ref: 5362658038b2eabb1cf1549e6629141ac053a72d
parent: a24a074bc3809078435fbcb45250967ec9a5891e
author: Noam Preil <noam@pixelhero.dev>
date: Sat Mar 23 08:57:39 EDT 2024
packet read optimizations
--- a/server.c
+++ b/server.c
@@ -36,28 +36,29 @@
static void
vtrecv(VtConn conn, char *buf)
{- u16int len;
- switch(read(conn.fd, buf, 2)){+ switch(read(conn.fd, buf, MaxPacketSize)){case 0:
vthangup(conn);
case 1:
vterr(conn, nil, "received a single byte for message size");
- case 2:
- len = U16GET(buf);
- if(read(conn.fd, buf + 2, len) != len)
- vterr(conn, nil, "failed to read message: %r");
+ default:
+ return;
}
}
static void
-vtversion(VtConn conn)
+vtversion(VtConn conn, char *buf)
{- char c;
+
+ long n, i;
// Response is one line of unknown size; discard bytes until EOL
if(fprint(conn.fd, "venti-02-neoventi\n") == 18){- while(read(conn.fd, &c, 1) == 1){- if(c == '\n'){- return;
+ n = read(conn.fd, buf, MaxPacketSize);
+ for(i = 0; i < n; i += 1){+ if(buf[i] == '\n'){+ if(i+1 == n)
+ return;
+ break;
}
}
}
@@ -110,7 +111,7 @@
static void
vthello(VtConn conn, char *buf)
{- vtversion(conn);
+ vtversion(conn, buf);
vtrecv(conn, buf);
if(buf[2] != VtThello)
vterr(conn, buf, "received message before hello: %d", buf[2]);
@@ -122,11 +123,50 @@
}
static void
-vtloop(VtConn conn, char *buf)
+vtloop(VtConn conn, char *packetbuf)
{+ long n;
+ char buf[0x10000];
+ u16int offset, sz;
while(1){- vtrecv(conn, buf);
- vtconnhandle(conn, buf);
+ //TODO: treat conn.buf as ring buffer? Avoids moving packet around.
+ // Maintain 64K of packet data in conn.buf.
+ // Process all full packets in the buffer.
+ // If the final packet is incomplete, move it to the beginning of the
+ // buffer, and read more into the buffer _after_ it.
+ // Then, repeat.
+ n = read(conn.fd, buf+sz, 0x10000-sz);
+ sz += n;
+ if(sz == 0)
+ // No data, and none will be coming.
+ vthangup(conn);
+ if(sz == 1)
+ vterr(conn, buf, "incomplete packet!");
+ while(offset+2 < sz){+ // As long as there's a complete packet, process it.
+ u16int len = U16GET(buf + offset);
+ if(2 + offset + len > sz){+ // missing part of packet!
+ break;
+ }
+ // Extract packet into packet buffer - this is needed because
+ // we modify the packet buffer in-place for response, and we need to
+ // have room to write a response without overwriting follow-up packets.
+ // TODO: should we drop the idea of modifying in place if we need to copy
+ // anyways? Don't want allocation churn, but we can just move packetbuf
+ // into VtConn and pass both the source and destination buffer around a lot.
+ // Not important right now.
+ memcpy(packetbuf, buf+offset, 2+len);
+ vtconnhandle(conn, packetbuf);
+ offset += 2+len;
+ }
+ if(offset == sz){+ sz = 0;
+ offset = 0;
+ continue;
+ }
+ sysfatal("TODO partial packet");+// vtrecv(conn, packetbuf);
}
}