[or-cvs] Make buffers grow and shrink as needed.
Nick Mathewson
nickm at seul.org
Tue Oct 14 01:34:33 UTC 2003
Update of /home/or/cvsroot/src/or
In directory moria.mit.edu:/tmp/cvs-serv18279/src/or
Modified Files:
buffers.c or.h test.c
Log Message:
Make buffers grow and shrink as needed.
Index: buffers.c
===================================================================
RCS file: /home/or/cvsroot/src/or/buffers.c,v
retrieving revision 1.45
retrieving revision 1.46
diff -u -d -r1.45 -r1.46
--- buffers.c 11 Oct 2003 23:38:20 -0000 1.45
+++ buffers.c 14 Oct 2003 01:34:31 -0000 1.46
@@ -13,9 +13,70 @@
size_t len;
size_t datalen;
};
-
+/* Size, in bytes, for newly allocated buffers. Should be a power of 2. */
+#define INITIAL_BUF_SIZE (4*1024)
+/* Maximum size, in bytes, for resized buffers. */
+#define MAX_BUF_SIZE (640*1024)
+/* Size, in bytes, for minimum 'shrink' size for buffers. Buffers may start
+ * out smaller than this, but they will never autoshrink to less
+ * than this size. */
+#define MIN_BUF_SHRINK_SIZE (16*1024)
#define BUF_OK(b) ((b) && (b)->buf && (b)->datalen <= (b)->len)
+/* Change a buffer's capacity. Must only be called when */
+static INLINE void buf_resize(buf_t *buf, size_t new_capacity)
+{
+ assert(buf->datalen <= new_capacity);
+ buf->buf = tor_realloc(buf->buf, new_capacity);
+ buf->len = new_capacity;
+}
+
+/* If the buffer is not large enough to hold "capacity" bytes, resize
+ * it so that it can. (The new size will be a power of 2 times the old
+ * size.)
+ */
+static INLINE int buf_ensure_capacity(buf_t *buf, size_t capacity)
+{
+ size_t new_len;
+ if (buf->len >= capacity)
+ return 0;
+ if (capacity > MAX_BUF_SIZE)
+ return -1;
+ new_len = buf->len*2;
+ while (new_len < capacity)
+ new_len *= 2;
+ log_fn(LOG_DEBUG,"Growing buffer from %ld to %ld bytes.",
+ buf->len, new_len);
+ buf_resize(buf,new_len);
+ return 0;
+}
+
+/* If the buffer is at least 2*MIN_BUF_SHRINK_SIZE bytes in capacity,
+ * and if the buffer is less than 1/4 full, shrink the buffer until
+ * one of the above no longer holds. (We shrink the buffer by
+ * dividing by powers of 2.)
+ */
+static INLINE void buf_shrink_if_underfull(buf_t *buf) {
+ size_t new_len;
+ if (buf->datalen >= buf->len/4 || buf->len >= 2*MIN_BUF_SHRINK_SIZE)
+ return;
+ new_len = buf->len / 2;
+ while (buf->datalen < new_len/4 && new_len/2 > MIN_BUF_SHRINK_SIZE)
+ new_len /= 2;
+ log_fn(LOG_DEBUG,"Shrinking buffer from %ld to %ld bytes.",
+ buf->len, new_len);
+ buf_resize(buf->buf, new_len);
+}
+
+/* Remove the first 'n' bytes from buf.
+ */
+static INLINE void buf_remove_from_front(buf_t *buf, size_t n) {
+ assert(buf->datalen >= n);
+ buf->datalen -= n;
+ memmove(buf->buf, buf->buf+n, buf->datalen);
+ buf_shrink_if_underfull(buf);
+}
+
/* Find the first instance of str on buf. If none exists, return -1.
* Otherwise, return index of the first character in buf _after_ the
* first instance of str.
@@ -58,7 +119,7 @@
buf_t *buf_new()
{
- return buf_new_with_capacity(MAX_BUF_SIZE);
+ return buf_new_with_capacity(INITIAL_BUF_SIZE);
}
@@ -99,7 +160,8 @@
assert(BUF_OK(buf) && reached_eof && (s>=0));
- /* this is the point where you would grow the buffer, if you want to */
+ if (buf_ensure_capacity(buf,buf->datalen+at_most))
+ return -1;
if(at_most > buf->len - buf->datalen)
at_most = buf->len - buf->datalen; /* take the min of the two */
@@ -135,6 +197,9 @@
int read_to_buf_tls(tor_tls *tls, int at_most, buf_t *buf) {
int r;
assert(tls && BUF_OK(buf));
+
+ if (buf_ensure_capacity(buf, at_most+buf->datalen))
+ return -1;
if (at_most > buf->len - buf->datalen)
at_most = buf->len - buf->datalen;
@@ -181,11 +246,11 @@
log_fn(LOG_DEBUG,"write() would block, returning.");
return 0;
} else {
- buf->datalen -= write_result;
*buf_flushlen -= write_result;
- memmove(buf->buf, buf->buf+write_result, buf->datalen);
+ buf_remove_from_front(buf, write_result);
log_fn(LOG_DEBUG,"%d: flushed %d bytes, %d ready to flush, %d remain.",
s,write_result,*buf_flushlen,(int)buf->datalen);
+
return *buf_flushlen;
/* XXX USE_TLS should change to return write_result like any sane function would */
}
@@ -202,9 +267,8 @@
if (r < 0) {
return r;
}
- buf->datalen -= r;
*buf_flushlen -= r;
- memmove(buf->buf, buf->buf+r, buf->datalen);
+ buf_remove_from_front(buf, r);
log_fn(LOG_DEBUG,"flushed %d bytes, %d ready to flush, %d remain.",
r,*buf_flushlen,(int)buf->datalen);
return r;
@@ -218,6 +282,9 @@
assert(string && BUF_OK(buf));
+ if (buf_ensure_capacity(buf, buf->datalen+string_len))
+ return -1;
+
/* this is the point where you would grow the buffer, if you want to */
if (string_len + buf->datalen > buf->len) { /* we're out of luck */
@@ -242,8 +309,7 @@
assert(string_len <= buf->datalen); /* make sure we don't ask for too much */
memcpy(string,buf->buf,string_len);
- buf->datalen -= string_len;
- memmove(buf->buf, buf->buf+string_len, buf->datalen);
+ buf_remove_from_front(buf, string_len);
return buf->datalen;
}
@@ -311,9 +377,7 @@
memcpy(body_out,buf->buf+headerlen,bodylen);
body_out[bodylen] = 0; /* null terminate it */
}
- buf->datalen -= (headerlen+bodylen);
- memmove(buf->buf, buf->buf+headerlen+bodylen, buf->datalen);
-
+ buf_remove_from_front(buf, headerlen+bodylen);
return 1;
}
@@ -362,8 +426,7 @@
*(reply+1) = 0xFF; /* reject all methods */
return -1;
}
- buf->datalen -= (2+nummethods); /* remove packet from buf */
- memmove(buf->buf, buf->buf + 2 + nummethods, buf->datalen);
+ buf_remove_from_front(buf,2+nummethods);/* remove packet from buf */
*replylen = 2; /* 2 bytes of response */
*reply = 5; /* socks5 reply */
@@ -395,8 +458,7 @@
}
strcpy(addr_out,tmpbuf);
*port_out = ntohs(*(uint16_t*)(buf->buf+8));
- buf->datalen -= 10;
- memmove(buf->buf, buf->buf+10, buf->datalen);
+ buf_remove_from_front(buf, 10);
return 1;
case 3: /* fqdn */
log_fn(LOG_DEBUG,"socks5: fqdn address type");
@@ -411,8 +473,7 @@
memcpy(addr_out,buf->buf+5,len);
addr_out[len] = 0;
*port_out = ntohs(*(uint16_t*)(buf->buf+5+len));
- buf->datalen -= (5+len+2);
- memmove(buf->buf, buf->buf+(5+len+2), buf->datalen);
+ buf_remove_from_front(buf, 5+len+2);
return 1;
default: /* unsupported */
log_fn(LOG_WARN,"socks5: unsupported address type %d",*(buf->buf+3));
@@ -468,8 +529,7 @@
}
log_fn(LOG_DEBUG,"Everything is here. Success.");
strcpy(addr_out, socks4_prot == socks4 ? tmpbuf : startaddr);
- buf->datalen -= (next-buf->buf+1); /* next points to the final \0 on inbuf */
- memmove(buf->buf, next+1, buf->datalen);
+ buf_remove_from_front(buf, next-buf->buf+1); /* next points to the final \0 on inbuf */
return 1;
default: /* version is not socks4 or socks5 */
Index: or.h
===================================================================
RCS file: /home/or/cvsroot/src/or/or.h,v
retrieving revision 1.164
retrieving revision 1.165
diff -u -d -r1.164 -r1.165
--- or.h 12 Oct 2003 07:19:10 -0000 1.164
+++ or.h 14 Oct 2003 01:34:31 -0000 1.165
@@ -100,7 +100,6 @@
#define MAXCONNECTIONS 1000 /* upper bound on max connections.
can be lowered by config file */
-#define MAX_BUF_SIZE (640*1024)
#define DEFAULT_BANDWIDTH_OP (1024 * 1000)
#define MAX_NICKNAME_LEN 32
#define MAX_DIR_SIZE 50000 /* XXX, big enough? */
Index: test.c
===================================================================
RCS file: /home/or/cvsroot/src/or/test.c,v
retrieving revision 1.42
retrieving revision 1.43
diff -u -d -r1.42 -r1.43
--- test.c 10 Oct 2003 01:48:32 -0000 1.42
+++ test.c 14 Oct 2003 01:34:31 -0000 1.43
@@ -46,6 +46,7 @@
void
test_buffers() {
+#define MAX_BUF_SIZE 640*1024
char str[256];
char str2[256];
@@ -60,7 +61,7 @@
if (!(buf = buf_new()))
test_fail();
- test_eq(buf_capacity(buf), MAX_BUF_SIZE);
+ test_eq(buf_capacity(buf), 2*1024);
test_eq(buf_datalen(buf), 0);
/****
@@ -76,7 +77,7 @@
s = open("/tmp/tor_test/data", O_RDONLY, 0);
eof = 0;
i = read_to_buf(s, 10, buf, &eof);
- test_eq(buf_capacity(buf), MAX_BUF_SIZE);
+ test_eq(buf_capacity(buf), 2*1024);
test_eq(buf_datalen(buf), 10);
test_eq(eof, 0);
test_eq(i, 10);
More information about the tor-commits
mailing list