Change buffer shrinking strategy: only try to shrink once every 3 minutes. Do not try to read over buffer size unless buffer is nearly empty.

svn:r4165

src/or/buffers.c

@@ -118,7 +118,7 @@ static INLINE void _split_range(buf_t *buf, char *at, size_t *len,
 }
 
 /** Change a buffer's capacity. <b>new_capacity</b> must be \>= buf->datalen. */
-static INLINE void buf_resize(buf_t *buf, size_t new_capacity)
+static void buf_resize(buf_t *buf, size_t new_capacity)
 {
   off_t offset;
 #ifdef CHECK_AFTER_RESIZE
@@ -134,6 +134,9 @@ static INLINE void buf_resize(buf_t *buf, size_t new_capacity)
   peek_from_buf(tmp, buf->datalen, buf);
 #endif
 
+  if (buf->len == new_capacity)
+    return;
+
   offset = buf->cur - buf->mem;
   if (offset + buf->datalen >= new_capacity) {
     /* We need to move stuff before we shrink. */
@@ -214,6 +217,7 @@ static INLINE int buf_ensure_capacity(buf_t *buf, size_t capacity)
   return 0;
 }
 
+#if 0
 /** If the buffer is at least 2*MIN_GREEDY_SHRINK_SIZE bytes in capacity,
  * and if the buffer is less than 1/8 full, shrink the buffer until
  * one of the above no longer holds.  (We shrink the buffer by
@@ -236,6 +240,9 @@ static INLINE void buf_shrink_if_underfull(buf_t *buf) {
          (int)buf->len, (int)new_len);
   buf_resize(buf, new_len);
 }
+#else
+#define buf_shrink_if_underfull(buf) do {} while (0)
+#endif
 
 void
 buf_shrink(buf_t *buf)
@@ -278,13 +285,11 @@ static INLINE int buf_nul_terminate(buf_t *buf)
  */
 buf_t *buf_new_with_capacity(size_t size) {
   buf_t *buf;
-  buf = tor_malloc(sizeof(buf_t));
+  buf = tor_malloc_zero(sizeof(buf_t));
   buf->magic = BUFFER_MAGIC;
   buf->cur = buf->mem = GUARDED_MEM(tor_malloc(ALLOC_LEN(size)));
   SET_GUARDS(buf->mem, size);
   buf->len = size;
-  buf->datalen = 0;
-//  memset(buf->mem,0,size);
 
   assert_buf_ok(buf);
   return buf;

src/or/connection.c

@@ -1036,12 +1036,22 @@ loop_again:
  */
 static int connection_read_to_buf(connection_t *conn, int *max_to_read) {
   int result, at_most = *max_to_read;
+  size_t bytes_in_buf, more_to_read;
 
   if (at_most == -1) { /* we need to initialize it */
     /* how many bytes are we allowed to read? */
     at_most = connection_bucket_read_limit(conn);
   }
 
+  bytes_in_buf = buf_capacity(conn->inbuf) - buf_datalen(conn->inbuf);
+ again:
+  if (at_most > bytes_in_buf && bytes_in_buf >= 1024) {
+    more_to_read = at_most - bytes_in_buf;
+    at_most = bytes_in_buf;
+  } else {
+    more_to_read = 0;
+  }
+
   if (connection_speaks_cells(conn) && conn->state > OR_CONN_STATE_PROXY_READING) {
     int pending;
     if (conn->state == OR_CONN_STATE_HANDSHAKING) {
@@ -1107,6 +1117,13 @@ static int connection_read_to_buf(connection_t *conn, int *max_to_read) {
     connection_read_bucket_decrement(conn, result);
   }
 
+  if (more_to_read && result == at_most) {
+    bytes_in_buf = buf_capacity(conn->inbuf) - buf_datalen(conn->inbuf);
+    tor_assert(bytes_in_buf < 1024);
+    at_most = more_to_read;
+    goto again;
+  }
+
   /* Call even if result is 0, since the global read bucket may
    * have reached 0 on a different conn, and this guy needs to
    * know to stop reading. */

src/or/main.c

@@ -103,6 +103,7 @@ static int nt_service_is_stopped(void);
 #endif
 
 #define CHECK_DESCRIPTOR_INTERVAL 60 /* one minute */
+#define BUF_SHRINK_INTERVAL 180 /* three minutes */
 #define TIMEOUT_UNTIL_UNREACHABILITY_COMPLAINT (20*60) /* 20 minutes */
 
 /********* END VARIABLES ************/
@@ -606,6 +607,7 @@ static void run_scheduled_events(time_t now) {
   static time_t last_rotated_certificate = 0;
   static time_t time_to_check_listeners = 0;
   static time_t time_to_check_descriptor = 0;
+  static time_t time_to_shrink_buffers = 0;
   or_options_t *options = get_options();
   int i;
 
@@ -744,6 +746,16 @@ static void run_scheduled_events(time_t now) {
   for (i=0;i<nfds;i++) {
     run_connection_housekeeping(i, now);
   }
+  if (time_to_shrink_buffers < now) {
+    for (i=0;i<nfds;i++) {
+      connection_t *conn = connection_array[i];
+      if (conn->outbuf)
+        buf_shrink(conn->outbuf);
+      if (conn->inbuf)
+        buf_shrink(conn->inbuf);
+    }
+    time_to_shrink_buffers = now + BUF_SHRINK_INTERVAL;
+  }
 
   /** 6. And remove any marked circuits... */
   circuit_close_all_marked();

src/or/or.h

@@ -1123,9 +1123,11 @@ buf_t *buf_new(void);
 buf_t *buf_new_with_capacity(size_t size);
 void buf_free(buf_t *buf);
 void buf_clear(buf_t *buf);
+void buf_shrink(buf_t *buf);
 
 size_t buf_datalen(const buf_t *buf);
 size_t buf_capacity(const buf_t *buf);
+unsigned int buf_n_times_resized(const buf_t *buf);
 const char *_buf_peek_raw_buffer(const buf_t *buf);
 
 int read_to_buf(int s, size_t at_most, buf_t *buf, int *reached_eof);