cmux: Remove round-robin circuit policy

Since 0.2.4, tor uses EWMA circuit policy to prioritize. The previous
algorithm, round-robin, hasn't been used since then but was still used as a
fallback.

Now that EWMA is mandatory, remove that code entirely and enforce a cmux
policy to be set.

This is part of a circuitmux cleanup to improve performance and reduce
complexity in the code. We'll be able to address future optimization with this
work.

Closes #25268

Signed-off-by: David Goulet <dgoulet@torproject.org>

1 files changed, 0 insertions, 17 deletions

diff --git a/src/or/or.h b/src/or/or.h
index 03efdd1d81..4d3a118499 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -3179,15 +3179,6 @@ typedef struct circuit_t {
   /** Index in smartlist of all circuits (global_circuitlist). */
   int global_circuitlist_idx;
 
-  /** Next circuit in the doubly-linked ring of circuits waiting to add
-   * cells to n_conn.  NULL if we have no cells pending, or if we're not
-   * linked to an OR connection. */
-  struct circuit_t *next_active_on_n_chan;
-  /** Previous circuit in the doubly-linked ring of circuits waiting to add
-   * cells to n_conn.  NULL if we have no cells pending, or if we're not
-   * linked to an OR connection. */
-  struct circuit_t *prev_active_on_n_chan;
-
   /** Various statistics about cells being added to or removed from this
    * circuit's queues; used only if CELL_STATS events are enabled and
    * cleared after being sent to control port. */
@@ -3467,14 +3458,6 @@ struct onion_queue_t;
 typedef struct or_circuit_t {
   circuit_t base_;
 
-  /** Next circuit in the doubly-linked ring of circuits waiting to add
-   * cells to p_chan.  NULL if we have no cells pending, or if we're not
-   * linked to an OR connection. */
-  struct circuit_t *next_active_on_p_chan;
-  /** Previous circuit in the doubly-linked ring of circuits waiting to add
-   * cells to p_chan.  NULL if we have no cells pending, or if we're not
-   * linked to an OR connection. */
-  struct circuit_t *prev_active_on_p_chan;
   /** Pointer to an entry on the onion queue, if this circuit is waiting for a
    * chance to give an onionskin to a cpuworker. Used only in onion.c */
   struct onion_queue_t *onionqueue_entry;