111 lines
2.5 KiB
Standard ML
111 lines
2.5 KiB
Standard ML
#!/usr/bin/env fun
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/*
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* Async-style HTTP GET using lib/async/scheduler.fun helpers
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*
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* This demonstrates building an "await-like" workflow without VM-level
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* async/await. We use a cooperative task that advances a small state
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* machine each tick, calling await_write/await_read to probe readiness.
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*/
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#include <async/scheduler.fun>
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host = "example.org"
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port = 80
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// Task state and step function
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fun http_get_step(t)
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// phases: 0=connect, 1=set nonblock, 2=send, 3=recv, 4=done
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if (t.phase == nil)
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t.phase = 0
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if (t.phase == 0)
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t.fd = tcp_connect(host, port)
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if (t.fd == 0)
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print("connect failed")
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t.done = 1
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return
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t.phase = 1
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return
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if (t.phase == 1)
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ok = fd_set_nonblock(t.fd, 1)
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if (ok == 0)
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print("failed to set nonblocking")
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sock_close(t.fd)
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t.done = 1
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return
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t.req = "GET / HTTP/1.1\r\nHost: " + host + "\r\nConnection: close\r\n\r\n"
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t.sent = 0
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t.phase = 2
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return
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if (t.phase == 2)
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// send request in chunks when writable
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if (t.sent < len(t.req))
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// short timeout to keep loop responsive
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wr = await_write(t.fd, 50)
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if (wr < 0)
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print("poll write error")
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sock_close(t.fd)
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t.done = 1
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return
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if (wr == 0)
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// not yet writable; yield to others
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return
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chunk = substr(t.req, t.sent, len(t.req) - t.sent)
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n = sock_send(t.fd, chunk)
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if (n < 0)
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print("send error")
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sock_close(t.fd)
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t.done = 1
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return
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t.sent = t.sent + n
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return
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// all sent; switch to receive
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t.buf = ""
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t.phase = 3
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return
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if (t.phase == 3)
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rd = await_read(t.fd, 100)
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if (rd < 0)
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print("poll read error")
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sock_close(t.fd)
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t.phase = 4
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t.done = 1
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return
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if (rd == 0)
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// try a small read to detect close, else wait more
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data = sock_recv(t.fd, 4096)
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if (len(data) == 0)
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sock_close(t.fd)
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t.phase = 4
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t.done = 1
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return
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t.buf = t.buf + data
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return
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// readable
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data = sock_recv(t.fd, 4096)
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if (len(data) == 0)
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sock_close(t.fd)
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t.phase = 4
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t.done = 1
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return
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t.buf = t.buf + data
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return
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if (t.phase == 4)
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// print first 200 chars and finish
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print(substr(t.buf, 0, 200))
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t.done = 1
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return
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// Spawn task and run
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task = task_spawn(http_get_step, {})
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run_until_done()
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/*
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Expected: prints the beginning of an HTTP response from example.org
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*/
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