DEV: haring: split the code between ring and buffer

By splitting the initialization and the parsing of the ring, we'll ease
the support for multiple ring sizes and get rid of the annoyances of the
optional lock.

dev/haring/haring.c

@@ -76,75 +76,21 @@ __attribute__((noreturn)) void usage(int code, const char *arg0)
 	    "", arg0);
 }
 
-/* This function dumps all events from the ring whose pointer is in <p0> into
- * the appctx's output buffer, and takes from <o0> the seek offset into the
- * buffer's history (0 for oldest known event). It looks at <i0> for boolean
- * options: bit0 means it must wait for new data or any key to be pressed. Bit1
- * means it must seek directly to the end to wait for new contents. It returns
- * 0 if the output buffer or events are missing is full and it needs to be
- * called again, otherwise non-zero. It is meant to be used with
- * cli_release_show_ring() to clean up.
+/* dump a ring represented in a pre-initialized buffer, starting from offset
+ * <ofs> and with flags <flags>
  */
-int dump_ring(struct ring_v1 *ring, size_t ofs, int flags)
+int dump_ring_as_buf(struct buffer buf, size_t ofs, int flags)
 {
-	struct buffer buf;
 	uint64_t msg_len = 0;
 	size_t len, cnt;
 	const char *blk1 = NULL, *blk2 = NULL, *p;
 	size_t len1 = 0, len2 = 0, bl;
 
-	/* Explanation: the storage area in the writing process starts after
-	 * the end of the structure. Since the whole area is mmapped(), we know
-	 * it starts at 0 mod 4096, hence the buf->area pointer's 12 LSB point
-	 * to the relative offset of the storage area. As there will always be
-	 * users using the wrong version of the tool with a dump, we need to
-	 * run a few checks first. After that we'll create our own buffer
-	 * descriptor matching that area.
-	 */
-	if ((((long)ring->buf.area) & 4095) != sizeof(*ring)) {
-		if (!force) {
-			fprintf(stderr, "FATAL: header in file is %ld bytes long vs %ld expected!\n",
-				(((long)ring->buf.area) & 4095),
-				(long)sizeof(*ring));
-			exit(1);
-		}
-		else {
-			fprintf(stderr, "WARNING: header in file is %ld bytes long vs %ld expected!\n",
-				(((long)ring->buf.area) & 4095),
-				(long)sizeof(*ring));
-		}
-		/* maybe we could emit a warning at least ? */
-	}
-
-	/* Now make our own buffer pointing to that area */
-	buf = b_make(((void *)ring + (((long)ring->buf.area) & 4095)),
-		     ring->buf.size, ring->buf.head, ring->buf.data);
-
-	/* explanation for the initialization below: it would be better to do
-	 * this in the parsing function but this would occasionally result in
-	 * dropped events because we'd take a reference on the oldest message
-	 * and keep it while being scheduled. Thus instead let's take it the
-	 * first time we enter here so that we have a chance to pass many
-	 * existing messages before grabbing a reference to a location. This
-	 * value cannot be produced after initialization.
-	 */
-	if (unlikely(ofs == ~0)) {
-		ofs = 0;
-
-		/* going to the end means looking at tail-1 */
-		ofs = (flags & RING_WF_SEEK_NEW) ? buf.data - 1 : 0;
-
-		//HA_ATOMIC_INC(b_peek(&buf, ofs));
-	}
-
 	while (1) {
-		//HA_RWLOCK_RDLOCK(RING_LOCK, &ring->lock);
-
 		if (ofs >= buf.size) {
 			fprintf(stderr, "FATAL error at %d\n", __LINE__);
 			return 1;
 		}
-		//HA_ATOMIC_DEC(b_peek(&buf, ofs));
 
 		/* in this loop, ofs always points to the counter byte that precedes
 		 * the message so that we can take our reference there if we have to
@@ -205,9 +151,6 @@ int dump_ring(struct ring_v1 *ring, size_t ofs, int flags)
 			ofs += cnt + msg_len;
 		}
 
-		//HA_ATOMIC_INC(b_peek(&buf, ofs));
-		//HA_RWLOCK_RDUNLOCK(RING_LOCK, &ring->lock);
-
 		if (!(flags & RING_WF_WAIT_MODE))
 			break;
 
@@ -217,6 +160,49 @@ int dump_ring(struct ring_v1 *ring, size_t ofs, int flags)
 	return 0;
 }
 
+/* This function dumps all events from the ring whose pointer is in <p0> into
+ * the appctx's output buffer, and takes from <o0> the seek offset into the
+ * buffer's history (0 for oldest known event). It looks at <i0> for boolean
+ * options: bit0 means it must wait for new data or any key to be pressed. Bit1
+ * means it must seek directly to the end to wait for new contents. It returns
+ * 0 if the output buffer or events are missing is full and it needs to be
+ * called again, otherwise non-zero. It is meant to be used with
+ * cli_release_show_ring() to clean up.
+ */
+int dump_ring_v1(struct ring_v1 *ring, size_t ofs, int flags)
+{
+	struct buffer buf;
+
+	/* Explanation: the storage area in the writing process starts after
+	 * the end of the structure. Since the whole area is mmapped(), we know
+	 * it starts at 0 mod 4096, hence the buf->area pointer's 12 LSB point
+	 * to the relative offset of the storage area. As there will always be
+	 * users using the wrong version of the tool with a dump, we need to
+	 * run a few checks first. After that we'll create our own buffer
+	 * descriptor matching that area.
+	 */
+	if ((((long)ring->buf.area) & 4095) != sizeof(*ring)) {
+		if (!force) {
+			fprintf(stderr, "FATAL: header in file is %ld bytes long vs %ld expected!\n",
+				(((long)ring->buf.area) & 4095),
+				(long)sizeof(*ring));
+			exit(1);
+		}
+		else {
+			fprintf(stderr, "WARNING: header in file is %ld bytes long vs %ld expected!\n",
+				(((long)ring->buf.area) & 4095),
+				(long)sizeof(*ring));
+		}
+		/* maybe we could emit a warning at least ? */
+	}
+
+	/* Now make our own buffer pointing to that area */
+	buf = b_make(((void *)ring + (((long)ring->buf.area) & 4095)),
+		     ring->buf.size, ring->buf.head, ring->buf.data);
+
+	return dump_ring_as_buf(buf, ofs, flags);
+}
+
 int main(int argc, char **argv)
 {
 	void *ring;
@@ -261,7 +247,7 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
-	return dump_ring(ring, ~0, 0);
+	return dump_ring_v1(ring, 0, 0);
 }