[MEDIUM] detect streaming buffers and tag them as such
Add the ability to detect streaming buffers, and set a
flag indicating it. It will later serve us in order to
dynamically resize them, and to prioritize file descriptors
during polls.
diff --git a/include/types/buffers.h b/include/types/buffers.h
index a79641d..583c517 100644
--- a/include/types/buffers.h
+++ b/include/types/buffers.h
@@ -53,6 +53,8 @@
#define BF_WRITE_STATUS (BF_PARTIAL_WRITE|BF_COMPLETE_WRITE|BF_WRITE_ERROR|BF_WRITE_NULL)
#define BF_CLEAR_WRITE (~BF_WRITE_STATUS)
+#define BF_STREAMER 4096
+#define BF_STREAMER_FAST 8192
/* describes a chunk of string */
@@ -72,6 +74,8 @@
unsigned int l; /* data length */
char *r, *w, *lr; /* read ptr, write ptr, last read */
char *rlim; /* read limit, used for header rewriting */
+ unsigned char xfer_large; /* number of consecutive large xfers */
+ unsigned char xfer_small; /* number of consecutive small xfers */
unsigned long long total; /* total data read */
char data[BUFSIZE];
};
diff --git a/src/stream_sock.c b/src/stream_sock.c
index 08cc65b..fab32ca 100644
--- a/src/stream_sock.c
+++ b/src/stream_sock.c
@@ -44,7 +44,7 @@
int stream_sock_read(int fd) {
__label__ out_eternity, out_wakeup, out_shutdown_r, out_error;
struct buffer *b = fdtab[fd].cb[DIR_RD].b;
- int ret, max, retval;
+ int ret, max, retval, cur_read;
int read_poll = MAX_READ_POLL_LOOPS;
#ifdef DEBUG_FULL
@@ -61,6 +61,7 @@
if ((fdtab[fd].ev & (FD_POLL_IN|FD_POLL_HUP)) == FD_POLL_HUP)
goto out_shutdown_r;
+ cur_read = 0;
while (1) {
/*
* 1. compute the maximum block size we can read at once.
@@ -110,6 +111,7 @@
if (ret > 0) {
b->r += ret;
b->l += ret;
+ cur_read += ret;
b->flags |= BF_PARTIAL_READ;
if (b->r == b->data + BUFSIZE) {
@@ -122,6 +124,35 @@
/* The buffer is now full, there's no point in going through
* the loop again.
*/
+ if (!(b->flags & BF_STREAMER_FAST) && (cur_read == b->l)) {
+ b->xfer_small = 0;
+ b->xfer_large++;
+ if (b->xfer_large >= 3) {
+ /* we call this buffer a fast streamer if it manages
+ * to be filled in one call 3 consecutive times.
+ */
+ b->flags |= (BF_STREAMER | BF_STREAMER_FAST);
+ //fputc('+', stderr);
+ }
+ }
+ else if ((b->flags & (BF_STREAMER | BF_STREAMER_FAST)) &&
+ (cur_read <= BUFSIZE / 2)) {
+ b->xfer_large = 0;
+ b->xfer_small++;
+ if (b->xfer_small >= 2) {
+ /* if the buffer has been at least half full twice,
+ * we receive faster than we send, so at least it
+ * is not a "fast streamer".
+ */
+ b->flags &= ~BF_STREAMER_FAST;
+ //fputc('-', stderr);
+ }
+ }
+ else {
+ b->xfer_small = 0;
+ b->xfer_large = 0;
+ }
+
EV_FD_CLR(fd, DIR_RD);
goto out_eternity;
}
@@ -133,6 +164,19 @@
* is closed.
*/
if (ret < max) {
+ if ((b->flags & (BF_STREAMER | BF_STREAMER_FAST)) &&
+ (cur_read <= BUFSIZE / 2)) {
+ b->xfer_large = 0;
+ b->xfer_small++;
+ if (b->xfer_small >= 3) {
+ /* we have read less than half of the buffer in
+ * one pass, and this happened at least 3 times.
+ * This is definitely not a streamer.
+ */
+ b->flags &= ~(BF_STREAMER | BF_STREAMER_FAST);
+ //fputc('!', stderr);
+ }
+ }
if (fdtab[fd].ev & FD_POLL_HUP)
goto out_shutdown_r;
break;