/uncommonlisp examples/portal-http-server.lsp
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;;; ./asm/uncommonlisp < examples/portal-http-server.lsp
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;;;
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;;; Default port 9085.
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(define *port* 9085)
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(define *max-requests* 100000)
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;;; ── Some state worth migrating ───────────────────────────────
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;;;
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;;; This is the "work" the server has done that a client might want
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;;; to pick up and resume. fib(30) and some lists.
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(define counter 0)
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(define my-int 42)
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(define my-list (list 1 2 3 4 5 6 7 8 9 10))
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(define my-str "portal was here")
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(define my-fib
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(let loop ((a 0) (b 1) (i 0))
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(if (= i 30) a (loop b (+ a b) (+ i 1)))))
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;;; ── S-expression portal serializer ───────────────────────────
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;;; Same pattern as rpc-server's response builder; no ports needed.
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(define (atom->string v)
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(cond
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((number? v) (number->string v))
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((symbol? v) (symbol->string v))
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((null? v) "()")
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((pair? v) (string-append "(" (list->string v) ")"))
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((string? v) (string-append "\"" v "\""))
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(else "#<unknown>")))
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(define (list->string lst)
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(cond
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((null? lst) "")
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((null? (cdr lst)) (atom->string (car lst)))
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(else (string-append (atom->string (car lst)) " " (list->string (cdr lst))))))
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(define (portal-body)
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;; Produce the S-expression portal as a single string.
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(string-append
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";; uncommonlisp portable portal\n"
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"(define counter " (number->string counter) ")\n"
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"(define my-int " (number->string my-int) ")\n"
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"(define my-list '(" (list->string my-list) "))\n"
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"(define my-str \"" my-str "\")\n"
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"(define my-fib " (number->string my-fib) ")\n"))
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;;; ── HTTP plumbing ────────────────────────────────────────────
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(define (http-response status ctype body)
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(string-append
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"HTTP/1.0 " status "\r\n"
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"Content-Type: " ctype "\r\n"
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"Content-Length: " (number->string (string-length body)) "\r\n"
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"Connection: close\r\n\r\n"
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body))
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;; Get second space-separated token from the request line (the path).
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(define (path-of req)
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(let ((len (string-length req)))
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(let loop1 ((i 0))
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(cond
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((= i len) "")
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((= (char->integer (string-ref req i)) 32)
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(let loop2 ((j (+ i 1)))
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(cond
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((= j len) (substring req (+ i 1) len))
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((= (char->integer (string-ref req j)) 32) (substring req (+ i 1) j))
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(else (loop2 (+ j 1))))))
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(else (loop1 (+ i 1)))))))
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(define (handle req)
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(let ((path (path-of req)))
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(cond
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((string=? path "/portal")
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(http-response "200 OK" "application/scheme" (portal-body)))
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((string=? path "/")
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(http-response "200 OK" "text/html"
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"<!doctype html><title>portal-http</title><h1>uncommonlisp portal-http</h1><p>GET /portal returns the S-expression portal.</p>"))
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(else
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(http-response "404 Not Found" "text/plain"
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(string-append "not found: " path "\n"))))))
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;;; ── Main loop ────────────────────────────────────────────────
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(define server (tcp-listen *port*))
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(define (serve-loop n snap)
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;; counter is mutated per request, so the portal body changes with use.
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(set! counter (+ counter 1))
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(if (>= n *max-requests*)
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(begin (display "request cap reached\n") (tcp-close server))
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(begin
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(let ((client (tcp-accept server)))
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(let ((req (tcp-recv client 4096)))
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(if (and req (> (string-length req) 0))
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(tcp-send client (handle req))
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#f))
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(tcp-close client))
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(heap-restore snap)
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(serve-loop (+ n 1) snap))))
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(display "portal-http on :") (display *port*)
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(display " — GET /portal for the S-exp portal") (newline)
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(serve-loop 0 (heap-snapshot))
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